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In the present paper, the computational fluid dynamics (CFD) method is used to investigate the variation of linear and nonlinear wave loads on a 10-MW large-scale monopile offshore wind turbine under typical sea conditions in the eastern seas of China. The effect of adding a structural ice-breaking cone configuration close to the mean water level on the monopile's hydrodynamic response is studied further. Results are derived with the use of the CFD model and are compared with the relevant results that are calculated using the Morison equation and the potential flow theory based on the high-order boundary element method. The fifth-order Stokes' theorem is used to model the incoming wave kinematics, and the volume of fluid (VOF) method is used to capture the free surface of waves and to accurately calculate the wave run-up on the monopile and cone configuration. The influence of different water depths and wave heights on the wave maximum vertical extent of wave uprush on the structure, pressure and horizontal wave forces on the monopile is investigated for both with and without the use of the cone configuration. Up–downward cone configuration results in better performance compared to the inverted cone configuration in terms of reduction of hydrodynamic nonlinear excitation loads and wave maximum vertical extent of wave uprush on the structure. [ABSTRACT FROM AUTHOR]

Owing to the importance of coalbed methane (CBM) as a source of energy, it is necessary to predict its future production. However, the production process of CBM is the result of the interaction of many factors, making it difficult to perform accurate simulations through mathematical models. We must therefore rely on the historical data of CBM production to understand its inherent features and predict its future performance. The objective of this paper is to establish a deep learning prediction method for coalbed methane production without considering complex geological factors. In this paper, we propose a multivariate long short-term memory neural network (M-LSTM NN) model to predict CBM production. We tested the performance of this model using the production data of CBM wells in the Panhe Demonstration Area in the Qinshui Basin of China. The production of different CBM wells has similar characteristics in time. We can use the symmetric similarity of the data to transfer the model to the production forecasting of different CBM wells. Our results demonstrate that the M-LSTM NN model, utilizing the historical yield data of CBM as well as other auxiliary information such as casing pressures, water production levels, and bottom hole temperatures (including the highest and lowest temperatures), can predict CBM production successfully while obtaining a mean absolute percentage error (MAPE) of 0.91%. This is an improvement when compared with the traditional LSTM NN model, which has an MAPE of 1.14%. In addition to this, we conducted multi-step predictions at a daily and monthly scale and obtained similar results. It should be noted that with an increase in time lag, the prediction performance became less accurate. At the daily level, the MAPE value increased from 0.24% to 2.09% over 10 successive days. The predictions on the monthly scale also saw an increase in the MAPE value from 2.68% to 5.95% over three months. This tendency suggests that long-term forecasts are more difficult than short-term ones, and more historical data are required to produce more accurate results. [ABSTRACT FROM AUTHOR]

This paper documents a 7800-year proxy record from the Shenjiadian peatland on the Sanjiang Plain in Northeast China. High-resolution plant macrofossil and colorimetric humification methods were used to reconstruct the vegetation and hydrologic history from a 193 cm-long sedimentary profile. Detrended correspondence analysis (DCA) was applied to transform the raw plant macrofossil data into latent indices of peatland water level. The vegetation community transited from an Equisetum fluviatile community to a Carex lasiocarpa community at approximately 3800 cal yr BP and was followed by a Carex-shrub community at approximately 480 cal yr BP. Based on the plant macrofossil DCA axis 1 scores and humification values, we distinguished four hydrologic periods: a wet period from 7800 cal yr BP to 4500 cal yr BP, dry periods up to 1600 cal yr BP, drier periods until 300 cal yr BP, and the driest period from 300 cal yr BP until the present. Through a comparison with other climate records, we suggest that the East Asian summer monsoon (EAM) was the main driving force for vegetation and water level changes to the Shenjiadian peatland through its impacts on precipitation. [ABSTRACT FROM AUTHOR]

Through the analysis of monitoring data with a time interval of 10 min during the rainy season of 2012, for three points of G37, zk8 and zk7 which are located on the main conduit of Zhaidi karst underground river system, the variation features of water level and hydraulic gradient are studied and the relations are established between gradient and water level or amplitude. (1) It is first discovered that there are different function relations such as linear, parabola and inverse parabola between the G37's water level and the hydraulic gradients of different conduit part. (2) The peak delay times for water level curves are <50 min and the maximum conducting speed of water press is faster than 13,020 m/h. (3) The upstream and downstream karst conduits have corresponding enlarging and shrinking amplitude function by the coefficients of 1.899/km and 0.125/km. (4) The gradient I variation is still linear to the level difference Δ H made by nine rainstorms. The conclusion and the methods of this paper have significance on the study of the regulation and storage capacity and groundwater resources evaluation of karst underground-river system. [ABSTRACT FROM AUTHOR]

Groundwater dynamic monitoring of assessment points and evaluation areas has a significant predictive effect for controlling the occurrence of disasters. Obtaining water level and water temperature change data can provide important theoretical significance and reference values. However, in some remote areas of China, the measurement data concerning water level change are mostly obtained by manual measurement. This measurement method not only wastes manpower, but also cannot ensure the accuracy and real-time nature of the data. Therefore, this paper carried out research and design on a fluviograph, based on the relationship between hydraulic pressure and water depth. In the paper, the fluviograph used ultra-small pressure sensors to complete the data acquisition of the water level, a STM32L011 single-chip microcomputer (STMicroelectronics, Geneva, Switzerland) to process the data, and LabVIEW software to display the final data. Additionally, the water level data record and water temperature information record can be fed back to the user and the manager. After laboratory testing, the water level variation error range of this fluviograph was 1–2 cm, and the water temperature error range was less than 1 °C, which indicates the accuracy of the metrical data. The results show that the fluviograph realizes the function of automatically recording the water level and water temperature of the monitoring point, and it improves the social production efficiency greatly. [ABSTRACT FROM AUTHOR]

Water and sediment regulation scheme (WSRS) is an annual water conservancy project which aims to alleviate sand depositions and reduce flood risks in the Yellow River of China since 2002. There are few researches on the sand bar within Yellow River tail channel and its estuary from each WSRS effect, though these relative researches are important to be carried out for a better understanding of WSRS. By interpreting two GF-1 satellite images in the end of 2013 and the start of 2015 after carefully controlling some potential bias factors from the change of water level, precipitation or tidal, we compared and analyzed the change of sand bars by one WSRS implemented in 2014 in this paper. Our results indicated this WSRS changed obviously the area/shape of sand bars. It made the area of the river sand bar decreased totally by 5.55 km2, while the estuarine sand bar increased by 2.08 km2. And it achieved the highest scour efficiency (90.11%) in the straight channel, but it achieved the lowest scour efficiency (44.71%) in the more bends channel. From the prospect in the change of estuarine sand bar, the west side area increased, while the east side area shrank. There were some broken small sand bars on the north side and they were forming a large sand bar. [ABSTRACT FROM AUTHOR]

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Utilizing the data of water level, observed by tide gauges in Hong Kong, China from 1962 ‒ 2017, the variation of sea level, tidal harmonic constants and other character values of water level in the sea area are determined and analyzed in this paper. The results show that the average changing rate of mean sea level is 1.06mm/a, however, both the trend and scale of each tide gauge’ s mean sea level changing rate are different. For example, the rate of Chi Ma Wan is (-3.85 ± 0.61) mm/a, while the rate of Waglan Island is (4.12 ± 0.76) mm/a and the the rate of Tsim Bei Tsui is (0.32 ± 0.32) mm/a. From 1962 to 2017, Sa and Ssa of Quarry Bay, calculated annually, have poor stability, and the changing trends of harmonic constants of shallow water constituents are obvious relatively. Diurnal and semidiurnal constituents are nearly stable, but in 2004―2008 the amplitudes of M2, O1 and K1 vary from other years. The level of lowest normal low water and lowest astronomical tide increase in the rate of 0.18 mm/a and 0.27 mm/a respectively. [ABSTRACT FROM AUTHOR]

Simple Summary: The critically endangered Siberian crane (Grus leucogeranus) relies on Poyang Lake's wetlands in China for wintering. Rapid changes in these wetlands, driven by climate shifts and human activities, affect habitat and food availability for these birds. Our study investigated Poyang Lake's hydrological dynamics over the past two decades and assessed the impact of related variables on crane populations. Employing advanced modeling, we predicted how varying water levels influence suitable habitats for Siberian cranes. Our findings revealed that a summer-inundated area exerted a notable influence on population fluctuations in crane species in the natural habitats of Poyang Lake. The scarcity of food, resulting from summer floods, compels cranes to adapt by exploring alternative food sources and new foraging grounds, including artificial habitats. During the dry season, the size of the inundated area primarily impacts the food availability for Siberian cranes, thereby influencing both their population size and distribution pattern, and a moderate water level of 8–10 m provides the highest amount of good habitat. Persistent winter droughts exacerbate the unsuitability of habitats, and the shortage of food in natural habitats may become a recurring occurrence in the future. This study emphasizes the importance of managing both natural and artificial habitats to support Siberian crane conservation amid environmental changes. To assess the Siberian crane (Grus leucogeranus)'s response to changing water levels and habitat quality at Poyang Lake, we analyzed the lake's hydrological trends over the past two decades with the Mann-Kendall and Sen slope methods. Additionally, we explored the link between the crane population size and hydrological conditions at the lake from 2011 to 2019. Meanwhile, five environmental factors, including habitat type, distance from shallow lakes, human footprint index, elevation and normalized vegetation index were selected, and the distribution patterns of suitable habitats for the Siberian crane under 10 water level gradients with intervals of about 1 m (5.3–14.2 m) were simulated by using an improved habitat suitability index model that determines the weights of evaluating factors based on the MaxEnt model. The results showed that the overall trend of the inundated area in Poyang Lake was shrinking in the last 20 years, with a significant increase in the area of exposed floodland during the early wintering period (Z = −2.26). The prolonged drought resulting from this will force vegetation succession, thereby diminishing the food resources for cranes in their natural habitat. The mean inundated area in June demonstrated a significant negative correlation with the population of Siberian cranes in natural habitats (r = −0.75, p = 0.02). Shortage of the Siberian crane-preferred Vallisneria tuber due to June flooding was the primary driver of the crane's altered foraging strategy and habitat shift. In years with relatively normal June inundation, indicating abundant Vallisneria resources, the relationship between the inundated area during the dry season and the crane population fit well, with a quadratic curve (R2 = 0.92, p = 0.02). The dry season's inundated area primarily affected the crane population and distribution pattern by influencing the availability of food resources, and both excessive and insufficient inundation areas were unfavorable for crane survival. The modeling results for habitat suitability indicated that as the water level decreased, the trend of the area of good habitat for the Siberian crane showed an inverted bell shape, peaking at a water level of 8.8 m, with optimal conditions occurring between 8 and 10 m. The combined effects of climate and human activities have made the shortage of food resources in Poyang Lake the new normal. The degradation of natural habitats has led to a decline in the quality of Siberian crane habitats, and artificial habitats can only be used as refuges to a certain extent. Thus, formulating strategies to restore natural habitats and enhance the management of artificial habitats is crucial for the conservation efforts of Siberian cranes. [ABSTRACT FROM AUTHOR]

A quaternary unconsolidated confined aquifer is one of the main sources of water inrush in Huaibei coalfield. Water abundance evaluation of the aquifer is the key to guiding water prevention in coal mining. Aiming at the issue of water abundance in the unconsolidated confined aquifer, a novel evaluation model was established based on three evaluation indexes: the depth of water level, the depth of roof and the sedimentary characteristics. Among them, the sedimentary characteristics were quantified in comprehensive consideration of three aspects: the aquifer lithology, sedimentary thickness of rock stratum and sedimentary sequence. Then, the evaluation model was validated with an accuracy of 90.57% and was applied to the Zhuxianzhuang coal mine in the Su-Lin mining areas, so the zoning prediction map of water abundance of the unconsolidated confined aquifer was obtained. The results show that medium water abundance areas are scattered in the middle part of the mine and other areas are of weak or extremely weak water abundance. The distribution characteristics of water abundance obtained from the actual detection results are consistent with that predicted by the model, which further proves the reliability of the model. The findings of this research provide a new method for the water abundance evaluation, which is of great importance to ensure safety production of coal mine under unconsolidated confined aquifer in the Su-Lin mining areas, as well as other similar mining areas. [ABSTRACT FROM AUTHOR]

In the context of global climate change, the frequency of watershed flooding events resulting from extreme rainfall has significantly increased. Especially at river or lake confluences, the presence of backwater effects greatly amplifies the flood risk. To investigate the influence of backwater effects on the hydraulic characteristics of rivers and lakes, this study focuses on the Dongping Lake in China. An enhanced two-dimensional hydrodynamic model was employed to simulate and analyze three different degrees of backwater effects. The results indicate that, compared to the working conditions without the backwater effect, the highest lake water level increased by 1.0 m and 0.1 m under severe and moderate backwater effect conditions, respectively. The total outflow flood volume decreased by 30.1% and 2.3%, respectively. The demolition time for the Jinshan Dam needs to be advanced by 12.5 h and 10.0 h, respectively, and the inundation area in the western region expanded by 2.73% and 0.32%. Additionally, the average inundation depth increased by 0.93 m and 0.08 m, respectively. These results provide valuable data support for the safe operation of Dongping Lake, the formulation of flood defense strategies, and, likewise, offer valuable insights into the risk management of flood events in other rivers and lakes with backwater effects. [ABSTRACT FROM AUTHOR]

Frequent threats from landslides in reservoir areas have caused a research boom in academia due to the commissioning of the Three Gorges Project and the continued promotion of hydropower development in southwestern China. In this study, a series of analyses, mainly flume experiment, were conducted on reservoir slope deposits with large landslide potentials. This article focuses on validating the deformation and hydrological response process of the experimental re-enactment under different changing water level conditions and comparing them to real case observations and monitoring. The experimental results provide a basis for the systematic formulation of the mechanism of slope deposit failure in the reservoir area. The occurrence of landslides on slope deposits is usually caused by the accumulation of multiple phases of deformation rather than one phase of deformation. The deformation of the slope deposits is mainly in the form of erosion collapse at the front edge and shearing-tension cracking at the rear edge. These are directly caused by the large increase in the water level during the impoundment period and the rapid drawdown of the water level or the coupling of continuous strong rainfall and water level drawdown during the operation period. In this case, the loss of fine particles, the seepage force, and the increase in pore water pressure all play an important role. In this study, we hope to provide some scientific insights into the warning and mitigation of slope mounding hazards in reservoir areas. [ABSTRACT FROM AUTHOR]

Chen, Y.; Huang, W., and Xu, S., 2014. Frequency analysis of extreme water levels in east and southeast coasts of China with analysis on effect of sea level rise. Qiantang bore as well as the storm surge are great disasters for river bank protection at the estuary of Qiantang River. Pearl River estuary is also frequently attacked by strong typhoon storm surge. The risk of damage from storm surge is expected to increase in both estuaries, exacerbated by sea level rise (SLR) and possible climate-induced increases in typhoon intensity and frequency. Adequate estimation on extreme water level will be essential to the coastal flood mitigation for both estuary areas with the effect of climate change. In this study, the popular frequency models Weibull, Lognormal, Gumbel, P-III and GEV are compared on Ganpu station located at the estuary of Qiantang River and Denglongshan station in Guangdong province, the optimal GEV model is recommended. For the risky analysis and management concern induced by the shortage of studied data, the estimated 50 year and 100 year extreme water levels respectively at Ganpu and Denglongshan stations are recommended in this study. Both studied stations located at different estuaries are all type II GEV model as the parameter of GEV distribution are higher than 0. The difference of the parameter and the reason causes the difference in the studied stations are analyzed and discussed in this paper. Furthermore, with the estimated 2.9mm/yr SLR by sea level bulletin of China, effect of SLR in frequency analysis on Denglongshan station is discussed. [ABSTRACT FROM AUTHOR]

This paper presents the application of an improved particle swarm optimization (PSO) technique for training an artificial neural network (ANN) to predict water levels for the Heshui Watershed, China. Daily values of rainfall and water levels from 1988 to 2000 were first analyzed using ANNs trained with the conjugate gradient, gradient descent, and Levenberg-Marquardt neural network (LM-NN) algorithms. The best results were obtained from the LM-NN, and these results were then compared with those from PSO-based ANNs, including the conventional PSO neural network (CPSONN) and the improved PSO neural network (IPSONN) with passive congregation. The IPSONN algorithm improves PSO convergence by using the selfish herd concept in swarm behavior. The results show that the PSO-based ANNs performed better than the LM-NN. For models run using a single parameter (rainfall) as input, the root mean square error (RMSE) of the testing data set for IPSONN was the lowest (0.152 m) compared to those for CPSONN (0.161 m) and LM-NN (0.205 m). For multiparameter (rainfall and water level) inputs, the RMSE of the testing data set for IPSONN was also the lowest (0.089 m) compared to those for CPSONN (0.105 m) and LM-NN (0.145 m). The results also indicate that the LM-NN model performed poorly in predicting the low and peak water levels in comparison to the PSO-based ANNs. Moreover, the IPSONN model was superior to CPSONN in predicting extreme water levels. Lastly, IPSONN had a quicker convergence rate compared to CPSONN. [ABSTRACT FROM AUTHOR]

These combinations can be climate variability and human activities, which can directly affect the streamflow and topography of the region, respectively. Since streamflow and topography can affect each other, it is difficult to determine the impact of streamflow and topography changes on water level. Since precipitation and potential evapotranspiration as well as other hydrological cycle variables can be caused changes in streamflow, water level can be related to components of the hydrological cycle according to Eq. (1) here. [Extracted from the article]

Waterlogging is drained by pump stations set on the inner river network in riverside cities. More importance is given to avoiding waterlog through an applicable design capacity of pump stations, confirmed by a reasonable method to deal with the complicated boundary of the pump drainage. Node's Water-level Control Method (NWCM) has been proposed in this paper. The core idea of NWCM was to transform the pump drainage boundary into the water level boundary, in accordance with the storage capacity curve and the characteristic of a less different water level in riverside cities. The design capacity of each pump station was obtained by unsteady flow calculation. In the case study, the design capacities of the eight pump stations of Hexi New Town in Nanjing City were confirmed conveniently by NWCM. The total design capacity was less than that obtained through regular methods due to the full consideration for storage capacity of inner river channels in the new method, which was designed in accordance with actual conditions. [ABSTRACT FROM AUTHOR]

Reservoirs are among the most effective tools for integrated water resources development and management. The dynamic control of reservoir flood limiting water level (FLWL) is a valuable and effective method to compromise the flood control and conservation for reservoir operation during the flood season. This paper focuses on joint operation and dynamic control of FLWL for cascade reservoirs. A composition and decomposition-based model that consists of an aggregation module, a storage decomposition module and a simulation operation module was developed. The model was applied to the Qingjiang basin in south of China using the 3-hour inflow data series for representative hydrological years. Application results indicate that the proposed model can make an effective tradeoff between the flood control and hydropower generation. Joint operation and dynamic control of FLWL can increase power production by 4.51 % (1.79 × 10 kWh) and increase water use rate by 2.73 %. It can enhance benefits of the Qingjiang cascade reservoirs without compromising flood prevention objectives. [ABSTRACT FROM AUTHOR]

For the past several decades, lots of adsorbent nanomaterials have been adopted for the enrichment of mercuric compounds. In this paper, graphene oxide bounded silica particles were employed as the absorbent for online preconcentration of Hg(II), methylmercury (MeHg) and ethylmercury (EtHg) by solid phase extraction. The adsorbent offered satisfactory adsorption capacities of 40.7 for Hg(II), 91.4 for MeHg and 103.8 mg g−1 for EtHg. Enrichment conditions such as type, concentration and volume of conditioning and eluting reagents were optimized. The pH, volume and flow rate of sample were also optimized. High enrichment factors (1963, 1881 and 1794 for Hg(II), MeHg and EtHg, respectively) were obtained with 10 mL sample (adjusted to pH 4–7) at 10 mL min−1 flow rate, 5 μL of 10 mM benzoic acid for elution and 4 mL of 1 mM 4-phenyl-3-aminothiourea for preconditioning. The detection limits obtained were downscaled to be 0.005 for Hg(II), 0.006 for MeHg and 0.009 ng L−1 for EtHg with relative standard deviations of all the analytes below 5%. Standard reference material and spiked water samples were analyzed for validating the method with satisfactory recoveries of 89–106%. The present method was successfully applied to determine mercury compounds in drinking water, and river and tap water, in which Hg(II), MeHg and EtHg were presented below the China's drinking standard limit of 1 μg L−1. Image 1 • GO was used as the SPE adsorbent for enriching mercury species. • Mercury speciation was analyzed by online enrichment and HPLC-ICP-MS. • EFs of 1794–1963 for Hg(II), MeHg and EtHg were obtained with 10 mL sample. • LODs were downscaled to pg L−1 levels for uncontaminated water samples. • Three mercurials in water were analyzed within 5 min for one analytical run. [ABSTRACT FROM AUTHOR]

• This study constructed an urban nexus accounting framework based on Multi-Scale Input Output model. • Shanghai is a net consumer city mainly imports embodied energy and water from domestic and developing regions. • Energy water nexus characteristics of industrial sectors can offer different ways to tackle environmental challenges. Large scale urbanization and industrial development has resulted in serious environmental challenges for China. Both energy and water are considered key to urban sustainability and for that matter resource accounting and tracing are drawing growing attention in the economy. This paper focuses on energy-water nexus of urban sectors in Shanghai (referred to year 2010) using multi-regional input-output (MRIO) analysis. This study outcome revealed that overall Shanghai is a net consumer city mainly imports embodied energy and water from domestic and developing regions of the world and exports little to developed regions. In depth analysis indicated that, except S17, S7, S10, S15 and S8 all other industrial sectors were net inflows of energy in Shanghai. Similarly, except S15, all other industrial sectors were net water consumers in Shanghai. The S16 (18.96 Mtce), S20 (11.06 Mtce) and S12 (7.71 Mtce) were ranked highest as net importer making up about 60.48% of total net inflows of embodied energy, whereas S1 (18053.48 Mt), S3 (6865.16 Mt) and S19 (2320.62 Mt) were ranked highest as net importer making up about 74.99% of total net inflows of embodied water. The developed nexus strength indicator uncovered the sectoral energy-water linkages. From a production perspective, the S15 exhibited high nexus strength level up to 1 with 50% contribution by each resource to the nexus. While from a consumption perspective, the S1 revealed high nexus strength level and water was the most frequent resource node contributing about 84% to the energy-water nexus. The energy-water nexus characteristics of industrial sectors can offer different ways to tackle environmental challenges. This study can provide a reference to policy makers in identifying key sectors that requires more focus in terms of easing environmental stress to achieve sustainability in urban development. In addition, called for coordination and regulating urban industrial trade structure in the future. [ABSTRACT FROM AUTHOR]

In typical photoelectrochemical (PEC) biosensing assays, electrodes are generally modified with photoactive probes and/or target recognition probes, which makes the processes complicated, time-consuming, and difficult to achieve excellent reproducibility. Hence, to overcome such shortcomings, we propose here an immobilization-free and label-free PEC aptasensor using solution-phase methylene blue (MB) as the PEC signal probe. Based on the unique T–Hg2+–T base pairs, and the diffusivity difference between free MB molecules and the MB/G-quadruplex composite towards the ITO electrode surface with negative charge, the “signal-off” approach for Hg2+ detection is developed. In the presence of target Hg2+, via the T–Hg2+–T bond formation, the two sticky ends of the hairpin DNA probe form a rigid duplex stem, which triggers the exonuclease III-facilitated target cycling amplification, and the formation of multiple G-quadruplexes. Upon the intercalation of MB in G-quadruplexes, significantly decreased photocurrent is obtained owing to the increased electrostatic repulsion between the MB/G-quadruplex composite and the ITO electrode. Therefore, highly sensitive and ultrasensitive Hg2+ determination is achieved, with a low detection limit of 1.2 pM, well below the maximum allowable Hg2+ level in drinking water defined by the WHO, China's Ministry of Health, and the US EPA. Due to the avoidance of sophisticated electrode modification and recognition probe immobilization processes, as well as an expensive labeling procedure, the PEC aptasensor proposed here demonstrates the advantages of simplicity, good reproducibility, rapidness and low cost. [ABSTRACT FROM AUTHOR]

• Water level in response to periodic loadings in two closely wells were compared. • Two wells show different response characteristics to different periodic loadings. • Permeability and noise perturbations lead to the different response sensitivity. Groundwater well can be used as a seismograph or as strainmeter, since the well water level is sensitive to seismic waves and other crustal strains through mechanical coupling between rock and groundwater. The use of the groundwater level in monitoring tectonic strain, however, is hindered by the enigmatic response discrepancy among wells (different responses may be recorded by even closely clustered wells). Therefore, understanding the factors that control the sensitivity of well-aquifer systems in response to different periodic loadings is important. In this paper, we analyzed two closely located wells that show no response to seismic waves and respond differently to earth tides and barometric pressure. We discuss these wells' sensitivity of response to periodic loadings by using the spectrum, barometric response function, tidal response, and slug test methods. Our results show that the different response characteristics are due to the differences in permeability and confinement of the well-aquifer systems. Well-aquifer systems with a low permeability cannot record coseismic responses, even if they can record clear tidal and barometric signals. In addition, periodic loading signals in shallow aquifers will be easily masked by the interference from the surface, for example rainfall or pumping, which diminishes the signal-to-noise ratio of the tectonic activity. Thus, the hydrogeological and tectonic settings are the two key factors that should be considered in choosing a suitable monitoring well location for tectonic strain monitoring. [ABSTRACT FROM AUTHOR]

Xiangxi River is a typical tributary of Three Gorges Reservoir (TGR) in China. Based on field observations in 2010, thermal stratification was significant in most months of the year. Through field data analysis and numerical simulations, the seasonal and spatial variation of thermal stratification as related to the impact of the operation of TGR were investigated. Thermal stratification was most pronounced from April to September in the Xiangxi River tributary. Air temperature (AT) and water level (WL) were the two dominant variables impacting thermal stratification. AT affected the surface water temperature promoting the formation of thermal stratification, and high WLs in TGR deepened the thermocline depth and thermocline bottom depth. These results provide a preliminary description of the seasonal variation and spatial distribution of thermal stratification, which is important for better understanding how thermal stratification affects algae blooms in Xiangxi River. [ABSTRACT FROM AUTHOR]

With pumps as the main devices, the main drainage system (MDS) is critical to mine construction and production. Considering the high cost of traditional manual pump scheduling strategy and the wide adoption of time-of-use (TOU) electricity traffic in coal mines, this paper attempts to reduce the mine operation cost by scheduling the pumps in the flat and valley periods instead of the peak period. For this purpose, the pump scheduling was considered as an optimization problem, the water level of the sump was predicted by double exponential smoothing, and then the optimal pump scheduling plan was derived by ant colony optimization (ACO). The pump scheduling plan obtained by the proposed method was proved cost efficient through experiments on a gold mine in China. [ABSTRACT FROM AUTHOR]

Abstract A 2-D unstructured finite element model is used to study how local and remote atmospheric forcing, sea level rise, and shoreline variation affect typhoon-induced storm surge in a small shallow bay, Zhanjiang Harbor (ZH). In this research, the spatial distribution of storm surge is divided into three patterns in ZH, denoted E-W, N-S, and S-N, using a quantitative method. In the Bay, local atmospheric effects (LAE) and remote atmospheric effects (RAE) both play important roles in the maximum residual water level. The contribution of RAE to the inflow is higher than that of the LAE, but the former is less important in the spatial distribution in ZH. In addition, the typhoon track influences the time of occurrence of the maximum surge by forcing the outer waters to ZH, then the spatial distribution of the surge residual in the bay is controlled by local winds, and different regions are threatened during different kinds of storm surge processes. Two sea level rise scenarios are set up in the paper as well, and the results show that the trends of the changes in LAE and RAE in the inner-bay are the opposite in the case of sea level rise; however, the total changes of the distribution are not the same in different categories. In general, the E-W category storm surge is weakened, while the N-S and S-N category storm surges have inverse changes in the north and south of ZH. There is a downward trend of the maximum surge gradient within the Bay, but relative to sea level rise itself this effect is not obvious. The establishment of the sea embankment increased the storm surge within the bay though it is not significant. Highlights • A quantitative method is used to categorize 3 patterns of the surge distribution in the bay. • Local atmospheric field dominates the surge distribution pattern in the bay. • How the track and intensity of typhoons affect distribution patterns is explained. [ABSTRACT FROM AUTHOR]

Dams are widely recognised as having significant negative consequences for the surrounding natural ecosystems and environment. China's Three Gorges Dam, being one of the largest in the world, stands to inflict more damage than most for numerous reasons. This paper reviews the current knowledge on the impacts of dams and impoundments with regard to reservoir riparian vegetation in order to apply this knowledge to the Three Gorges Project. It also summarises research performed to date on the effects of the Three Gorges Dam on the local riparian zone and vegetation. The known and potential outcomes for local plant communities are examined in terms of their responses to the increased water levels, altered hydrological characteristics and other adverse effects associated with the construction of the dam. Vegetation responses will be diverse and change over time, but will ultimately result in a markedly different landscape and riparian zone within the Three Gorges Reservoir. These changes will take place through a loss of previous vegetation, potential invasion by exotics and result from the significant alteration in hydrological regimes and also erosion and sedimentation processes influencing and creating novel plant communities. Management of the environmental consequences of the Three Gorges Project should take into account factors associated with these processes, in order to facilitate vegetation recovery in the reservoir and to conserve biodiversity of the surrounding ecosystems. [ABSTRACT FROM AUTHOR]

The riparian vegetation zone plays an important role in river ecosystems, flow resistance, water velocity distribution, and water level variation. In this paper, the impacts of riparian reed zones on river flow and water level were studied by comparing measurements in river reaches with or without riparian reed zones in the Chaodongweigang River of Taihu Lake Basin, China. The effects of the density, stem diameter, and rigidity of reeds on flow regime, water velocity, and water level were investigated. Subsequently, flow resistance on the river’s longitudinal water level caused by the riparian reed zone was studied. The results showed three water velocity zones in the river reach where there were riparian reeds, including the slack water zone, the transition zone of flow velocity, and the river’s main flow zone. The water velocities in the three zones were related to reed density, diameter, and rigidity. The water-surface slope in the river reach with a riparian reed zone was larger than that without a reed zone. It showed that the riparian reed zone influenced the river flood discharge to some degree and resulted in increased water level upstream. Additionally, the water level of the river cross section exhibited a concave shape that the water level was higher in the riparian reed zone than in the center of river midstream, section with a riparian reed zone exhibited a concave shape; the water level was higher in the riparian reed zone than in midstream, and the water level difference was influenced mainly by the reed density. [ABSTRACT FROM AUTHOR]

The destruction of channel lining under frost action in seasonally frozen regions has become a prominent factor restricting water transportation in western regions of China, which has also caused a lot of waste of water resources. A novel assembled channel lining for reducing frost heave destruction was presented in this paper. The assembled channel and a normal channel with the trapezoidal section were carried out in the laboratory, considering different water level storage in the high-temperature period. The results revealed that the freezing depths in the channel was quite different, and the order from large to small is the channel embankment, center of the bottom and slope toe. Meanwhile, compared to the variation of water level, the influence of water storage in the channel on the frost heave deformation is more significant than that in the absence of water in the channel. The triangular prism block with the large cross-section set at the slope toe of the assembled channel not only has the insulation effect and a specific anti-seepage function at the channel foundation soil to a certain extent, but also connects the independent concrete plates one by one with the loop-end buckle groove to make the channel deformation uniform under the frost heave. Therefore, the assembled channel could be considered as a novel channel structure to prevent and reduce the frost heave damage in seasonally frozen regions. • An assembled channel lining for preventing the frost heave damage of channel was presented firstly. • The experiment between the assembled channel and normal channel with the trapezoidal section were carried out in laboratory. • The triangular prism block has the insulation and anti-seepage function at the channel foundation soil to a certain extent. [ABSTRACT FROM AUTHOR]

The development of predictive models of the spatial distribution of schistosomiasis are hampered by the existence of different regional subspecies of the Oncomelania hupensis snail that serve as intermediate hosts for the disease in China. The habitats associated with these different subspecies vary considerably, with mountainous habitats in the west and floodplain habitats in the east. Despite these challenges, con tin uing environmental change resulting from the construction of the Three Gorges Dam and global warming that threaten to increase snail habitat, as well as limited public health resources, require the ability to accurately map and prioritize areas at risk for schistosomiasis. This paper describes a series of ongoing studies that rely on remotely sensed data to predict schistosomiasis risk in two regions of China. The first study is a classification of Landsat TM image~yto identify snail habitats in mountainous regions of Sichuan Province. The accuracy of this classification was assessed in an independent field study, which revealed that seasonal flooding may have contributed to misclassification, and that the incorporation of soil maps may greatly improve classification accuracy A second study presents the use of Landsat TM and water level data to understand seasonal differences in Oncomelania hupensis habitat in the lower Yangtze River region. [ABSTRACT FROM AUTHOR]

Effective management of reservoir sedimentation necessitates the characterization of flood events, especially in relation to the propagation of the flow peak (Qpeak) and the suspended sediment concentration peak (SSCpeak). This study, based on a one‐dimensional river network hydro‐sediment model together with field data, presents an exploration of the flood events in the Three Gorges Reservoir (TGR) with focus on the propagating characteristics of Qpeak and SSCpeak. The findings reveal that the main flood season (from July to September) contributed over 80% of the annual sediment load into the TGR, with the mainstream Yangtze and its tributary, the Jialing River, being the primary sediment sources. After the impoundment of the TGR, the propagation time of Qpeak decreases with the raise of the water level in front of dam (WLdam). The increases in Qpeak discharge extends the range of river reach dominated by kinematic wave, resulting in an increase trend in Qpeak propagation time. The propagating speed of SSCpeak is closely related to the ratio of sediment concentration to flow discharge and WLdam. Finally, the propagating durations of Qpeak and SSCpeak in the TGR are compared, and empirical formulas are proposed for quantifying their difference. [ABSTRACT FROM AUTHOR]

Water level prediction in large dammed rivers is an important task for flood control, hydropower generation, and ecological protection. The variations of water levels in large rivers are traditionally simulated based on hydrological models. Recently, most studies have begun applying deep learning (DL) models as an alternative method for forecasting the dynamics of water levels. However, it is still challenging to directly apply DL to the simultaneous prediction of water levels across multiple sites. This study attempts to develop a hybrid framework by combining the Physical-based Hydrological model (PHM) and Long Short-Term Memory (LSTM). This study hypothesizes that our hybrid model can enhance the predictive accuracy of water levels in large rivers, because it considers the temporal-spatial information of mainstream-tributaries relationships. The effectiveness of the proposed model (PHM-BP-LSTM) is evaluated using the daily water levels from 2012 to 2018 in the Three Gorges Reservoir (TGR), China. Firstly, we use a hydrological model to produce a large amount of water level data to solve the limited training data set. Then, we use the Back Propagation (BP) neural network to capture the mainstream-tributaries relationship. The future changes in water levels in the different mainstream stations are simultaneously predicted by the LSTM model. We reveal that our hybrid model yields satisfactory accuracy for daily water level simulations at fourteen mainstream stations of the TGR. We further demonstrate the proposed model outperforms the traditional machine learning methods in different prediction scenarios (one-day-ahead, three-day-ahead, seven-day-ahead), with RMSE values ranging from 0.793 m to 1.918 m, MAE values ranging from 0.489 m to 1.321 m, and the average relative errors at each mainstream station are controlled below 4%. Overall, our PHM-BP-LSTM, combining physical process and deep learning, can be viewed as a potentially useful approach for water level prediction in the TGR, and possibly for the rapid forecast of changes in water levels in other large rivers. [ABSTRACT FROM AUTHOR]

The downstream water level of a reservoir is influenced by its own discharge, changes in external hydraulic conditions, and the value of the previous period's downstream water level, and is very sensitive to hourly changes. However, the influence mechanisms of this change and an accurate prediction method have yet to be investigated. In this study, the downstream water level of Xiangjiaba reservoir in China's Jinsha river was used as a case study to analyze the impact of backwater effects caused by river rising during the flood season and the effect of sharp fluctuations caused by the peak regulation flow during the non-flood season. Moreover, an accurate prediction method at short-term two hourly scale is proposed. This study quantified the backwater effect caused by the rising tributaries of Hengjiang and Minjiang rivers. The random forest algorithm (RF) was used to downscale and rank multidimensional feature data, build different model factor sets, and build a downstream water level prediction model using five different methods. The results showed that the data mining model had the best fit and good prediction ability for the downstream water level of the Xiangjiaba reservoir under the influence of complicated hydraulic factors during the flood season, and can effectively control the fluctuation error during the peak regulation period. The research findings can be applied to other similar basins to improve the reservoir's short-term refined operational levels. [ABSTRACT FROM AUTHOR]

Under increasing anthropogenic pressure, species with a previously contiguous distribution across their ranges have been reduced to small fragmented populations. The critically endangered Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis), once commonly observed in the Yangtze River-Poyang Lake junction, is now rarely seen in the river-lake corridor. In this study, static passive acoustic monitoring techniques were used to detect the biosonar activities of the Yangtze finless porpoise in this unique corridor. Generalized linear models were used to examine the correlation between these activities and anthropogenic impacts from the COVID-19 pandemic lockdown and boat navigation, as well as environmental variables, including hydrological conditions and light levels. Over approximately three consecutive years of monitoring (2020–2022), porpoise biosonar was detected during 93% of logged days, indicating the key role of the corridor for finless porpoise conservation. In addition, porpoise clicks were recorded in 3.80% of minutes, while feeding correlated buzzes were detected in 1.23% of minutes, suggesting the potential existence of localized, small-scale migration. Furthermore, both anthropogenic and environmental variables were significantly correlated with the diel, lunar, monthly, seasonal, and annual variations in porpoise biosonar activities. During the pandemic lockdown period, porpoise sonar detection showed a significant increase. Furthermore, a significant negative correlation was identified between the detection of porpoise click trains and buzzes and boat traffic intensity. In addition to water level and flux, daylight and moonlight exhibited significant correlations with porpoise biosonar activities, with markedly higher detections at night and quarter moon periods. Ensuring the spatiotemporal reduction of anthropogenic activities, implementing vessel speed restrictions (e.g., during porpoise migration and feeding), and maintaining local natural hydrological regimes are critical factors for sustaining porpoise population viability. [ABSTRACT FROM AUTHOR]

With the extensive production and use of antibiotics for medicinal and veterinary purposes, antibiotics and genes that code for antibiotic resistance are now present in various environmental media with higher frequencies of occurrence and at higher concentrations than before. Particularly, China has led the world in the production and consumption of antibiotics, which might lead to higher pollution levels of antibiotic resistance genes and pose a threat to human health. Here, we review the sources of antibiotic resistance genes in China, and their spatial distribution and pollution levels in surface water, e.g., in lakes and rivers, atmosphere, and soil. Statistics indicate that higher levels of antibiotics and related antibiotic resistance genes were detected in eastern China compared with other regions, and that tetracycline and sulfanilamide resistance genes are the most prevalent. The absolute concentrations of antibiotic resistance genes are 102 − 105 copies per milliliter of water, 104–108 copies per gram of soil, and 104–106 copies per cubic meter of atmosphere. We also analyze the pollution status and fate of antibiotic resistance genes in wastewater treatment processes. Then, the biological and abiotic factors affecting the transfer and distribution of antibiotic resistance genes are elucidated. We discuss the risks of antibiotic resistance genes for ecological safety and human health. [ABSTRACT FROM AUTHOR]

Purpose: Substantial quantities of sedimentary materials are transported from the Yangtze River toward the water level fluctuation zone (WLFZ) of the Three Gorges Reservoir (TGR). Sediment and riparian soil coring across the elevation gradient in the WLFZ of the TGR over a 6-year period are used to interpret deposition patterns, particle size properties, total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), and nutrient ratios using fluvial and suspended sediment data from upstream under flow regime manipulation of the reservoir. Materials and methods: Sediment and associated riparian soil cores were extracted in 2013 and 2019 across various elevation gradients in the WLFZ of the TGR. A total of 15 sediments and 24 soil cores were extracted. The sectioned sediment and soil subsamples were analyzed for particle size distribution (PSD) (including sand, silt, and clay fractions); median particle size (MPS) distributions, TOC, TN, TP, and various nutrient ratios were calculated. Upstream suspended sediment and hydrological data were used to interpret sediment deposition, carbon, associated nutrient deposition, and storage dynamics across the elevation gradient. Results and discussion: Sediment deposition and relative fining of sediment and riparian soil were irregular, decreased with an increase in elevation, and increased with time. In 2013, the distributions of TOC, TN, TP, and nutrient ratios were irregular, and comparatively stable distributions were observed in 2019, which increased from lower to upper elevation gradient. With a few exceptions, similar trends were also observed in riparian soil core profiles. We conclude that water level fluctuations, water residence time, suspended sediment dynamics, time, and topography played a significant role in determining changes in sediment and riparian soil properties over time. Fine sediment-induced carbon and nutrient lateral translocations and subsequent interactions in sediment and soil layers due to repeated inundation cycles change the sediment and soil properties over time. Conclusions: This study interprets sedimentary carbon and nutrient redistribution and translocation processes. The concentrations of carbon and nutrients in sediments and soils change over time due to various fluvial, sedimentary, and geochemical processes, including the hydrological regime, flow regulation manipulation, repeated inundation cycles, water residence time, and suspended sediment dynamics. Fine sediment-associated lateral translocations cause the enrichment of these components in sediments and riparian soils. Sediment deposition is declining in this region due to environmental protection and conservation initiatives. [ABSTRACT FROM AUTHOR]

In the Three Gorges reservoir region, central China, seismic activity increased substantially after the reservoir impoundment in 2003 which continues till date. Previous studies show that these are reservoir-triggered earthquakes and various factors are responsible for the increase in seismic activity after the reservoir impoundment. However, these studies do not provide a comprehensive assessment of influence of reservoir water level variations on spatiotemporal distribution of earthquakes. In this study, we statistically analyze the influence of the water level variations on the increased seismic activity in the reservoir region for the period from May 2003 to April 2020, using the power spectrum and singular spectrum techniques. Our statistical analyses confirm the influence of long-term variations in the water level time series on the occurrence of earthquakes after the reservoir impoundment. The analysis also indicates a positive role of annual reservoir water level fluctuations in the total seismicity of the region. Depending on the cluster patterns and relationship with faults, the earthquakes of the Three Gorges reservoir region are divided into three seismic zones (A, B, and C). For zone C, both the power spectrum and singular spectrum analyses confirm the strong periodic influence of reservoir water level variations on the earthquakes. Increase in seismicity of zone B is only in the initial period but not in the later stages of water impoundment and our statistical analyses indicate that the seismicity of this zone is not directly related to the annual reservoir water level variations. This confirms the conjecture in the earlier studies that the seismicity of this zone is related to the collapse of coal mines present in the area in the initial stages of reservoir impoundment. For zone A, our statistical analyses do not show strong influence of the annual reservoir water level variations on the occurrence of earthquakes. We suggest that this is due to the contribution of various other factors along with reservoir impoundment in the occurrence of earthquakes in this zone, as also opined in some earlier studies. [ABSTRACT FROM AUTHOR]

Groundwater is crucial for economic development in arid and semiarid areas. The Shiyang River Basin (SRB) has the most prominent water use issues in northwestern China, and overexploited groundwater resources have led to continuous groundwater-level decline. The key governance planning project of the SRB was issued in 2007. This paper synthetically combines remote-sensing data from Gravity Recovery and Climate Experiment (GRACE) data and precipitation, actual evapotranspiration, land use, and in situ groundwater-level data to evaluate groundwater storage variations on a regional scale. Terrestrial water storage anomalies (TWSA) and groundwater storage anomalies (GWSA), in addition to their influencing factors in the SRB since the implementation of the key governance project, are analyzed in order to evaluate the effect of governance. The results show that GRACE-derived GWS variations are consistent with in situ observation data in the basin, with a correlation coefficient of 0.68. The GWS in the SRB had a slow downward trend from 2003 to 2016, and this increased by 0.38 billion m³/year after 2018. As the meteorological data did not change significantly, the changes in water storage are mainly caused by human activities, which are estimated by using the principle of water balance. The decline in GWS in the middle and lower reaches of the SRB has been curbed since 2009 and has gradually rebounded since 2014. GWS decreased by 2.2 mm EWH (equivalent water height) from 2011 to 2016, which was 91% lower than that from 2007 to 2010. The cropland area in the middle and lower reaches of the SRB also stopped increasing after 2011 and gradually decreased after 2014, while the area of natural vegetation gradually increased, indicating that the groundwater level and associated ecology significantly recovered after the implementation of the project. [ABSTRACT FROM AUTHOR]

With the deep coal mining in China, the contradiction between the mine water inrush from aquifer underling the coal seam and the decline ecological water level is more and more serious. Based on the analysis of the assemblage characteristics between the No. 5 coal seam and the aquifer(auifuge) in Chenghe mining area, the present study is to investigate the depth of destroyed floor by combining the theoretical calculation and in-situ measurement. The influence of coal seam mining on the confined water underling the coal seam has been studied from the perspective of aquifer structure, ecological water level and water quality. The results indicate that the maximum depth of destroyed floor of the No. 5 coal seam is 8-10. 8 m, and the main control factors of the depth of destroyed floor are the dip length of working face and the lithologic association of floor. And there is a positive correlation between the dip length of working face and the depth of destroyed floor, a negative correlation between lithologic association of floor and the depth of destroyed floor. Influence degree of the aquifer structure from large to small can be divided into Ⅰ,Ⅱ,Ⅲ level area, and the Ⅰ level areas are mainly distributed in the central-south and north,which covers an area of 6. 78 km2,accounting for 45． 2% of the total area; there is no obvious effect on water level and water quality. The paper puts forward a grouting reinforcement technology to protect water resources and stabilize the ecological water level in mining, and finds an effective way for the healthy development of coal industry in Weibei region. [ABSTRACT FROM AUTHOR]

Evaluation of lake ecological security is important for sustainable management of lakes and regional ecological environment construction. Dongting Lake is the second largest freshwater lake in China; its ecological security directly threatens the ecological security of the middle and lower reaches of the Yangtze River. In this paper, the ecological security evaluation index system of the Dongting Lake is constructed, including target layer (first order), criterion layer (second order), and index layer (last order). The target layer is the ecological security of the lake, the standard layer includes five indicators, and the index layer includes 11 indicators. The comprehensive evaluation method is used to evaluate the ecological security of the Dongting Lake by assessing all indexes of every layer. The weight of each index is determined by analytic hierarchy process. The evaluation results showed that the ecological security score of the Dongting Lake is 58 points, belonging to sub-security level. At present, the Dongting Lake has problems of low ecological water level, reduced lake surface area, eutrophication, and reduced lake storage capacity. Therefore, in future, the industrial and domestic pollution sources should be controlled, and the carrying capacity of water environment should be improved. [ABSTRACT FROM AUTHOR]

• Interval extended by TFN is used to determine the 2-tuple weighted vectors. • 2-tuple water-richness evaluation model is built by an extended ITL-VIKOR using TFN. • Model is verified by three dimensional high-density resistivity method. • Water-richness evaluation is extended to binary pattern for the first time. Jiaozuo coalfield is the most typical in Northern China type coalfield. When it mined the Permian coal seams, it was threatened by water inrush from the confined aquifer of thin karst fissure limestone in the lower Carboniferous. How to scientifically evaluate and predict the water-richness of thin karst fissure limestone in Carboniferous system has become the most important work in mine water control and prevention. Taking the mining of coal seam No. 2 1 of Shanxi Formation in Guhanshan coal mine as an example, this paper analyzed the water-richness main controlling factors of L 8 Limestone Aquifer of Taiyuan Formation, and selected four evaluation indexes, i.e. water inflow of drilling, the thickness of L 8 Limestone Aquifer, the water level of L 8 Limestone Aquifer and fault fractal dimension. The 2-tuple linguistic weights of all factors were obtained by the use of interval 2-tuple linguistic method extended by triangular fuzzy numbers. Following the above outlines, the mathematical model for the 2-tuple linguistic evaluation of water-richness was established based on ITL-VIKOR method extended by triangular fuzzy numbers. The data of geophysical exploration were collected to test the accuracy of the model. In addition, the results of 2-tuple linguistic assessment of water-richness and geophysical exploration were used to evaluate the water-richness of L 8 Limestone Aquifer, which extends the evaluation and prediction of water abundance for karst fractured aquifers to dyadic array. These results have been applied to guide the safe mining in Guhanshan coal mine, and will be further extended to the mines with similar geological conditions. It is our goal to establish an intelligent application system to ensure safe production in coal mines, which is great beneficial to the technical personnel engaged in mine water prevention and control. [ABSTRACT FROM AUTHOR]

Global climate change has led to large fluctuations in lake levels in recent years as meteorological and hydrological parameters have changed and water use has been intense. Water scientists use various computer models to analyze the hydrological variables recorded in the past and make projections for all future scenarios. Based on the technological progress, six different types of algorithms were studied in this review to predict the water level in lakes. The prediction results show that Deep Learning (DL) has the highest accuracy in terms of the evaluation metrics. Since the Artificial Intelligence (AI) field is still emerging and continue to improve, this study highlights better comprehension of current applications and the problems that need to be investigated more for LWL forecasting techniques. It reveals that the studies mainly focused on lakes either in USA or China and there is room for improvement for other locations that are scarcely investigated. • This paper presents a systematic literature review for lake and reservoir water level studies for the first time. • Researchers favored input parameters as lake water level, precipitation and temperature among others. • The studies can be extended towards the direction of least studied areas such as deep learning based algorithms. • Increasing water level prediction areas recently indicates it became a hot topic because of visible climate change effects. [ABSTRACT FROM AUTHOR]

Many large-deep reservoirs have been built, are under construction, or are planned in southwestern China, to meet increasingly high energy demands. The construction of dams can significantly alter the natural hydrodynamic and thermal conditions of rivers, thereby, threatening aquatic ecosystems, e.g., fish and algae communities. However, the impacts of large-deep reservoir operations on the hydrodynamic and thermal conditions and their potential influence on aquatic ecosystems have seldom been addressed. In this study, a quasi-3D hydrodynamic model is developed to describe the hydrodynamic and thermal conditions of a large deep reservoir, Nuozhadu, the largest reservoir along the Lancang River. The water temperature and flow velocity after the impoundment of the reservoir are examined. To explore how reservoir operation changes the hydrodynamic and thermal conditions, five groups of reservoir operational scenarios based on different water levels and discharge rates are conducted. Our results indicate that a lower water level combined with a higher discharge rate can increase the flow velocity and decrease the surface water temperature in the reservoir, which may contribute to diminishing the growth of Cyanobacteria. Meanwhile low water levels can also increase the outflow water temperature to protect the downstream fish. Further, the LowLevel and MaxPower schemes were designed to provide ecologically favorable hydrodynamic conditions, and to maximize power generation, respectively. The LowLevel scheme was found to reduce the duration of high surface water temperature (>25°C) by 18 days annually and reduce the outflow temperature by 0.8°C in the fish spawning period, at the expense of a 10% reduction in power generation. This study contributes to a better knowledge of the linkage among hydrodynamic, thermal conditions, and ecological impacts due to reservoir operation, and provides a novel perspective regarding the ecological safety of a large deep reservoir operation. [ABSTRACT FROM AUTHOR]

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Ensuring the long-term, efficient, and safe operation of reservoir dams relies on the slope stability of embankment dams. Periodic fluctuations of the reservoir water level due to reservoir scheduling operations make the slope of the reservoir bank vulnerable to instability. To investigate the influence of various factors and their interactions with embankment dam slope stability under changing reservoir water levels, a global sensitivity analysis method is proposed that accounts for seepage–stress coupling. An embankment dam in Shaanxi Province, China, is studied as an example, with COMSOL Multiphysics software simulating the seepage and slope stability of the dam under fluctuating reservoir water level conditions and seepage–stress coupling. The global sensitivity analysis of factors affecting dam slope stability is accomplished by combining Plackett–Burman and Box–Behnken experimental designs, with ANOVA determining the sensitivity of each factor and interaction term. The results demonstrate that during the impoundment period of the reservoir, the saturation line is concave, and the overall stability safety of the dam slope increases first and then tends to be stable, according to the coefficient. The internal friction angle φ, cohesion c, and soil density ρs represent the three most sensitive factors affecting the stability and safety of the dam slope, while c × ρs is a second-order interaction term with significant sensitivity to the stability and safety coefficient of the dam slope. The reservoir drainage period infiltration line is convex, and dam slope stability first reduced and then increased. The magnitude of water level change H, internal friction angle φ, cohesion c, and soil density ρs are the four most sensitive factors for the coefficient of safety of dam slope stability, while c × ρs, H × ρs, and φ × ρs are the second-order interaction terms with significant sensitivity to the coefficient of safety of dam slope stability. These research findings and methods can offer valuable technical support and reference for the investigation and evaluation of the stability of embankment dam slopes. [ABSTRACT FROM AUTHOR]

Dams and reservoirs are human-made infrastructures that have attracted increasing attention because of their societal and environmental significance. Towards better management and conservation of reservoirs, a dataset of reservoir-catchment characteristics is needed, considering that the amount of water and material flowing into and out of reservoirs depends on their locations on the river network and the properties of the upstream catchment. To date, no dataset exists for reservoir-catchment characteristics. The aim of this study is to develop the first database featuring reservoir-catchment characteristics for 3254 reservoirs with storage capacity totaling 682 595 km3 (73.2 % of reservoir water storage capacity in China) to support the management and conservation of reservoirs in the context of catchment level. To ensure a more representative and accurate mapping of local variables of large reservoirs, reservoir catchments are delineated into full catchments (their full upstream contributing areas) and intermediate catchments (subtracting the area contributed by upstream reservoirs from the full upstream part of the current reservoir). Using both full catchments and intermediate catchments, characteristics of reservoir catchments were extracted, with a total of 512 attributes in six categories (i.e., reservoir and catchment body characteristics, topography, climate, soil and geology, land cover and use, and anthropogenic activity characteristics). Besides these static attributes, time series of 15 meteorological variables of catchments were extracted to support hydrological simulations for a better understanding of drivers of reservoir environment change. Moreover, we provide a comprehensive and extensive reservoir dataset on water level (data available for 20 % of 3254 reservoirs), water surface area (99 %), storage anomaly (92 %), and evaporation (98 %) from multisource satellites such as radar and laser altimeters and images from Landsat and Sentinel satellites. These products significantly enhance spatial and temporal coverage in comparison to existing similar products (e.g., 67 % increase in spatial resolution of water level and 225 % increase in storage anomaly) and contribute to our understanding of reservoir properties and functions within the Earth system by incorporated national or global hydrological modeling. In situ data of 138 reservoirs are employed in this study as a valuable reference for evaluation, thus enhancing our confidence in the data quality and enhancing our understanding of the accuracy of current satellite datasets. Along with its extensive attributes, the Reservoir dataset in China (Res-CN) can support a broad range of applications such as water resources, hydrologic/hydrodynamic modeling, and energy planning. Res-CN is on Zenodo through 10.5281/zenodo.7664489 (Shen et al., 2022c). [ABSTRACT FROM AUTHOR]

Anthropogenic land-use change, irrigation, is considered to strongly modulate the hydroclimate at the regional scale by directly triggering evaporative cooling as the preliminary local effect. However, subsequent interactions with the background climate are highly nonlinear, which introduces diverse and unexpected consequences. The North China Plain (NCP) is one of the regions where irrigation has expanded the most rapidly since the twentieth century. The scarce rainfall in this region makes it necessary for irrigation to supplement the level of soil water for agricultural production. In this study, we quantify the effect of irrigation on the regional climate in China. Two regional climate models, WRF and RegCM, are used to mimic the large-scale practice of irrigation on the NCP. The results of our experiments show consistent cooling and moistening effects centered over the NCP across all experiments. Although the moisture budget and wind field pattern demonstrate that the vertical downdraft and low-level divergence could inhibit rainfall, the humidification dominates the climatic response in the dry April–June and increases the amount of precipitation significantly and consistently in the NCP region and the surrounding area in northern China. The enhanced CAPE increases sharply on some "calm days" when the vertical moisture advection is small, especially during the afternoon, triggering frequent light rains convectively by destabilizing the atmosphere. The consistent response to irrigation in two different models that employ structurally different land surface schemes could enhance the robustness of the physical mechanism behind the precipitation increase in the heavily irrigated region of NCP. [ABSTRACT FROM AUTHOR]

The southwestern region of China is close to the Eurasian earthquake zone. Many engineering areas in southwestern China are affected by earthquakes and are close to the epicenter of earthquakes that occur in this region. During earthquakes, slopes with weak interlayers are more likely to cause large-scale landslides. In response to the low stability of slopes with weak interlayers in reservoir dam areas, the dynamic response law and failure mechanism of weak interlayered slopes under the combined action of reservoir water and seismic forces were studied through shaking table model tests and finite element numerical simulation software. The height of the water level and the size of the seismic waves were changed during these tests. The research results indicate that seismic waves are influenced by weak interlayers and are repeatedly superimposed between the weak interlayers and the slope surface, resulting in an acceleration amplification effect that increases by approximately 1.8 times compared to homogeneous slopes. Vertical earthquakes have a significant impact on the dynamic response of slopes, and their peak acceleration amplification coefficient can reach 0.83 times the horizontal peak acceleration. The stability of weak interlayers during earthquakes is the worst within the range of the direct action of reservoir water. The failure mode of a slope is as follows: earthquake action causes cracking in the upper part of the slope, and as the earthquake increases in intensity, and the infiltration of reservoir water intensifies, the cracks expand. The soft and muddy interlayer in the front section of the slope forms a sliding surface, and ultimately, the sliding failure forms an accumulation body at the foot of the slope. In reservoir dam areas, the stability of a slope is closely related to the engineering safety of the reservoir dam. Therefore, when a strong earthquake and the water level in a reservoir jointly affect a weak-interlayer slope, the slope is in the stage of plastic deformation and instability. The stability of the slope may be overestimated, and the slope is likely vulnerable to sliding instability, which needs to be monitored and treated. [ABSTRACT FROM AUTHOR]

Dam operation is regarded as an effective way to increase water, food, and energy security for society. However, with the increasing water demand and frequent extreme droughts, numerous rivers worldwide go through periods of water scarcity and water ecosystem deterioration to varying degrees. Balancing the water supply and ecological flow of the dam-regulated river network is essential in the context of river restoration. In this study, we proposed a hydrodynamic and water quality model of a dam-regulated river network balancing water supply and ecological flow using the Environmental Fluid Dynamics Code (EFDC). A section of Jinjiang watershed located in the southwestern of China was chosen as the study area. Firstly, the model was calibrated and validated. By comparing the simulated values with the measured values, the statistical analysis results showed that the relative root mean-squared error (RRMSE) values of water level, COD and NH3-N were 5.5–8.1%, 23.6% and 28.4%, respectively, indicating an adequate degree of agreement between simulation and observation. Based on the established model, dam operation schemes under a dry hydrologic scenario and emergency contamination scenario were formulated to ensure the requirement of ecological water flow and water quality simultaneously. For the dry hydrologic scenario, the ecological water requirement could be satisfied through the dam operation. However, in an emergency contamination scenario, regional water quality requirements cannot be met through dam operation. The dam operation only plays a role in controlling the scope of pollution. This study is expected to provide scientific support for dam-regulated river network management and downstream river ecosystem protection. [ABSTRACT FROM AUTHOR]

Mountainous regions are prone to dammed lake disasters due to their rough topography, scant vegetation, and high summer rainfall. By measuring water level variation, monitoring systems can detect dammed lake events when mudslides block rivers or boost water level. Therefore, an automatic monitoring alarm method based on a hybrid segmentation algorithm is proposed. The algorithm uses the k-means clustering algorithm to segment the picture scene in the RGB color space and the region growing algorithm on the image green channel to select the river target from the segmented scene. The pixel water level variation is used to trigger an alarm for the dammed lake event after the water level has been retrieved. In the Yarlung Tsangpo River basin of the Tibet Autonomous Region of China, the proposed automatic lake monitoring system was installed. We pick up data from April to November 2021, during which the river experienced low, high, and low water levels. Unlike conventional region growing algorithms, the algorithm does not rely on engineering knowledge to pick seed point parameters. Using our method, the accuracy rate is 89.29% and the miss rate is 11.76%, which is 29.12% higher and 17.65% lower than the traditional region growing algorithm, respectively. The monitoring results indicate that the proposed method is a highly adaptable and accurate unmanned dammed lake monitoring system. [ABSTRACT FROM AUTHOR]

Floodplain wetlands are among the most dynamic ecosystems on Earth, featuring high biodiversity and productivity. They are also sensitive to anthropogenic disturbances and are globally threatened. Understanding how flow regime drives the spatiotemporal dynamics of wetland habitats is fundamental to effective conservation practices. In this study, using Landsat imagery and the random forest (RF) machine learning algorithm, we mapped the winter distribution of four wetland habitats (i.e., Carex meadow, reedbed, mudflat, and shallow water) in East Dongting Lake, a Ramsar wetland in the middle to lower Yangtze Basin of China, for 34 years (1988–2021). The dynamics of wetland habitats were explored through pixel-by-pixel comparisons. Further, the response of wetland habitats to flow regime variations was investigated using generalized additive mixed models (GAMM). Our results demonstrated the constant expansion of reedbeds and shrinkage of mudflats, and that there were three processes contributing to the reduction in mudflat: (1) permanent replacement by reedbed; (2) irreversible loss to water; and (3) transitional swapping with Carex meadow. These changes in the relative extent of wetland habitats may degrade the conservation function of the Ramsar wetland. Moreover, the duration of the dry season and the date of water level withdrawal were identified as the key flow regime parameters shaping the size of wetland habitats. However, different wetland vegetation showed distinct responses to variations in flow regime: while Carex meadow increased with earlier water withdrawal and a longer dry season, reedbed continuously expanded independent of the flow regime corresponding to the increase in winter rainfall. Our findings suggested that flow regime acts in concert with other factors, such as climate change and sand mining in river channels, driving wetland habitat transition in a floodplain landscape. Therefore, effective conservation can only be achieved through diverse restoration strategies addressing all drivers. [ABSTRACT FROM AUTHOR]

Archaeologists frequently invoke climate change as a driving cause for ancient expansions of human populations, but geomorphic changes can also play an important role in opening or closing routes of migration. In China, archaeological evidence demonstrates that valleys in the Jialing River's watershed were important routes for the movement of Neolithic populations from the catchments of the Yellow River to the Yangtze River. Here, we examine how fluvial geomorphological regime shifts may have also influenced the migration pathways and adaptive strategies of Neolithic people into the Sichuan Basin by using a combination of sedimentological and palynological analysis at Luojiaba, an archaeological site located on one of the eastern tributaries of the Jialing River. The results show that people settled on seasonally stable landforms, including the Zhonghe River floodplain at Luojiaba (5300–4800 cal. B.P.). They carried out fishing and hunting activities on the front edge of the floodplain close to the river channel and built dwelling features on the higher ground at the back edge of the floodplain, which was not affected by seasonal floods. We hypothesize that during the Holocene Climatic Optimum before 5500 cal. B.P., high water levels as well as severe surface erosion caused by a strong East Asian Summer Monsoon (EASM) blocked pathways into the upper reaches of the Jialing River watershed. Only after a series of cold, dry climate events driven by a decrease in EASM intensity ca. 5500–5000 cal. B.P. did water levels recede significantly. This allowed alluvial aggradation to occur, which created floodplains and terraces along the valley that may have opened a new route for the migration into the Sichuan Basin. Our results reveal the human–environment dynamics surrounding Luojiaba in the uplands of southwestern China and highlight the impact of coupled climatic‐geomorphic regime shifts on human settlement and subsistence strategies, across both space and time. [ABSTRACT FROM AUTHOR]