Endorheic Research Articles

A new algorithm for the energy–water balance model to quantitatively reconstruct Holocene precipitation and vegetation: a case study from Dali Lake, North China

Quantitatively reconstructing precipitation is an important component of paleoclimate research. The mean annual precipitation (MAP) of a closed-basin lake can be estimated by the energy–water balance model (EWBM). The EWBM can be divided into linear and nonlinear models, with determination of evaporation over water and land surface being the main components. However, the influence of vegetation changes on different models and the potential of the models to reconstruct vegetation remain unclear. Dali Lake, a closed-basin lake in the marginal region of the East Asian summer monsoon (EASM), is selected as the study region to test the feasibility of a new algorithm, i.e., the comparative method. This method is performed by comparing the reconstructed MAPs given by linear and nonlinear models for each stepwise reduced or increased forest fraction until both MAPs are approximately equal within the error range. The results indicate that the linear model is more sensitive to vegetation changes than the nonlinear model; however, both linear and nonlinear models can obtain the modern MAP correctly. Additionally, the comparative method can successfully determine the vegetation cover. Using the reported paleolake levels of Dali Lake, we calculate the Holocene MAP and vegetation of the Dali Lake basin. The results show that the early and middle Holocene MAP obtained by the comparative method is ∼10 mm higher than that obtained by the nonlinear model, while the difference in the late Holocene is not insignificant. The reconstructed vegetation is generally consistent with the pollen-indicated vegetation changes in the Dali Lake region and the monsoon marginal zone in North China. Our study suggests that both linear and nonlinear models can provide reliable MAP values for basins with known vegetation. For basins with unknown vegetation, the nonlinear model with variable parameters or the more advantageous comparative method is preferred. In cases where the basin mainly consists of two vegetation types, the comparative method enables to reconstruct the fraction of two vegetation types.

An effective multiphysics toolkit for lithium prospecting: From geophysics to the static reservoir model in the Pozuelos salt flat, Argentina

Energy transition drives the energy sector to renewable energy and electrification, being the critical minerals key players in the industrial development map. They comprise rare-earth elements and 35 other elements, including lithium, which holds 60% of its world reserves in the so-called lithium triangle located in Argentina, Bolivia, and Chile. The low electrical resistivities, variations in salt concentrations, low acoustic impedances, and dynamics of the hydrogeologic system make brine monitoring a complex geophysical exploratory problem. So, the objective is to find a suitable combination of geophysical techniques that fit the lithium exploration objectives, which are the characterization of the salt flat in-depth, fluid detection, basement delineation, definition of the main structures and main faults, and detection of semifresh water aquifers that contribute to its recharge and that are key to the reservoir water balance of an endorheic basin, which has the resource in solution. For this purpose, the evaluation of several prospecting methods in different salt flats was executed, concluding that full tensor magnetotellurics (MT), electrical resistivity tomography, and gravity comprise a toolkit that fits the objectives set. The methodology was validated at the Pozuelos salt flat. The results show that the fresh water-brines contact and the recharge system were well-defined and imaged by ERT. The full tensor MT detected two ultraconductive units: a shallower multilayer system saturated with brines, has a 400 m thickness, whereas the deeper unit has a 500 m thickness. Both MT and gravity characterized the basement, and gravity successfully delineated the main structures. The geophysical interpretation is in concordance with shallow and deep exploration wells. Finally, the integration of geophysical and well data allowed the construction of a 3D static reservoir model that finds the deepest basement area at approximately 900 m depth and discriminates eight lithofacies.

Spatiotemporal analysis of precipitation variability in an endorheic basin of Turkey with coordinated regional climate downscaling experiment data

Understanding how temporal precipitation variability will behave in the future is crucial. Change point detection and sub-trend analysis were done on monthly total precipitation data acquired from the Coordinated Regional Climate Downscaling Experiment project in this study. Sub-periods have been determined based on the natural structure of the data set, as opposed to standard sub-period determination approaches. For the period 1971–2100, six different time series were used under three global climate models (CNRM-CERFACS-CNRM-CM5, ICHEC-EC-EARTH, MPI-M-MPI-ESM-LR) and two emission scenarios (Representative Concentration Pathway (RCP) 4.5 and RCP 8.5). The study area has been selected to be the Konya Endorheic Basin in Turkey, which has been significantly influenced by climate change and human impacts. For change point detection, the Pruned Exact Linear Time method (PELT) and Binary Segmentation (BS) were employed, for trend analysis, Mann Kendall (MK) and Şen-Innovative Trend Analysis (Şen-ITA), and for both change point detection and sub-trend analysis, the Onyutha Trend Test (OTT) was utilized. The findings revealed four change points and five sub-periods. Summer precipitation has reduced considerably at a 95% significance level. There is strong evidence that precipitation has decreased between 1981 and 2070. Precipitation decreases similarly in the middle basin for the 1981–2000 and 2041–2070 years.

Modeling and assessing the impacts of climate change on groundwater recharge in endorheic basins of Northwest China

Climate change imposing additional stressors on groundwater resources globally, thereby predicting groundwater recharge (GR) changes is crucial to sustainably managing water resources, especially in the arid endorheic basins. Groundwater in the Endorheic Basins of Northwest China (NWEB) is potentially impacting regional socio-economic output and ecosystem stability due to the imbalance between supply and extraction exacerbated by climate change. Hence, recognizing the impacts of climate change on past and future GR is imperative for groundwater supply and sustainable groundwater management in the NWEB. Here, the impact of historical (1971–2020) and projected (2021–2100) climate changes on GR across the entire NWEB and three distinctive landscape regions (i.e., mountainous, oasis, and desert) were assessed. A coupled distributed hydrologic model (CWatM-HBV model), which integrates the Community Water Model (CWatM) and the HBV model, was run with three shared socioeconomic pathways (SSP1–2.6, SSP2–4.5, and SSP3–7.0) forcing from 10 general circulation models (GCMs) to simulate and analyze the interannual and seasonal variations of GR, along with their driving factors. Over the past 50 years, both precipitation and runoff have undergone significant increases, and leading to a dramatic rise in GR (0.09 mm yr−1). The future annual growth rate of GR is projected to range from 0.01 to 0.09 mm yr−1 from SSP1–2.6 to SSP3–7.0 across the entire NWEB, with the majority of the increase expected during the spring and summer seasons, driven by enhanced precipitation. GR from the mountainous region is the primary source (accounting for approximately 56–59 %) throughout the NWEB with the greatest increase anticipated. Precipitation and runoff have significant influences on GR in mountainous areas, and the impact of precipitation on GR is expected to increase over time. Changes in GR in oasis and desert areas are mainly limited by precipitation variation and increase in the SSP2–4.5 and SSP3–7.0 scenario. Additionally, the processes of glacial retreat and permafrost degradation will complicate the GR dynamics although the process is largely interfered with by anthropogenic environmental changes, especially in oasis-desert systems. The average annual recharge in the NWEB was 8.9 mm in the historical period and 13.6 ± 4.1 mm in the future. Despite an increase in GR due to climate change, groundwater storage is likely to continue to decline due to complex water demands in the NWEB. This study highlights the significance of future precipitation changes for GR and contributes to the understanding of the influence of climate change on groundwater systems and advances the sustainable management of water resources.

The application and modification of WRF-Hydro/Glacier to a cold-based Antarctic glacier

Abstract. The McMurdo Dry Valleys (MDV) are home to a unique microbial ecosystem that is dependent on the availability of freshwater. This is a polar desert and freshwater originates almost entirely from surface and near-surface melt of the cold-based glaciers. Understanding the future evolution of these environments requires the simulation of the full chain of physical processes from net radiative forcing, surface energy balance, melt, runoff and transport of meltwater in stream channels from the glaciers to the terminal lakes where the microbial community resides. To establish a new framework to do this, we present the first application of WRF-Hydro/Glacier in the MDV, which as a fully distributed hydrological model has the capability to resolve the streams from the glaciers to the bare land that surround them. Given that meltwater generation in the MDV is almost entirely dependent on small changes in the energy balance of the glaciers, the aim of this study is to optimize the multi-layer snowpack scheme that is embedded in WRF-Hydro/Glacier to ensure that the feedbacks between albedo, snowfall and melt are fully resolved. To achieve this, WRF-Hydro/Glacier is implemented at a point scale using automatic weather station data on Commonwealth Glacier to physically model the onset, duration and end of melt over a 7-month period (1 August 2021 to 28 February 2022). To resolve the limited energetics controlling melt, it was necessary to (1) limit the percolation of meltwater through the ice layers in the multi-layer snowpack scheme and (2) optimize the parameters controlling the albedo of both snow and ice over the melt season based on observed spectral signatures of albedo. These modifications enabled the variability of broadband albedo over the melt season to be accurately simulated and ensured that modelled surface and near-surface temperatures, surface height change and runoff were fully resolved. By establishing a new framework that couples a detailed snowpack model to a fully distributed hydrological model, this work provides a stepping stone to model the spatial and temporal variability of melt and streamflow in the future, which will enable some of the unknown questions about the hydrological connectivity of the MDV to be answered.

Assessment of Potential Accumulation of Trifluoroacetate in Terminal Lakes.

Trifluoroacetate (TFA) is the anionic form of the shortest perfluorocarboxylic acid (PFCA) and is ubiquitous in the environment at concentrations that are typically much higher than those of other PFCAs. As a stable and nonvolatile anion, it is expected to accumulate in terminal lakes in endorheic basins. This research sampled eight terminal lakes in the Western United States to determine the degree to which TFA is concentrating in these lakes and compare the data to samples collected from three of these lakes 25 years ago. The first observation was that three of the six terminal lakes sampled had higher TFA concentrations than their input streams, while the last two lakes lacked surface water inputs at the sampling time. The TFA concentrations in Mono Lake effectively remained constant over 25 years despite the input stream concentrations increasing 6.5-fold. In contrast, Pyramid Lake concentrations increased approximately the expected amount based on a simplistic analysis of input flows and concentrations. An additional observation was that lakes in basins with agricultural activity appeared to have higher TFA concentrations, which suggests an agricultural input.

Participant approach model in a basin: A case study from Turkey

Abstract The Beyşehir Lake Basin, which is the study area, is the second largest sub-basin within the Konya province, located southwest of the Konya Closed Basin in terms of surface by 7,308 km2. Some basin characteristics such as slope, elevation classes, land use, aspect groups, land capability class, erosion status were examined by a Geographic Information System. The aims of the study were to determine the problems and the requests and suggestions of the people living in the basin, and to reveal the needs and deficiencies. For these purposes, the current and potential situation of the basin was evaluated using a holistic evaluation approach, which represents the most important of the watershed management principles, and the solutions were concluded in the light of the findings of the study. Migration, inadequacy of agricultural activities, lack of pasture areas for livestock activities, lack and neglect of irrigation water and irrigation infrastructure, lack of basic infrastructure such as village roads, and soil losses due to lack of erosion structures were the most obvious problems of the basin based on the results of the Ask–Find–Resolve analyses.

Satellite-based drought assessment in the endorheic basin of Lake Balkhash

Introduction: This study investigates into the drought-prone region of the Lake Balkhash basin, conducting a thorough analysis spanning 2 decades, emphasizing its significant impact on agriculture and water challenges in Central Asia. Beyond the specific focus on this region, the research aims to contribute valuable insights that extend our understanding of the broader implications of drought in the area.Methods: Utilizing MODIS satellite imagery, the study employs the Vegetation Health Index a comprehensive indicator combining the Vegetation Condition Index and Temperature Condition Index ranging from 0 (extreme aridity) to 100 (optimal moisture). The assessment of drought conditions from 2000 to 2020 includes probabilistic mapping, trend analysis, and Pearson’s correlation coefficients. Connections with hydrological factors, such as river water levels and the Balkhash Lake area, are explored, along with in-depth analyses of land use data and the GRACE dataset on water equivalent thickness, enhancing the study’s depth and reliability.Results: Drought affected approximately 44% of the Balkhash Lake Basin during the study period, impacting both Kazakhstan and China. Severe drought episodes occurred in 2000, 2008, 2014, and 2015, highlighting the region’s vulnerability. Analysis of drought trends revealed diverse patterns: 23% exhibited an increase, 17% showed a decrease, and 60% remained stable. Correlations between drought and hydrological parameters varied among stations, with positive correlations at Kapshagay and Shelek Stations, a weak correlation at Ayagoz Station, and a significant positive correlation at Lepsy despite the elevation.Discussion: This research underscores the intricate link between drought and hydrological factors in the Balkhash Lake Basin, emphasizing the need for precise water resource management and climate adaptation. Crucial strategies include proactive monitoring, tailored interventions, and the application of probabilistic drought mapping to enhance water supply management, contributing actionable insights for sustainable practices in the region.Conclusion: This study significantly advances our understanding of drought dynamics in the Balkhash Lake Basin, recommending adaptive strategies, site-specific interventions, and sustainable water management. The findings provide a crucial foundation for informed water resource decisions in Central Asia, emphasizing the importance of region-specific approaches to address diverse challenges posed by drought.

Late Neogene and Quaternary Lacustrine History of the Great Salt Lake-Bonneville Basin

The Great Salt Lake-Bonneville basin has contained lakes for many millions of years and has been hydrographically closed for most of its history. Lakes in the lacustrine system have ranged from saline to fresh, and from shallow to deep. Tectonics, specifically crustal extension, which began roughly 20 million years ago as part of the formation of the Basin and Range Province, is the cause of lake-basin formation. Much of the rock record of lakes from Miocene time is faulted and has been eroded and/or buried. Pliocene and Quaternary lakes are better known. For much of the past ~5 Ma the basin has probably appeared similar to today, with a shallow saline terminal lake in a dry desert surrounded by mountains. Freshwater marshes and fluvial systems existed on the basin floor during part of the past ~5 Ma, probably were caused by the lack of inflow from the upper Bear River during the Neogene Period and most of the Pleistocene Epoch (that river was diverted into the basin during the Late Pleistocene), combined with a warm and dry climate. The largest deep-lake cycles were caused by changes to a cold and wet climate, which affected the water budget of the lake system and were correlated with periods of global glaciation. Based on limited data, the total length of time deep lakes existed in the basin is thought to be less than 10% of the past ~773 ka. Lake Bonneville, the most-recent of the deep-lake cycles, was probably the deepest and largest manifestation of the lake system in the history of the basin. Named deep-lake cycles during the past ~773 ka, are Lava Creek (~620 ka), Pokes Point (~430 ka), Little Valley (~150 ka), Cutler Dam (~60 ka), and Bonneville (~30 -13 ka). Of the Quaternary deep-lake cycles, only Lake Bonneville is represented by lacustrine landforms, outcrops, and cores of offshore deposits; no landforms from older deep-lake cycles exist (some may be buried under Lake Bonneville deposits but are not visible at the surface), and pre-Bonneville lakes are represented by sediments in limited outcrops and drill holes (including a set of cores taken by A.J. Eardley in the mid 20th century). During the past ~773 ka, deep-lake cycles were correlated with changes in the total volume of global glacial ice; the available evidence indicates that prior to ~773 ka deep-lake cycles were rare.

A volatile sulfur sink aids in reconciling the sulfur isotope mass balance of closed basin lakes

Sedimentary rocks from the early Eocene Green River Formation comprise the largest known lacustrine oil shale deposits, contain remarkably well-preserved fossils, and provide a unique record of climate evolution across the Early Eocene Climate Optimum, a period of high atmospheric CO2. The depositional environment of these intermountain lakes spanned from relatively fresh and fluvially influenced to expanded and stratified saline closed basin lakes under the influence of the Laramide orogeny and alternating humid and arid climatic conditions. As the surface area of the lakes expanded, alkalinity and salinity increased, with depositional cycles that linked to evaporative cycles and marked by an increasing abundance of organic matter-rich shales (TOC > 10 wt%). Simultaneously, an intriguing 20 ‰ positive shift in the sulfur isotope composition of sulfide minerals and organic sulfur is observed. Given that this trend cannot be simply explained by a change in the source of sulfate delivered to the basin, the evolution of biogeochemical sulfur cycling and the balance of fluxes in response to basin evolution remain unresolved. Here, we combine the sulfur isotope compositions of pyrite, organic sulfur, and carbonate-associated sulfate and molecular proxies of euxinia in samples from the Uinta basin's depocenter. We find that organic matter-rich sediments reflect deposition in a stratified water column with enhanced burial of pyrite and sulfurized organic matter, while organic-lean facies present evidence of, at least transiently, euxinic conditions reaching the photic zone during arid conditions presumably because of evaporation. As the lake became both saline-stratified and euxinic, we observe that δ34S values of all measured sulfur-bearing sedimentary proxies increase and evolve along a 1:1 line, a trend independent of facies that we interpret as reflecting a sulfate-limited system despite saline conditions. The isotopic mass balance of sulfur fluxes implies the existence of a sink of sulfur depleted in 34S that is spatially decoupled from burial in the depocenter. Modeling sulfur biogeochemical processes in a saline stratified lake system allows us to estimate that at least 50 % of the sulfur entering the lake could have been lost from the upper part of the euxinic water column where the fractionation factor imparted by microbial sulfate reduction is expressed. We propose that the overall isotopic enrichment of the system was caused by H2S degassing during arid climate intervals, presumably enhanced by transient water column mixing events. Further, episodic intrusion of euxinic bottom waters into the upper part of the water column might have triggered mass fish and plankton mortality, consequently facilitating the formation of these exceptionally fossiliferous and organic matter-rich rocks. Our study finds that volatile outgassing may be an underappreciated mechanism for the sulfur mass balance of stratified lacustrine systems.

Fish Diversity and Use of Nearshore and Open‐Water Habitats in Terminal Lakes

Terminal lakes face conservation challenges due to consumptive water use and changes in climate. We quantified the extent of the littoral and open water zones in 18 terminal lakes spanning five continents and show that lake level declines produce variable changes in littoral zone surface area. While littoral zones account for a small portion of the habitat in these lakes, 77% of the fish species inhabit these zones and 87.5% consume littoral–benthic organisms. We found that littoral zone surface area correlates with littoral zone fish species richness (P < 0.01; R2 = 0.47) as well as the number of species relying on benthos (P < 0.01; R2 = 0.44). However, we found (1) no correlation between the percent of the lake's surface area that is littoral and the percent of the fish community that inhabits the littoral zone (Pearson's r = 0.3; P = 0.3), and (2) no correlation between the percent of the lake's surface area that is littoral and the percent of the fish community that consumes benthic organisms (Pearson's r = −0.1; P = 0.8). Because many terminal lakes are desiccating, conservation of biodiversity in the nearshore zones of these lakes may be warranted.

Delineation of endorheic drainage basins in the MERIT-Plus dataset for 5 and 15 minute upscaled river networks

The MERIT-Hydro networks re-gridded by the Iterative Hydrography Upscaling (IHU) algorithm do not retain exo- or endorheic basin attributes from the original data. Here we developed methods to assign such attributes to those and any other digital river networks. The motivation is that endorheic inland drainage basins are essential for hydrologic modelling of global and regional water balances, land surface water storage, gravity anomalies, sea level rise, etc. First, we create basin attributes that explicitly label endorheic and exorheic catchments by the criteria of direct or hidden connectivity to the ocean without changing their flow direction grid. In the second step we alter the delineation of endorheic basins by the merging algorithm that eliminates small inland watersheds to the adjacent host basins. The resulting datasets have a significantly reduced number of endorheic basins while preserving the total land portion and topology of the inland basins. The data was validated using the Water Balance Model by comparing volume of endorheic inland depressions with modelled water accumulation in their inland lakes.

Bacterial diversity and chemical ecology of natural product-producing bacteria from Great Salt Lake sediment.

Great Salt Lake (GSL), located northwest of Salt Lake City, UT, is the largest terminal lake in the USA. While the average salinity of seawater is ~3.3%, the salinity in GSL ranges between 5% and 28%. In addition to being a hypersaline environment, GSL also contains toxic concentrations of heavy metals, such as arsenic, mercury, and lead. The extreme environment of GSL makes it an intriguing subject of study, both for its unique microbiome and its potential to harbor novel natural product-producing bacteria, which could be used as resources for the discovery of biologically active compounds. Though work has been done to survey and catalog bacteria found in GSL, the Lake's microbiome is largely unexplored, and little to no work has been done to characterize the natural product potential of GSL microbes. Here, we investigate the bacterial diversity of two important regions within GSL, describe the first genomic characterization of Actinomycetota isolated from GSL sediment, including the identification of two new Actinomycetota species, and provide the first survey of the natural product potential of GSL bacteria.

Sustainable decision making based on systems integration and decision support system promoting endorheic basin sustainability

Sustainability has become a target in official policy rhetoric. However, the gap between scientific investigation and practical decision-making poses a significant challenge in achieving sustainability, particularly in endorheic regions. Addressing this challenge requires the translation of scientific outcomes into available decision-making information. In this study, we propose a sustainable decision-making methodology, namely, decision rehearsal, that has four stages: the scientification of decision-making problems, the politicization of scientific knowledge, the translation of scientific findings into decision-making information, and the translation of decision-making information into policy action. Based on this theoretical framework, an ensemble artifact, referred to as the River Basin Sustainable Development Decision Support System (RSDSS), was designed, built and evaluated from a design science research perspective to address a class of sustainability problems in endorheic basins. This system integrates a watershed-integrated model, disaggregated sustainable development goals (SDGs), localized shared socioeconomic pathways (SSPs), and a sustainability assessment model, which can assist decision- and policy-makers in more deeply understand the impacts of different policy assumptions on the interactions between human and natural systems and watershed sustainability. Some related RSDSS cases are discussed to demonstrate the ability of the RSDSS to resolve complex watershed problems, which implies that the RSDSS can promote sustainable river basin management.

Evaluating the groundwater quality in Northern Tarim Basin by resistivity inverted from magnetotelluric data

Groundwater is a potentially significant resource for agricultural and industrial uses in Tarim Basin, the largest arid endorheic basin in China. Hydrogeochemical and hydrogeologic researches have provided detailed information of groundwater chemical type, composition, ion content and flow. However, there is lacking in quantitative estimation of groundwater in whole basin scale subject to the limits of samples as well as the unclear underground structure. To address the problem, 3-D electrical resistivity model constructed from inversion of magnetotelluric (MT) data was used to calculate the Total Dissolved Solids (TDS) of groundwater based on previous experimental studies and empirical equations. The TDS model shows relatively high value in the east of the study area and in deep, primarily controlled by depth, flow direction, stratigraphy, and water table gradient. Groundwater can be classified into five categories in terms of TDS range in Standard for Groundwater Quality. Finally, the volume of each type and average available quantity of Classes I ∼ III (TDS < 1 g/L) per person were estimated by taking account of population distribution. Mapping groundwater TDS and volume reveals that human activities also play a role in groundwater salinity. The evaluation of groundwater quality and volume based on TDS provides a basis for future urban construction and development as well.

Influence of initial compaction and confining pressure on the hydraulic conductivity of compacted iron ore tailings

The hydraulic conductivity of iron tailings is an important factor affecting the stability of tailings storage facilities. Stacking compacted filtered ore tailings is a promising alternative for safer tailings disposal. These tailings storage facilities’ internal drainage systems must be designed appropriately to avoid excessive seepage pressure, saturation, and slope failure. In this context, the factors that affect hydraulic conductivity must be adequately evaluated. Therefore, the hydraulic conductivity behavior of compacted iron ore tailings still needs to be investigated. In addition, the effect of high confining pressure on hydraulic conductivity needs to be evaluated. This study investigates the impact of the initial compaction and the confining pressure on hydraulic conductivity. For this, the flexible wall permeameter tests were carried out on filtered ore tailings compacted in three degrees of compaction: 77, 94, and 101% of optimum dry density as determined by the standard Proctor method. These specimens were saturated and then consolidated with different confining pressure. It is possible to affirm that the increased confining pressure decreases the hydraulic conductivity. The hydraulic conductivity decreases by less than one order of magnitude, regardless of the initial compaction. Moreover, the data suggest that hydraulic conductivity’s decay rate depends on initial compaction—the hydraulic conductivity of the loose specimen decays at a greater rate than that of the dense specimens. However, the reductions of the void ratio under the confining pressure of 1600 kPa and 2200 kPa were not enough to decrease the hydraulic conductivity. Thus, under high-stress confining, the hydraulic conductivity becomes practically constant.

Saving Walker Lake: A Pleistocene Terminal Lake in the Anthropocene

Abstract: Just to the east of the Sierra Nevada mountain range a series of Pleistocene terminal lakes are present in the Great Basin of the intermountain West between the Rockies and the Sierra. Among them is Walker Lake, fed by the branches of the Walker River that flow eastward from their snow-melt sources in the Sierra. The terminal lakes have no natural outlets. Water is lost from the lakes' surfaces by evaporation during the hot summer months in the high desert. Since the arrival of Euro-Americans in the nineteenth century, the diversion of water for agricultural, industrial, and domestic uses from the Walker River has reduced the level of the lake to a point where it no longer supports a once-thriving fishery of native cutthroat trout. In the past, western Nevada Paiute peoples relied on the lake's fish as a food source. In the twentieth century the inland anadromous trout drew sports fishing enthusiasts. Climate change has caused additional strains on the water supply for the lake to the point where many have declared Walker Lake a dead lake with only shrinking shorelines and increased salinization in its future. In response, Nevada's U.S. senator Harry Reid, members of the Walker River Indian Reservation, sport fishing organizations, as well as environmental organizations pushed for legislation from Congress to promote efforts to save the lake in the 1990s. These efforts have produced some promising results.

Comparative analysis of hydroclimatic characteristics on the territory of the Amur, Angara-Yenisei and drainage Torey basins (Eastern Transbaikalia)

A comparative analysis of hydroclimatic characteristics was carried out on the territory of the Amur, Angara-Yenisei and Torey closed drainage basins of Eastern Transbaikalia. According to monitoring weather stations, high rates of air temperature growth have been established for the territory of the mountain-taiga zone of the Angara-Yenisei basin, where the linear trend was 2.2, while for the arid steppe zone of the Torey endorheic basin – 1.8. The smallest linear trend of 1.5 was identified for the territory of the Amur Basin. In all studied basins, synchronous cyclicity of precipitation and water levels was revealed against the background of their average annual decrease.

Hydrochemical and Isotopic Characteristics and the Spatiotemporal Differences of Surface Water and Groundwater in the Qaidam Basin, China

In the context of climate change, precipitation and runoff in the arid inland basins of northwest China have undergone significant changes. The Qaidam Basin (QB) is a typical highland arid inland area. Understanding the spatial and temporal variations in surface water and groundwater chemistry and isotopes, as well as their causes, is crucial for future water resource management and ecological protection. Samples of river, lake, and groundwater, as well as others, were collected and tested in five typical watersheds in the summer and winter. The hydrochemistry and isotopic spatiotemporal differences in various water bodies were studied using the significant difference method, water vapor flux models, hydrochemistry, isotopes, and other methods for cause analyses. The results indicate the following: (1) There are differences in hydrochemistry between the southern and northern basins because the southern basin is more influenced by the dissolution of salt rocks and evaporation, whereas the northern basin is mainly affected by carbonate weathering. (2) The enrichment of δD and δ18O in the northern basin gradually increases from west to east, while in the southern basin, it is the opposite. This is because the southern basin receives a larger contribution of water vapor from the mid-latitude westerlies, while the northern basin primarily relies on local evaporation as its water vapor source. (3) Significant differences are observed in the total dissolved solids (TDS) and hydrochemical types of river water and groundwater between the summer and winter due to higher rates of rock weathering and evaporation in the summer. (4) The more pronounced seasonal differences in hydrogen and oxygen stable isotopes in the southern basin are due to higher rates of internal water vapor circulation in the summer. (5) The similarity in characteristics between river water and groundwater is the result of strong exchanges between river water and groundwater from piedmonts to terminals. The spatiotemporal heterogeneity of terminal lakes is attributed to the accumulation of salts and groundwater replenishment from other sources.

Accelerated integrated watershed management enhances agricultural carbon sequestration and water use efficiency in an endorheic basin

With the continuous promotion of integrated river basin management (IRBM) in endorheic watersheds, the oasis surface processes have undergone significant changes. However, these underlying surface characteristics have not been well integrated into models for simulating carbon-water flux thus far. In this work, a regional SWAT-TECO model was constructed by coupling the modified TECO simulator with irrigation, film mulching, and soil hydraulic redistribution processes within the SWAT framework. The results indicated that the carbon sequestration and water use efficiency (WUE) showed an increasing trend after IRBM implementation in Heihe endorheic basin. WUE was projected to improve under future climate change and can be further enhanced by a maximum of 6.37 % through improving irrigation water use efficiency by 20 %, maintaining existing planting scale, increasing film mulching by 20 %, and reducing fertilizer application by 10 %. These findings can guide the formulation of high-water efficiency agricultural management strategies in global endorheic basins.