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As a major grain-producing region in China, the North China Plain (NCP) faces serious challenges such as water shortage and land subsidence. In late 2014, the Central Route of the South-to-North Water Diversion Project (SNWD-C) began to provide NCP with water resources. However, the effectiveness of this supply in mitigating land subsidence remains a pivotal and yet unassessed aspect. In this paper, we utilized various geodetic datasets, including the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow On (GRACE-FO), Global Navigation Satellite System (GNSS) and leveling data, to conduct a spatial-temporal analysis of the equivalent water height (EWH) and vertical ground movement in the NCP. The results reveal a noteworthy decline in EWH from 2011 to 2015, followed by a slight increase with minor fluctuations from 2015 to 2020, demonstrating a strong correlation with the water resources supplied by the SNWD-C. The GRACE-derived surface deformation rate induced by hydrological loading is estimated to be <1 mm/yr. In comparison, GNSS-derived vertical ground movements exhibit considerable regional differences during the 2011–2020 period. Substantial surface subsidence is evident in the central and eastern NCP, contrasting with a gradual uplift in the front plain of the Taihang Mountains. Three-stage leveling results indicate that the rate of subsidence in the central and eastern plains is gradually increasing with the depression area expanding from 1960 to 2010. Based on these geodetic results, it can be inferred that the SNWD-C's operation since 2014 has effectively mitigated the reduction in terrestrial water storage in the NCP. However, land subsidence in the NCP persists, as the subsidence rate does not turn around in sync with the change in EWH following the operation of SNWD-C. Consequently, it's necessary to maintain and enforce existing policies, including controlling groundwater exploitation and water resources supply (e.g., SNWD-C) to curtail the exacerbation of land subsidence in the NCP. Additionally, continuous monitoring of land subsidence by GRACE, GNSS, leveling and other geodetic techniques is crucial to enable timely policy adjustments based on monitoring results. [ABSTRACT FROM AUTHOR]

The North China Plain (NCP) has been in a state of groundwater depletion for a long time, which led to a widespread vertical ground subsidence. To reveal the groundwater storage (GWS) variation characteristics in NCP in recent years, this paper uses Gravity Recovery and Climate Experiment (GRACE) and its Follow-On RL06 monthly gravity solutions to obtain the terrestrial water storage (TWS) changes in NCP (February 2011 to March 2021) and subtract the hydrological components from Global Land Data Assimilation System (GLDAS). Thus, the GWS decline rate was revealed at long-term rate of ‒2.94 cm/year and changes in 2013 and 2015. The groundwater depletion rate of ‒0.18 cm/year from 2011 to 2013, accelerated to ‒3.91 cm/year from 2013 to 2015, and the rate of GWS eased to ‒3.02 cm/year from 2015 to March 2021. The vertical displacements obtained by solving the Continuous Global Positioning System (CGPS) observations reveal a significant relief trend of surface subsidence at some stations after the Middle Route Project (MRP) completion. As well combined the special geological conditions of the basement type of CGPS stations (bedrock or sediment), and the overall vertical displacement of the east central plain (ECP) and the piedmont plain (PP) was calculated respectively using the Thiessen polygon approach. Correlation analysis between vertical displacements and GWS timeseries was performed, with Pearson correlation coefficients (PR) of 0.89 and ‒0.74, respectively. The GWS changes of the ECP were further correlated with the vertical displacement changes of the four sediment CGPS stations distributed in the southern part of the ECP. The results showed that the PR of three sediment stations, HECX, TJBH and TJWQ, were all around 0.85, and the vertical displacements of the three stations are consistent with groundwater depletion. All these indicate that the depletion of groundwater has affected the surface subsidence rate to some extent, and the vertical displacement changes of sediment stations can be used to infer the depletion of GWS. [ABSTRACT FROM AUTHOR]

Groundwater droughts can explain developments and changes in groundwater from a climatological perspective. The North China Plain (NCP) is a typical underground funnel area. Therefore, groundwater drought studies in the NCP can provide better understanding of the local hydrogeological characteristics from new perspectives. In this paper, the GRACE groundwater drought index (GGDI) was used to evaluate groundwater drought events in the NCP. Additionally, a new method was proposed in this study for investigating groundwater drought events at the spatiotemporal scale. On this basis, the centroid theory was used to construct an appropriate groundwater drought migration model for the NCP. The results showed that (1) the groundwater drought frequency in the NCP was 24.54%. In addition, the most severe groundwater drought events in the study occurred in March 2020. (2) In total, 49 groundwater drought events occurred in the NCP over the 2003–2020 period. The most intense groundwater drought event occurred over the June 2018–December 2020 period (DE.49), covering the entire study area. DE.29 was the second most intense groundwater drought event over the August 2012–September 2013 period (14 months), resulting in a maximum arid area of 75.57% of the entire study area. (3) The migration of the groundwater drought events was in the southwest–northeast and northeast–southwest directions, which was consistent with the terrain inclination, while most of the groundwater drought centroids were concentrated in Area II. The groundwater drought event identification method and the groundwater drought migration model were effective and reliable for assessing groundwater drought events in the NCP and provided a better understanding of developments and changes in groundwater droughts, which is of great practical significance and theoretical value for the rational development and use of groundwater resources, as well as for guiding industrial and agricultural activities. [ABSTRACT FROM AUTHOR]

Objectives: As an important grain-producing area and the most populous plain area in China, the groundwater resources in the North China Plain are seriously exploited for agricultural irrigation and domestic water use, and it is of great ecological significance and socio-economic value to accurately monitor the changes of groundwater storage in the region and continuously recharge and restore the groundwater. Methods: The gravity satellite data were used to invert the groundwater storage changes in the North China Plain, and compared and analyzed with the hydrological model, precipitation information, South-North water transfer project and groundwater well information, and proposed a method to integrate shallow groundwater storage changes and deep groundwater changes to obtain the contribution of total groundwater. Re⁃ sults: The results show that: (1) Both gravity satellite and global land data assimilation system model estimated water storage changes in the North China Plain exhibit obvious seasonal characteristics. (2) The correlation coefficients between the gravity satellite inversions and the shallow groundwater well estimations are consistent in terms of interannual variability, multi-year trend variability and seasonal variability, with correlation coefficient greater than 0.8. (3) Considering the contribution of deep groundwater, the estimated results of integrating shallow and deep groundwater well information and the gravity satellite inversions are in better agreement than those using only shallow groundwater, and indicate that shallow groundwater is the main variation of groundwater storage change. (4) From 2003 to 2017, groundwater in the North China Plain is in a long-term deficit state, with a gravity satellite estimated groundwater deficit rate of-1.3± 0.6 cm/a. From 2018 to 2020, the gravity satellite estimated groundwater deficit rate is −1.9±0.7 cm/a, which is almost consistent with the total groundwater deficit rate of -1.8±0.8 cm/a during the same period taking into account the deep groundwater; the groundwater trend in 2021 is increasing, and the growth rate of gravity satellite inversion is 12.7±1.8 cm/a, which is more consistent with the total ground-water well estimation in the same period. The correlation coefficient is 0.98, and the weighted fused total groundwater storage change is more consistent than that estimated by using only shallow groundwater. (5) Precipitation and North-South water transfer project have a direct impact on water storage changes in the North China Plain, making a significant contribution to the mitigation of groundwater storage deficits and groundwater restoration. Conclusions: The research method in this paper provides a new way to accurately observe groundwater storage changes in the North China Plain, and provides reliable verification of gravity satellite monitoring results. [ABSTRACT FROM AUTHOR]

The Banquan Basin is a pull-apart basin with the largest scale and the most prominent structure due to dextral slip of the Tanlu Fault Zone (TLFZ) in late Cenozoic. The depositional history of the basin records the start time and evolution of the right-lateral strike-slip movement of the TLFZ. This paper studies the sedimentary and tectonic evolution of the Banquan Basin by seismic reflection exploration, borehole detection and cosmogenic nuclide chronology. We analyze the coupling relationship between the pull-apart basin and the strike-slip fault and discuss the start time and tectonic significance of the right-lateral strike-slip of the TLFZ. Our study indicates that the Banquan Basin has undergone three evolutionary stages: weak rifting during the pre-pull-apart period, strong extension during the syn-pull-apart period and subsidence during the post-pull-apart period. This implies that the TLFZ, which controls the evolution of the basin, experienced an evolutionary process of weak activity, intensified activity and migration of activity toward the central basin. The sedimentary filling of the basin has strong response to the episodic pull-apart and extension of the basin. Lying upon the basement of the basin, a thin layer of Miocene mudstone slowly accumulated due to local rifting before the strong pull-apart event. Along with the dextral slipping and pull-apart process, the basin was filled with alluvial fan facies, fluvial facies and floodplain facies strata from bottom to top. The latest tectonic movement of the TLFZ in the North China Block in late Cenozoic was dominated by episodic dextral strike-slip motion, and this deformation pattern started at 4.01±1.27 Ma. The latest tectonic deformation in North China since late Cenozoic was governed by eastward extrusion and tectonic orogenesis of the eastern margin of the Qinghai-Xizang Plateau since late Miocene. The eastward thrusting of the Liupanshan fault zone and sinistral shearing of the Qinling fault zone led to the anticlockwise rotation and pushing of secondary blocks in North China, resulting in a planar bookshelf faulting and rotation pattern. This unique deformation pattern transferred eastwards to the North China Plain at ∼ Ma and the process continues to the present time. This planar bookshelf rotation, accompanied with regional sinistral strike-slip movement of the ∼EW-trending boundary fault zones to the north and south of the North China Block and dextral strike-slip motion of the NNE-trending boundary faults between secondary blocks, is likely to be the long-range effect of the strong extrusion of the eastern margin of the Qinghai-Xizang Plateau. [ABSTRACT FROM AUTHOR]

The PM2.5 (fine particulate matter with diameter ≤2.5 μm) concentration anomalies over the North China Plain (NCP) in early and late winter sometimes show a subseasonal reversal, which brings a great challenge for precise control of air pollution, and mechanisms are not well understood. This paper reveals the key role of the Barents Sea sea‐ice in this reversal. In early winter, a negative Scandinavian‐like pattern causes an anticyclonic anomaly over Northeast Asia and thus leads to the positive PM2.5 concentration anomaly over the NCP. In addition, anomalous warm advection associated with the positive North Atlantic Oscillation‐like pattern accelerates winter sea‐ice loss in the Barents Sea, especially in late winter, which increases the surface turbulent heating flux. These heating causes a negative Polar/Eurasian‐like pattern that induces a cyclonic anomaly over Northeast Asia and eventually leads to a negative PM2.5 concentration anomaly over the NCP in late winter. Vice versa. Plain Language Summary: In this study, we find that there is a significant seesaw pattern of PM2.5 concentration anomalies over the North China Plain (NCP) in early and late winter. Further results reveal that variations in Barents Sea sea‐ice play a crucial role. More specifically, a negative (positive) Scandinavian‐like pattern in early winter tends to induce an anticyclonic (a cyclonic) anomaly over Northeast Asia. This anticyclonic (cyclonic) anomaly leads to a higher (lower) PM2.5 concentration anomaly over the NCP in early winter. In addition, a North Atlantic Oscillation‐related warm (cold) temperature advection promotes (inhibits) the sea‐ice loss in the Barents Sea, especially in late winter. The Barents Sea‐ice loss (increment) in late winter tends to heat (cool) the lower‐level atmosphere and thus triggers an anticyclonic (a cyclonic) response in the upper troposphere there. The anticyclonic (cyclonic) response in the Barents Sea region as a part of the negative (positive) Polar/Eurasian‐like pattern induces a cyclonic (an anticyclonic) anomaly over Northeast Asia, which leads to a lower (higher) PM2.5 concentration anomaly over the NCP in late winter. These findings could be of great value for the subseasonal predictions of PM2.5 concentrations over the NCP in winter. Key Points: PM2.5 concentration anomaly over the North China Plain shows an visibly subseasonal reversal in early and late winter on interannual scaleThe Scandinavia‐like pattern and Polar/Eurasian‐like pattern are responsible for the seesaw pattern of PM2.5 concentration anomaliesThe sea‐ice variations in the Barents Sea play a key role in modulating such atmospheric circulations [ABSTRACT FROM AUTHOR]

Extreme temperature events are becoming more frequent due to global warming, and have critical effects on natural ecosystems, social and economic spheres, human production and life. Predicting changes in temperature extremes and trends under future climate scenarios helps to assess the impact of climate change accurately. Based on climate observations from 54 meteorological stations in the North China Plain and the projection data from seven general circulation models (GCMs) from the Coupled Model Intercomparison Project phase 6 (CMIP6), this paper researches nine representative extreme temperature indices under four typical climate scenarios. The aim is to reveal the temporal and spatial variations in extreme temperature indices in the North China Plain during the past (1971–2010) and the future (2061–2100). The results show that: using a support vector machine (SVM) to perform regression analysis on the multi-GCMs prediction results, the root mean square error (RMSE) and relative standard deviation (RSD) of the multi-model ensemble simulations obtained by the SVM method are lower than those of the arithmetic mean method and can better match the trend of the historical extreme temperature index; the extreme high temperature index is predicted to show a significant upward trend in the future, while the extreme low temperature index will decrease significantly; and there are significant spatial differences in the extreme temperature index in both historical and future periods, with the extreme temperature index under the high radiation forcing scenario (SSP585) showing the most considerable variation and the most significant spatial differences. [ABSTRACT FROM AUTHOR]

Drought has a significant impact on agricultural production, but the evolution of drought in the North China Plain (NCP) and its impact on winter wheat yield remain unclear. In this paper, we used the Standardized Precipitation Evapotranspiration Index (SPEI) and combined with the Standardized Yield Residual Series (SYRS) and the Vegetation Condition Index (VCI) to study the spatiotemporal distribution of drought at different time scales and its impact on winter wheat yield. We found that: (1) The southern NCP was dominated by mild drought at the 1-month scale. In the northern NCP, mild drought was observed at the short-time scale and moderate drought at the medium- and long-time scales; (2) the frequency of mild drought was high and the frequency of moderate drought was a step lower. Moreover, drought risks were increasing in the north-central, eastern, and northeastern NCP, while the southern, west-central, southeastern, and northwestern NCP were becoming wetter (at the 6- and 9-month scales); (3) the maximum correlation coefficients were concentrated in the seedling to the greening stages. (4) Drought affected winter wheat with a lag of approximately 3 months, and the VCI was the most sensitive to the short-term SPEI. [ABSTRACT FROM AUTHOR]

Over-exploitation of groundwater in China has severely affected irrigation agriculture, especially in the North China Plain, and it also threatens the environment. Although water-saving technologies (WSTs) have been introduced for decades, sustained commitment to WST is not being met. This paper investigates factors affecting adoption and sustained adoption of WST based on 261 households in the North China Plain. We employ Heckman's two-stage sample selection process: (1) households decide whether to adopt WST or not and (2) households decide whether to sustainably adopt (adopt for a long time) WST or not. Particular attention is paid to the role of water scarcity in the initial adoption and sustained adoption stages. Several indicators relating to water scarcity are used to calculate a water scarcity index based on principal component analysis. The results showed that water scarcity exerts a significant and positive effect on both adoption and sustained adoption of WST. Non-adopters and non-sustained adopters face less severe water scarcity than adopters. Membership in cooperative organizations significantly improves the likelihood of sustained adoption; 63.6% of sustained adopters have a membership in cooperative organizations, compared with 18.2% of non-sustained adopters. The number of plots negatively affects the sustained adoption of WST; sustained adopters on average have 3.0 plots, and non-sustained adopters have 5.3 plots. Education, extension service, farm size, off-farm work, relatives working in the local government and irrigation costs are positively and significantly associated with adoption and sustained adoption decisions. Finally, we find that labor-saving capacity significantly influences both stages, whereas capital-saving capacity is only significant in the adoption stage. Only 10% of non-adopters consider adoption of WST as more labor- and capital-saving than conventional irrigation practices, in comparison with nearly 50% of adopters. These results imply that the extension of WST should consider focusing more on cooperative organizations and hold more demonstrations for farmers. Moreover, given that the degree of water shortage varies from region to region, the WST extension standards should vary accordingly. Governments should strengthen awareness by enhancing education and publicity concerning water scarcity and conservation. [ABSTRACT FROM AUTHOR]

• Driving factors of groundwater level variation have been evaluated and ranked. • Attention-GRU model shows the best performance on groundwater level prediction. • Ecological water supplement shows variance effects in the North China Plain. • Specific yield updates exhibit a significant influence during specific period. • Groundwater storage variation presents different features in the North China Plain. The continuous ecological river supplement has enhanced the recharge of groundwater in the North China Plain, and alleviated the depletion of groundwater resources. In the study of ecological river supplement, efficient quantitative prediction of groundwater level (GWL) and groundwater storage (GWS) is a crucial issue. To predict GWL and estimate the variation of GWS in the North China Plain, this paper uses the attention-gated recurrent unit (Attention-GRU) model as a primary method and coefficient of determination (R2) and root mean square error (RMSE) as the indices to evaluate model performance. Compared to traditional recursive neural network (RNN) and long short-term memory (LSTM) model, Attention-GRU model demonstrated an outstanding performance, as the RMSE is respectively 0.5 m and 2.28 m in the training and testing periods, and the R2 is 0.87 and 0.68. With the usage of the convolution neural network (CNN) model, the specific yield field was continuously updated from 2018 to 2021. The average annual variation of GWS estimated by this method is respectively −15.19 × 104 m3, −13.29 × 104 m3, 2.55×104 m3 and 100.05×104 m3 from 2018 to 2021 in the North China Plain. Besides, the semiannual GWS variation, calculated using the updated specific yield, is −59.56 × 104 m3 in 2022. Furthermore, the influence of the reference time length and the driving factors were evaluated. Results show that the precipitation, evaporation and human activities are the most important temporal features influencing the changes in GWS, and the changes in different areas have varying local characteristics. In the piedmont plain, river ecological recharge played a crucial role for groundwater storage recovery. When it moved to the coastal plain, the contribution rate of recharge decreased from 23% to 11%. In addition, the optimal reference time length used in Attention-GRU model varies in different hydrogeology divisions, and the specific yield variation would result in substantial differences for the GWS estimation under different climate conditions and human activities. The systematic framework proposed in this paper is effective for evaluating and predicting GWL and GWS, and thereby able to support the management and development of groundwater, and provide a guidance for ecological river supplement. [ABSTRACT FROM AUTHOR]

In December 2023, a super warm spell occurred in the North China Plain, setting a new daily maximum temperature record for all Decembers since 1961. By using station observed temperatures in China and NCEP/NCAR reanalysis datasets, this paper examines the extremity of the event. The peak temperature anomaly during the event exceeded 13 °C for the entire region mean and exceeded 22 °C for a single station, both of which have never been observed before. Further analyses indicated that the super warm spell event was not limited in a local area, but rather had a significant large-scale background, characterized by a remarkable dipole temperature anomaly spatial pattern in the Eurasian continent. Composite analyses revealed that one of the dominant circulation factors was the Siberian high. Prior to the occurrence of the historic warm spell days, the Siberian high was generally weaker than normal by 2–3 standard deviations. During this super warm spell event, the Siberian high was the fifth weakest in the research period. The composite results indicate that the weaker Siberian high weakened the local meridional pressure gradient and blocked the cold air from high latitudes. In addition to the Siberian high, the sea level pressure anomaly pattern in Asia, both in the composite and in 2023, also shows a typical dipole structure. The dipole structure weakens the large-scale meridional pressure gradient and maintains the zonal circulation in the Eurasian continent. This may be related to the anomalous polar front jet. In December 2023, the polar front jet was the strongest during the research period. A stronger polar front jet typically weakens the winter monsoon by promoting zonal circulations, resulting in higher temperatures across most of Asia. Thus, it can be inferred that the super warm spell in early December 2023 in the North China Plain was the result of a combination of the polar front jet and the Siberian high. • A record-breaking warm spell in Dec 2023 occurred under a large-scale dipole of temperature anomalies in Eurasia continent. • The common and individual general circulation characteristics are compared and diagnosed. • The strongest polar front jet and the fifth weakest Siberian high in December jointly contributed to the event. [ABSTRACT FROM AUTHOR]

Over the past decade, surface ozone has emerged as a significant air pollutant in China, especially in the North China Plain (NCP). For effective ozone management in the NCP, it is crucial to accurately estimate the surface ozone levels and identify the primary influencing factors for ozone pollution in this region. This study utilized ozone precursors such as volatile organic compounds (VOCs) and nitrogen oxides (NOX), meteorological data, land cover, normalized difference vegetation index (NDVI), terrain, and population data to build an extreme gradient boosting (XGBoost)-based ozone estimation model in the NCP during 2019 to 2021. Four ozone estimation models were developed using different NO2 and formaldehyde (HCHO) datasets from the Sentinel-5 TROPOMI observations and Copernicus Atmosphere Monitoring Service (CAMS) reanalysis data. Site-based validation results of these four models showed high accuracy with R2 values above 0.86. Among these four models, two models with higher accuracy and higher spatial coverage ratio were selected, and their results were averaged to produce the final ozone estimation products. The results indicated that VOCs and NOX were the two main pollutants causing ozone pollution in the NCP, and their relative contributions accounted for more than 23.34% and 10.23%, respectively, while HCHO also played a significant role, contributing over 5.64%. Additionally, meteorological factors also had a notable impact, contributing 28.63% to ozone pollution, with each individual factor contributing more than 2.38%. The spatial distribution of ozone pollution identified the Hebei–Shandong–Henan junction as a pollution hotspot, with the peak occurring in summer, particularly in June. Therefore, for this hotspot region in the NCP, promoting the reduction in VOCs and NOx can play an important role in the mitigation of O3 pollution and the improvement in air quality in this region. [ABSTRACT FROM AUTHOR]

In this paper, we investigate Holocene precipitation changes in northern China to improve the understanding of the East Asian summer monsoon (EASM) and provide an environmental context for the development of Chinese civilisation. Our study is based on an analysis of 260 pollen samples from Holocene lacustrine sediments at Ningjinpo in northern China, and employs the biomisation method to reconstruct regional vegetation types and vegetation changes, and to decipher their driving factors, by incorporating regional climatic data and information on human activities. Results indicate that, in the early Holocene (10,000–8100 cal yr B.P.), regional climate was dry, with annual precipitation of 470 mm. In the middle Holocene (8100–3000 cal yr B.P.), a rapid increase was observed in precipitation, reaching 580 mm. During the late Holocene (2600–600 cal yr B.P.), climate became drier again, with annual precipitation decreasing to 480 mm. Between 10,000–600 cal yr B.P., vegetation exhibited distinct successional patterns dominantly influenced by climate, transitioning from meadow-steppe to forest, and then back to meadow-steppe. After 600 cal yr B.P., vegetation succession decoupled from climate change, with human activities emerging as the primary driving force, as indicated by the substantial increase in anthropogenic pollen and charcoal concentrations. In the future, under the combined influence of global warming and intensified human activity, the implementation of scientific environmental planning measures will become increasingly important for the restoration and sustainable development of regional vegetation ecosystems. • Unambiguous high-resolution precipitation record from the North China Plain. • Human activities variedly impact vegetation evolution since 2600 cal yr B.P. • A shift from natural to anthropogenic vegetation change happened at 600 cal yr B.P. [ABSTRACT FROM AUTHOR]

This paper examines the local and non-local climatic effects of wetter arid areas of Northwestern China (ANWC) in summer using a fully coupled climate model. In response to soil moisture increase, the local air temperature significantly decreases, and precipitation increases in summer. The wetter ANWC results in a warmer and rainless climate over the Central part of North China Plain (CNCP). While the influence of increasing soil moisture on the Tibetan Plateau (TP) precipitation is negligible due to the high altitude. A cooler climate over ANWC leads to an abnormal descending motion occurring. Meanwhile, an anomalous high pressure and an abnormal anticyclonic circulation occurs in 500 hPa over the west of ANWC. Correspondingly, a huge anomalous cyclone circulation occurs over the northeastern part of China and Mongolia, which can hinder the northward movement of the East Asian summer Monsoon (EASM) and reduce the water vapor transport into Central China Plain. As a result, the weakened EASM thus leads to rainless over CNCP. As soil moisture increases over ANWC is stronger, the magnitudes of the influence on the atmospheric field become larger. This study highlights the wetter ANWC effect on local climate and provides more information about the mechanism of wetter ANWC remote effect on non-local climate. • This paper examines the local and non-local climatic effects of wetter arid areas of Northwestern China (ANWC) in summer using a fully coupled climate model. • It finds that the wetter ANWC can result in a warmer and rainless climate over the Central part of North China Plain (CNCP) through a complex atmospheric circulation response. • A cooler climate leads to an abnormal descending motion occurring over ANWC. • A huge anomalous cyclone circulation over the northeastern part of China and Mongolia can block the East Asian summer Monsoon northward and decrease the water vapor transport into Central China Plain. • This study highlights the wetter ANWC effect on local climate and provides more information about the mechanism of wetter ANWC remote effect on non-local climate. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this paper is: to track the methods by which farmers access groundwater for irrigation in the North China Plain (NCP); to explore whether climate factors influence farmers’ decisions on the methods of groundwater access for irrigation; and to examine whether the amount of groundwater use for irrigation and crop yield systematically differ across groups of farmers using various methods of groundwater access, and how climate factors affect them.Design/methodology/approach Descriptive statistical analysis and econometric models are used on household survey data collected over several years and county-level climate data.Findings Over the past few decades, a significant share of farmers have switched the methods of groundwater access from collective tubewells to own tubewells or groundwater markets. Farmers who bought water from groundwater markets applied less water to wheat plots than those who had their own tubewells. However, wheat yield was not negatively affected. Both average climate conditions and long-term variations were found to be related to farmers’ choice of methods of groundwater access for irrigation. More frequent droughts and increasingly volatile temperatures both increased the likelihood of farmers gaining groundwater irrigation from markets.Originality/value The analysis results suggest farmers are using groundwater markets to help them adapt to climate change. Applying empirical analysis to identify the impact of the methods by which farmers access groundwater for irrigation on the amount of groundwater use and crop yield will help policy makers design reasonable adaptation policies for the NCP. [ABSTRACT FROM AUTHOR]

Herbicide residues in farmland soils have attracted a great deal of attention in recent decades. Their accumulation potentially decreases the activity of microbes and related enzymes, as well as disturbs the nitrogen cycle in farmland soils. In previous studies, the influence of natural factors or nitrogen fertilization on the soil nitrogen cycle have frequently been examined, but the role of herbicides has been ignored. This study was conducted to examine the effects of herbicides on NH3 volatilization- and denitrification-related nitrogen loss through three rotation cycles from 2013 to 2016. The four treatments included no urea fertilizer (CK), urea (CN), urea+acetochlor-fenoxaprop-ethyl (AC-FE), and urea+2,4D-dicamba (2,4D-DI) approaches. The results showed that the application of nitrogen fertilizer significantly increased the nitrogen losses from ammonia volatilization and denitrification in the soil. Ammonia volatilization was the main reason for the gaseous loss of urea nitrogen in a wheat–maize rotation system in the North China Plain (NCP), which was significantly higher than the denitrification loss. In the CK treatment, the cumulative nitrogen losses from ammonia volatilization and denitrification during the three crop rotation cycles were 66.64 kg N hm−2 and 8.07 kg N hm−2, respectively. Compared with CK, the nitrogen losses from ammonia volatilization and denitrification under the CN treatment increased 52.62% and 152.88%, respectively. The application of AC-FE and 2,4D-DI significantly reduced the nitrogen gas losses from the ammonia volatilization and denitrification in the soil. Ammonia volatilization reduction mainly occurred during the maize season, and the inhibition rates of AC-FE and 2,4D-DI were 7.72% and 11.80%, respectively, when compared with CN. From the perspective of the entire wheat–maize rotation cycle, the inhibition rates were 5.41% and 7.23% over three years, respectively. Denitrification reduction also mainly occurred in the maize season, with the inhibition rates of AC-FE and 2,4D-DI being 34.12% and 30.94%, respectively, when compared with CN. From the perspective of the entire wheat–maize rotation cycle, the inhibition rates were 28.39% and 28.58% over three years, respectively. Overall, this study demonstrates that herbicides could impact the nitrogen cycle of farmland soil ecosystems via the suppression of ammonia volatilization and denitrification rates, thus reducing gaseous N losses and mitigating global climate change. [ABSTRACT FROM AUTHOR]

Aerosols play a crucial role in the surface radiative budget by absorbing and scattering both shortwave and longwave radiation. While most aerosol types exhibit a relatively minor longwave radiative forcing when compared to their shortwave counterparts, dust aerosols stand out for their substantial longwave radiative forcing. In this study, radiometers, a sun photometer, a microwave radiometer and the parameterization scheme for clear-sky radiation estimation were integrated to investigate the radiative properties of aerosols. During an event in Xianghe, North China Plain, from 25 April to 27 April 2018, both the composition (anthropogenic aerosol and dust) and the aerosol optical depth (AOD, ranging from 0.3 to 1.5) changed considerably. A notable shortwave aerosol radiative effect (SARE) was revealed by the integrated system (reaching its peak at −131.27 W·m−2 on 26 April 2018), which was primarily attributed to a reduction in direct irradiance caused by anthropogenic aerosols. The SARE became relatively consistent over the three days as the AODs approached similar levels. Conversely, the longwave aerosol radiative effect (LARE) on the dust days ranged from 8.94 to 32.93 W·m−2, significantly surpassing the values measured during the days of anthropogenic aerosol pollution, which ranged from 0.35 to 28.67 W·m−2, despite lower AOD values. The LARE increased with a higher AOD and a lower Ångström exponent (AE), with a lower AE having a more pronounced impact on the LARE than a higher AOD. It was estimated that, on a daily basis, the LARE will offset approximately 25% of the SARE during dust events and during periods of heavy anthropogenic pollution. [ABSTRACT FROM AUTHOR]

In recent years, China's crop production growth rate has decreased. This has provoked questions on whether the grain yields have reached their potential. Taking the North China Plain (NCP) as the study area, this study first simulated the potential yield of an irrigated maize crop with the WOFOST model, using daily weather data for 1960–2017. The yield gap was quantified for 1998–2017, and finally, the total potential maize production was estimated. The results indicate that during 1960–2017, the average potential yield for the region varied annually from 9.5 to 13.5 t ha−1, showing an obvious downward trend at a rate of 37.6 kg ha−1 per year. The long‐term mean potential yield at all 327 counties ranged from 9.9 to 13.7 t ha−1, increasing from south to north. The annual maize yield gap was between an average of 2.7–6.0 t ha−1 (29.0%–51.3%) of the potential yield for the NCP during 1998–2017. At county‐level, the yield gap varied between 1.9 and 7.8 t ha−1 and exceeded 5.0 t ha−1 for 99 counties (30.3% of all counties). Attainable yields can be increased by 0.1–5.2 t ha−1 at county‐level, and by 2.2 t ha−1 for the whole NCP, implying that the maize production has the potential to increase with 20.8 Mt. To increase maize production, the focus areas should be the southcentral NCP, which have a larger yield gap during 2012–2017. [ABSTRACT FROM AUTHOR]

The Hutuo River Drinking Water Source Area is an important water source of Shijiazhuang (North China Plain). Knowing the characteristics of groundwater chemistry/quality is essential for the protection and management of water resources. However, there are few studies focused on the groundwater chemistry evolution over the drinking water area. In this study, total of 160 groundwater samples were collected in November 2021, and the spatial distribution of groundwater chemistry and related controlling factors were analyzed using hydrological and multivariate analysis. The entropy-weighted water quality index (EWQI) was introduced to assess the groundwater quality. The results show that the hydrogeochemical types of groundwater are Ca-HCO3 (78.1%), mixed Ca-Mg-Cl (20%), and Ca-Cl (1.9%) in the area. Graphical and binary diagrams indicate that groundwater hydrochemistry is mainly controlled by water–rock interaction (i.e., rock weathering, mineral dissolution, and ion exchange). Five principal components separated from the principal component analysis represent the rock–water interaction and agricultural return, redox environment, geogenic sources, the utilization of agricultural fertilizer, the weathering of aluminum silicates, and dissolution of carbonates, respectively. More than 70% of the samples are not recommended for irrigation due to the presence of high salt content in groundwater. EWQI assessment demonstrates that the quality of the groundwater is good. The outcomes of this study are significant for understanding the geochemical status of the groundwater in the Hutuo River Drinking Water Source Area, and helping policymakers to protect and manage the groundwater. [ABSTRACT FROM AUTHOR]

The spatiotemporal evolution characteristics of precipitation infiltration recharge during the past 50 years are discussed in this paper. This research is significant for groundwater resource rational utilization. The distribution of precipitation infiltration recharge coefficients in the 1960s, 1980s, and 2000s can be obtained using unsaturated zone lithology and depth to water table at different times. The amount of precipitation infiltration recharge in the 1960s, 1980s, and 2000s can be calculated using precipitation infiltration recharge coefficients and precipitation data from the Ministry of Water Resources of China. Results show that the change in the precipitation infiltration recharge coefficient is closely related to the water table decrease. From the 1960s to the 1980s, the precipitation infiltration recharge coefficient clearly increased in all units. From the 1980s to the 2000s, the value slightly increased in the ancient Yellow River alluvial-proluvial and eastern alluvial-marine plains and slightly decreased in the piedmont alluvial-proluvial and central alluvial-lacustrine plains. The piedmont alluvial-proluvial and ancient Yellow River alluvial-proluvial plains exhibited a large precipitation infiltration recharge coefficient for the coarse lithology. The amounts of precipitation infiltration recharges were 16.23×10 (1960s), 19.11×10 (1980s), and 19.42×10 m/a (2000s). The amount of precipitation infiltration recharge increased from the 1960s to the 1980s then decreased from the 1980s to the 2000s in the piedmont alluvial-proluvial and the central alluvial-lacustrine plains. However, this value increased from the 1960s to the 2000s in the ancient Yellow River alluvial-proluvial and eastern alluvial-marine plains. [ABSTRACT FROM AUTHOR]

The growing concern surrounding climate change has gradually drawn attention to the influence of climate factors on drought occurrence. In order to effectively prevent the occurrence of drought and reasonably utilize water resources, the vegetation health index (VHI) was used to characterize drought in North China Plain (NCP) in this study. Furthermore, six climate factors: air temperature (AT), precipitation (P), evapotranspiration (ET), specific humidity (SH), soil moisture (SM), and soil temperature (ST) were selected. The pole symmetric mode decomposition (PSMD) and improved gridded trend test (IGT) were used to analyze the spatial–temporal characteristics of drought and climate factors in NCP from 1982 to 2020. By calculating the cumulative climatic factors of 0 months, 1 month, 2 months, and 3 months, the correlation between drought and the climatic factors with different cumulative scales was analyzed. The results showed that: (1) from 1982 to 2020, the drought in NCP showed a downward trend and the climate factors showed an upward trend; (2) with the increase in AT, P, ET, SH, SM, and ST, VHI showed an upward trend, and SM showed the strongest correlation with VHI; (3) the optimal cumulative lag time (CLT) for AT, P, ET, SH, SM, and ST were 1.67 months, 1.48 months, 1.95 months, 1.69 months, 0.89 months, and 1.81 months, respectively; and (4) AT was the main driving factor of drought in NCP. This study contributes to the early warning and prediction of drought events, providing a scientific basis for water management authorities in drought management and decision making, and mitigating the negative impacts of drought on socio-economic aspects. [ABSTRACT FROM AUTHOR]

Irrigation has excellent potential for altering surface characteristics and the local climate. Although studies using site observations or remote sensing data have demonstrated an irrigation cooling effect (ICE) on the air temperature (Tem) and land surface temperature (LST), it is difficult to eliminate other stress factors due to different backgrounds. We characterized the irrigation effect as the differences (Δ) of LST and DCT (DCT = LST − Tem) between irrigated and adjacent non-irrigated areas. An improved method was proposed to detect it over the North China Plain (NCP) based on satellite observations. We also investigated the effects of irrigation on Tem, precipitation, NDVI, and ET, and explored the relationships between them. The results show that irrigation induced a decrease in the daytime/nighttime LST and DCT (−0.13/−0.09 and −0.14/−0.07 °C yr−1), Tem (−0.023 °C in spring), and precipitation (−1.461 mm yr−1), and an increase in NDVI (0.03 in spring) and ET (0.289 mm yr−1) across the NCP. The effect on nighttime LST and NDVI increased by 0.04 °C 10 yr−1 and 0.003 10 yr−1, and that on ET weakened by 0.23 mm 10 yr−1 during 2000–2015. The ICE on the LST had evident spatiotemporal heterogeneity, which was greater in the daytime, in the spring, and in the northern area of the NCP (dry–hot conditions). The daytime ICE in the NCP and northern NCP was 0.37 and 0.50 °C during spring, respectively, with the strongest ICE of 0.60 °C in Henan; however, the ICE was less evident (<0.1 °C) in the southern NCP throughout the year. The ΔNDVI, ΔET, and ΔTem were the main factors driving ICE, explaining approximatively 22%, 45%, and 25% of the daytime ICE, respectively. For every unit of these measures that was increased, the daytime ICE increased by about 7.3, 4.6, and 1.5 °C, respectively. This study highlights the broad irrigation effect on LST, ET, NDVI, and the climate, and provides important information for predicting climate change in the future. The improved method is more suitable for regions with uneven terrain and a varying climate. [ABSTRACT FROM AUTHOR]

Environmental tracers are proving to be a unique tool for assessing groundwater sustainability, such as characterization of recharge, identification of pathways and sources of contaminants, and prediction of groundwater change in response to excessive abstraction. This paper helps to better understand the groundwater sustainability in the Quaternary aquifer from the tracer data in the North China Plain. Relatively modern ground waters occur in the piedmont plain with H-He age less than 40 a within a depth 100 m. These ground waters are mainly recharged from the local precipitation and irrigation return. The recharge rate estimated by tracers is in the range of 0.24 to 0.32 m/a. Paleowater which is dated from 10 000 a B.P. to more than 35 000 a B.P. by radiocarbon dating is found in highly-confined portions of Quaternary aquifer systems. This indicates that water recharge took place during the past glacial period. The tracers have suggested a slow natural replenishment rates to the central plain. The aquifer has been overexploited currently. Some strategies that can be implemented to promote a sustainable groundwater supply are needed to implement in future. [ABSTRACT FROM AUTHOR]

Food safety and its related influencing factors in China are the hot research topics currently, and cultivated land conversion is one of the significant factors influencing food safety in China. Taking the North China Plain as the study area, this paper examines the changes of cultivated land area using satellite images, estimates land productivity from 1985 to 2005 using the model of Estimation System for Land Productivity (ESLP), and analyzes the impact of cultivated land conversion on the land production. Compared with the grain yield data from statistical yearbooks, the results indicate that ESLP model is an effective tool for estimating land productivity. Land productivity in the North China Plain showed a slight decreasing trend from 1985 to 2005, spatially, increased from the north to the south gradually, and the net changes varied in different areas. Cultivated land area recorded a marginal decrease of 8.0 × 10 ha, mainly converted to other land uses. Cultivated land conversion had more significant negative impacts on land production than land productivity did. Land production decreased by about 6.48 × 10 t caused by cultivated land conversion between 1985 and 2005, accounting for 91.9% of the total land production reduction. Although the land productivity increased in Anhui and Jiangsu provinces, it can not offset the overall adverse effects caused by cultivated land conversion. Therefore, there are significant meanings to control the cultivated land conversion and improve the land productivity for ensuring the land production in the North China Plain. [ABSTRACT FROM AUTHOR]

The extent to which the South-to-North Water Transfer Project has influenced the trend in water storage deficit in the North China Plain since its official opening in late 2014 has not been systematically assessed. We evaluated the changes in terrestrial water storage (TWS) in the North China Plain based on the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-on (GRACE-FO) long-term gravity satellite observations from 2002 to 2022, using spherical harmonic (SH) solutions from the Center for Space Research (CSR), GeoForschungsZentrum (GFZ), Jet Propulsion Laboratory (JPL), and Mass Concentration (Mascon) solutions from CSR, Goddard Space Flight Center (GSFC), JPL, and compared with the South-to-North Water Transfer water supply (13.91 Gt/a). The CSR-SH solution that best matched the water supply was selected, and it was found that the rate of change in TWS in the North China Plain from 2002 to 2015 was (−8.48 ± 1.87) Gt/a, and the rate of change from 2015 to 2019 increased significantly to (5.44 ± 4.87) Gt/a, indicating that the TWS in the plain changed from deficit to gain. The South-to-North Water Transfer Project has played a positive role in significantly improving the water stress situation in North China. Simultaneously, by comparing the inversions of six time-varying gravity field models (CSR-SH, GFZ-SH, JPL-SH, CSR-Mascon, GSFC-Mascon, and JPL-Mascon) with the South-to-North Water Transfer water supply and measured groundwater well data, and by calculating the uncertainty using the 'three-cornered hat method' (TCH), a comprehensive comparison is made to conclude that the CSR-SH model is most effective with a minimum difference of 0.01 Gt/a from the annual water supply, a minimum difference of 0.04 Gt/a from the measured well data, and a small uncertainty of 3.04 cm. This study reveals the important impact of the South-to-North Water Transfer Project on TWS in the North China Plain, which is of reference value for water resource management decisions in China. [ABSTRACT FROM AUTHOR]

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The Longyao ground fissure (LGF) is the longest and most active among more than 1000 ground fissures on the North China Plain. There have been many studies on the formation mechanism of the LGF, due to its scientific importance and its potential for damage to the environment. These studies have been based on both regional tectonic analysis and numerical simulations. In order to provide a better understanding of the formation mechanism, the deformation of the crack and its surrounding environment should be taken into consideration. In this paper, PS-InSAR technology was employed to assess the ground deformation of LGF and its surrounding area, using L-band ALOS-1 PALSAR images from 2007 to 2011. The characteristics of ground deformation, relationships between fissure activity and surrounding faults and groundwater exploitation were analyzed. This study shows that the north side of Longyao fault (LF) is uplifting while the south side is subsiding. This provides the tectonic conditions responsible for the activity of the ground fissure. Local groundwater exploitation also plays an important role in the development of ground fissures. InSAR observations were modeled to infer the loading depth (-2.8 km) and the slip rate (31.1 mm/yr) of LF. [ABSTRACT FROM AUTHOR]

In order to improve the efficiency of nutrient use whilst also meeting projected changes in the demand for food within China, new nutrient management frameworks comprised of policy, practice and the means of delivering change are required. These frameworks should be underpinned by systemic analyses of the stocks and flows of nutrients within agricultural production. In this paper, a 30-year time series of the stocks and flows of nitrogen (N), phosphorus (P) and potassium (K) are reported for Huantai county, an exemplar area of intensive agricultural production in the North China Plain. Substance flow analyses were constructed for the major crop systems in the county across the period 1983–2014. On average across all production systems between 2010 and 2014, total annual nutrient inputs to agricultural land in Huantai county remained high at 18.1 kt N, 2.7 kt P and 7.8 kt K (696 kg N ha − 1 ; 104 kg P ha − 1 ; 300 kg K ha − 1 ). Whilst the application of inorganic fertiliser dominated these inputs, crop residues, atmospheric deposition and livestock manure represented significant, yet largely unrecognised, sources of nutrients, depending on the individual production system and the period of time. Whilst nutrient use efficiency (NUE) increased for N and P between 1983 and 2014, future improvements in NUE will require better alignment of nutrient inputs and crop demand. This is particularly true for high-value fruit and vegetable production, in which appropriate recognition of nutrient supply from sources such as manure and from soil reserves will be required to enhance NUE. Aligned with the structural organisation of the public agricultural extension service at county-scale in China, our analyses highlight key areas for the development of future agricultural policy and farm advice in order to rebalance the management of natural resources from a focus on production and growth towards the aims of efficiency and sustainability. [ABSTRACT FROM AUTHOR]

The heartlands of many of the world's civilizations are situated within alluvial plains, where thick alluvial sediments obscure much of the archaeological record. However, the use of alluvial geoarchaeology remains patchy, particularly in the world's largest alluvial basins. We present results from our geoarchaeological survey at Neihuang County, Henan Province, China, as an example for alluvial geoarchaeological research in the North China Plain and to develop a generalized framework for landscape evolution in the area during the Holocene. We reconstruct the alluvial history of the area around Neihuang County by synthesizing stratigraphic data from seven outcrops into distinct depositional units. Our findings suggest that much of the archaeological record in the North China Plain is buried by meters of sediment or eroded away by the ancient channels of the Yellow River and other tributary streams. Therefore, the presence of buried archaeological sites and river scour in recorded outcrops suggests that the nonsystematic archaeological surveys that are commonly used to interpret cultural changes are not accurate reflections of archaeological site distributions. From the results of this case study, we recommend that archaeologists and paleoclimatologists should exercise more caution when using settlement distribution data gathered through nonsystematic pedestrian surveys to make inferences about ancient processes of cultural change or social dynamics in the North China Plain. [ABSTRACT FROM AUTHOR]

The generalized complementary relationship (CR) of evaporation was investigated in the irrigated winter wheat/summer maize double‐cropping sites in North China Plain (NCP), a region influenced by the East Asian dry winter and wet summer monsoon. Different generalized CRs exist in the winter wheat (dry) and summer maize (wet) seasons with abrupt changes in June and October. The seasonal abrupt change in the CR is attributed to the sudden reversed water vapor transport with the winter and summer monsoon and the wheat/maize rotation with irrigation in the winter wheat season. The separation and abrupt change in the complementary behavior require that two‐stage phased parameters corresponding to the wheat (dry) and maize (wet) seasons should be adopted by the generalized complementary functions for operational evaporation estimation in the irrigated double cropping NCP. Plain Language Summary: The irrigated double cropping North China Plain (NCP) is characterized with rapid winter wheat/summer maize rotation on the land surface and sudden reversed water vapor transport in the upper‐air with East Asian monsoon, coincidentally in June and October. There are corresponding abrupt changes of the complementary relationship, a theory relating changes in landscape evaporation and atmospheric evaporation demand. It reveals the impacts of the processes related to large‐scale changes in atmospheric circulations on the complementary behavior and the requirement of different parameters during the two stages for operational evaporation estimation using the complementary principle in the irrigated double cropping NCP. Key Points: Different generalized complementary relationships (CRs) exist in winter wheat and summer maize seasons with an abrupt changeAbrupt change of the CR is mainly attributed to upper‐air circulations with East Asian monsoonWheat season irrigation contributes to the abrupt change via interrupting the connection between land surface and atmosphere [ABSTRACT FROM AUTHOR]

In the North China Plain, water shortage seriously restricts economic development, and agricultural irrigation depends heavily on groundwater extraction. Irrigation water and precipitation may directly recharge groundwater in the irrigated agricultural region. Therefore, calculating the recharge of precipitation and irrigation to groundwater is essential for the sustainable utilization of water resources. Furthermore, determining the transformation relationship of precipitation-soil water-groundwater is helpful to understand the hydrological cycle process better. The average groundwater recharge calculated by the chloride mass balance method is between 66 and 144 mm/year, accounting for only 7–17% of the total precipitation and irrigation water. The hydrogen (2H) and oxygen (18O) isotopes reveal that precipitation only affects soil water in topsoil, and soil water in deep soil is recharged upward by groundwater. The hydrochemical composition of soil water shows high concentrations of salt in unsaturated zones. Infiltration water dissolves salt through the unsaturated zone and carries them into the shallow groundwater, causing the deterioration of shallow groundwater quality. These results contribute to the effective management of groundwater resources and the control of agricultural pollution in groundwater. [ABSTRACT FROM AUTHOR]

The depletion of shallow groundwater has seriously affected the sustainable development of water resources in the North China Plain (NCP). Based on 556 well monitoring observations over a period of 13 years, we quantitatively evaluated the shallow groundwater sustainability in the NCP via various indices (e.g., the reliability, resilience, vulnerability, and sustainability indices), and further discussed the contribution of different drivers (including climatic and non-climatic factors). The main conclusions are summarized as follows: (1) the yearly trend of shallow groundwater shows a serious long-term deficit in the Piedmont Plain but is not significant in the East-Central Plain. (2) As for the sustainability of shallow groundwater in the NCP, the reliability is below the medium level (reliability < 0.5) in most areas and the ability of shallow aquifers to restore groundwater is very weak (resilience < 0.2), while the lack of groundwater storage in most shallow aquifers is not serious (vulnerability < 0.4). The final sustainability index (<0.1) shows the poor sustainability of most shallow aquifers in the NCP. (3) The non-climatic factor is the dominant driver of shallow groundwater depletion in the NCP when compared to the climatic factor. This result is helpful to formulate the water management policies for sustainable shallow groundwater storage in the NCP. [ABSTRACT FROM AUTHOR]

Spring wheat–summer maize (SWSM) annual crop systems were formed to satisfy the maize grain mechanized harvest thermal requirement in the thermal–resource–limited region of the North China Plain. However, the nitrogen (N) application rate effect on SWSM annual yield formation, N accumulation and utilization were barely evaluated. Two–year field experiments were conducted to evaluate the effects of the N application rate on the annual yield of SWSM, observe N accumulation and utilization, and identify the optimized N application. The experiments were conducted under 5 N levels of 0 (N0), 180 (N180), 240 (N240), 300 (N300), and 360 (N360) kg ha−1. The results showed that spring wheat, summer maize and annual cereal yield under the N240 and N480 treatments obtained the highest grain yield (GY) of 5038, 1282 and 16,320 kg ha−1, respectively, and the optimal N application rate was estimated using a linear–plateau model to be 231–307, 222–337 and 463–571 kg ha−1 with maximum GY of 4654–5317, 11,727–12,003 and 16,349–16,658 kg ha−1, respectively. With the increase in the N application rate, the dry matter accumulation (DM) were significantly increased by 16.9–173.5% for spring wheat and 11.1≈–76.8% for summer maize, respectively; and the annual cereal DM was 15.1–179.7% greater than that with N0 treatment, respectively. Spring wheat, summer maize and the annual cereal total N accumulation (TN) under N360 and N720 treatments were significantly increased by 5.4–19.1%, 16.6–32.3% and 11.5–26.2%, respectively, compared to the other treatments; however, N use efficiency for biomass and grain production (NUEbms and NUEg) were decreased significantly by 10.9–13.6% and 8.9–20.7%, 6.8–13.8% and 12.2–15.6%, and 5.5–11.7% and 10.0–16.0%, respectively. Meanwhile, the N partial factor productivity (PFPN), N agronomy use efficiency (ANUE), N recovery efficiency (NRE) and N uptake efficiency (NEupk) under the N240 treatment for spring wheat and summer maize obtained high levels of 20.99 and 47.01 kg−1, 9.27 and 16.35 kg−1, 32.53% and 32.44%, and 0.85 and 0.72 kg−1, respectively. Correlation analysis showed that the N application rate, TN and NEupk played significantly positive roles on GY, spring wheat spilke grain number, summer maize ear grain number and 1000–grain weight, DM LAImax and SPADmax, while NUEbms, NUEg, PFPN and ANUE always played negative effects. These results demonstrate that spring wheat, summer maize and annual cereal obtained the highest GY being 4654–5317, 11,727–12,003 and 16,349–16,658 kg ha−1 with the optimal N application rate 231–307, 222–337 and 463–571 kg ha−1, respectively, which provide N application guidance to farmer for spring wheat–summer maize crop systems to achieve annual mechanical harvesting in the thermal–resource–limited region of the North China Plain. [ABSTRACT FROM AUTHOR]

The accuracy prediction for the crop yield is conducive to the food security in regions and/or nations. To some extent, the prediction model for crop yields combining the crop mechanism model with statistical regression model (SRM) can improve the timeliness and robustness of the final yield prediction. In this study, the accumulated biomass (AB) simulated by the Agricultural Production Systems sIMulator (APSIM) model and multiple climate indices (e.g., climate suitability indices and extreme climate indices) were incorporated into SRM to predict the wheat yield in the North China Plain (NCP). The results showed that the prediction model based on the random forest (RF) algorithm outperformed the prediction models using other regression algorithms. The prediction for the wheat yield at SM (the period from the start of grain filling to the milky stage) based on RF can obtain a higher accuracy (r = 0.86, RMSE = 683 kg ha−1 and MAE = 498 kg ha−1). With the progression of wheat growth, the performances of yield prediction models improved gradually. The prediction of yield at FS (the period from flowering to the start of grain filling) can achieve higher precision and a longer lead time, which can be viewed as the optimum period providing the decent performance of the yield prediction and about one month's lead time. In addition, the precision of the predicted yield for the irrigated sites was higher than that for the rainfed sites. The APSIM-simulated AB had an importance of above 30% for the last three prediction events, including FIF event (the period from floral initiation to flowering), FS event (the period from flowering to the start of grain filling) and SM event (the period from the start of grain filling to the milky stage), which ranked first in the prediction model. The climate suitability indices, with a higher rank for every prediction event, played an important role in the prediction model. The winter wheat yield in the NCP was seriously affected by the low temperature events before flowering, the high temperature events after flowering and water stress. We hope that the prediction model can be used to develop adaptation strategies to mitigate the negative effects of climate change on crop productivity and provide the data support for food security. [ABSTRACT FROM AUTHOR]

As the largest groundwater drainage region in China, the per capita water resources in the North China Plain (NCP) account for only one-seventh of the country's available water resources. Currently, the NCP is experiencing a serious water shortage due to the overexploitation of groundwater resources and a subsequent series of natural disasters. Thus, accurate regional assessments and effective water resource management policies are of critical importance. To accomplish this phenomenon, the daily terrestrial water storage anomaly (TWSA) over the NCP is calculated from the combination of the GNSS vertical deformation sequences (seasonal items) and GRACE (trend items). The groundwater storage anomaly (GWSA) in the NCP is obtained by subtracting the canopy water, soil water, and snow water equivalent components from the TWSA. The inversion results of this study are verified by comparisons with the Global Land Data Assimilation System (GLDAS) data products. The elevated annual amplitude areas are located in Beijing and Tianjin, and the Pearson correlation coefficient (PCC), root mean square error (RMSE), and Nash–Sutcliffe efficiency (NSE) between the two GWSA results are 0.67, 4.01 cm, and 0.61, respectively. This indicates that the methods proposed in this study are reliable. Finally, the groundwater drought index was calculated for the period from 2011 to 2021, and the results showed that 2019 was the driest year, with a drought severity index value of −0.12, indicative of slightly moderate drought conditions. By calculating and analyzing the annual GWSA, this work shows that the South–North Water Transfer Project does provide some regional drought mitigation. [ABSTRACT FROM AUTHOR]

Accurate short-term forecasts of daily reference evapotranspiration (ET0) are essential for real-time irrigation scheduling. Many models rely on current and historical temperature data to estimate daily ET0. However, easily accessible temperature forecasts are relatively less reported in short-term ET0 forecasting. Furthermore, the accuracy of ET0 forecasting from different models varies locally and also across regions. We used five temperature-dependent models to forecast daily ET0 for a 7-day horizon in the North China Plain (NCP): the McCloud (MC), Hargreaves-Samani (HS), Blaney-Criddle (BC), Thornthwaite (TH), and reduced-set Penman–Monteith (RPM) models. Daily meteorological data collected between 1 January 2000 and 31 December 2014 at 17 weather stations in NCP to calibrate and validate the five ET0 models against the ASCE Penman–Monteith (ASCE-PM). Forecast temperatures for up to 7 d ahead for 1 January 2015–19 June 2021 were input to the five calibrated models to forecast ET0. The performance of the five models improved for forecasts at all stations after calibration. The calibrated RPM is the preferred choice for forecasting ET0 in NCP. In descending order of preference, the remaining models were ranked as HS, TH, BC, and MC. Sensitivity analysis showed that a change in maximum temperature influenced the accuracy of ET0 forecasting by the five models, especially RPM, HS, and TH, more than other variables. Meanwhile, the calibrated RPM and HS equations were better than the other models, and thus, these two equations were recommended for short-term ET0 forecasting in NCP. [ABSTRACT FROM AUTHOR]

The North China Plain is a major grain-producing area, but faces water scarcity, which directly threatens food security. The problem is more severe under climate change and the seasonal impact of climate change on winter wheat is different. Thus, it is of great importance to explore the spatiotemporal characteristics of irrigation requirements (IR) and the factors influencing IR in different growth periods of winter wheat, but it has not received much attention. Therefore, we used relative contribution, partial correlation and path analyses to assess the spatiotemporal characteristics of the IR and primary factors influencing the IR of winter wheat in various growing stages in the North China Plain. The results indicated that wind speed and net solar radiation showed a significant downward trend; no prominent trend was noted in IR (multiyear average, 302.3 mm). Throughout the growing season of winter wheat, IR increased gradually from the southern to northern extent of the North China Plain. The irrigation demand of winter wheat in stage P2 (green-up to heading) was the largest. Furthermore, the dominant drivers of IR in terms of spatial distribution and inter-annual variation were phenological period (Phe), effective precipitation (Pe) and relative humidity (RH); however, the degree of their effects varied across the growth stages and growing regions of winter wheat. Each factor exerted both direct and indirect effects on IR and Phe exhibited the strongest indirect effect on IR. The major factors contributing most to IR were Pe and RH in the P1 stage (sowing to green-up) and Phe, Pe and RH in the P2 and P3 (heading to maturity) stages. Pe and RH limited IR, whereas Phe promoted it. Our findings will help improve agricultural water management in the future. [ABSTRACT FROM AUTHOR]

In the North China Plain, drought usually occurs during the interval between wheat harvest and maize sowing in normal and dry years. The first irrigation for maize plays a critical role in guaranteeing seed germination and grain yields. Using experimental data from Xinxiang in 2019 and survey data of 641 farmers from the North China Plain in 2020, this study adopts a cost-benefit analysis method to investigate the impacts of irrigation time and well depths on farmers' costs and benefits in maize production. The results showed that farms with well depth > 120 m accounted for 49% of total farms, especially in Hebei Province, and 38% wells had low water yield < 2.7 m3 kW−1 h−1. Delaying the time of the first irrigation made maize yields decline by up to 307 kg ha−1 day−1. Well depths increased irrigation costs and total maize production cost in an exponential manner, causing farmers' benefits to decrease exponentially with well depths. With well depth > 180 m, the proportion of irrigation cost to total cost rose to 14%, whereas well depth > 230 m directly caused the farmers' profits negative. A critical well depth of 230 m was put forward as the upper limit for farmers adopting maize planting in the NCP. The concept of 'rotational irrigation strategy' and suggestions of adopting drip irrigation, sprinkler irrigation, or hose-reel sprinkler irrigation were recommended to advance 6–8 days for the first irrigation period, compared with traditional flood irrigation. [ABSTRACT FROM AUTHOR]

Groundwater plays a critical role in the global water cycle and is the drinking source for almost half of the world’s population. However, exact quantification of its storage change remains elusive due primarily to limited ground observations in space and time. The Gravity Recovery and Climate Experiment (GRACE) twin-satellite data have provided global observations of water storage variations at monthly sampling for over a decade and a half, and is enable to estimate changes in groundwater storage (GWS) after removing other water storage components using auxiliary datasets and models. In this paper, we present an overview of GWS changes in three main aquifers within China using GRACE data, and conduct a comprehensive accuracy assessment using in situ ground well observations and hydrological models. GRACE detects a significant GWS depletion rate of 7.2 ± 1.1 km3/yr in the North China Plain (NCP) during 2002–2014, consistent with ground well observations and model predictions. The Liaohe River Basin (LRB) experienced a pronounced GWS decline during 2005–2009, at a depletion rate of 5.0 ± 1.2 km3/yr. Since 2010, GRACE-based GWS reveal a slow recovery in the LRB, with excellent agreement with ground well observations. For the whole study period 2002–2014, no significant long-term GWS depletion is found in the LRB nor in the Tarim Basin. A case study in the Inner Tibetan Plateau highlights there still exist large uncertainties in GRACE-based GWS change estimates. [ABSTRACT FROM AUTHOR]

To meet the growing demand for socioeconomic development, a large amount of groundwater is extracted from confined aquifers worldwide. The North China Plain has experienced considerable groundwater depletion and subsidence during the past six decades. In this study, we use Sentinel-1A/B SAR images from 2015 to 2020 to map the ground subsidence of the Tianjin–Langfang area. Three subsiding zones centered at Guangyang, Wuqing–Bazhou, and Jinghai are identified with maximum subsidence rates of 98.1, 121.8, and 104.7 mm/yr. Seasonal and long-term signals are separated from time series subsidence and hydraulic measurements using continuous wavelet transform to retrieve aquifer parameters. The long-term subsidence, which fits well with an exponential decaying model, remarkably slows down in our study area. The elastic skeletal storage coefficients range between 0.52×10−3 and 9.66×10−3. We then retrieve the spatial–temporal variations of total groundwater storage, recoverable groundwater storage, and irreversible groundwater storage. Groundwater storage depletion rates are apparently reducing, which benefits from the operation of the South-to-North Water Transfer Project and local groundwater management practices. [ABSTRACT FROM AUTHOR]

Abstract: SMCR_N is a recently developed sophisticated model which simulates crop response to nitrogen fertilizer for a wide range of crops, and the associated leaching of nitrate from arable soils. The objective of this study was to investigate the possibility of using SMCR_N model as a research tool to investigate interactions between the amount and timing of N application and effects on vegetable production and environmental impact. In this paper, we used data from 16 field plot experiments to carry out the model calibration and found out that the simulated values of crop dry weight were strongly correlated with the measured values throughout growth in all the experiments with a R2 of 0.9248. Then we choose the field plot 1 to carry out the model validation. The simulated soil mineral N concentration was less satisfactory, although statistically the simulated values of soil mineral N concentration were still correlated fairly well with the measured values (R2 = 0.766). This indicate that the model has the potential to optimize N use and assess the impact of N leaching in eggplant production under the temperate continental monsoon climate of the North China Plain. [Copyright &y& Elsevier]

Abstract: Wheat–maize double cropping is the most important cropping system on the Hebei Plain and is one of the most important cropping systems in China. In a scenario of greater food demand, and increasing water and rural labour scarcity, it is critical that the annual productivity of the system is improved in water-energy-cost efficient and low carbon ways. Based on farm surveys, this paper benchmarked the performance of wheat–maize double crops on the Hebei Plain during the 2004–2005 season. These farm yields were assessed both against experimental yields collected from on-farm maximum yield trials conducted during the same 2004–2005 season and relative to simulated estimates of the climate-driven potential productivity of the region. The survey of 362 farms in six counties of the Hebei Plain during the 2004–2005 season found wheat yields ranging from 3375kgha−1 to 9000kgha−1 with an overall average yield of 6556kgha−1. Maize yields averaged 7549kgha−1 and ranged from 3375kgha−1 to 11,250kgha−1. The aggregate production for the wheat–maize double crops grown in the 2004–2005 season averaged 14,105kgha−1 across the six counties. This was 72% of the average production (19,586kgha−1) recorded from on-farm trials conducted in each of the six counties and 60% of the simulated average production potential (24,147kgha−1) for the Hebei Plain in the 2004–2005 season. Thus, the annual productivity of the current cropping system could be increased with currently available technologies by 28%, while a yield increase of 42% is possible if farm yields approach the simulated yield potential. Based on farmer interviews and field observations, a number of real and perceived reasons for the current yield gaps in farmers’ fields were recognised. For instance, irrigation at stem-elongation of wheat is a current recommendation, yet only a proportion of the surveyed farmers were able to follow this strategy due to lack of access to shared irrigation facilities. Improving the region''s infrastructure to enable more timely irrigation of crops will be a necessary prerequisite to improved productivity. The results from the farm surveys and on-farm trials indicate that, with current recommended practices, farmers can improve their annual farm productivity and close the current yield gaps. However, the survey identified that increasing system performance and efficiency will require a focus on both agronomic and socio-economic issues. [Copyright &y& Elsevier]

Summary: Groundwater overdraft threatens the future of irrigated agriculture in the North China Plain. Because irrigated winter wheat is the dominant user of extracted groundwater, improved understanding of water cycling through the soil–plant–atmosphere continuum during wheat cultivation in the North China Plain is necessary for improving the sustainable utilization of limited water resources and promoting food security. In this paper, a combination of micrometeorological and stable isotope techniques was used to investigate evapotranspiration and soil water dynamics in a typical winter wheat agro-ecosystem (Luancheng Agro-ecosystem Experiment Station, Hebei Province). Stable isotope mixing models were used with eddy covariance evapotranspiration estimates and micro-lysimeter evaporation measurements to partition evapotranspiration and determine temporal variability of root water uptake depths. Results suggest that evaporation during the winter wheat irrigation season can reach up to 30% of the total water consumption (almost two typical irrigations). The main depths of root water uptake were 0–40cm. Therefore, it is suggested that the planned irrigation wetting depth can be reduced at least to 40cm, rather than the traditional 100cm, as a means of water conservation. Widespread implementation of these practices could amount to a significant water savings for the North China Plain. [Copyright &y& Elsevier]

Abstract: The North China Plain (NCP) is one of the main productive regions for winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) in China. However, water-saving irrigation technologies (WSITs), such as sprinkler irrigation technology and improved surface irrigation technology, and water management practices, such as irrigation scheduling have been adopted to improve field-level water use efficiency especially in winter wheat growing season, due to the water scarcity and continuous increase of water in industry and domestic life in the NCP. As one of the WSITs, sprinkler irrigation has been increasingly used in the NCP during the past 20 years. In this paper, a three-year field experiment was conducted to investigate the responses of volumetric soil water content (SWC), winter wheat yield, evapotranspiration (ET), water use efficiency (WUE) and irrigation water use efficiency (IWUE) to sprinkler irrigation regimes based on the evaporation from an uncovered, 20-cm diameter pan located 0–5cm above the crop canopy in order to develop an appropriate sprinkler irrigation scheduling for winter wheat in the NCP. Results indicated that the temporal variations in SWC for irrigation treatments in the 0–60-cm soil layer were considerably larger than what occurred at deeper depths, whereas temporal variations in SWC for non-irrigation treatments were large throughout the 0–120-cm soil layer. Crop leaf area index, dry biomass, 1000-grains weight and yield were negatively affected by water stress for those treatments with irrigation depth less than 0.50E, where E is the net evaporation (which includes rainfall) from the 20-cm diameter pan. While irrigation with a depth over 1.0E also had negative effect on 1000-grains weight and yield. The seasonal ET of winter wheat was in a range of 206–499mm during the three years experiments. Relatively high yield, WUE and IWUE were found for the irrigation depth of 0.63E. Therefore, for winter wheat in the NCP the recommended amount of irrigation to apply for each event is the total 0.63E that occurred after the previous irrigation provided total E is in a range of 30–40mm. [Copyright &y& Elsevier]

Abstract: Serious water deficits and deteriorating environmental quality are threatening agricultural sustainability in the North China Plain (NCP). This paper addresses spatial and temporal availability of water resources in the NCP, identifies the effects of soil management, irrigation timing and amounts, and crop genetic improvement on water use efficiency (WUE), and then discusses knowledge gaps and research priorities to further improve WUE. Enhanced irrigation and soil nutrient (mainly nitrogen) management are the focal issues in the NCP for enhancing WUE, which are shown to increase WUE by 10–25% in a wheat–maize double cropping system. Crop breeding has also contributed to increased of WUE and is expected to play an important role in the future as genetic and environmental interactions are understood better. Agricultural system models and remote sensing have been used to evaluate and improve current agronomic management practices for increasing WUE at field and regional scales. The low WUE in farmer''s fields compared with well-managed experimental sites indicates that more efforts are needed to transfer water-saving technologies to the farmers. We also identified several knowledge gaps for further increasing WUE in the NCP by: (1) increasing scientific understanding of the effects of agronomic management on WUE across various soil and climate conditions; (2) quantifying the interaction between soil water and nitrogen in water-limited agriculture for improving both water and nitrogen-use efficiency; (3) improving irrigation practices (timing and amounts) based on real-time monitoring of water status in soil-crop systems; and (4) maximizing regional WUE by managing water resources and allocation at regional scales. [Copyright &y& Elsevier]

The North China Plain is the political and economic center of China, and it is also the area most seriously affected by groundwater exploitation. Therefore, it is crucial to model and predict groundwater levels in the North China Plain. In this study, using data from groundwater monitoring stations in the North China Plain from 2010 to 2018, wavelet analysis was applied to study the periodicity of shallow groundwater depths in the region, and a spectrum analysis model was established to simulate and predict the groundwater depth in the North China Plain. The results showed a strong correlation between the first significant period and the distance of the station from the Yellow River. The periodic characteristics obtained by the wavelet analysis were substituted into the spectrum analysis model. This improvement significantly increased the accuracy of the modeling results. Moreover, the application of the improved model showed that the groundwater depth in the North China Plain will increase the following year, except for most of Beijing and the coastal areas. Through the study, we understood the dynamic and periodic characteristics of the groundwater level, and proposed a combined method of wavelet analysis and spectrum analysis for groundwater level simulation and prediction, and these results have important guiding for the comprehensive development and protection of groundwater. [ABSTRACT FROM AUTHOR]

Hydraulic conductivity is a basic property of rocks and soil, and its estimation varies as a function of the scale and purpose of the study. This work combines geomorphological analysis, geological data, and groundwater investigations from literature to assess large-scale anisotropies in hydraulic conductivity in the North China Plain. The study area encompasses 144,000 km2 and represents the most important groundwater system of China, affected in the last 40 years by severe groundwater depletion, pollution, and subsidence. The investigation area is at the center of a massive groundwater project, the South to North Water Transfer Project, which was designed and implemented to alleviate water scarcity and facilitate environmental recovery. A conceptual model based on geomorphological evidence, supported by borehole logs, and satellite image analysis is used to assess the hydraulic conductivity anisotropies at the regional scale. The model divides the alluvial plain into four geomorphological zones with similar hydraulic conductivity characteristics. Along the general groundwater flow direction, upstream hydraulic conductivity is assumed isotropic but strong anisotropies are deduced downstream. An accurate hydraulic conductivity assessment is essential to improve quantitative studies of contaminant transport, artificial aquifer recharge, and land subsidence in the North China Plain and elsewhere. [ABSTRACT FROM AUTHOR]

Accurate characterization of heterogeneity in groundwater basins is crucial to the sustainable management of groundwater resources. This study explores the temporal sampling issues and the role of flux measurements in the characterization of heterogeneity in groundwater basins using numerical experiments. The experiments involve a digital basin imitating the groundwater basin of the North China Plain (NCP), where the groundwater exploitation reduction program is ongoing. Using the experiments, we champion that the reduction program could collect groundwater level information induced by operational variations of existing pumping wells at different locations in the basin. Such a dataset could serve as a basin‐scale hydraulic tomography (HT) to characterize the basin‐scale heterogeneity cost‐effectively. Both steady‐state and transient‐state inversion experiments demonstrate the advantage of HT surveys in characterizing basin‐scale heterogeneity over conventional pumping tests at fixed well locations. Additionally, head data at the early, intermediate, and late time from well hydrographs should be selected for the HT analysis to maximize HT's power and save computational costs. When accurate geological zones are incorporated in prior information, flux measurements significantly improve parameter estimates based on conventional pumping tests. However, their effects are less noticeable for long‐term HT surveys in such basin‐scale aquifers without fissures or fractures. This basin‐scale tomographic survey example serves a guide for field data collection and optimization of the analysis of future basin‐scale HT. [ABSTRACT FROM AUTHOR]

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The fall armyworm Spodoptera frugiperda, an invasive insect pest native to the Americas, has established populations throughout eastern China. The North China Plain—a key corn‐producing area in East China with a unique topography—was invaded by fall armyworm in 2019 and is seriously threatened by this migratory pest. However, the spatiotemporal extent of the migratory movements of fall armyworm from the North China Plain remains poorly understood. Using an air transport‐based trajectory modeling approach that incorporates flight behavior, we simulated the potential nocturnal migration trajectories of fall armyworm from the North China Plain based on historical meteorological data from June to October of 2015–2019, and examined the night‐time atmospheric conditions associated with their possible flights. The emigration patterns showed monthly variation in the main landing area and common migration direction. The displacement of newly emerged moths from the North China Plain was concentrated in the Northeast China Plain (including Liaoning, Jilin and Heilongjiang provinces) before late summer, after which they were most likely to undertake return flights to the south (especially into Hubei, Anhui and Hunan provinces). This southwest‐northeast aerial migration corridor follows the topography of East China and is affected by the East Asian monsoon. These topographic‐atmospheric conditions have resulted in the North China Plain becoming a key stopover for fall armyworm populations engaging in multigenerational long‐distance migration across East China. These findings contribute to our knowledge of fall armyworm migration and will aid in the implementation of management and control strategies against this highly migratory agricultural pest. [ABSTRACT FROM AUTHOR]