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Our study examined the relationships between riparian plant communities and their soil properties along the midstream of the Heihe River in northwestern China's arid region. Significant variations in species composition were observed across the upper, middle, and lower reaches of this midstream (adonis2 and anosim, p < 0.001). The lower reaches exhibited higher species diversity (Shannon index up to 2.12) compared to the other reaches. Gramineous plants, particularly Agropyron cristatum (L.) Gaertn. and Equisetum ramosissimum Desf., dominated all reaches, with relative abundances exceeding 50% in the upper reach sites. The soil ionic concentration showed distinct spatial heterogeneity, peaking at site 9 (upper reaches) and lowest at site 3 (lower reaches). Species diversity indices negatively correlated with SO42−, Mg2+, and Ca2+ concentrations, while salt-tolerant species like Agropyron cristatum (L.) Gaertn. and Phragmites australis Trin. positively correlated with Na+ and Cl− levels. Soil nutrients had weaker but notable effects on the distribution of Onopordum acanthium L. and Artemisia argyi H. Lév. and Vaniot. These findings suggest that riparian plant community distribution along the Heihe River is influenced by complex interactions between hydrological processes, salt dynamics, and soil physicochemical properties, such as anion and cation concentrations and electrical conductivity (EC). Our research provides valuable insights for understanding and managing riparian ecosystems in arid regions. [ABSTRACT FROM AUTHOR]

Monitoring the status and dynamics of desertification is one of the most important parts of combating it. In this study, 30 m high-resolution information on land desertification and restoration in the Heihe River basin (HRB) was extracted from the land cover database. The results indicate that land desertification coexists with land restoration in the HRB. In different periods, the area of land restoration was much larger than the area of land desertification in the HRB, and the HRB has undergone land restoration. Upstream of the HRB, there is a continuing trend of increasing land desertification associated with overgrazing in a context where climate change favors desertification reversal. In the middle and lower reaches, although climate variability and human activities favor land desertification, land desertification is still being reversed, and land restoration dominates. Implementing the eco-environmental protection project and desertification control measures, especially the Ecological Water Distribution Project (EWDP), contributes to the reversal of desertification in the middle and lower reaches of the HRB. However, the EWDP has indirectly led to the lowering of the water table in the middle reaches, resulting in local vegetation degradation. Therefore, there is an urgent need to transform the economic structure of the middle reaches to cope with water scarcity and land desertification. [ABSTRACT FROM AUTHOR]

Objective The alpine region is the source area of many large rivers globally, and understanding river-groundwater interactions in the region is critical to the scientific management of watershed water resources. Due to the widespread occurrence of permafrost, the distribution and dynamics of riverbed taliks play a vital role in controlling river-groundwater exchange in alpine regions, leading to the complex, unique characteristics of the hydraulic relationship between them. However, there have been few investigations on river-groundwater interactions in alpine regions due to the harsh field conditions, and these available studies have dominantly used isotope and hydrochemical tracing methods, which are expensive and not accurate. Methods In this study, the low-cost and accurate temperature signal was used as a tracer to quantify the exchange between river and groundwater. A vertical 1D transient heat transport analytical model was used to quantify river-groundwater exchange rates at different depths. The spatiotemporal variations in river-groundwater interactions were analyzed using the temperature data measured by a distributed optical fibre sensing system. Results Results show a substantial spatiotemporal variation in the exchange between river and groundwater in alpine regions. Season and climate can control the exchange rate between river and groundwater, and even the direction of exchange. It is also found that the exchange rate of river and groundwater increases with the depth of the active layer. Conclusion The study indicates that the temperature tracing method is suitable for studying river-groundwater interactions in alpine areas dominated by permafrost. Furthermore, the combination of two temperature tracing methods can effectively improve the accuracy and provide a feasible research framework for alpine regions where hydrogeological data are scarce.

The operation of cascade reservoir systems has altered river hydrology and sediment distribution patterns. In this study, 31 surface water and sediment samples were collected from the Heihe River from July to August in 2019 and 2020 to investigate the spatial distribution and sources of heavy metals and assess their ecological risks. The results revealed that the concentrations of heavy metals in surface water were much lower than the quality standards for surface water in China, and there were no significant differences in the natural reaches, center and tail of the reservoir. Cd in surface sediments was at a heavy contamination and high risk level, and the heavy metal pollution levels in the main streams and tributaries differed greatly, especially in the graded reservoirs with a gradual accumulation trend. This may be related to the fact that there were many fine-grained sediments in the reservoir center near the dam. Factor analysis-multiple linear regression (FA-MLR) revealed that heavy metals mainly come from natural factors and anthropogenic input, with anthropogenic inputs mainly coming from mining activities in the tributaries and industrial and agricultural activities in the main stream. HIGHLIGHTS The effects of cascade dam construction on the spatial distribution of heavy metals in surface water and sediments of Heihe River in China were systematically studied.; The operation of cascade dams has a significant effect on the spatial distribution of heavy metals in surface sediments.; Heavy metals pollution and ecological risk of surface sediments were mainly concentrated for natural river sections in tributaries.;

Oasis degradation and terminal lake shrinkage are prevalent consequences of the disputed distribution of water resources in inland river basins, hindering regional sustainable development. The Ecological Water Diversion Project (EWDP) is regarded as an important measure to restore the desert-oasis ecosystem in inland river basins, and thus it is essential to comprehensively evaluate the response of eco-hydrological and socioeconomic systems to the EWDP. Based on multiple indicators, we used trend analysis, linear regression, partial least square regression, and structural equation model to disentangle the quantitative effects of the EWDP on the change of eco-hydrological and socioeconomic conditions in the Ejina Oasis (EO) in the lower reaches of the Heihe River in northwest China. Our results indicate that the ecological deterioration was prevalent before the execution of the EWDP, including the increase of groundwater depth, the disappearance of lakes, the decrease of NDVI. After the EWDP, runoff released to EO increased 69.15%, the mean groundwater depth decreased 0.48 m, 52.28% of the study area showed a significant increase in NDVI, areas of forest and grassland increased 20.17 and 25.65 km2, respectively. The EWDP improved the hydrological regime and prompted the recovery of the oasis. Besides, socioeconomic development was facilitated under the restoration of the eco-hydrological conditions, characterized by the expansion of farmland and the thrive of the tourism industry. The hydrological variables promoted the improvement of the ecological condition with a direct strength of 0.93 and facilitated the development of the socioeconomic conditions in EO with an indirect strength of 0.84. Runoff was the most important positive contributor both to the NDVI and GDP in EO. This comprehensive evaluation framework can offer valuable insight for water resources management and sustainable development in the inland river basin of arid areas. [ABSTRACT FROM AUTHOR]

Rates of river incision are widely used to track changes in rock uplift rate and climate over time and space. However, the relationship between the spatiotemporal variation of river incision and past tectonic or climatic processes is still unclear. Here, we focus on the spatial patterns of river incision in the interior and front of the Qilian Shan in the northeastern Tibetan Plateau. A sequence of late Quaternary terraces is well preserved along the Heihe River across the central Qilian Shan. We complement existing chronologic data with five new optically stimulated luminescence ages and one cosmogenic radionuclide 10Be exposure age of terrace abandonment. At the mountain front, the river incision rate was ∼1 mm/yr over the past 100 kyr, while the range was from 2 to 7 mm/yr during the Holocene. We attribute the fast incision rates during the Holocene to the progressive decrease of the river gradient induced by the warm and wet Holocene climate. In the interior of the mountains (the Qilian basin site), the river incision rates were close to 1 mm/yr since ∼53 ka, suggesting that the upstream incision rate remained stable from the late Pleistocene to the Holocene. This observation further suggests that the adjustment of the climate-induced longitudinal river profile is limited to the downstream reach, especially along the front of the mountain range. We conclude that the long-term incision rate (during the late Pleistocene) is explained by ongoing uplift driven by fault activity, which determines the background rate of fluvial incision (∼1 mm/yr). On the other hand, denudation rates on the millennial timescale estimated by previous studies in this region are < 1 mm/yr, suggesting that landscape-scale erosion lags behind trunk river incision.

Surface water–groundwater interactions in arid zones are characterized by water exchange processes in a complex system comprising intermittent streams/terminal lakes, shallow aquifers, riparian zone evapotranspiration, and groundwater withdrawal. Notable challenges arise when simulating such hydrological systems; for example, field observations are scarce, and hydrogeological parameters exhibit considerable spatial heterogeneity. To reduce the simulation uncertainties, in addition to groundwater head and river discharge measurements, we adopted remote sensing-based evapotranspiration data and lake area dynamics as known conditions to calibrate the model. We chose the Ejina Basin, located in the lower reaches of the Heihe River Basin in arid northwest China, as the study area to validate our modelling approach. The hydrological system of this basin is characterized by intensive, spatiotemporally variable surface water–groundwater interactions. The areas of the terminal lakes into which all river runoff flows vary significantly depending on the ratio between river runoff and lake evaporation. Simulation results with a monthly time step from 2000 to 2017 indicate that river leakage accounted for approximately 61% of the total river runoff. Our study shows that for areas where surface water and groundwater observations are sparse, combining remote sensing product data of surface water areas and evapotranspiration can effectively reduce the uncertainty in coupled surface water and groundwater simulations. [ABSTRACT FROM AUTHOR]

Spatial variations in grain size parameters can reflect river sediment transport patterns and depositional dynamics. Therefore, 22 surficial sediment samples taken from the Heihe River and its cascade reservoirs were analyzed to better understand the impact of cascade reservoir construction on sediment transport patterns in inland rivers in China. The results showed that the longitudinal distribution of sediment grain size in the Heihe River was significantly affected by the influence of the cascade reservoirs. The retention rate in the cascade reservoir of the Heihe River reached 79% (193.53 Mt/year), which caused most of the fine sand to accumulate in the reservoir, and the sediment fining degree reached approximately 50%. However, the water discharged from the dam caused serious erosion of the riverbed and coarsening of the sediment, and the coarsening degree was approximately 500%. The backwater zone of the reservoir was influenced by both backwater and released water, and the coarsening degree of sediment was approximately 101%. Sedimentary environmental analysis revealed that the characteristics of the sediment grain size in an upstream tributary of the Heihe River were more influenced by source material than by hydrodynamic conditions, while the grain size characteristics of the mainstream sediments were controlled mainly by hydrodynamic conditions. The characteristics of sediment transport in different reaches of the Heihe River were studied, and the results may provide references for the operation of cascade reservoirs and the sediment control of reservoirs. [ABSTRACT FROM AUTHOR]

Huangzangsi reservoir is a key control regulation and storage project in the main stream of Heihe River. The reservoir is developed with multi?objectives and the water supply objects refer to the natural ecology, national defense scientific research of Ejina Oasis in the lower reaches, irrigation, industrial, domestic and power generation use in the middle reaches of Ejina Oasis. In addition, the middle reaches of Heihe River has the characteristics of repeated conversion and reuse of surface water and groundwater, complex boundary conditions and man? y limiting factors, which brings great difficulties to the demonstration of reservoir regulation capacity. According to the reservoir development task of “rational allocation of ecological, economic and social water use in the middle and lower reaches of the Heihe River, improving the comprehensive management capacity of water resources of the river, taking into account the comprehensive utilization of power generation and other comprehensive utilization”, based on the different water demand characteristics and requirements of the middle and lower reaches of the Heihe River within the reservoir water supply range, according to the reservoir operation mode, using the Heihe dual structure water resources allocation model, a multi?scheme and long series runoff regulation calculation was carried. According to the comprehensive analysis, it is rec? ommended that the regulating capacity of Huangzangsi Reservoir should be 295 million m 3, which can meet the needs of water diversion scheme, water supply, irrigation and power generation of Heihe River and help to upgrade the integrated management of water resources of Heihe River. [ABSTRACT FROM AUTHOR]

The Heihe River has entered the period of rich water for more than ten years. In order to reasonably predict the water inflow process in the upper reaches of the Heihe River, reduce the effect of dry season on the agricultural water use in the middle reaches and the ecological water use in the lower reaches, and provide reference for flood-control work of the Huangzangsi Water Conservancy Project which is being built on the upper reaches of Heihe River main stream, the approaches such as M-K Based mutation analysis, Morlet continuous wave- let transform analysis and R/ S analysis were employed to predict the annual runoff evolution of Yingluo Gorge in the upper reaches of Heihe River main stream. In accordance with the results, the following conclusions can be drawn: the annual runoff of Yingluo Gorge has an overall upward trend from 1954 to 2017. In 2011, a sudden change occurred, which was the abrupt change point, and since then, the trend has been significantly upward. The datum show that the average annual runoffs from 2011 to 2017 are always higher than 423 million m 3 which is the average runoff for many years and that the annual average runoff from 1954 to 2010 is lower than 51 million m 3 which is the average runoff for many years. The annual runoff of Yingluo Gorge is mainly affected by two main periods. According to the periodic variation, there is a continuous upward trend for the annual runoff of Yingluo Gorge under the influence of the first main period. However, there also exists the fluctuation in the upward trend with the transition from peak period to alley period in the second main period. Hurst index indicates that there exists a long-term correlation characteristic in the annual runoff of Yingluo Gorge, and that there is a great possibility that the overall change trend of the annual runoff in the future will be consistent with the past. It means that the annual runoff of Yingluo Gorge will probably keep an up-ward trend. [ABSTRACT FROM AUTHOR]

Water and energy fluxes are inextricably interlinked within the interface of the land surface and the atmosphere. In the regional earth system models, the lower boundary parameterization of land surface neglects lateral hydrological processes, which may inadequately depict the surface water and energy fluxes variations, thus affecting the simulated atmospheric system through land‐atmosphere feedbacks. Therefore, the main objective of this study is to evaluate the hydrologically enhanced regional climate modelling in order to represent the diurnal cycle of surface energy fluxes in high spatial and temporal resolution. In this study, the Weather Research and Forecasting model (WRF) and coupled WRF Hydrological modelling system (WRF‐Hydro) are applied in a high alpine catchment in Northeastern Tibetan Plateau, the headwater area of the Heihe River. By evaluating and intercomparing model results by both models, the role of lateral flow processes on the surface energy fluxes dynamics is investigated. The model evaluations suggest that both WRF and coupled WRF‐Hydro reasonably represent the diurnal variations of the near‐surface meteorological fields, surface energy fluxes and hourly partitioning of available energy. By incorporating additional lateral flow processes, the coupled WRF‐Hydro simulates higher surface soil moisture over the mountainous area, resulting in increased latent heat flux and decreased sensible heat flux of around 20–50 W/m2 in their diurnal peak values during summertime, although the net radiation and ground heat fluxes remain almost unchanged. The simulation results show that the diurnal cycle of surface energy fluxes follows the local terrain and vegetation features. This highlights the importance of consideration of lateral flow processes over areas with heterogeneous terrain and land surfaces. [ABSTRACT FROM AUTHOR]

The development and utilization of water resources in HeiheRiver basin have brought about ecological and environmental problems for a long time. With the continuous development of the basin economy and society, contradictions between agricultural irrigation water and ecological water oasis are increasing. After the completion and operation of the Huangzangsi Water Control Project, which is located on the upstream of Heihe River, it will control 65%-84% of the total inflow from the upstream of the river and will be in the core of Heihe River water resources project management system. In order to give full play to the Huangzangsi Water Control Project the important role of water allocation in the Heihe River, based on the investigation and collection of hydrology and meteorology of the main river, water use law and water conveyance efficiency in the middle and lower reaches, the design standard of the project and cascade hydropower stations on the lower reaches, it established an optimal scheduling model, formulated the satisfactory solution assessment standard and determined the reservoir operation scheme by using multi-objective genetic algorithm model. The results show that the model can effectively improve the scientificity and fairness of Heihe water resources dispatching and has higher operability and flexibility, which can provide theoretical support for the dispatching operation of Huangzangsi Water Control Project. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Actinobacteria are known for their metabolic potential of producing diverse secondary metabolites such as antibiotics. Actinobacteria also playimportant roles in biogeochemical cycling and how soils develop. However, little is known about the effect of the vegetation type on the actinobacterial community structures in soils from arid regions. For these reasons, we have analyzed the actinobacterial communities of five types of ecosystem (tree grove, shrub, meadow, desert, and farm) in the Heihe river basin. Using 16S rRNA high-throughput sequencing, we found 11 classes of Actinobacteria, with dominant classes of Actinobacteria (36.2%), Thermoleophilia (28.3%), Acidimicrobiia (19.4%). Five classes, 15 orders, 20 families and 36 genera were present in all samples. The dominant generalist genera were Gaiella, Solirubrobacter, Nocardioides, Mycobacterium, and Pseudonocardia. The actinobacterial community structures were significantly affected by the environment and vegetation type. The diversity of the actinobacterial community in the desert ecosystem was high, and this ecosystem harbored the highest proportion of unclassified sequences, representing rare Actinobacteria. Functional metagenomic prediction, using PICRUSt, indicated that Actinobacteria play an important role in nitrogen cycling in both desert and cultivated farm ecosystems.

River basin cyberinfrastructure with the Internet of Things (IoT) as the core has brought watershed data science into the big data era, greatly improving data acquisition and sharing efficiency. However, challenges in analyzing, processing, and applying very large quantities of observational data remain. Given the observational needs in watershed research, we studied the construction of river basin cyberinfrastructure and developed an integrated observational data control system (IODCS). The IODCS is an important platform for processing large quantities of observational data, including automated collection, storage, analysis, processing, and release. This paper presents various aspects of the IODCS in detail, including the system’s overall design, function realization, big data analysis methods, and integrated models. We took the middle reaches of the Heihe River Basin (HRB) as the application research area to show the performance of the developed system. Since the system began operation, it has automatically received, analyzed, and stored more than 1.4 billion observational data records, with an average of more than 14 million observational data records processed per month and up to 21,011 active users. The demonstrated results show that the IODCS can effectively leverage the processing capability of massive observational data and provide a new perspective for facilitating ecological and hydrological scientific research on the HRB.

Knowledge of the composition of modern fluvial sediments is important for understanding the combined effect of lithology and climatic factors on the erosion and sedimentation within drainage basins, However, this information is incomplete in arid and semiarid environments. In this study, 37 modern fluvial sediment samples were collected from the Heihe River and its major tributaries, in the NE Tibetan Plateau, and for analyses of heavy minerals, trace and rare earth elements (REEs) and grain size. The main aim was to explore the influence of erosion, transport and deposition processes on sediment composition, and to define appropriate provenance indicators specific to these rivers. Along the Heihe River, the amount of unstable minerals is abundant and not changing, these result suggests that chemical weathering plays only a minor role. The composition of six sediment samples obtained from the upper-middle reaches of Heihe River are influenced by hydrodynamic sorting processes, which resulted in enrichment of heavy minerals. In addition, the mineralogical and geochemical compositions lead to different conclusions regarding the contributions from tributaries to the sediments in the middle-lower reaches of the Heihe River. This may reflect the occurrence of contrasting hydrodynamic conditions in Heihe River and its tributaries which result in the transport of different size fractions. Moreover, the <63 μm fraction of the sediments from the Heihe River basin has been affected by inputs of eolian dust, which means that this fraction is less influenced by the rock types within the sediment source areas than is the case for the other size fractions. Therefore, we conclude that the sand fraction is more suitable for source to sink analysis of fluvial sediments within this and comparable environments. In the upper areas of the Fengle River basin, the combination of low temperature, sparse vegetation coverage and high precipitation have resulted in intense erosion. This case reminds us to note the effect of the climatic zonation on the provenance analysis in arid regions. [ABSTRACT FROM AUTHOR]

Estimation of the leakage rate from riverbeds is an important task to quantify the interaction between surface and ground waters and to perform effective management of water resources, especially under arid climate conditions, where leakage from riverbeds helps to preserve the existence of riparian ecosystems. One of the methods for estimating the leakage rate from a riverbed is the use of diurnal temperature oscillations in riverbed sediments. The data from monitoring the temperature of the sediments in the lower reaches of the Heihe riverbed (northwestern China) are used to calculate the leakage rate from the riverbed. The results of the leakage rate calculations are compared to the data obtained by solving an inverse problem using the one-dimensional model of heat and moisture transfer in the riverbed sediments according to the data of the annual observation cycle. Good agreement of the calculated and model leakage rates is observed when the temperature sensors, whose data are used for the calculation of the leakage rates, are spaced at a significant distance (≥0.3 m) and at a depth greater than 0.3 m. [ABSTRACT FROM AUTHOR]

Large hydrologic basins involve multiple stakeholders, and coupled dynamic social and ecological processes. Managing such basins has long been a challenge. Balancing the demand for water from nature against that from humans is always difficult, particularly in arid watersheds. Here, we analyze potential institutional causes of ecological degradation and how it can be reversed by introducing new forms of governance. The framework and assumptions are illustrated using China's second-largest endorheic basin, where empirical evidence shows that the introduction of a new governing authority connecting midstream and downstream actors facilitated the establishment of a new governance regime that is better aligned with the biophysical scales of the watershed. A trans-regional water allocation project initiated by the new higher-level authority successfully rescued downstream oases and restored a dried terminal lake. These outcomes suggest that when social and ecological structures are better aligned our ability to manage the interplay between social and ecological processes increases. However, the lack of direct connection between the actors of the middle and lower reaches resulted in the paradox of an increase in water demand. We therefore suggest that measures to stimulate the emergence of horizontal social ties linking different critical groups of actors across the watershed could further the alignment of the institutional and biophysical structures—without these changes sustainable management of river basins and other common pool resources will remain problematic. [ABSTRACT FROM AUTHOR]

Actinobacteria are known for their metabolic potential of producing diverse secondary metabolites such as antibiotics. Actinobacteria also playimportant roles in biogeochemical cycling and how soils develop. However, little is known about the effect of the vegetation type on the actinobacterial community structures in soils from arid regions. For these reasons, we have analyzed the actinobacterial communities of five types of ecosystem (tree grove, shrub, meadow, desert, and farm) in the Heihe river basin. Using 16S rRNA high-throughput sequencing, we found 11 classes of Actinobacteria, with dominant classes of Actinobacteria (36.2%), Thermoleophilia (28.3%), Acidimicrobiia (19.4%). Five classes, 15 orders, 20 families and 36 genera were present in all samples. The dominant generalist genera were Gaiella , Solirubrobacter , Nocardioides , Mycobacterium , and Pseudonocardia. The actinobacterial community structures were significantly affected by the environment and vegetation type. The diversity of the actinobacterial community in the desert ecosystem was high, and this ecosystem harbored the highest proportion of unclassified sequences, representing rare Actinobacteria. Functional metagenomic prediction, using PICRUSt, indicated that Actinobacteria play an important role in nitrogen cycling in both desert and cultivated farm ecosystems. [ABSTRACT FROM AUTHOR]

For the Heihe River basin, the effective improvement of the capacity of comprehensive management is inseparable from the guidance, promotion, regulation and guarantee of the rules and laws, especially of the legislation. According to the reality and development trend of the Heihe River basin management, the necessity of the formulation of “Regulation on the Administration of the Heihe River Basin” is based on the following five aspects, including the strengthening of comprehensive management of the Heihe River basin, the promotion of construction of ecological civilization, the application of the strictest water resources control system, the guarantee of construction and operation of the water conservancy key project and the improvement of the legalization of river basin management. In terms of environment, timing, basis and reference of legislation, the feasibility of formulating the “Regulation on the Administration of the Heihe River Basin” was discussed and the legislative framework of the regulation was proposed by this article. [ABSTRACT FROM AUTHOR]

In this study, the discharge ofLangxinshan Hydrometric Station was used to calculate the river discharge entering into Ejina Oasis during the period of winter and spring (from November to following March) since the regular regulation of the Heihe River by the mathematical statistics and correlation analysis. The results indicate that the discharge in winter and spring period is stable in interannual variation and mostly accounts for 34% of the whole year. With the guarantee rates of 25%, 50% and 75%, the water supply of Ejina Oasis from Langxinshan Station is 193 million m3, 145 million m3 and 86 million m3 respectively. Based on above results and the ecological water requirement of Ejina Oasis, a reasonable water allocation scheme has been proposed that when the discharge of the main stream is 25%, 50% and 75% guaranteed, the input discharge ratio of east and west branch channels is 57∶43, 61∶39 and 70∶30 respectively. [ABSTRACT FROM AUTHOR]

The evaporation and leakage of continental river channel seriously affect the efficiency of water transportation and management of water resources in arid region. In order to realize the optimal allocation of the Heihe River ecological water transfer, it is necessary to quantify the amount of river loss accurately. In this article, the relationship between discharge and the surface area of river was established based on the observed hydrological data and the area interpreted by remote sensing. With the relationship and meteorological data, the evaporation and leakage of LangxinshanZhengyixia section were calculated respectively by water balance method. The results show that the channel leakage is the mainly water loss in the lower reaches of the Heihe River. The annual leakage of ZhengyixiaLangxinshan section is about 277 million m3 and the evaporation is about half of the leakage. For different reaches, the evaporation and leakage of ZhengyixiaShaomaying section are about 3-5 times of the ShaomayingLangxinshan section respectively, while the trends of the two sections are basically the same. [ABSTRACT FROM AUTHOR]

Significant uncertainty remains in understanding the groundwater flow pathways in the northeastern Qinghai–Tibet Plateau. Hydrogeochemical and isotopic data as well as hydrogeological data were combined to explore the groundwater flow path in a representative cold alpine catchment in the headwater region of the Heihe River. The results indicate that the suprapermafrost groundwater chemical components were mainly affected by calcite dissolution and evaporation, whereas the geochemistry of subpermafrost groundwater was controlled by dolomite and gypsum dissolution, calcite precipitation, and albite and halite dissolution. Distinct hydrogeochemical characteristics and controlling processes suggest a poor hydraulic connectivity between the suprapermafrost and subpermafrost groundwater. The hydraulic connectivity between permafrost groundwater and groundwater in the seasonally frozen area was confirmed by their similar hydrogeochemical features. In the seasonally frozen area, a silty clay layer with low permeability separates the aquifer into the deep (depth >20 m) and shallow (depth <20 m) flow paths. The deep groundwater was characterized by the enhanced dedolomitization and enhanced cation exchange processes compared with the shallow groundwater. Groundwater in the seasonally frozen area finally discharges as base flow into the stream. These results provide useful information about the groundwater flow systems in the unique alpine gorge catchments in Qinghai–Tibet Plateau. The above findings suggest that the permafrost distribution and the aquifer structures within the seasonally frozen area have significant impact on groundwater flow paths. Cross‐validation by drilling work and hydrograph data confirms that the hydrogeochemical and isotopic tracers combined with field investigations can be relatively low‐cost tools in interpreting the groundwater flow paths in similar alpine catchments. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In northwestern China, many historical nomadic kingdoms and Chinese dynasties sought to control the Heihe River basin, an important location on the eastern part of the ancient Silk Road. Archaeologists have argued that changes in material culture are tied to the frequent turnover in polities in the area, but no published evidence supports these claims. In this paper, we evaluate the relative importance of environmental and political factors in determining the spatiotemporal pattern of archaeological sites in the middle and lower reaches of the Heihe River basin by using previously published high-resolution paleoclimate records and a variety of historical documents. Our results indicate that humans intensively exploited the Heihe River basin during Han dynasty (202BC–AD 220). Following the Han dynasty, during the Wei-Jin (AD 222–589) and Sui-Tang (AD 581–907) periods the number of archaeological sites. In the Western Xia-Yuan period (AD 1038–1368), people mainly settled in the lower reaches of the Heihe River basin and only returned to the middle reaches of the Heihe River basin during the Ming and Qing dynasties (AD 1368–1912). Although climate change and the local environment affected human activities in Heihe River basin, geopolitical events, such as forced mass migrations, are more responsible for influencing the distribution of archaeological sites over the past 2000 years. [ABSTRACT FROM AUTHOR]

Graphic abstract Highlights • The uplift history of the northeastern margin of the Tibetan Plateau is investigated based on river sands detrital apatite fission track data. • Before the Indian-Asian collision, the North Qilian Shan had already uplifted. • The mountain-river-basin patterns were established in the early Miocene. Abstract Thermochronometry of modern river sands exploits the natural sampling of detritus in a river catchment to infer plausible regional exhumation patterns, when combined with available bedrock thermochronometric information. Apatite fission track age distributions for six detrital samples are reported in this study to resolve the exhumation history of the upper reaches of the Heihe River, draining North Qilian Shan and Tuole Shan, the northeastern margin of the Tibetan Plateau. The apatite fission track (AFT) ages include four major populations: late Paleozoic (300 ± 55–293 ± 43 Ma), early Mesozoic (223 ± 15–205 ± 17 Ma), late Jurassic-Cretaceous (112 ± 6.2–84.8 ± 5.6 Ma), and Cenozoic (63.8 ± 5.9–19.3 ± 1.7 Ma). The ages of these populations correspond well with the deformation and cooling history of the study area. The late Paleozoic and early Mesozoic AFT age populations record cooling events resulting from continental collision between the Qiantang and Kunlun blocks. The late Jurassic-Cretaceous AFT age populations are interpreted to record cooling events associated with exhumation of North Qilian Shan and Tuole Shan due to the collision of the Lhasa block with Asian continent. The Cenozoic AFT age populations record several cooling events. A cooling event is recorded corresponding to exhumation of North Qilian Shan and Tuole Shan due to late stress from the Lhasa-Asia collision, causing deformation nearly synchronous with the India-Asia collision. Another cooling event is recorded corresponding to uplift and exhumation in Oligocene time due to ongoing India-Asia convergence. North Qilian Shan and Tuole Shan were constructed as a distal effect of India-Asia convergence in the early Miocene while approaching their present mountain-river-basin distributions. Thermochronometry applied to Heihe River sediments provide convinced evidence of multi-stage exhumation of most northeastern margin of the Tibetan Plateau in the late Paleozoic-Cenozoic. [ABSTRACT FROM AUTHOR]

Highlights • Clogging complicates the interpretations of falling head tests. • The modified Hvorslev formula allows us to account for the clogging process. • Field investigations demonstrate the applicability of the modified Hvorslev formula. Abstract Estimating streambed hydraulic conductivity is particularly important in arid and semi-arid regions, where surface water infiltration from ephemeral dryland streams helps maintain riparian ecosystems. In situ permeameter tests are widely used to estimate the hydraulic conductivity of streambed sediments. Previous studies have demonstrated that one of the major factors controlling spatiotemporal variations in streambed hydraulic conductivity in such areas is streambed clogging by suspended sediments. Recently, a modified Hvorslev (1951) formula was theoretically proposed to account for the effect of streambed clogging on streambed hydraulic properties due to suspended particle sedimentation during falling-head tests. To validate the modified formula, fieldwork was conducted at five sites in the lower Heihe River, a typical intermittent river of north-western China, in September 2017. A simple PVC pipe with an inner diameter of 4 cm was used as a permeameter for the field tests. Both muddy river water and clean water were used to fill the permeameter to conduct comparative tests. To differentiate the interpretation of the field testing data obtained with clean water, the data obtained with muddy river water were analysed with an equation considering an iteratively increasing total hydraulic resistance of riverbed sediments due to the effects of riverbed clogging. The estimated vertical hydraulic conductivity for the top 0.3 m of riverbed sediments varied from 1 to 41 m/day. The proposed model was shown to accurately estimate the hydraulic conductivity of riverbed sediments using both clean and muddy water during slug tests. [ABSTRACT FROM AUTHOR]

In order to make the system bolt most effective in strengthening and supporting the high-steep rock slope, taking the object anchored by the system bolt-the rock mass slope as the starting point, a method of optimizing the design of system bolt parameters of high and steep rock slope based on structural plane combination analysis was proposed. The system bolt design process was established from structural plane combination analysis to determine the optimal unfavorable structural plane, the optimal anchor angle and the optimal bolt length. It was used to optimize the design of the system bolt parameters of the left abutment rock slope of the Huangzangsi Key Water Control Project and calculated by the rigid body limit equilibrium method, so the stability coefficient of the supported rock slope was the largest. The method fully considered the structural planes of different occurrences of rock mass. The system bolt designed by the method had the best effect on the support of excavation slope, which made the design of the system bolt support more scientific, safer and more economical. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The simulations from climate models require bias correction prior to use in impact assessments or when used as predictors in statistical or dynamic downscaling models. Recent works have sought to address each of these limitations and the results are the Multivariate Recursive Nesting Bias Correction (MRNBC) and Multivariate recursive Quantile-matching Nested Bias Correction (MRQNBC) methods. The model was applied to a mountain region of Heihe River. A comparison of the historical and generated statistics shows that the model preserves all the important characteristics of meteorological variables at daily, monthly, seasonally and annual time scales. This study has documented the performance of Multivariate Recursive Nesting Bias Correction to remove the discrepancy between the predictors in the simulated GCM and the reanalysis NCEP data and assess the projected future precipitation accuracy in the headwater region of Heihe River. A relatively high spatial resolution GCM outputs—ACCESS1-3—from the CMIP5 Earth System Models (ESMs) was employed to downscale for the historical 1960-2005 and the future period 2010-2100 under the scenarios of Representative Concentration Pathways RCP4.5 and RCP8.5. The MRNBC method can dramatically increase the performance of the simulated precipitation data. Verified by statistical score metrics applied for evaluation of the results, the developed method appears to be an important statistical tool in the correction of the bias between the GCM output and the reanalysis data, leading to significant improvements in the predictive performance accuracy of the precipitation projections. The projected precipitation under RCP8.5 appeared to exhibit the significant increasing trend relative to the RCP4.5 scenario in the headwater region of Heihe River. Future precipitation will increasing by 8% and 20% for near and long term period under RCP4.5 and increasing 14% and 37% for near and long term period, under RCP8.5, respectively. [ABSTRACT FROM AUTHOR]

In order to analyze Heihe River middle reaches area of the ecological environment change trend and its formation mechanism，this paper selected the 2000 and 2011 study area remote sensing image data to establish the land use type matrix for remote sensing image data analysis. The results show that:a） in 2000-2011，in the middle reaches of Heihe River，the mainly evolution trend of the ecological environment is from the unused land to cultivated land，other types of land use conversion is also frequently; b) the main factors which the trend of the ecological environment are the results of the interaction between the natural factors and human factors, among them, human factor occupies the mainly position. [ABSTRACT FROM AUTHOR]

The Altyn Tagh fault is the northern boundary of Tibetan Plateau. As one of the most well-known strike-slip fault in the world, great achievements on tectonic deformation and Late Quaternary slip rate have been made. However, there is a long-lasting debate on whether the Altyn Tagh fault extends into the Jinta Basin or even eastward. In this paper, we use satellite image interpretation, field investigation, trench excavation, and optical stimulated luminescence dating to study newly found NS striking scarps in the eastern end of Jinta Nan Shan. The results are as follows: firstly, a group of normal faults develop on terrace T2 of Heihe River, the total length amounts to ∼40 km, total scarp height is 30±5 m; secondly, four paleoseismic events have been interpreted from three trenches, approximate ages of events are 79.97±19.14 ka BP, 62.55±13.10∼55.41±10.77 ka BP, before 16.89±2.08 ka BP, 8.52±1.49 ka BP, respectively; thirdly, just like NS normal faults in the western end of Altyn Tagh fault, the newly found NS extensional faults are likely the terminating tectonics of the eastern end of Altyn Tagh fault, the large Altyn Tagh fault may end in the eastern end of Jinta Nan Shan. [ABSTRACT FROM AUTHOR]

Interactions between surface water and groundwater are dynamic and complex in large endorheic river watersheds in Northwest China due to the influence of both irrigation practices and the local terrain. These interactions interchange numerous times throughout the middle reaches, making streamflow simulation a challenge in endorheic river watersheds. In this study, we modified the linear-reservoir groundwater module in SWAT (Soil and Water Assessment Tools, a widely used hydrological model) with a new nonlinear relationship to better represent groundwater processes; we then applied the original SWAT and modified SWAT to the Heihe River Watershed, the second largest endorheic river watershed in Northwest China, to simulate streamflow. After calibrating both the original SWAT model and the modified SWAT model, we analyzed model performance during two periods: an irrigation period and a non-irrigation period. Our results show that the modified SWAT model with the nonlinear groundwater module performed significantly better during both the irrigation and non-irrigation periods. Moreover, after comparing different runoff components simulated by the two models, the results show that, after the implementation of the new nonlinear groundwater module in SWAT, proportions of runoff components changed-and the groundwater flow had significantly increased, dominating the discharge season. Therefore, SWAT coupled with the non-linear groundwater module represents the complex hydrological process in the study area more realistically. Moreover, the results for various runoff components simulated by the modified SWAT models can be used to describe the hydrological characteristics of lowland areas. This indicates that the modified SWAT model is applicable to simulate complex hydrological process of arid endorheic rivers. [ABSTRACT FROM AUTHOR]

Groundwater is a major driving force for plant community distribution in arid areas worldwide. Although it is well known that groundwater has a significant impact on soil and vegetation, there is little information on how groundwater depth affects soil and vegetation in an arid inland basin desert riparian ecosystem. Therefore, quantitative analysis of the relationships among groundwater depth, soil properties and plant community distribution is necessary. A desert riparian ecosystem in the lower reaches of the Heihe River in an arid area of Northwest China was used to determine quantitative relationships among groundwater depth, soil and vegetation. Groundwater depth significantly increased with increased distance from the river. Soil and vegetation characteristics showed a significant trend with increasing groundwater depth. With increasing groundwater depth, soil water content, soil total nitrogen, soil total carbon, soil available phosphorus and soil available potassium decreased, while the soil bulk density and soil carbon:nitrogen (C:N) ratio increased. Soil pH and soil electrical conductivity followed quadratic function relationships with groundwater depth. Species richness, aboveground biomass, community coverage, community height, foliage projective cover and leaf area index all significantly decreased with increased groundwater depth. Groundwater depth and soil were associated with vegetation variance, explaining 85.8% of the vegetation variance. Groundwater depth was more important in explaining vegetation variance than soil properties (soil bulk density) and soil pH. Our observations indicate that changes in groundwater depth would have a significant influence on desert riparian forest vegetation, and that maintaining appropriate groundwater depth is necessary to preserve the riparian ecosystem. [ABSTRACT FROM AUTHOR]

The Precipitation-Runoff Modeling System (PRMS) has been applied to simulate rainfall runoff in Zamask-Yingluoxia subbasin of the Heihe River Basin in this study. By using observed data in the subbasin, the model has been calibrated by comparing model simulations of daily stream flow to observed data at Yinglouxia station for the period of summer in 2004. Then model verification was conducted by keeping the same model parameters for the simulation of the period from 1 January 2003 to 31 December 2006. Results from model verification indicate that the model is able to provide good accuracy of simulations of daily rainfall runoff and river flow at Yinglouxia station, with a Nash-Sutcliffe Efficiency coefficient of 0.90 and the root-mean-square error of 15.7 m³/s. The error of maximum peak flow is 6.9 m³/s (1.8%) and the error of mean flow is 1.4 m³/s (2.5%). Comparing to previous studies, results indicate the improvement of model accuracy in simulations of daily rainfall runoff. The calibrated and verified hydrological model can be used to support flood hazard mitigations and water resource management in the Zamask-Yingluoxia subbasin. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The lower reaches of the Heihe River, in northwestern China, is characterised by unique local edaphic conditions that have influenced the development of local desert riparian forests. This study examines the variations in spatial variation patterns to reveal the relationships between plant species diversity and soil moisture/salinity/texture gradients at different soil depths, providing insights into the management and restoration of vegetation in ecosystems in the study area. The species–environmental relationships are investigated by redundancy analysis based on the plant species diversity matrix and the edaphic gradient matrix. A survey of 61 sampling plots identified 37 plant species in the study area. The distribution pattern of the plant species diversity are mainly affected by soil moisture, soil salinity, and soil texture at different soil depths. These edaphic factors are able to explain 98.47% of the total variation in the analysed vegetation dataset. Soil moisture, salinity, and texture content vary in terms of both the soil depths and the vegetation types in the study area. The plant community Class IV, xeric shrub, has the lowest soil water content among different vegetation types. The surface soil salinity differs for different plants and follows the order:Sophora alopecurides > Tamarix chinensis > Populus euphratica. [ABSTRACT FROM AUTHOR]

Key message : The heterogeneous stem radial growth of Populus euphratica and its correlation with hydrology and climate factors were investigated by a tree-ring study in Ejina Oasis in Northwest China. Abstract: Over the last several decades, riparian forests in Northwest China have been extremely vulnerable to the increasing pressures from human activity and climate change. However, it is unclear how forests correlate with these influences over time and on a wide scale. In the present study, we developed 28 tree-ring chronologies of Populus euphratica in the Ejina Oasis, in the lower reaches of Northwestern China's Heihe River, to evaluate the oasis-scale riparian forest growth variation and its correlation with the runoff regulation. We identified three hydrologic periods using regime-shift analysis: a natural runoff period from 1954 to 1989, when the oasis was sustained by natural river flows; a degradation period from 1990 to 2002, when excessive upstream withdrawals of runoff decreased flows to the oasis; and a recovery period, from 2003 to 2010, when water allocation projects restored flows. In general, stem radial growth of poplar trees in the oasis showed decreasing and increasing trends in the degradation period and recovery period, respectively, with high spatial heterogeneity in each period. Our analysis of the relationship between the chronologies and corresponding hydrologic and climatic data revealed that the runoff-recharged hyporheic groundwater depth was the major factor that limited tree stem radial growth. Thus, it is important to allocate water between the middle and lower reaches, and inside the lower reaches, to mitigate or prevent the adverse effects of low runoff. Our study also demonstrates that researchers must carefully consider the high spatial heterogeneity during dendrochronological research in an arid riparian forest. [ABSTRACT FROM AUTHOR]

A Grid-based Integrated Surface-Groundwater Model (GISMOD) was developed to estimate the required irrigation water using a control-site method. The entire catchment is divided into multiple grid cells of equal size, and several grid cells can be chosen as the control sites by users in this model. The grid cells from the upper stream of each control site, which have a land-use type of farmland, are automatically identified as a controlled grid cell. The crop information around each controlled grid cell is set to be the same as its corresponding control site. Next, the irrigation water requirement for each controlled grid cell is calculated using a crop coefficient method that is integrated into the human water-use module of the GISMOD. After runoff is generated, the actual discharge of each control site is computed by comparing the available water sources with the irrigation water requirement based on the water-supply operation rules of the model. This paper subsequently presents a case study in the upper-middle reaches of the Heihe River to evaluate the performance of the GISMOD. The results demonstrate that the actual water consumption for irrigation in the Heihe River basin could be generally estimated by the GISMOD on a monthly basis. [ABSTRACT FROM AUTHOR]

Vegetation phenology is a sensitive indicator of ecosystem response to climate change, and plays an important role in the terrestrial biosphere. Improving our understanding of alpine vegetation phenology dynamics and the correlation with climate and grazing is crucial for high mountains in arid areas subject to climatic warming. Using a time series of SPOT Normalized Difference Vegetation Index (NDVI) data from 1998 to 2013, the start of the growing season (SOS), end of the growing season (EOS), growing season length (GSL), and maximum NDVI (MNDVI) were extracted using a threshold-based method for six vegetation groups in the Heihe River headwaters. Spatial and temporal patterns of SOS, EOS, GSL, MNDVI, and correlations with climatic factors and livestock production were analyzed. The MNDVI increased significantly in 58% of the study region, whereas SOS, EOS, and GSL changed significantly in < 5% of the region. The MNDVI in five vegetation groups increased significantly by a range from 0.045 to 0.075. No significant correlation between SOS and EOS was observed in any vegetation group. The SOS and GSL were highly correlated with temperature in May and April–May, whereas MNDVI was correlated with temperature in August and July–August. The EOS of different vegetation groups was correlated with different climatic variables. Maximum and minimum temperature, accumulated temperature, and effective accumulated temperature showed stronger correlations with phenological metrics compared with those of mean temperature, and should receive greater attention in phenology modeling in the future. Meat and milk production were significantly correlated with the MNDVI of scrub, steppe, and meadow. Although the MNDVI increased in recent years, ongoing monitoring for rangeland degradation is recommended. [ABSTRACT FROM AUTHOR]

The uplifting of the Tibetan Plateau has significantly changed the environment in surrounding areas by delivering abundant water and sediment. The Heihe River draining the Qilian Shan in the NE Tibetan Plateau acts as a dominant sediment routing system from the uplifted NE Tibetan Plateau to the Hexi Corridor as well as the Badain Jaran Desert. Reconstructing the evolution of the Heihe River could provide evidence for the birth of the Badain Jaran Desert and enhance the understanding of sedimentary basin fill and the relationship between tectonism, drainage evolution and environmental changes. With this aim, two parallel cores (DWJ and XKJD with depths of 140 and 68.2 m, respectively) were drilled in the floodplain of the Heihe River. The facies analysis of the sedimentary sequences from the drilling cores showed that the sedimentary environment changed from the lake system to a delta system and finally to a fluvial system at the depths of ∼133.3 and ∼68 m, respectively. The magnetostratigraphic results revealed ages of approximately 1.75 and 1.12 Ma for the DWJ and XKJD cores, respectively, and an age of approximately 1.1 Ma for the transition from delta to fluvial environment in both the cores. The change of the sedimentary environment at approximately 1.1 Ma was caused by the formation of the integrated Heihe River. The integrated Heihe River may have developed via mechanisms such as river capture and river diversion due to the uplifting of the North Qilian Shan and the Longshou Shan. The present study suggested that the formation of large inland rivers, such as the Heihe River and the Shiyang River in NW China, played an important role in the evolution of the deserts and the Loess Plateau. [ABSTRACT FROM AUTHOR]

The article analyses a transdisciplinary wicked upstream-downstream conflict over water allocation in an arid region of Inner Mongolia (China). This conflict is about scarce water resources which can be either allocated to irrigation agriculture upstream or to preservation and restoration a rare ecosystem downstream. This conflict is located at the interface of environmental and agricultural ethics. The case study is about Heihe River, agricultural demands for irrigation in the region of Zhangye, and endangered Tugai forest at downstream Heihe in Ejina oasis. Authors use a theoretical approach of environmental philosophy and rely on the concept of 'strong sustainability'. From this background two normative yardsticks are derived: a constant natural capital rule and the overall satisfactory goodness of a river basin. Both yardsticks are not met at Heihe. Downstream, we see the endangered Tugai forest as a location which should be preserved de re. We argue for a viable institutional water saving strategy within the agricultural areas of Zhangye district by which Tugai forests at downstream Heihe might be restored. Our case study indicates that even wicked problems can find proper and prudent solutions. [ABSTRACT FROM AUTHOR]