Search

Rising temperatures entail important changes in the soil hydrologic processes of the northern permafrost zone. Using the ICON‐Earth System Model, we show that a large‐scale thaw of essentially impervious frozen soil layers may cause a positive feedback by which permafrost degradation amplifies the causative warming. The thawing of the ground increases its hydraulic connectivity and raises drainage rates which facilitates a drying of the landscapes. This limits evapotranspiration and the formation of low‐altitude clouds during the snow‐free season. A decrease in summertime cloudiness, in turn, increases the shortwave radiation reaching the surface, hence, temperatures and advances the permafrost degradation. Our simulations further suggest that the consequences of a permafrost cloud feedback may not be limited to the regional scale. For a near‐complete loss of the high‐latitude permafrost, they show significant temperature impacts on all continents and northern‐hemisphere ocean basins that raise the global mean temperature by 0.25 K. Plain Language Summary: Landscapes in the Arctic and subarctic zone are often very wet with highly water saturated soils and an extensive lake‐ and wetland cover. To some extent, this is due to the perennially frozen soil layers that underlay large parts of these regions and inhibit the movement of water through the ground. Thus, a thawing of the frozen soils, caused by rising temperatures, may ultimately lead to a drying of the landscapes. Here, we use simulations with the ICON‐Earth System Model to show that such a drying increases regional temperatures via an atmospheric feedback: During the warm season, dryer conditions at the surface reduce the moisture transport into the atmosphere. This decreases the relative humidity in the boundary layer and the low‐altitude cloud cover. Since clouds reflect more sunlight than the snow‐free land surface, the reduced cloudiness increases the available energy, hence, temperatures and advances the thawing of the ground. Higher temperatures in the Arctic and subarctic zone, in turn, have important consequences for the net energy exchange between equatorial and polar regions. Thus, the effects of a large‐scale drying of high‐latitude soils may not be limited to the regional scale but could notably increase global mean temperatures. Key Points: Advanced degradation of permafrost may facilitate large‐scale landscape dryingDependency of clouds on terrestrial hydrology allows for feedback between permafrost thaw, diminished cloudiness and rising temperaturesThis feedback could amplify global warming notably [ABSTRACT FROM AUTHOR]

Global climate models (GCMs) are unable to produce detailed runoff conditions at the basin scale. Assumptions are commonly made that dynamical downscaling can resolve this issue. However, given the large magnitude of the biases in downscaled GCMs, it is unclear whether such projections are credible. Here, we use an ensemble of dynamically downscaled GCMs to evaluate this question in the Sierra‐Cascade mountain range of the western US. Future projections across this region are characterized by earlier seasonal shifts in peak flow, but with substantial inter‐model uncertainty (−25 ± 34.75 days, 95% confidence interval (CI)). We apply the emergent constraint (EC) method for the first time to dynamically downscaled projections, leading to a 39% (−28.25 ± 20.75 days, 95% CI) uncertainty reduction in future peak flow timing. While the constrained results can differ from bias corrected projections, the EC is based on GCM biases in historical peak flow timing and has a strong physical underpinning. Plain Language Summary: Global climate models (GCMs) provide information on projected changes. However, their resolution is too coarse to assess future land surface changes at the regional scale. Dynamical downscaling resolves this issue, by refining the representation of hydroclimate conditions at a higher‐resolution. However, GCMs have unique historical biases that remain despite dynamical downscaling. Typically these GCM biases are ignored, resulting in assessments at the regional scale with large uncertainty. Here, we use an approach, called emergent constraint (EC), to reduce the uncertainty in projected changes in the timing of high flow conditions across the Sierra Nevada and Cascade region of the western United States. While this approach was introduced nearly two decades ago with coarse‐resolution GCM data, this is the first time the EC approach has been used at the regional scale with dynamical downscaling. From our analysis, we find high flow events are likely to occur earlier in the future for the Sierra‐Cascade region. This conclusion contains substantial uncertainty without the use of the EC approach. While this study focuses on the timing of high flows, it opens the door to a variety of follow‐on studies, seeking to produce more robust projections of hydroclimate change across the western US. Key Points: For the first time, an emergent constraint (EC) is used to reduce uncertainty in hydroclimate projections from a dynamically downscaled ensembleWe show that snowmelt‐driven basins in the western United States are very likely to experience earlier peak flows in the futureWith EC, uncertainty in future peak flow timing is reduced by roughly 39%; however, bias corrected results can differ [ABSTRACT FROM AUTHOR]

Fish assemblages, defined by taxonomy or functional traits, –respond to regional and local habitat variation. Our hypothesis was that fish assemblages could be best predicted using reach‐scale (RS) hydrology variables over valley‐scale (VS) hydrogeomorphology variables for US and Mongolian rivers. We further predicted that fish traits were predicted better by RS than VS variables. We evaluated the FS and VS hydrogeomorphologies of rivers in the United States and Mongolia in each of three ecoregions: grassland, forest and endorheic. Fishes were collected using a backpack electrofisher, following standard protocols. Constrained ordination analyses were conducted at three scales: among continents, by continents and by individual ecoregions within continents. We found no significant difference in mean variation explained by VS versus RS or by taxonomy versus traits. Ecoregions differed in factors contributing to fish assemblage patterns, likely a result of differences in hydrogeomorphology, hydrological connectivity and historical influences. We found that fish assemblages were structured by hydrogeomorphic processes occurring at VS and RS, and that variables predicting fish assemblages varied with scale and whether fishes were classified by taxonomy or traits. Although anthropogenic impacts were substantially higher for western US rivers than for Mongolian rivers, we were unable to detect strong differences in our ability to predict fish assemblage variation from RS and VS habitat variables. [ABSTRACT FROM AUTHOR]

The Oceania region has often been overlooked in fundamental hydrological research owing to assumptions that cultural complexities hinder such efforts. However, this perspective is somewhat naïve. Substantial evidence demonstrates that Pacific Islanders actively engage in research, contributing both local Indigenous knowledge and expert capabilities in “island hydrology.” Numerous projects and publications by Pacific Island scholars showcase this expertise. To enhance self-reliance in smaller Pacific nations, it is crucial to improve access to advanced hydrology education and secure funding to support it. Overcoming these challenges is essential to unlocking the full potential of future hydrological research in the Pacific Islands. [ABSTRACT FROM AUTHOR]

The impact of an episodic river flood is intimately linked to its duration. Yet it is still unclear how often should a river be observed to accurately determine the occurrence and duration of extreme events. Here we assess flow statistics along with peak flow event detection and duration as a function of the discharge sampling period for large tributaries of the Mississippi basin using hourly gages over 2010–2022. Median event durations above high quantiles spatially vary from around 2 days upstream to 30 days downstream. Discharge mean, standard deviation, and quantiles can all be estimated within 2.5% error for sampling periods up to 8 days. A minimum temporal sampling 4× (2×) finer than peak flow event median duration is required to detect 95 ± 3% (85 ± 5%) of events and to estimate their duration within 90 ± 5% (75 ± 10%) median accuracy. Our findings have direct implications for future satellite missions concerned with capturing flood events. Plain Language Summary: High flow events and their duration in rivers are key aspects of flood studies. Yet, it is still unclear how often a river should be observed to detect floods and determine their durations. Analyzing hourly stream gage data in the Mississippi River basin from 2010 to 2022, we calculate that flood events vary widely in duration from upstream (2 days) to downstream (30 days). We show that observing large rivers every few days is sufficient to compute common long‐term river flow statistics within 2.5% error. However, capturing most floods and accurately assessing their duration (within 10% error) requires monitoring at least four times more frequently than the typical duration of these events. This means that if a major flood typically lasts 10 days, the river data should be collected at least every 2–3 days. Our findings have implications for the design of monitoring systems concerned with the accurate capture of floods, including those using Earth orbiting satellites. Key Points: Peak flow events in the Mississippi basin range from 2 days upstream to 30 days downstream, hence exhibiting acute spatial variabilityDecadal mean, standard deviation and quantiles of hourly discharge can all be computed within 2.5% error up to an 8‐day sampling periodSampling periods must be a factor of 4 finer than median peak flow event durations to estimate durations within 90 ± 5% median accuracy [ABSTRACT FROM AUTHOR]

Giant evaporite deposits formed during the Messinian Salinity Crisis (MSC) in the Mediterranean Sea during the upper Miocene. The primary cause is a restricted Atlantic-Mediterranean connection, but the detailed hydroclimate evolution of this event is still a matter of debate. Here we reconstruct the triple oxygen and hydrogen isotopic composition of paleo brines from structurally bonded water in Messinian gypsum from Cyprus. A two-stage evaporation model is constructed to best approximate the hydrological conditions at which Messinian gypsum formed in marginal basins of the Mediterranean Sea. Subsequently, hydroclimatic parameters like paleo relative humidity (RH) are modelled using an iterative curve fitting isotope model approach. The results of our limited dataset reveal a slightly lower RH during the third compared to the second stage of the MSC. This apparent drop in RH is consistent with previous observations from the literature. Besides absolute values of RH, our model allows reconstructing the triple oxygen and hydrogen isotopic composition of the open Mediterranean Sea. This provides an estimate for the proportions of continental water vs. Atlantic seawater flowing into the basin, serving as a proxy for the size of the strait of Gibraltar. The model implies a continental water fraction of around 75–81 % both for the second and third stage of the MSC. In addition, we determined the 87Sr/86Sr of our samples to: i) confirm their stratigraphy; and ii) estimate the relative proportion of continental water vs. Atlantic seawater entering the Mediterranean using Sr mass balance calculations. The combined oxygen and Sr isotope records indicate a persistent connection to the Atlantic supporting the hypothesis that the striking drop in 87Sr/86Sr at the beginning of MSC stage 3 is mainly related to an increased contribution of continental water with low 87Sr/86Sr and high Sr concentrations from the Paratethys. Our results show that the combination of triple oxygen, hydrogen, and Sr isotope data provides a powerful tool to disentangle paleo-hydroclimate even in such complicated hydrological settings as the Mediterranean Sea during the MSC. [ABSTRACT FROM AUTHOR]

Assessing direct fitness effects of individual genetic diversity is challenging due to the intensive and long‐term data needed to quantify survival and reproduction in the wild. But resolving these effects is necessary to determine how inbreeding and outbreeding influence eco‐evolutionary processes. We used 8 years of capture–recapture data and single nucleotide polymorphism genotypes for 1906 individuals to test for effects of individual heterozygosity on stage‐specific survival probabilities in the salamander Gyrinophilus porphyriticus. The life cycle of G. porphyriticus includes an aquatic larval stage followed by metamorphosis into a semi‐aquatic adult stage. In our study populations, the larval stage lasts 6–10 years, metamorphosis takes several months, and lifespan can reach 20 years. Previous studies showed that metamorphosis is a sensitive life stage, leading us to predict that fitness effects of individual heterozygosity would occur during metamorphosis. Consistent with this prediction, monthly probability of survival during metamorphosis declined with multi‐locus heterozygosity (MLH), from 0.38 at the lowest MLH (0.10) to 0.06 at the highest MLH (0.38), a reduction of 84%. Body condition of larvae also declined significantly with increasing MLH. These relationships were consistent in the three study streams. With evidence of localised inbreeding within streams, these results suggest that outbreeding disrupts adaptations in pre‐metamorphic and metamorphic individuals to environmental gradients along streams, adding to evidence that headwater streams are hotspots of microgeographic adaptation. Our results also underscore the importance of incorporating life history in analyses of the fitness effects of individual genetic diversity and suggest that metamorphosis and similar discrete life stage transitions may be critical periods of viability selection. [ABSTRACT FROM AUTHOR]

In depressional freshwater wetlands, habitat size, hydrology, and fish predation are considered key controls on invertebrate assemblages. However, the relative importance of each of these factors is difficult to isolate because the factors are frequently correlated. We assessed controls exerted by habitat size, hydrology, and fish occurrence in a set of 10 Carolina bay wetlands where these factors were largely independent. Invertebrate assemblages were sampled seasonally for six years. Using Joint Species Distribution Modeling of presence/absence and relative abundance data, < 6% of the variance in overall invertebrate assemblages was explained by the combined effects of size, hydrology, and fish occurrence: hydrology explained the most. However, when assessing responses of individual taxa, 32% were responsive, again primarily to variation in hydrology. Habitat size was minimally important. Fish occurrence affected only a handful of taxa, but some of those were key ecologically (abundant consumers). Most taxa responded to only one of the three environmental factors; effect sizes for responses ranged from 2 to 15.6% of total variance explained. Overall, the influences of habitat size, hydrology, and fish occurrence were less important to invertebrates in Carolina bay wetlands than we had presumed, given the prominence of these controls in the wetland invertebrate literature. [ABSTRACT FROM AUTHOR]

The geochemical and isotopic composition of deep groundwater in sedimentary acquitards reveals a complex paleo-hydrological system affected by intensive tectonic activity. Water samples collected from deep research boreholes in the Golan Heights (Middle East) exhibit a unique combination of high salinity (>2,000 mg/L Cl) with low Na/Cl (<0.7) and Mg/Ca (<0.3) equivalent ratios, calcium chloride water type [Ca > (HCO3 + SO4)], relatively low δ18OVSMOW and δ2HVSMOW values (–7 and –42‰, respectively), and enriched 87Sr/86Sr ratios compared to the host rocks. The salinity source is related to ancient lagoonary hypersaline brines (10–5 Ma) that existed along the Dead Sea Rift (DSR). These brines intruded into the rocks surrounding the DSR and, based on the current study, also extended away from the rift. Following their subsurface intrusion, the brines have been gradually diluted by 18O- and 2H-depleted freshwater recharged at high elevations, nowadays leaving only traces of the brines that originally intruded. It is also shown that variable hydraulic conductivities in different formations control the dilution rates and subsequently the preservation of the entrapped brines. A paleo-hydrological reconstruction is provided to demonstrate intrusion and backflow dynamics and also the relationship to freshwater dilution, which was triggered by a tectonically active basin of the nearby continental DSR. Brines that initially migrated from the rift have since been gradually flushed back to the rift through the current natural outlets. As the system discharges, it mixes and converges with a separate hydrogeological system, while still preserving some of the geochemical signals of the ancient brines. [ABSTRACT FROM AUTHOR]

Water is the basis for human survival and growth, and it holds great importance for ecological and environmental protection. The Hindu Kush Himalaya (HKH) is known as the "Water Tower of Asia", where water influences changes in the global water cycle and ecosystem. It is thus very important to efficiently measure the status of water in this region and to monitor its changes; with the development of satellite-borne sensors, water surface extraction based on remote sensing images has become an important method through which to do so, and one of the most advanced and accurate methods for water surface extraction involves the use of deep learning networks. We designed a network based on the state-of-the-art Vision Transformer to automatically extract the water surface in the HKH region; however, in this region, terrain shadows are often misclassified as water surfaces during extraction due to their spectral similarity. Therefore, we adjusted the training dataset in different ways to improve the accuracy of water surface extraction and explored whether these methods help to reduce the interference of terrain shadows. Our experimental results show that, based on the designed network, adding terrain shadow samples can significantly enhance the accuracy of water surface extraction in high mountainous areas, such as the HKH region, while adding terrain data does not reduce the interference from terrain shadows. We obtained the water surface extraction results in the HKH region in 2021, with the network and training datasets containing both water surface and terrain shadows. By comparing these results with the data products of Global Surface Water, it was shown that our water surface extraction results are highly accurate and the extracted water surface boundaries are finer, which strongly confirmed the applicability and advantages of the proposed water surface extraction approach in a wide range of complex surface environments. [ABSTRACT FROM AUTHOR]

This article introduces the Lake Environmental Data Harvester (LED) System, a robotic platform designed for the development of an innovative solution for monitoring remote alpine lakes. LED is intended as the first step in creating portable robotic tools that are lightweight, cost-effective, and highly reliable for monitoring remote water bodies. The LED system is based on the Shallow-Water Autonomous Multipurpose Platform (SWAMP), a groundbreaking Autonomous Surface Vehicle (ASV) originally designed for monitoring wetlands. The objective of LED is to achieve the comprehensive monitoring of remote lakes by outfitting the SWAMP with a suite of sensors, integrating an IoT infrastructure, and adhering to FAIR principles for structured data management. SWAMP's modular design and open architecture facilitate the easy integration of payloads, while its compact size and construction with a reduced weight ensure portability. Equipped with four azimuth thrusters and a flexible hull structure, SWAMP offers a high degree of maneuverability and position-keeping ability for precise surveys in the shallow waters that are typical of remote lakes. In this project, SWAMP was equipped with a suite of sensors, including a single-beam dual-frequency echosounder, water-quality sensors, a winch for sensor deployment, and AirQino, a low-cost air quality analysis system, along with an RTK-GNSS (Global Navigation Satellite System) receiver for precise positioning. Utilizing commercial off-the-shelf (COTS) components, a Multipurpose Data-Acquisition System forms the basis for an Internet of Things (IoT) infrastructure, enabling data acquisition, storage, and long-range communication. This data-centric system design ensures that acquired variables from both sensors and the robotic platform are structured and managed according to the FAIR principles. [ABSTRACT FROM AUTHOR]

The Himalayan water tower provides crucial water resources for Asia. Permafrost degradation is deemed to exert important impacts on streamflow in the Himalayan rivers. Yet, the magnitudes of such impacts remain poorly quantified. Here, we established a robust hydrological model that incorporated active layer deepening and ground ice melt for the drainage basin of the largest river in the northern Himalayas-the Yarlung Zangbo River (YZR). We estimated that permafrost degradation led to ∼0.65 km3/yr decrease in surface runoff and ∼0.35 km3/yr increase in baseflow and ground ice melt contributed ∼0.25% to the annual streamflow in the YZR for the period 2001–2022. The "fill-and-spill" mechanism helps explain the seeming contradiction of observed increasing versus decreasing baseflow in different permafrost regions worldwide. We propose that the dilution of riverine dissolved organic carbon (DOC) concentrations by baseflow may lead to the riverine DOC hysteresis patterns. This study not only lays solid scientific basis for water resources management in the Himalayas, but also yields new insights into how to interpret measured river discharge and nutrient flux in permafrost regions over the globe. [ABSTRACT FROM AUTHOR]

For irrigation in agriculture, water is a natural resource. Recycling water use is vital for the sustainable development of ecological environment and for resource conservation. Different substances that are thought to be pollutants and contribute to the deterioration of water quality are present in the wastewater from daily life and industrial activity. This research propose novel method in agricultural water management using feature extraction as well as classification based on DL methods. Inputs are collected as agriculture field water management as well as processed for noise removal, normalization and smoothening. Processed input data features are extracted utilizing kernel convolutional component analysis network. The extracted features has been classified using Quadratic reinforcement NN. Experimental analysis are carried out in terms of accuracy, precision, recall, positive predictive value, RMSE and mAP. Proposed technique attained accuracy of 92%, precision of 86%, recall of 65%, positive predictive value of 71%, RMSE of 55%, MAP of 51%. [ABSTRACT FROM AUTHOR]

Water is a finite resource but an essential one. The continuously increasing demand leads to competition and conflict over limited resources. Syria, Jordan, and Israel compete over the water resources in the transboundary Yarmouk River basin where two water agreements dictate the allocation of water. The two arrangements are far from being efficient and fair while little cooperation is being made over sharing the resources that are being over-exploited. In this study, water sustainability was investigated under projected developments and trends based on the current use and allocation regime in the watershed using several scenarios. A one bucket soil moisture model was adopted and optimized in order to fully represent the ever-changing hydrology of the basin using the Water Evaluation and Planning (WEAP) tool. Demands along with the existing water infrastructure and their operation were modelled despite the lack of many data and the huge uncertainty in some. Simulation of business as usual scenario showed that continuing with the current use cannot be sustainable in the short and long term. The growth of both agriculture and population produced huge water shortages in all demand sectors. Under climate change scenarios RCP 4.5 and RCP 8.5, surface water availability and the retention of dams reduced significantly. The share of Jordan from the Yarmouk River was the most vulnerable to climate change impacts. Enhancing irrigation efficiency and a more stable population growth based on the UN medium variant population projection showed improvements in water coverage within all demand sectors. Analysis of future scenarios suggests that water shortage is expected in all riparian states of the basin but can be mitigated by reducing demands. [ABSTRACT FROM AUTHOR]

Fundamental insight into the long-term 'geoecohydrological' dynamics of rivers and floodplains is required for their sustainable management. To study these dynamics, a multi-proxy approach is essential. While suitable proxies are available for reconstructing floodplain geomorphology and past vegetation, the suitability of the available proxies for past hydrology to reconstruct floodplain wetness has not yet been evaluated. In this study, we apply a multi-proxy analysis combining testate amoebae and several geochemical proxies for decomposition (humification, carbon and nitrogen stable isotopes), in comparison to sedimentological (stratigraphy, loss on ignition) and palaeobotanical records, to obtain independent hydrological reconstructions of alluvial floodplains in contrasting environmental settings to explore the suitability of the available proxies for past hydrology to reconstruct floodplain wetness. This study concludes that testate amoebae cannot provide a continuous and reliable hydrological reconstruction, as they are insufficiently preserved in alluvial peat deposits. In addition, mineral particles within the tests size range hamper the analysis in mineral-dominated sediment units. As organic matter decomposition is low when water tables are high and vice versa, we expected the decomposition proxies to reflect the hydrological conditions. While the amount of humic acids appears to depend mainly on the substrate rather than the decomposition of the organic matter in it, the analyses of carbon and nitrogen stable isotopes provide promising results, for both peat and non-peat deposits. [ABSTRACT FROM AUTHOR]

Space gravity missions have enabled the quantification of the mass component of sea‐level rise over the past two decades. Barystatic sea‐level rise is predominantly driven by melting polar ice sheets and mountain glaciers. However, continental hydrological processes also contribute to global sea level change at significant magnitudes. We show that for most coastal areas in low‐to‐mid latitudes, up to half of manometric sea‐level rise is due to changes in water storage in ice‐free continental regions. At other locations the direct attraction effect of anthropogenic pumping of groundwater over the duration of the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow‐On (GRACE‐FO) mission offsets sea‐level rise from ice sheet and glacier melt. If these trends in continental hydrological storage were to slow or stop, these regions would experience greatly accelerated sea‐level rise, posing a risk to coastal settlements and infrastructure, however, for most coastal communities current rates of sea‐level rise would be significantly reduced. Plain Language Summary: It is well understood that melting of polar ice sheets and mountain glaciers cause increases in ocean mass, leading to a corresponding rise in global sea level. What is not as obvious is that multi‐year changes in the storage of water on continents not covered by ice also contribute significantly to changes in global sea level. Over recent years and in some locations, the magnitude of these "continental hydrology" contributions to sea level changes have been comparable to the contributions of the ice‐covered regions. In some cases, the former have offset the ice sheet contributions, thus reducing regional sea‐level rise to substantially smaller magnitudes. Through an analysis of space gravity data, we have quantified the effects of continental hydrology on regional sea level and show that changes caused both naturally (e.g., through La Niña events) and through anthropogenic activities (e.g., extraction of groundwater) can increase or decrease regional sea level by significant amounts. Key Points: Exchange of water between continents and oceans causes global sea level change at rates comparable to the contributions of ice sheetsThe direct gravitational attraction effect on local sea level is of a larger magnitude than the far‐field sea level changesInter‐annual continental hydrology signal impacts on local sea level have negated the impacts of melting polar ice sheets in some locations [ABSTRACT FROM AUTHOR]

The increasing prevalence of low snow conditions in a warming climate has attracted substantial attention in recent years, but a focus exclusively on low snow leaves high snow years relatively underexplored. However, these large snow years are hydrologically and economically important in regions where snow is critical for water resources. Here, we introduce the term "snow deluge" and use anomalously high snowpack in California's Sierra Nevada during the 2023 water year as a case study. Snow monitoring sites across the state had a median 41 y return interval for April 1 snow water equivalent (SWE). Similarly, a process-based snow model showed a 54 y return interval for statewide April 1 SWE (90% CI: 38 to 109 y). While snow droughts can result from either warm or dry conditions, snow deluges require both cool and wet conditions. Relative to the last century, cool-season temperature and precipitation during California's 2023 snow deluge were both moderately anomalous, while temperature was highly anomalous relative to recent climatology. Downscaled climate models in the Shared Socioeconomic Pathway-370 scenario indicate that California snow deluges--which we define as the 20 y April 1 SWE event--are projected to decline with climate change (58% decline by late century), although less so than median snow years (73% decline by late century). This pattern occurs across the western United States. Changes to snow deluge, and discrepancies between snow deluge and median snow year changes, could impact water resources and ecosystems. Understanding these changes is therefore critical to appropriate climate adaptation. [ABSTRACT FROM AUTHOR]

The retrieval of continuous snow water equivalent (SWE) directly from passive microwave observations is hampered by ambiguity, which can potentially be mitigated by incorporating knowledge on snow hydrological processes. In this paper, we present a data assimilation (DA)-based SWE retrieval framework coupling the QCA-Mie scattering (DMRT-QMS) model (a dense medium radiative transfer (RT) microwave scattering model) and a one-dimensional column-based multiple-layer snow hydrology model. The snow hydrology model provides realistic estimates of the snowpack physical parameters required to drive the DMRT-QMS model. This paper devises a strategy to specify those internal parameters in the snow hydrology and RT models that lack observational records. The modeled snow depth is updated by assimilating brightness temperatures (Tbs) from the X, Ku, and Ka bands using an ensemble Kalman filter (EnKF). The updated snow depth is then used to predict the SWE. The proposed framework was tested using the European Space Agency's Nordic Snow Radar Experiment (ESA NoSREx) dataset for a snow field experiment from 2009 to 2012 in Sodankylä, Finland. The achieved SWE retrieval root mean square error of 34.31 mm meets the requirements of NASA and ESA snow missions and is about 70% less than the open-loop SWE. In summary, this paper introduces a novel SWE retrieval framework that leverages the combined strengths of a snow hydrology model and a radiative transfer model. This approach ensures physically realistic retrievals of snow depth and SWE. We investigated the impact of various factors on the framework's performance, including observation time intervals and combinations of microwave observation channels. Our results demonstrate that a one-week observation interval achieves acceptable retrieval accuracy. Furthermore, the use of multi-channel and multi-polarization Tbs is preferred for optimal SWE retrieval performance. [ABSTRACT FROM AUTHOR]

The application of ICESAT-2 altimetry data in river hydrology critically depends on the accuracy of the mean water surface elevation (WSE) at a virtual station (VS) where satellite observations intersect solely with water. It is acknowledged that the ATL13 product has noise elevations of the adjacent land, resulting in biased high mean WSEs at VSs. Earlier studies have relied on human intervention or water masks to resolve this. Both approaches are unsatisfactory solutions for large river basins where the issue becomes pronounced due to many tributaries and meanders. There is no automated procedure to partition the truly representative water height from the totality of the along-track ICESAT-2 photon segments (portions of photon points along a beam) for increasing precision of the mean WSE at VSs. We have developed an automated approach called "auto-segmentation". The accuracy of our method was assessed by comparing the ATL13-derived WSEs with direct water level observations at 10 different gauging stations on 37 different dates along the Lower Murray River, Australia. The concordance between the two datasets is significantly high and without detectable bias. In addition, we evaluated the effects of four methods for calculating the mean WSEs at VSs after auto-segmentation processing. Our results reveal that all methods perform almost equally well, with the same R2 value (0.998) and only subtle variations in RMSE (0.181–0.189 m) and MAE (0.130–0.142 m). We also found that the R2, RMSE and MAE are better under the high flow condition (0.999, 0.124 and 0.111 m) than those under the normal-low flow condition (0.997, 0.208 and 0.160 m). Overall, our auto-segmentation method is an effective and efficient approach for deriving accurate mean WSEs at river VSs. It will contribute to the improvement of ICESAT-2 ATL13 altimetry data utility on rivers. [ABSTRACT FROM AUTHOR]

Changes in climate shift the geographic locations that are suitable for malaria transmission because of the thermal constraints on vector Anopheles mosquitos and Plasmodium spp. malaria parasites and the lack of availability of surface water for vector breeding. Previous Africa-wide assessments have tended to solely represent surface water using precipitation, ignoring many important hydrological processes. Here, we applied a validated and weighted ensemble of global hydrological and climate models to estimate present and future areas of hydroclimatic suitability for malaria transmission. With explicit surface water representation, we predict a net decrease in areas suitable for malaria transmission from 2025 onward, greater sensitivity to future greenhouse gas emissions, and different, more complex, malaria transmission patterns. Areas of malaria transmission that are projected to change are smaller than those estimated by precipitation-based estimates but are associated with greater changes in transmission season lengths. [ABSTRACT FROM AUTHOR]

Synthetic aperture radars (SARs) have enabled allweather sensing of land surfaces, which has significantly benefitted surface hydrology. In this article, we explore various hydrological applications enabled by Indian Space Research Organisation’s (ISRO’s) recently launched Earth observation satellite-04 (EOS-04) C-band SAR satellite. We present the preliminary results of EOS-04 driven flood inundation mapping, monitoring of water bodies and study of river dynamics. Novel application of EOS-04 SAR data in estimation of sedimentation rate is presented for Jayakwadi reservoir, Maharashtra, India. Additionally, this article explores the integrated use of SAR and altimeter data for estimation of lake and reservoir water level and volume. We have used multidate observations from EOS-04 SAR and Sentinel-3A/ 3B altimeters to derive river width and estimate area– water level hypsometric curves for reservoirs. Long-term and near real-time availability of EOS-04 data can provide an indispensable tool for monitoring water bodies and extreme events like floods, at regional scales. [ABSTRACT FROM AUTHOR]

Agricultural land cover in the U.S. Midwest is a major source of nutrient pollution that has led to impairment of stream water quality. This study examines the impact of a forested state park on nutrient concentrations within an agriculturally dominated watershed. Water samples were collected over a 2‐year study period from eight stream sampling sites along four creeks and processed for total nitrogen (TN), nitrate (NO3−‐N$$ {\mathrm{NO}}_3^{-}\hbox{-} \mathrm{N} $$), total phosphorus (TP), and orthophosphate (PO43−‐P$$ {\mathrm{PO}}_4^{3-}\hbox{-} \mathrm{P} $$). Hydrology, channel morphology, and remotely sensed land cover and vegetation data were also collected and analyzed within the study area. Results indicate that water quality responses to a forested state park vary between TN, NO3−‐N$$ {\mathrm{NO}}_3^{-}\hbox{-} \mathrm{N} $$, TP, and PO43−‐P$$ {\mathrm{PO}}_4^{3-}\hbox{-} \mathrm{P} $$, and water quality variables are uniquely influenced by watershed and stream characteristics. The greatest water quality benefits most frequently occurred within the two smallest study streams with the greatest residence times and proportion of watershed areas within the forested state park. Overall, the greatest improvements to water quality occurred during periods of low stream discharge and when riparian vegetation was greenest. The results of this study suggest that conservation of forested areas within agriculturally dominated watersheds can provide water quality improvements in the U.S. Midwest. Targeting watersheds that drain small streams with long residence times for conservation may be most beneficial to improving water quality. [ABSTRACT FROM AUTHOR]

Gauge-measured precipitation (Pm) is prone to negative bias; therefore, using corrected gauge-measured precipitation (Pc) is critical in climate and hydrology studies, although it is utilized insufficiently in existing research. This study uses Pm and Pc to establish extreme precipitation indices (EPIs) and compares the differences in their evolution characteristics and their responses to large-scale circulation indices (LSCIs). Theil's slope and the modified Mann–Kendall test are used to identify the evolution characteristics of EPIs. Probabilistic condition selection and momentary conditional independence and the Liang-Kleeman information flow are adopted to evaluate the causal relationship between the EPIs and LSCIs. The main results are as follows: (1) The magnitude, intensity, and frequency of the Pc-based EPIs are higher than those of the Pm-based EPIs in China, except for the consecutive dry days (CDD). This result suggests that previous estimates of Pm-based EPIs underestimated the magnitude, intensity, and frequency at most stations, especially in the Southwestern River where droughts and flood areas may have been underestimated. Thus, the frequency of Southwestern River droughts and floods and their sudden transitions may be higher. (2) The slope increases in the Pc-based EPIs (except for the Southwestern River), and their significance levels are lower than those of the Pm-based EPIs. Conversely, the slope decreases in the Pc-based EPIs (except for the Southwestern River), and their significance levels (except for the Songliao River) are higher than those of the Pm-based EPIs. The internal variability of the climate system and the external forcing in some basins are the reasons for the significantly increasing slopes of very wet days (R95p), simple daily intensity index (SDII), and extremely wet days (R99p). However, the significant decreasing slopes are attributed to internal climate variability. (3) Unlike the Pm-based EPIs, the Pc-based EPIs did not alter the causal relationship with LSCIs, indicating that Pc did not change the causal relationship with LSCIs. The trend, magnitude, intensity, and frequency differ for Pc and Pm. Therefore, Pc and Pm data should be used cautiously in meteorological, hydrological, ecological, environmental, and agricultural simulations in future research. [ABSTRACT FROM AUTHOR]

Silt-rich meltwater plume deposits (MPDs) analyzed from marine sediment cores have elucidated relationships that are clearly connected, yet difficult to constrain, between subglacial hydrology, ice-marginal landforms, and grounding-zone retreat patterns for several glacial catchments. Few attempts have been made to infer details of subglacial hydrology, such as flow regime, geometry of drainage pathways, and mode(s) of sediment transport through time, from grain-scale characteristics of MPDs. Using sediment samples from MPD, till, and grounding-zone proximal diamicton collected offshore of six modern and relict glacial catchments in both hemispheres, we examine grain shape distributions and microtextures (collectively, grain micromorphology) of the silt fraction to explore whether grains are measurably altered from their subglacial sources via meltwater action. We find that 75 % of all imaged grains (n = 9400) can be described by 25 % of the full range of measured shape morphometrics, indicating grain shape homogenization through widespread and efficient abrasive processes in subglacial environments. Although silt grains from MPDs exhibit edge rounding more often than silt grains from tills, grain surface textures indicative of fluvial transport (e.g., v-shaped percussions) occur in only a modest number of grains. Furthermore, MPD grain surfaces retain several textures consistent with transport beneath glacial ice (e.g., straight or arcuate steps, (sub)linear fractures) in comparable abundances to till grains. Significant grain shape alteration in MPDs compared to their till sources is observed in sediments from glacial regions where (1) high-magnitude, potentially catastrophic meltwater drainage events are inferred from marine sediment records and (2) submarine landforms suggest supraglacial melt contributed to the subglacial hydrological budget. This implies that quantifiable grain shape alteration in MPDs could reflect a combination of high-energy flow of subglacial meltwater, persistent sediment entrainment, and/or long sediment transport distances through subglacial drainage pathways. Integrating grain micromorphology into analysis of MPDs in site-specific studies could therefore aid in distinguishing periods of persistent, well-connected subglacial discharge from periods of sluggish or disorganized drainage. In the wider context of deglacial marine sedimentary and bathymetric records, a grain micromorphological approach may bolster our ability to characterize ice response to subglacial meltwater transmission through time. This work additionally demonstrates that glacial and fluvial surface textures are retained on silt-sized quartz grains in adequate amounts for microtexture analysis, which has heretofore been conducted exclusively on the sand fraction. Therefore, grain microtextures can be examined on silt-rich glaciogenic deposits that contain little to no sand as a means to evaluate sediment transport processes. [ABSTRACT FROM AUTHOR]

Shallow landslides triggered by heavy rainfalls are slope instabilities, developed in the most superficial eluvial layers, involving the first 2 m from the ground level. A crucial predisposing factor in shallow landslides occurrence is the soil water content, generally measured trough sensors installed in the first soil layers. However, despite being a very precise approach, this monitoring technique provides for a site-specific dataset. An integrated method to extend the hydrological characterization from site-specific to slope scale is presented, combining geotechnical analyses, field data monitoring, and geophysical investigations, in two experimental test sites located on Italian Apennines. Ten Electrical Resistivity Tomographies (ERT) of the first soil horizons were performed through different array geometries (2D-3D-Time-Lapse), calibrated and interpreted basing on stratigraphic logs, trenches, and monitored soil water content field data. The test sites colluvial covers composition was analyzed and compared to resistivity values to build conceptual hydrogeological models of the deep-water circulation. In addition, two time-lapse (4D) ERT surveys were performed in both test sites simulating very intense precipitations, to determine the resistivity variations at different soil drainage conditions, thus estimating the average bulk permeability. Bulk permeability can be also a useful input parameter for slope stability models, widely employed in engineering practices. This integrated method proved to be very useful for the hydrogeological characterization of the subsoil at slope scale, where it is susceptible to slope instability, improving the knowledge of water circulation, as well as the bulk permeability heterogeneities, which are shallow landslides triggering parameters. [ABSTRACT FROM AUTHOR]

Five years ago, an article in WIREs Water provided the first comprehensive analysis of historic (legacy) landfill sites vulnerable to coastal flooding and erosion at a national scale (England). This update expands upon that article by considering the potential impacts of climate change upon inland historic landfills. Globally, there are hundreds of thousands of landfills that predate modern environmental regulations, and where waste is not isolated from the surrounding environment, but climate change impacts on the pollution risk from historic landfills in freshwater environments has received little attention. Where climate change causes an increase in the frequency and magnitude of fluvial flood events, this will increase leachate generation and the probability of landfill erosion and solid waste release. Where there is increased drought the landfill capping materials may crack, opening up new pollutant pathways, and increasing the risk of solid waste release. Changes to groundwater movement resulting from climate change may open new leachate pathways, and in England alone, thousands of historic landfills are in (groundwater) Source Protection Zones where modern regulations to protect drinking water supplies would not permit their construction. This increased contaminant release from historic landfills in freshwater environments may impact surface and/or groundwater quality and ecological health, increase costs for drinking water monitoring/treatment, or make some abstraction sources unviable. This is especially of concern where receptors are subject to multiple pressures and may cause tipping points to be reached. Further research is warranted into contaminant behavior, receptor vulnerability, historic landfill risk prioritization, and mitigation/remediation methods. This article is categorized under:Engineering Water > Engineering WaterScience of Water > Water QualityScience of Water > Water and Environmental ChangeWater and Life > Stresses and Pressures on Ecosystems [ABSTRACT FROM AUTHOR]

Stable isotopic compositions of carbon and nitrogen (δ13C, δ15N) of archaeological grains/seeds recovered from different cultural layers of an Indus (Harappan) archaeological site 4MSR (29°12'87.2"N; 73°9'421"E; Binjor, western Rajasthan, India) provide insights into the Harappan agriculture between ~2900 to ~1800 BCE. The δ13C values were used to retrieve hydrological status, while δ15N values were used to gauge agricultural intensification. Isotopic data of grains/seeds were generated representing three Indus phases (i) Early phase (~2900−2600 BCE), (ii) Transitional phase (~2600−2500 BCE), and (iii) Mature phase (~2500−1800 BCE). We find δ13C values of barley grains (winter crop) varied in overlapping ranges for all the three phases −21.34‰ ± 1.9; −22.55‰ ± 1.6 and −22.75‰ ± 1.7 respectively (n=10 for each phase) indicating insignificant changes in hydrology for winter crops. For summer crops like cotton, average δ13C values for Transitional phase −23.44‰ ± 1.8 were not significantly different from those of Mature phase −22.55‰ ± 2.5. The δ15Nbarley values varied in wider range, however, intra-phase variability appears to have overlapping values but showing overall increase from Early (7.72‰ ± 1.8) to Mature phase (11.17‰±7.2) indicating a plausible agricultural intensification. We also measured δ13C of host soil organic matter (SOM) and sediment δ15N to assess regional environmental conditions. In contrast to the trends observed for archaeological grains/seeds, δ13CSOM values showed a statistically significant enriching trend from Early (−23.54‰ ± 1.4) to Mature phase (−20.40‰ ± 1.9) hinting a growing aridity in the region. We surmise that Harappan farmers of western Rajasthan region might be managing arable hydrological conditions in their fields through agricultural interventions to continue agriculture practices despite growing aridity in the vicinity. The high proportion of water-demanding crop cotton during the Mature phase despite of changing environmental conditions, also corroborate our interpretation, possibly grown for the trade purposes. [ABSTRACT FROM AUTHOR]

We investigated the stable isotope hydrology of Sable Island, Nova Scotia, Canada over a five year period from September, 2017 to August, 2022. The δ2H and δ18O values of integrated monthly precipitation were weakly seasonal and ranged from –66 to –15 ‰ and from –9.7 to –1.9 ‰, respectively. Fitting these monthly precipitation data resulted in a local meteoric water line (LMWL) defined by: δ2H = 7.22 ± 0.21 · δ18O + 7.50 ± 1.22 ‰. Amount-weighted annual precipitation had δ2H and δ18O values of –36 ± 11 ‰ and –6.1 ± 1.4 ‰, respectively. Deep groundwater had more negative δ2H and δ18O values than mean annual precipitation, suggesting recharge occurs mainly in the winter, while shallow groundwater had δ2H and δ18O values more consistent with mean annual precipitation or mixing of freshwater with local seawater. Surface waters had more positive values and showed evidence of isolation from the groundwater system. The stable isotopic compositions of plant (leaf) water, on the other hand, indicate plants use groundwater as their source. Fog had δ2H and δ18O values that were significantly more positive than those of local precipitation, yet had similar 17O-excess values. δ2H values of horsehair from 4 individuals lacked seasonality, but had variations typical to those of precipitation on the island. Differences in mean δ2H values of horsehair were statistically significant and suggest variations in water use may exist between spatially disparate horse communities. Our results establish an important initial framework for ongoing isotope studies of feral horses and other wildlife on Sable Island. [ABSTRACT FROM AUTHOR]

Isotope technology is widely used in geochemical mechanisms analysis; however, studies on the origin of pit lake water by isotopes in coal concentration areas in grassland are rare. In this study, 20 groups of water samples were collected, which were subjected to chemical analysis to determine the hydrogeochemical characteristics of pit lake water. The mechanisms of pit lake water formation and recharge–evaporation were ascertained through principal component analysis and the Rayleigh fractionation model. The results indicate that the phreatic water is least affected by evaporation, followed by confined water, surface water and pit lake water. The ionic composition of surface water, phreatic water and most of the confined water is mainly affected by leaching, some confined water can be recharged by surface or phreatic water; while the ionic composition of pit lake water is dominantly affected by evaporation (69.4 %) and is less affected by groundwater recharge (17.1 %) and human activities (11.5 %). The pit lake water is recharged by precipitation, phreatic water and the lateral runoff of confined water; however, the proportion of phreatic and confined water recharge is small. The evaporative loss of the pit lake water is 40–61 % of the initial water body. [ABSTRACT FROM AUTHOR]

Accurate and punctual precipitation data are fundamental to understanding regional hydrology and are a critical reference point for regional flood control. The aims of this study are to evaluate the performance of three widely used precipitation datasets—CRU TS, ERA5, and NCEP—as potential alternatives for hydrological applications in the Bahr el Ghazal River Basin in South Sudan, Africa. This includes examining the spatial and temporal evolution of regional precipitation using relatively accurate precipitation datasets. The findings indicate that CRU TS is the best precipitation dataset in the Bahr el Ghazal Basin. The spatial and temporal distributions of precipitation from CRU TS reveal that precipitation in the Bahr el Ghazal Basin has a clear wet season, with June–August accounting for half of the annual precipitation and peaking in July and August. The long-term annual total precipitation exhibits a gradual increasing trend from the north to the south, with the southwestern part of the Basin having the largest percentage of wet season precipitation. Notably, the Bahr el Ghazal Basin witnessed a significant precipitation shift in 1967, followed by an increasing trend. Moreover, the spatial and temporal precipitation evolutions reveal an ongoing risk of flooding in the lower part of the Basin; therefore, increased engineering counter-measures might be needed for effective flood prevention. [ABSTRACT FROM AUTHOR]

This study presents the field performance of a five-layer composite cover to mitigate acid mine drainage in legacy sulfide tailings in northern Ontario, Canada. Installed in 2008, this cover comprised sand, clay, geosynthetic clay liner, sand, and waste rock layers. To evaluate the effectiveness of the cover in reducing water and oxygen ingress, groundwater and vadose zone hydrological characterization, stable water isotope analysis, pore-gas measurements, oxygen flux calculations, and variably saturated flow modeling were conducted. The results indicate that the clay layer stayed nearly saturated in the spring, fall, and winter, but temporary desiccation occurred during the summer. Compared to uncovered tailings, the cover significantly lowered diffusive oxygen flux. In the summer, fall, and winter, the capillary barrier effect of the cover functioned effectively and inhibited percolation. Atmospheric pore-gas oxygen concentrations at one out of the three monitoring locations indicate potential cover imperfections that enabled oxygen transport into the tailings. In the spring and early summer, snowmelt infiltration resulted in percolation that compromised the capillary barrier effect, as well as lateral drainage. The resulting increase in water saturation in the cover limited oxygen transport. Despite potential cover imperfections, this composite cover reduced oxygen and water ingress a decade after installation. [ABSTRACT FROM AUTHOR]

Vegetation canopies intercept and redistribute rainfall into throughfall and stemflow, which transfer substantial amounts of elements into the soil, influencing soil microbial community, plant survival, and plant community succession. Despite advancements in ecohydrological research, the implication of nutrient enrichment resulting from this redistribution of rainfall by canopies remains largely unexplored. To address this gap, we conducted a systematic review of 1020 papers published between 2000 and 2022, gathering data on nutrient concentration and enrichment for critical ions (including K+, Na+, Ca2+, Mg2+, NH4+, Cl−, NO3− and SO42−) from the Web of Science and Chinese Knowledge Infrastructure databases. We aimed to synthesize the mechanisms, quantify the enrichments, and identify global patterns of nutrient enrichment in stemflow and throughfall across climate zones, and vegetation types and ecosystems. The results of this study indicate that stemflow exhibits, on average, 2.1 times greater ion concentration (6.13 mg L−1) compared to throughfall. In particular, among the investigated ions, SO42− (12.45 and 6.32 mg L−1) for stemflow and throughfall, respectively, and Cl− (9.21 and 4.81 mg L−1) exhibit the highest concentrations in both rainfall redistribution components, while K+ (13.7 and 5.8) and Mg2+ (5.6 and 2.8) have the highest enrichment factors. Across climate zones, throughfall and stemflow show the lowest ion concentrations but the highest enrichment factors in extremely humid regions. Along the temperature gradient, ion concentrations are the highest in cold climates with no clear patterns observed for enrichment factors with increasing temperature. In addition, shrubs, conifers, mixed forests, and artificial ecosystems demonstrate enrichment factors 1.1 to 3.0 times greater than those of trees, broad- leaved plants, pure forests, and natural ecosystems. These findings emphasize the need for increased attentions to artificial ecosystems, such as urban and agricultural ecosystems, which often received limited research focus, especially regarding shrubs and conifers exhibiting stronger nutrients enrichment capabilities. Future investigations should integrate soil moisture analysis to better understand the impact of rainfall redistribution on the nutrient enrichment processes, patterns, and nutrient balance in global terrestrial ecosystems. [ABSTRACT FROM AUTHOR]

Hydrological modeling, leveraging mathematical formulations to represent the hydrological cycle, is a pivotal tool in representing the spatiotemporal dynamics and distribution patterns inherent in hydrology. These models serve a dual purpose: they validate theoretical robustness and applicability via observational data and project future trends, thereby bridging the understanding and prediction of natural processes. In rapid advancements in computational methodologies and the continuous evolution of observational and experimental techniques, the development of numerical hydrological models based on physically-based surface-subsurface process coupling have accelerated. Anchored in micro-scale conservation principles and physical equations, these models employ numerical techniques to integrate surface and subsurface hydrodynamics, thus replicating the macro-scale hydrological responses of watersheds. Numerical hydrological models have emerged as a leading and predominant trend in hydrological modeling due to their explicit representation of physical processes, heightened by their spatiotemporal resolution and reliance on interdisciplinary integration. This article focuses on the theoretical foundation of surface-subsurface numerical hydrological models. It includes a comparative and analytical discussion of leading numerical hydrological models, encompassing model architecture, numerical solution strategies, spatial representation, and coupling algorithms. Additionally, this paper contrasts these models with traditional hydrological models, thereby delineating the relative merits, drawbacks, and future directions of numerical hydrological modeling. [ABSTRACT FROM AUTHOR]

Bend cutoff is a fundamental process shaping meandering rivers. Despite the widely accepted differentiation between neck and chute cutoffs, a significant knowledge gap persists regarding the factors responsible for the occurrence of each cutoff regime and the specific conditions triggering the regime. Here, we used field and photogrammetric data derived from a global set of 22 meandering rivers, stretching more than 5500 km in total river length, to disentangle the controlling factors behind the cutoff regime in meandering rivers. We found that whether a meandering river forms a chute rather than neck meander cutoff depends primarily on the variability of overbank discharges. Short-lived, high-magnitude overbank floods promote the formation of chute cutoffs, aided by (though not required) reduced riparian vegetation density, enhanced stream power, and flow confinement within the river valley. In contrast, neck cutoffs are prevalent in rivers characterized by limited variations in bankfull hydrology, typically associated with low-magnitude, long-lasting overbank floods. Distinct cutoff regimes also discernibly affected floodplain geomorphology, with a chute regime resulting in more frequent cutoff occurrences. Our results suggest that human-induced alterations of river hydrologic regime can potentially cause fundamental shifts in the cutoff behavior of meandering rivers, thus affecting sediment residence time and carbon fluxes in alluvial floodplains. [ABSTRACT FROM AUTHOR]

Speleothem δ13C in monsoonal China differs from speleothem δ18O, which is widely used as a climatic proxy for several complex control reasons. Nevertheless, δ13C records have the potential to reveal the implications of hydroclimatic changes. This study reports a speleothem δ13C record from Didonghe (DDH) Cave in central China spanning 34 to 13 kyr BP. After we investigated the factors that influence speleothem δ13C, we found that the δ13C record showed that DDH Cave can prompt directional shifts via local hydroclimatic changes, such as in vegetation types, biomass, and rock–water interaction processes, suggesting that δ13C is mainly controlled by the local hydroclimate. Ensemble empirical mode decomposition (EEMD) results revealed a coupling relationship between δ18O and δ13C on multiple timescales, which suggested that changes in precipitation caused by large-scale monsoonal circulation are controlled by regional hydrological conditions to a great extent. However, the hydrological conditions of the cave were relatively mild and humid during the last glacial maximum (LGM), which revealed the impact of evaporation on changes in the region's hydrological conditions. We also found that the δ18O and δ13C profiles decoupled when δ13C changed with a shift in the location of the westerly during HS1. The δ13C record correlates well with other paleoclimate records, suggesting that regional hydrological conditions are also modulated by the Earth's internal and external driving factors. [ABSTRACT FROM AUTHOR]

As known "ecosystem engineers", beavers influence river hydrology, geomorphology, biochemistry, and biological assemblages. However, there is a lack of research regarding the effects of beaver activities on freshwater meiofauna. In this study, we investigated the taxonomic and functional composition of the benthic copepod assemblage of a segment of the Tiber River (Italy) where a beaver dam, created about 7 weeks before our survey, had formed a semi-lentic habitat upstream and a lotic habitat downstream of the dam. We also analyzed the copepod assemblage before and after a flood event that destroyed the beaver dam, providing a unique opportunity to observe changes in a naturally reversing scenario. Our analyses revealed that, while the taxonomic composition and functional traits of the copepod assemblage remained largely unchanged across the recently formed semi-lentic and lotic habitats, substantial differences were evident between the dammed and undammed states. The dammed state showed lower copepod abundances, biomass, and functionality than the undammed one. These results highlight the role of beaver dams in changing the composition and functionality of meiofaunal assemblages offering insights into the dynamic interactions within aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Northern Mexico is home to more than 32 million people and is of significant agricultural and economic importance for the country. The region includes three distinct hydroclimatic regions, all of which regularly experience severe dryness and flooding and are highly susceptible to future changes in precipitation. To date, little work has been done to characterize future trends in either mean or extreme precipitation over northern Mexico. To fill this gap, we investigate projected precipitation trends over the region in the NA-CORDEX ensemble of dynamically downscaled simulations. We first verify that these simulations accurately reproduce observed precipitation over northern Mexico, as derived from the Multi-Source Weighted-Ensemble Precipitation (MSWEP) product, demonstrating that the NA-CORDEX ensemble is appropriate for studying precipitation trends over the region. By the end of the century, simulations forced with a high-emissions scenario project that both mean and extreme precipitation will decrease to the west and increase to the east of the Sierra Madre highlands, decreasing the zonal gradient in precipitation. We also find that the North American monsoon, which is responsible for a substantial fraction of the precipitation over the region, is likely to start later and last approximately three weeks longer. The frequency of extreme precipitation events is expected to double throughout the region, exacerbating the flood risk for vulnerable communities in northern Mexico. Collectively, these results suggest that the extreme precipitation-related dangers that the region faces, such as flooding, will increase significantly by the end of the century, with implications for the agricultural sector, economy, and infrastructure. Significance Statement: Northern Mexico regularly experiences severe flooding and its important agricultural sector can be heavily impacted by variations in precipitation. Using high-resolution climate model simulations that have been tested against observations, we find that these hydroclimate extremes are likely to be exacerbated in a warming climate; the dry (wet) season is projected to receive significantly less (more) precipitation (approximately ±10% by the end of the century). Simulations suggest that some of the changes in precipitation over the region can be related to the North American monsoon, with the monsoon starting later in the year and lasting several weeks longer. Our results also suggest that the frequency of extreme precipitation will increase, although this increase is smaller than that projected for other regions, with the strongest storms becoming 20% more frequent per degree of warming. These results suggest that this region may experience significant changes to its hydroclimate through the end of the century that will require significant resilience planning. [ABSTRACT FROM AUTHOR]

Accurate hydrological data with high spatial resolution is important for flood risk and water resource management, particularly under the context of climate change. The cost of monitoring networks, as well as the characteristics of the hydrological environment itself, can be a barrier to meeting these data requirements, however. This study covers the design and testing of a low-cost, "build-it-yourself", instream water depth sensor providing an assessment of its potential in future hydrological monitoring projects. The low-cost sensor was built using an Arduino microcontroller, a differential pressure sensor and a thermistor, a real-time clock, and an SD card module. The low-cost logger was deployed in tandem with a factory-calibrated Solinst®LevelLogger® 5 Junior for 6 months in the River Wissey, UK. We found the mean absolute error of the Arduino-based logger relative to the commercial setup to be ±0.69 cm for water depth and ±0.415 °C for water temperature. Economically, the Arduino-based logger offers an advantage, costing a total of £133.35 (USD 168.26 at time of publication) comparative to the industrial comparison's cost of £408 (USD 514.83 at time of publication). This study concludes that the low cost of the Arduino-based logger gives a strong advantage to its incorporation in hydrological data collection, if the trade-offs (i.e., time investment and accuracy) are considered acceptable and appropriate for a project. [ABSTRACT FROM AUTHOR]

Invasive species pose a significant threat to global biodiversity, prompting the need for novel management strategies. We investigated the effect of pond placement in preventing colonization by Gambusia holbrooki, an invasive fish impacting amphibians, including the threatened green and golden bell frog (Litoria aurea). Because Gambusia moves between aquatic systems during surface flow events, we aimed to determine whether constructing ponds on elevated plots devoid of fish was less likely to be colonized due to the absence of two‐way water connectivity with sources from below. Over eight consecutive years, we monitored Gambusia presence at 50 ponds within an industrialized area of Kooragang Island, New South Wales, Australia, home to one of the largest extant subpopulations of L. aurea. This included 24 constructed ponds, 19 of which were on elevated plots, along with 26 historic ponds already present prior to the study. None of the ponds constructed on elevated plots were ever colonized by Gambusia during the study period, while most (three out of five) constructed at lower elevation and historical ponds (25 out of 26) were. Our findings indicate that the elevated plots acted as plateau safe havens, with elevation difference rather than proximity to Gambusia sources the key driver preventing colonization. These plateaus are now functioning as some of the only Gambusia‐free breeding habitat for L. aurea in this area. This research highlights the role of landscape topography and intentional pond placement in safeguarding newly constructed wetlands from invasive fish, providing insights for wetland conservation and biodiversity protection. [ABSTRACT FROM AUTHOR]

Over the past two decades, the Gravity Recovery and Climate Experiment (GRACE) satellite mission and its successor, GRACE-follow on (GRACE-FO), have played a vital role in climate research. However, the absence of certain observations during and between these missions has presented a persistent challenge. Despite numerous studies attempting to address this issue with mathematical and statistical methods, no definitive optimal approach has been established. This study introduces a practical solution using Linear Regression Analysis (LRA) to overcome data gaps in both GRACE data types—mascon and spherical harmonic coefficients (SHCs). The proposed methodology is tailored to monsoon patterns and demonstrates efficacy in filling data gaps. To validate the approach, a global analysis was conducted across eight basins, monitoring changes in total water storage (TWS) using the technique. The results were compared with various geodetic products, including data from the Swarm mission, Institute of Geodesy and Geoinformation (IGG), Quantum Frontiers (QF), and Singular Spectrum Analysis (SSA) coefficients. Artificial data gaps were introduced within GRACE observations for further validation. This research highlights the effectiveness of the monsoon method in comparison to other gap-filling approaches, showing a strong similarity between gap-filling results and GRACE's SHCs, with an absolute relative error approaching zero. In the mascon approach, the coefficient of determination (R2) exceeded 91% for all months. This study offers a readily usable gap-filling product—SHCs and smoothed gridded observations—with accurate error estimates. These resources are now accessible for a wide range of applications, providing a valuable tool for the scientific community. [ABSTRACT FROM AUTHOR]

In this paper, a combined air/water source heat pump water heater is presented. At ordinary time, the heater can be used for hot water heating in water-source mode to improve the energy efficiency. While in cold season, it gives priority to air-source mode for water heating to improve operational safety. Experiments were conducted to investigate the thermodynamic performance of the heater in each operation mode, and the experiment results were analyzed. The research indicated that its operation was reliable during the long-time running. This paper offers a promising energy-saving method in future. [ABSTRACT FROM AUTHOR]

Tree establishment on peatlands has various adverse effects on the environment, with one of the most significant being their transformation from carbon sinks to carbon sources. This transformation has largely been instigated by economic-driven ditching initiatives. In this study, 80 peat-rooted pine seedlings were subjected to hydrological scenarios corresponding to natural, ditched, and rewetted conditions to investigate how different management strategies affect tree growth and survival. The study was conducted in a greenhouse where all plants were exposed to identical conditions except for the water level, and focused on factors like stomatal conductance, plant survival, length, biomass, and radial tree growth. Wet conditions, specifically treatments rewetted and natural, resulted in consistently lower stomatal conductance compared to drier treatments. Plant survival was affected, with 15 deaths in the rewetted and 2 in natural groups. Moreover, length, biomass, radial growth, and cell formation were significantly lower for the groups exposed to wet conditions. Rewetting can therefore effectively control tree colonisations, and thereby preventing water consumption, litter fertilisation, and other positive feedback effects for the trees that might be negative for the carbon uptake and biodiversity in peatlands. This study thereby offers valuable insights for rewetting initiatives in tree colonised peatland ecosystems. [ABSTRACT FROM AUTHOR]

The Amazon is the largest drainage basin on Earth and contains a wide variety of abiotic landscape features. In spite of this, the geodiversity in this basin has not yet been objectively evaluated. We address this knowledge gap by combining a meta-analysis of an existing global geodiversity map and its components with a systematic literature review, to identify the key characteristics of geodiversity in the Amazon drainage basin (ADB). We also evaluate how these global geodiversity component maps, that are based on the geology, geomorphology, soils and hydrology, could be refined to better reflect geodiversity in the basin. Our review shows that geology—through lithological diversity and geological structures—and hydrology—through hydrological processes that influence geomorphology and soil diversity—are the main determinants of geodiversity. Based on these features, the ADB can be subdivided into three principal regions: (i) the Andean orogenic belt and western Amazon, (ii) the cratons and eastern Amazon, and (iii) the Solimões-Amazon river system. Additional methods to map geomorphological and hydrological diversity have been identified. Future research should focus on investigating the relationship between the geodiversity components and assess their relationship with biodiversity. Such knowledge can enhance conservation plans for the ADB. This article is part of the Theo Murphy meeting issue 'Geodiversity for science and society'. [ABSTRACT FROM AUTHOR]

The aim of UNESCO Global Geoparks (UGGs) is to protect globally significant geoheritage and geodiversity, but quantitative evidence on the global representativeness of geodiversity components (i.e. geology, soils, geomorphology and hydrology) in these geoparks is in short supply. Here, we provide a first assessment by deriving a global map of geodiversity to test whether the presence of geodiversity components in UGGs is representative for the global availability and distribution of geodiversity. Using openly accessible global datasets and a newly developed workflow, we have calculated metrics for each geodiversity component and a global geodiversity index; we then quantified whether UGGs represent global geodiversity and then compared their components to a randomized spatial distribution of geoparks. Our results show that lithological and topographical diversity are more represented in UGGs than outside these sites, while soil type and hydrological diversity are not significantly different. Furthermore, individual soil types and lithological classes are under-represented and unevenly distributed in Asian and European UGGs. This is probably caused by the concentration of geoparks in Asian and European mountains. To better conserve geodiversity, we suggest an initiative to consider the protection and representation of all geodiversity components in their global context. This article is part of the Theo Murphy meeting issue 'Geodiversity for science and society'. [ABSTRACT FROM AUTHOR]

Records of sedimentation collected from Cariboo Lake, situated in the northern Columbia Mountains, British Columbia, Canada, are analyzed to assess Holocene fluvial and glacial watershed dynamics. The aim of this study is to provide a proxy record of Holocene hydroclimate and glacier change from sediment archives at a higher temporal resolution compared to available records for the Interior Ranges of British Columbia. Deglacial and Holocene sediment accumulation is observed to reach a maximum thickness of 35 m in deep parts of the lake, using sub-bottom acoustic soundings. A transition from massive to well-stratified sediments is observed in the sub-bottom acoustic record during final phases of valley deglaciation in the region (~10.5–9 cal ka BP). Laminae couplets are interpreted to be deposited annually according to two 14C dates and a varve counting chronology. Two long cores, 2.9 and 3.8 m in length, were selected for analysis with estimated basal dates of 2 cal ka BP. Trends in downcore sediment characteristics were linked to environmental changes in the glaciated catchment headwaters at a temporal resolution of ~100 years. Upstream lake filtering of river floodplains and lakes prevented finding a higher temporal resolution linkage between the sediment characteristics and headwater fluvial and glacial activity. Despite some upstream filtering, the Cariboo River was found to be the primary source of sediment to the long core sites. Observed grain size and varve thickness from two long cores show above average trends, which are coincident with cooler temperatures and the primary glacier advances over the last 2 ka. [ABSTRACT FROM AUTHOR]

Soil temperature is an important index of climate change, and the analysis of soil temperature change is of great significance for understanding climate change and ecohydrological processes. This study was based on the measured meteorological data of a meteorological station, combined with the soil temperature data of 0–10, 10–40, 40–100 and 100–200 cm from the Global Land Data Assimilation System (GLDAS-NOAH). The Mann–Kendall test, wavelet analysis, linear tendency estimation and other methods were used to analyze the variability, periodicity and trend of soil temperature in Lhasa from 2006 to 2022. The results showed that the soil temperature of different soil layers had abrupt changes in annual and seasonal time series, and all showed a warming phenomenon after abrupt changes. In terms of periodicity, the average annual soil temperature of different soil layers has similar periodic changes, and the periodic oscillation is strong around 10a, which is the main cycle of soil temperature change. The soil temperature in Lhasa showed a significant rising trend in the interannual and seasonal time series, and the average annual rising trend of soil temperature was greater than that of air temperature. The correlation between soil temperature and mean air temperature (MAT), maximum air temperature (Tmax), minimum air temperature (Tmin) and snow depth (SD) was investigated by Pearson correlation analysis. Soil temperature in spring, autumn and winter had a strong correlation with MAT, Tmax and Tmin, showing a significant positive correlation. The negative correlation between soil temperature and SD in 0–40 cm soil in spring and winter was more severe. The research results show that Lhasa has experienced a rise in air temperature and soil temperature in the past 17 years, and reveal the specific changes in soil temperature in Lhasa against the background of climate change. These findings have reference significance for understanding the impact of climate change on the natural environment. [ABSTRACT FROM AUTHOR]

Low-order streams and riparian wetlands are important contributors to the drainage network in the landscape. However, there has been little research into the nature of these ecosystems in Brazil. Our estimates show that riparian wetlands of low-order streams and other small associated wetlands cover at least 25% of the forested part of the Amazon basin and about 10% of the Cerrado region. Information on the semi-arid Caatinga is lacking, but ~ 3% of the area may be occupied by riparian wetlands and other small wetland types, many of which are periodically dry. Riparian vegetation includes a very large richness in tree species. The amount and species richness of herbaceous plants depend on light availability. In-streams of the semi-arid region of Brazil, hydrophytes are restricted by unpredictable flash floods and periodic drought. Aquatic food webs are largely based on the organic matter produced by the riparian vegetation. Large-scale agriculture and cattle ranching pose a serious threat to riparian wetlands, their biodiversity, and their function as a buffer in the hydrological cycle of the landscape. A nation-wide screening program would provide a more detailed picture and allow the elaboration of a national conservation and restoration program for the Brazilian riparia. [ABSTRACT FROM AUTHOR]

Hydropedology is an interdisciplinary field that studies the interactions between soil and water, recognizing that soils influence hydrological processes through their hydraulic properties, and serve as indicators of hydrological behaviour through their morphological properties that are shaped by water regimes. Given the practical implications of hydropedology and its integration into South Africa's latest soil classification system, an updated categorization of soil forms and 1 657 (1 629 + 28) families was necessary, organizing them into three overarching response groups based on their predominant hydrological responses: recharge, interflow, and responsive. Within these groups, recharge soils are further classified into deep, shallow, and slow subgroups, interflow soils encompass soil/bedrock, shallow, and slow categories, while responsive soils are subdivided into responsive shallow and responsive wet. This paper aims to enhance the reader's comprehension of hydrological responses and simplify the intricacies integrated into South Africa's official soil classification system. [ABSTRACT FROM AUTHOR]

Freshwater mussels preserve valuable information about hydrology, climate, and population dynamics, but developing seasonal chronologies can be problematic. Using clumped isotope thermometry, we produced high-resolution reconstructions of modern and historic (~ 1900) temperatures and δ18Owater from mussel shells collected from an impounded river, the Brazos in Texas, before and after damming. We also performed high-resolution growth band analyses to investigate relationships between mussel growth rate, rainfall, and seasonal temperature. Reconstructed δ18Owater and temperature vary little between the modern (3R5) and historic shell (H3R). However, a positive relationship between reconstructed δ18Owater and growth rate in H3R indicates that aside from diminished growth in winter, precipitation and flow rate are the strongest controls on mussel growth in both modern and pre-dam times. Overall, our results demonstrate (1) the impact, both positive and negative, of environmental factors such as flow alteration and temperature on mussel growth and (2) the potential for clumped isotopes in freshwater mussels as a paleohydrology and paleoclimate proxies in terrestrial environments. [ABSTRACT FROM AUTHOR]

In groundwater hydrology, aquitard heterogeneity is often less considered compared to aquifers, despite its significant impact on groundwater hydraulics and groundwater resources evaluation. A semi‐analytical solution is derived for pumping‐induced well hydraulics and groundwater budget with consideration of vertical heterogeneity in aquitard hydraulic conductivity (K) and specific storage (Ss). The proposed new solution is innovative in its partitioning of the aquitard into multiple homogeneous sub‐layers to enable consideration of various forms of vertically heterogeneous K or Ss. Two scenarios of analytical investigations are explored: one is the presence of aquitard interlayers with distinct K or Ss values, a common field‐scale occurrence; another is an exponentially depth‐decaying aquitard Ss, a regional‐scale phenomenon supported by statistical analysis. Analytical investigations reveal that a low‐K interlayer can significantly increase aquifer drawdown and enhance aquifer/aquitard depletion; a high‐Ss interlayer can noticeably reduce aquifer drawdown and increase aquitard depletion. Locations of low‐K or high‐Ss interlayers also significantly impact well hydraulics and groundwater budget. In the context of an exponentially depth‐decaying aquitard Ss, a larger decay exponent can enhance aquifer drawdown. When using current models with a vertically homogeneous aquitard, half the sum of the geometric and harmonic means of exponentially depth‐decaying aquitard Ss should be used to calculate aquitard depletion and unconfined aquifer leakage. [ABSTRACT FROM AUTHOR]