<div><div>Climate change–driven warming has amplified the widespread impacts of droughts, causing severe socio-economic stress and resource insecurity, thereby highlighting the need for accurate quantification of drought intensity for timely and effective mitigation. Drought has been traditionally associated with rainfall deficit (below-normal precipitation), yet emerging evidence suggests that changes in distribution of precipitation spells (precipitation variability) may intensify drought risk. In this study, we examine global meteorological drought dynamics during 1951–2016 to assess whether the precipitation–drought linkage has changed. Further an attribution analysis to identify the dominant climatic drivers has also been conducted. Our results reveal that between 1951 and 2016, global drought frequency has increased up to six times, primarily due to changing climatic variables like rainfall deficit, evaporative losses, and rainfall variability. Predominant post the 1980 s, this trend is concentrated in the Tropical and Subtropical regions. Further, the traditional link between drought events and rainfall deficit has weakened, wherein drought likelihood during surplus rainfall years rose by 60 %. While total precipitation remained relatively stable, drought-prone hotspots experienced a 40 % increase in meteorological droughts, attributed to enhanced variability in precipitation distribution. This variability has led to significant drought events, with drought index values falling below −1. This impact is profound, in the Tropical zone, affecting diverse climates from monsoon regions to arid deserts. This pattern highlights how precipitation variability—more than mean rainfall deficit alone— drives tropical drought dynamics, reshaping our understanding of hydroclimate behavior and risk in Earth-system contexts.</div></div><div><h3>Plain language summary</h3><div>From 1951 to 2016, the number of drought episodes worldwide have increased up to six times. This increase was predominant after the 1980 s specially in the tropical and subtropical regions. Interestingly, we find that a nearabout 60 % increase is witnessed in drought events occurring during wetter-than-normal years. Thus, droughts are no longer explained only by reduced total rainfall. This shift signals that rainfall patterns are undergoing uneven distribution over time and space, specially over drought hotspots where drought frequency increased by 40 % with minimal change in rainfall magnitudes. These findings show that rainfall variability, rather than mean rainfall decline alone, is increasingly driving drought risk in the tropics. This can prove to be a vital contribution in modifying drought early-warning systems and water planning measures to better manage future drought impacts.</div></div><div><h3>Key points:</h3><div>1. Global drought frequency exhibits a sixfold increase since 1951, with hints of intensification over the Tropical zone.</div><div>2. The probability of occurr
{"title":"Global shifts in rainfall drought relationship: weakening association in tropics","authors":"Gauranshi Raj Singh , C.T. Dhanya , Aniket Chakravorty","doi":"10.1016/j.jhydrol.2026.135240","DOIUrl":"10.1016/j.jhydrol.2026.135240","url":null,"abstract":"<div><div>Climate change–driven warming has amplified the widespread impacts of droughts, causing severe socio-economic stress and resource insecurity, thereby highlighting the need for accurate quantification of drought intensity for timely and effective mitigation. Drought has been traditionally associated with rainfall deficit (below-normal precipitation), yet emerging evidence suggests that changes in distribution of precipitation spells (precipitation variability) may intensify drought risk. In this study, we examine global meteorological drought dynamics during 1951–2016 to assess whether the precipitation–drought linkage has changed. Further an attribution analysis to identify the dominant climatic drivers has also been conducted. Our results reveal that between 1951 and 2016, global drought frequency has increased up to six times, primarily due to changing climatic variables like rainfall deficit, evaporative losses, and rainfall variability. Predominant post the 1980 s, this trend is concentrated in the Tropical and Subtropical regions. Further, the traditional link between drought events and rainfall deficit has weakened, wherein drought likelihood during surplus rainfall years rose by 60 %. While total precipitation remained relatively stable, drought-prone hotspots experienced a 40 % increase in meteorological droughts, attributed to enhanced variability in precipitation distribution. This variability has led to significant drought events, with drought index values falling below −1. This impact is profound, in the Tropical zone, affecting diverse climates from monsoon regions to arid deserts. This pattern highlights how precipitation variability—more than mean rainfall deficit alone— drives tropical drought dynamics, reshaping our understanding of hydroclimate behavior and risk in Earth-system contexts.</div></div><div><h3>Plain language summary</h3><div>From 1951 to 2016, the number of drought episodes worldwide have increased up to six times. This increase was predominant after the 1980 s specially in the tropical and subtropical regions. Interestingly, we find that a nearabout 60 % increase is witnessed in drought events occurring during wetter-than-normal years. Thus, droughts are no longer explained only by reduced total rainfall. This shift signals that rainfall patterns are undergoing uneven distribution over time and space, specially over drought hotspots where drought frequency increased by 40 % with minimal change in rainfall magnitudes. These findings show that rainfall variability, rather than mean rainfall decline alone, is increasingly driving drought risk in the tropics. This can prove to be a vital contribution in modifying drought early-warning systems and water planning measures to better manage future drought impacts.</div></div><div><h3>Key points:</h3><div>1. Global drought frequency exhibits a sixfold increase since 1951, with hints of intensification over the Tropical zone.</div><div>2. The probability of occurr","PeriodicalId":362,"journal":{"name":"Journal of Hydrology","volume":"671 ","pages":"Article 135240"},"PeriodicalIF":6.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147359934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-05-01Epub Date: 2026-03-04DOI: 10.1016/j.jhydrol.2026.135238
Qingsong Wu , Hao Wei , Xing Yuan , Lu Lu , Shengqi Jian , Jiawei Li
Attribution of water resource changes is crucial for revealing the evolutionary laws of water resource systems and improving the efficiency of water resource management. This study conducts systematic research through theoretical interpretation, methodological development and case application. First, the water balance principle and water budget balance theory are integrated to clarify an attribution framework centered on the water cycle process. Second, a water budget balance equation and a distributed human-water relationship model covering the entire “input-transformation-consumption-output” chain are constructed. Third, a two-level attribution system is established by coupling the balance equation, distributed model, control variable method and contribution rate quantification: the first level quantifies the driving contributions of climate change and human activities to changes in natural runoff; the second level analyzes the driving effects of precipitation, incoming surface runoff, natural evapotranspiration, human water consumption, external transferred water and water storage on actual runoff changes. Finally, the method is applied to the Qin River Basin in China across multi-temporal (multi-year average, annual, monthly) and spatial (entire basin, basin divisions) scales. Results show that the method integrates multi-source information to clarify the driving mechanisms of water resource changes, with strong effectiveness and applicability across scales; basin runoff changes during 2001–2022 were dominated by climatic factors, while human activities promoted natural runoff increase but reduced actual runoff; the basin’s natural runoff decreased by 0.982 × 108 m3 when comparing the periods 2001–2010 and 2011–2020, with the contribution rates of climate change and human activities being −118.0% and 18.0%, respectively; the combined effects of reduced precipitation, decreased natural evapotranspiration, increased human water consumption, increased external transferred water, and increased water storage led to a 0.508 × 108 m3 decrease in actual runoff, with the corresponding contribution rates of −47.3%, 276.4%, −173.5%, −1.1%, and −154.5%. The primary novelty lies in a hierarchical framework that distinguishes between natural and actual runoff drivers, providing finer attribution resolution compared with conventional methods.
{"title":"A two-level attribution method for water resource changes based on water budget balance and distributed simulation","authors":"Qingsong Wu , Hao Wei , Xing Yuan , Lu Lu , Shengqi Jian , Jiawei Li","doi":"10.1016/j.jhydrol.2026.135238","DOIUrl":"10.1016/j.jhydrol.2026.135238","url":null,"abstract":"<div><div>Attribution of water resource changes is crucial for revealing the evolutionary laws of water resource systems and improving the efficiency of water resource management. This study conducts systematic research through theoretical interpretation, methodological development and case application. First, the water balance principle and water budget balance theory are integrated to clarify an attribution framework centered on the water cycle process. Second, a water budget balance equation and a distributed human-water relationship model covering the entire “input-transformation-consumption-output” chain are constructed. Third, a two-level attribution system is established by coupling the balance equation, distributed model, control variable method and contribution rate quantification: the first level quantifies the driving contributions of climate change and human activities to changes in natural runoff; the second level analyzes the driving effects of precipitation, incoming surface runoff, natural evapotranspiration, human water consumption, external transferred water and water storage on actual runoff changes. Finally, the method is applied to the Qin River Basin in China across multi-temporal (multi-year average, annual, monthly) and spatial (entire basin, basin divisions) scales. Results show that the method integrates multi-source information to clarify the driving mechanisms of water resource changes, with strong effectiveness and applicability across scales; basin runoff changes during 2001–2022 were dominated by climatic factors, while human activities promoted natural runoff increase but reduced actual runoff; the basin’s natural runoff decreased by 0.982 × 10<sup>8</sup> m<sup>3</sup> when comparing the periods 2001–2010 and 2011–2020, with the contribution rates of climate change and human activities being −118.0% and 18.0%, respectively; the combined effects of reduced precipitation, decreased natural evapotranspiration, increased human water consumption, increased external transferred water, and increased water storage led to a 0.508 × 10<sup>8</sup> m<sup>3</sup> decrease in actual runoff, with the corresponding contribution rates of −47.3%, 276.4%, −173.5%, −1.1%, and −154.5%. The primary novelty lies in a hierarchical framework that distinguishes between natural and actual runoff drivers, providing finer attribution resolution compared with conventional methods.</div></div>","PeriodicalId":362,"journal":{"name":"Journal of Hydrology","volume":"671 ","pages":"Article 135238"},"PeriodicalIF":6.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147360412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-05-01Epub Date: 2026-03-06DOI: 10.1016/j.jhydrol.2026.135245
Monica Esmond , Dioni Cendón , Harald Hofmann , Mark de Bruyn , Matthew Currell
Natural springs are vital ecotones which connect surface and groundwaters, play critical ecological roles and sustain important cultural values worldwide. Increasing pressures on hydrological systems from anthropogenic-induced changes threaten springs and their connected waterways. Methods to characterise spring groundwater sources and the dynamics controlling discharge are critical to inform evidence-based management. This study presents an eco-hydrogeological approach synthesising geochemical tracer data (hydrochemistry, stable and radio-isotopes) with environmental DNA (eDNA) from springs and spring-fed surface waters, to develop a conceptual model of groundwater flow paths and water sources for Great Artesian Basin springs in Carnarvon Gorge, northern Australia. Analysis of δ2H, δ18O, 3H, 14C and 36Cl identified vertical inter-aquifer flow as a major control on local groundwater dynamics. 87Sr/86Sr helped to constrain dominant water sources for springs and confirmed multiple recharge zones within and surrounding the gorge. eDNA was in certain areas more sensitive than the isotopic tracers to differences in recharge area and flow paths, e.g., distinguishing between groundwater from the same aquifer(s) emerging at different springs hydraulically separated by gorge topography. 3H showed a statistically significant relationship with eDNA beta diversity and non-linear modelling supported the hypothesised elevation-driven vertical hydraulic gradient controlling groundwater flow to springs. This is among the first studies to demonstrate the value of integrating ecological with isotopic tracers in the context of developing more robust and nuanced conceptual models of complex aquifer-spring-surface water dynamics. We highlight the need for multi-tracer approaches to inform the protection of springs, connected waters, and associated ecological and cultural values.
{"title":"A multi-tracer approach to constraining water sources of culturally and ecologically significant natural springs: Combining environmental isotopes and environmental DNA","authors":"Monica Esmond , Dioni Cendón , Harald Hofmann , Mark de Bruyn , Matthew Currell","doi":"10.1016/j.jhydrol.2026.135245","DOIUrl":"10.1016/j.jhydrol.2026.135245","url":null,"abstract":"<div><div>Natural springs are vital ecotones which connect surface and groundwaters, play critical ecological roles and sustain important cultural values worldwide. Increasing pressures on hydrological systems from anthropogenic-induced changes threaten springs and their connected waterways. Methods to characterise spring groundwater sources and the dynamics controlling discharge are critical to inform evidence-based management. This study presents an eco-hydrogeological approach synthesising geochemical tracer data (hydrochemistry, stable and radio-isotopes) with environmental DNA (eDNA) from springs and spring-fed surface waters, to develop a conceptual model of groundwater flow paths and water sources for Great Artesian Basin springs in Carnarvon Gorge, northern Australia. Analysis of δ<sup>2</sup>H, δ<sup>18</sup>O, <sup>3</sup>H, <sup>14</sup>C and <sup>36</sup>Cl identified vertical inter-aquifer flow as a major control on local groundwater dynamics. <sup>87</sup>Sr/<sup>86</sup>Sr helped to constrain dominant water sources for springs and confirmed multiple recharge zones within and surrounding the gorge. eDNA was in certain areas more sensitive than the isotopic tracers to differences in recharge area and flow paths, e.g., distinguishing between groundwater from the same aquifer(s) emerging at different springs hydraulically separated by gorge topography. <sup>3</sup>H showed a statistically significant relationship with eDNA beta diversity and non-linear modelling supported the hypothesised elevation-driven vertical hydraulic gradient controlling groundwater flow to springs. This is among the first studies to demonstrate the value of integrating ecological with isotopic tracers in the context of developing more robust and nuanced conceptual models of complex aquifer-spring-surface water dynamics. We highlight the need for multi-tracer approaches to inform the protection of springs, connected waters, and associated ecological and cultural values.</div></div>","PeriodicalId":362,"journal":{"name":"Journal of Hydrology","volume":"671 ","pages":"Article 135245"},"PeriodicalIF":6.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147388364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-05-01Epub Date: 2026-03-05DOI: 10.1016/j.jhydrol.2026.135237
Hannah Hapich , Tim H.M. van Emmerik , Kryss Waldschläger , Benjamin Maurer , Zhaoqing Yang , Andrew B. Gray
Tire wear particles (TWPs) are an important class of microplastics due to their toxicity and abundance. Because most TWPs are generated on impervious road surfaces, urban wash-off is the critical first phase of waterborne transport from their zone of production to stormwater drainage. However, little is known about the driving factors behind their mobilization. In this study, we use a rainfall simulator to investigate how surface roughness, rainfall intensity, and surface slope affect wash-off behaviors of TWPs. We also analyze how the size and shape of mobilized TWPs change over the course of simulated storm events. We found that low surface roughness, high rainfall intensity (most significant factor), and low slope result in the most rapid conveyance of TWP load. On average, large particles (>1000 µm) travelled faster than small particles (<125 µm). Particle shape explained a very small amount of variance in TWP wash-off velocity but was found to be more important under higher surface roughness conditions. In addition to wash-off velocity, we found similar conditions controlled the percent mobilization of TWPs. Low surface roughness and high rainfall intensity resulting in higher TWP wash-off rates is consistent with mineral sediment wash-off behavior. Conversely, low surface slope and large particle size leading to faster conveyance is directly opposed to mineral sediment wash-off. Our findings suggest drag-dominated flow, and that sufficient runoff depth is the most important parameter governing TWP wash-off. These findings are important first steps to understanding wash-off behaviors of TWPs and informing future modeling efforts and mitigation strategies.
{"title":"Urban wash-off of tire wear particles","authors":"Hannah Hapich , Tim H.M. van Emmerik , Kryss Waldschläger , Benjamin Maurer , Zhaoqing Yang , Andrew B. Gray","doi":"10.1016/j.jhydrol.2026.135237","DOIUrl":"10.1016/j.jhydrol.2026.135237","url":null,"abstract":"<div><div>Tire wear particles (TWPs) are an important class of microplastics due to their toxicity and abundance. Because most TWPs are generated on impervious road surfaces, urban wash-off is the critical first phase of waterborne transport from their zone of production to stormwater drainage. However, little is known about the driving factors behind their mobilization. In this study, we use a rainfall simulator to investigate how surface roughness, rainfall intensity, and surface slope affect wash-off behaviors of TWPs. We also analyze how the size and shape of mobilized TWPs change over the course of simulated storm events. We found that low surface roughness, high rainfall intensity (most significant factor), and low slope result in the most rapid conveyance of TWP load. On average, large particles (>1000 µm) travelled faster than small particles (<125 µm). Particle shape explained a very small amount of variance in TWP wash-off velocity but was found to be more important under higher surface roughness conditions. In addition to wash-off velocity, we found similar conditions controlled the percent mobilization of TWPs. Low surface roughness and high rainfall intensity resulting in higher TWP wash-off rates is consistent with mineral sediment wash-off behavior. Conversely, low surface slope and large particle size leading to faster conveyance is directly opposed to mineral sediment wash-off. Our findings suggest drag-dominated flow, and that sufficient runoff depth is the most important parameter governing TWP wash-off. These findings are important first steps to understanding wash-off behaviors of TWPs and informing future modeling efforts and mitigation strategies.</div></div>","PeriodicalId":362,"journal":{"name":"Journal of Hydrology","volume":"671 ","pages":"Article 135237"},"PeriodicalIF":6.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147387993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-05-01Epub Date: 2026-02-28DOI: 10.1016/j.jhydrol.2026.135212
Tianyue Sun , Yuan Zhang , Xiaoming Feng , Bojie Fu , Donggang Guo , Weipeng Wang
Extreme precipitation events (EPEs) are expected to become increasingly frequent and severe in the future. As a critical meteorological factor, extreme precipitation (EPre) strongly regulates ecosystem carbon sequestration, highlighting the need to understand its effects on global terrestrial ecosystems. However, quantitative assessments of how ecosystem carbon sequestration adapts to EPre at the global scale and over the long term are still lacking. To address this issue, we define EPEs using threshold-based methods and extreme climate indices. Using observational data from 29 FLUXNET stations, we employ partial correlation analysis and Random Forest model to systematically quantify the response, adaptation, and recovery of gross primary productivity (GPP) to EPEs. The results demonstrate that: (1) A total of 499 EPEs persisting for more than five days comprised 95% of all identified EPEs. The duration of these EPEs ranged from 5 to 28 days in evergreen needleleaf forest, mixed forest, and deciduous broadleaf forest ecosystems, while woody savannas ecosystems exhibited significantly longer durations. (2) EPre significantly reduced ecosystem carbon sequestration. In most ecosystems (excluding evergreen broadleaf forests and woody savannas), the mean partial correlation coefficient between EPre and GPP was less than −0.66 (p < 0.05). Furthermore, EPre accounted for more than 41% of the observed decline in GPP. (3) Most ecosystems (deciduous broadleaf forests, evergreen broadleaf forests, evergreen needleleaf forests, mixed forests and woody savannas) typically recovered their carbon sequestration capacity within 12 days. The duration of EPEs and vapor pressure deficit during the recovery period were identified as the primary drivers influencing the recovery of GPP. Our findings refine the understanding of diverse ecosystem responses to extreme precipitation and offer a framework for enhancing the simulation of such events in dynamic vegetation models.
{"title":"Response and adaptation of global terrestrial vegetation production to extreme precipitation","authors":"Tianyue Sun , Yuan Zhang , Xiaoming Feng , Bojie Fu , Donggang Guo , Weipeng Wang","doi":"10.1016/j.jhydrol.2026.135212","DOIUrl":"10.1016/j.jhydrol.2026.135212","url":null,"abstract":"<div><div>Extreme precipitation events (EPEs) are expected to become increasingly frequent and severe in the future. As a critical meteorological factor, extreme precipitation (EPre) strongly regulates ecosystem carbon sequestration, highlighting the need to understand its effects on global terrestrial ecosystems. However, quantitative assessments of how ecosystem carbon sequestration adapts to EPre at the global scale and over the long term are still lacking. To address this issue, we define EPEs using threshold-based methods and extreme climate indices. Using observational data from 29 FLUXNET stations, we employ partial correlation analysis and Random Forest model to systematically quantify the response, adaptation, and recovery of gross primary productivity (GPP) to EPEs. The results demonstrate that: (1) A total of 499 EPEs persisting for more than five days comprised 95% of all identified EPEs. The duration of these EPEs ranged from 5 to 28 days in evergreen needleleaf forest, mixed forest, and deciduous broadleaf forest ecosystems, while woody savannas ecosystems exhibited significantly longer durations. (2) EPre significantly reduced ecosystem carbon sequestration. In most ecosystems (excluding evergreen broadleaf forests and woody savannas), the mean partial correlation coefficient between EPre and GPP was less than −0.66 (p < 0.05). Furthermore, EPre accounted for more than 41% of the observed decline in GPP. (3) Most ecosystems (deciduous broadleaf forests, evergreen broadleaf forests, evergreen needleleaf forests, mixed forests and woody savannas) typically recovered their carbon sequestration capacity within 12 days. The duration of EPEs and vapor pressure deficit during the recovery period were identified as the primary drivers influencing the recovery of GPP. Our findings refine the understanding of diverse ecosystem responses to extreme precipitation and offer a framework for enhancing the simulation of such events in dynamic vegetation models.</div></div>","PeriodicalId":362,"journal":{"name":"Journal of Hydrology","volume":"671 ","pages":"Article 135212"},"PeriodicalIF":6.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147334594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-05-01Epub Date: 2026-03-03DOI: 10.1016/j.jhydrol.2026.135239
Weize Wang , Peng Hu , Zefan Yang , Qin Yang , Jianhua Wang , Dandong Cheng , Jiwei Zhu
Human activities have reduced hydrological connectivity in many wetlands, leading to weakening of the mediating role of water in facilitating the diffusion and exchange of materials, energy, and ecological information, resulting in ecosystem fragmentation. In this study, hydrodynamic modelling, characteristic value extraction, and spatially constrained hierarchical clustering were employed to develop a wetland partitioning method based on hydrological connectivity. The spatial variations in hydrologically connected subareas in different hydrological years and the impacts of hydraulic engineering and topography on hydrological connectivity in the Zhalong Wetland, China, were investigated. The results indicated that hydrologically connected subareas in wetlands can be delineated via this method. In wet year, the study area can be divided into 7 hydrologically connected subareas. Moreover, the number of subareas is larger in normal and dry years (11 and 12 hydrologically connected subareas, respectively) than in wet year. These subareas are the result of erosion due to reservoir discharge, obstruction of roads and ditches, and natural topography. The surface water quality parameters in wetlands vary among hydrologically connected subareas owing to differences in flow patterns, source‒sink dynamics, and aquatic vegetation distributions. Compared with field sampling and statistical clustering, this method requires substantially less data, which makes it potentially applicable in data-scarce regions. This study provides technical support for hydrological and ecological monitoring and wetland management.
{"title":"A wetland partitioning method based on the hydrological connectivity and the underlying causes of their occurrence","authors":"Weize Wang , Peng Hu , Zefan Yang , Qin Yang , Jianhua Wang , Dandong Cheng , Jiwei Zhu","doi":"10.1016/j.jhydrol.2026.135239","DOIUrl":"10.1016/j.jhydrol.2026.135239","url":null,"abstract":"<div><div>Human activities have reduced hydrological connectivity in many wetlands, leading to weakening of the mediating role of water in facilitating the diffusion and exchange of materials, energy, and ecological information, resulting in ecosystem fragmentation. In this study, hydrodynamic modelling, characteristic value extraction, and spatially constrained hierarchical clustering were employed to develop a wetland partitioning method based on hydrological connectivity. The spatial variations in hydrologically connected subareas in different hydrological years and the impacts of hydraulic engineering and topography on hydrological connectivity in the Zhalong Wetland, China, were investigated. The results indicated that hydrologically connected subareas in wetlands can be delineated via this method. In wet year, the study area can be divided into 7 hydrologically connected subareas. Moreover, the number of subareas is larger in normal and dry years (11 and 12 hydrologically connected subareas, respectively) than in wet year. These subareas are the result of erosion due to reservoir discharge, obstruction of roads and ditches, and natural topography. The surface water quality parameters in wetlands vary among hydrologically connected subareas owing to differences in flow patterns, source‒sink dynamics, and aquatic vegetation distributions. Compared with field sampling and statistical clustering, this method requires substantially less data, which makes it potentially applicable in data-scarce regions. This study provides technical support for hydrological and ecological monitoring and wetland management.</div></div>","PeriodicalId":362,"journal":{"name":"Journal of Hydrology","volume":"671 ","pages":"Article 135239"},"PeriodicalIF":6.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147360415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-10DOI: 10.1016/j.jhydrol.2026.134921
Jan-Markus Homberger , Glenn Strypsteen , Abbey L. Marcotte , Sasja van Rosmalen , Michel Riksen , Juul Limpens
Coastal dunes provide critical flood protection for low-lying coastal areas, raising the question of whether these defenses can be maintained in a future climate. Dune development is driven by interactions between sediment transport and vegetation growth. Both processes are affected by climate, notably changes in precipitation. However, tools to assess future precipitation impacts on dune development remain limited.
To address this, we coupled an ecohydrological model with a dune development model (AeoLiS) to simulate plant–water interactions and their influence on dune development. After validating the coupled model against observed dune volumes, we explored how rainfall changes affect dunes formed by planting marram grass and spontaneously forming embryo dunes. We compared dune development under extremely wet, dry, and future climate scenarios against a baseline, running 100 stochastic simulations for each.
Our results show that wet conditions promote rapid vegetation growth, increasing embryonic and artificial dune volumes and crest heights. Dry conditions enhanced inland sediment transport and increased variability in development. Under future projections, embryo dune volumes increased by 2.7% and artificial dune volumes by 0.4%. Compared to embryo dunes, artificial dunes were more affected by extremely dry conditions, reducing the median volume by 1.6% and crest height by 21 cm.
Overall, our findings highlight rainfall as a key driver of dune-building through its control on vegetation growth, which mediates sediment trapping. Therefore, coastal management strategies aimed at dune stabilization may benefit from increased rainfall, while those that rely on active, mobile dune systems may become less effective under enhanced vegetation growth.
{"title":"Plant-water interactions shape coastal dune evolution in a changing climate","authors":"Jan-Markus Homberger , Glenn Strypsteen , Abbey L. Marcotte , Sasja van Rosmalen , Michel Riksen , Juul Limpens","doi":"10.1016/j.jhydrol.2026.134921","DOIUrl":"10.1016/j.jhydrol.2026.134921","url":null,"abstract":"<div><div>Coastal dunes provide critical flood protection for low-lying coastal areas, raising the question of whether these defenses can be maintained in a future climate. Dune development is driven by interactions between sediment transport and vegetation growth. Both processes are affected by climate, notably changes in precipitation. However, tools to assess future precipitation impacts on dune development remain limited.</div><div>To address this, we coupled an ecohydrological model with a dune development model (AeoLiS) to simulate plant–water interactions and their influence on dune development. After validating the coupled model against observed dune volumes, we explored how rainfall changes affect dunes formed by planting marram grass and spontaneously forming embryo dunes. We compared dune development under extremely wet, dry, and future climate scenarios against a baseline, running 100 stochastic simulations for each.</div><div>Our results show that wet conditions promote rapid vegetation growth, increasing embryonic and artificial dune volumes and crest heights. Dry conditions enhanced inland sediment transport and increased variability in development. Under future projections, embryo dune volumes increased by 2.7% and artificial dune volumes by 0.4%. Compared to embryo dunes, artificial dunes were more affected by extremely dry conditions, reducing the median volume by 1.6% and crest height by 21 cm.</div><div>Overall, our findings highlight rainfall as a key driver of dune-building through its control on vegetation growth, which mediates sediment trapping. Therefore, coastal management strategies aimed at dune stabilization may benefit from increased rainfall, while those that rely on active, mobile dune systems may become less effective under enhanced vegetation growth.</div></div>","PeriodicalId":362,"journal":{"name":"Journal of Hydrology","volume":"668 ","pages":"Article 134921"},"PeriodicalIF":6.3,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145957205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-12DOI: 10.1016/j.jhydrol.2026.134936
Abdullah A. Alsumaiei
With soaring evaporation rates and shrinking freshwater resources, hyper-arid regions require accurate instruments to measure atmospheric water loss, making pan evaporation forecasting a crucial aspect of contemporary water resources management. This paper proposes a hybrid framework that integrates the Physics-Constrained Neural Network (PCNN) and the Bat Algorithm (BA) to predict daily pan evaporation in Kuwait. The proposed PCNN incorporates physical constraints into the loss function, including vapor pressure deficit, net radiation, and aerodynamic resistance based on surface energy balance theory, to ensure both predictive accuracy and physical plausibility, unlike traditional machine learning models. Daily meteorological data and Class A pan evaporation data from two different stations, Kuwait International Airport (KIA) and Abdaly, are used to train and test the model. The obtained results demonstrate a high accuracy and good generalizability with RMSE of 0.904 mm/day, 1.186 mm/day, and R2 of 0.953 and 0.884 at KIA and Abdaly, respectively. The model’s consistency with thermodynamic principles is also confirmed by a new metric called physics residual RMSE (PRMSE). Tests of robustness in the presence of synthetic noise show that the model is insensitive to uncertainty in its inputs. The added value of the PCNN–BA framework is demonstrated through systematic comparison with established data-driven models, showing that the proposed approach achieves competitive predictive accuracy while explicitly enforcing physical consistency. The resulting framework is computationally efficient and scalable, making it suitable for hyper-arid environments and directly applicable to desert agriculture, irrigation scheduling, and water resources management under data-limited and water-scarce conditions.
{"title":"Physics-constrained neural network for daily pan evaporation forecasting in hyper-arid climates optimized by the Bat Algorithm","authors":"Abdullah A. Alsumaiei","doi":"10.1016/j.jhydrol.2026.134936","DOIUrl":"10.1016/j.jhydrol.2026.134936","url":null,"abstract":"<div><div>With soaring evaporation rates and shrinking freshwater resources, hyper-arid regions require accurate instruments to measure atmospheric water loss, making pan evaporation forecasting a crucial aspect of contemporary water resources management. This paper proposes a hybrid framework that integrates the Physics-Constrained Neural Network (PCNN) and the Bat Algorithm (BA) to predict daily pan evaporation in Kuwait. The proposed PCNN incorporates physical constraints into the loss function, including vapor pressure deficit, net radiation, and aerodynamic resistance based on surface energy balance theory, to ensure both predictive accuracy and physical plausibility, unlike traditional machine learning models. Daily meteorological data and Class A pan evaporation data from two different stations, Kuwait International Airport (KIA) and Abdaly, are used to train and test the model. The obtained results demonstrate a high accuracy and good generalizability with RMSE of 0.904 mm/day, 1.186 mm/day, and <em>R</em><sup>2</sup> of 0.953 and 0.884 at KIA and Abdaly, respectively. The model’s consistency with thermodynamic principles is also confirmed by a new metric called physics residual RMSE (PRMSE). Tests of robustness in the presence of synthetic noise show that the model is insensitive to uncertainty in its inputs. The added value of the PCNN–BA framework is demonstrated through systematic comparison with established data-driven models, showing that the proposed approach achieves competitive predictive accuracy while explicitly enforcing physical consistency. The resulting framework is computationally efficient and scalable, making it suitable for hyper-arid environments and directly applicable to desert agriculture, irrigation scheduling, and water resources management under data-limited and water-scarce conditions.</div></div>","PeriodicalId":362,"journal":{"name":"Journal of Hydrology","volume":"668 ","pages":"Article 134936"},"PeriodicalIF":6.3,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145957200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-13DOI: 10.1016/j.jhydrol.2026.134967
Yabing Li , Zhifang Zhou , Ning Zhang
Accurate prediction of transient flow and vertical leakage in multilayer aquifer systems is critical for sustainable groundwater management and contaminant risk assessment. Conventional groundwater models often simplify subsurface conditions by assuming homogeneous aquitards, isotropic aquifers, constant pumping rates, and idealized boundary conditions, limiting their applicability in realistic field settings. This study develops semi-analytical solutions for three-dimensional transient flow toward a partially penetrating well under variable discharge in a complex aquifer-aquitard system. The model incorporates aquifer anisotropy and vertical heterogeneity in aquitard hydraulic conductivity (K) and specific storage (Ss). It considers representative upper boundary conditions: constant head, water table with delayed drainage, and no-flux. Solutions are derived in the Laplace-Hankel domain and numerically inverted to quantify drawdown and leakage response. Results show that stronger aquitard Ss decay enhances early- and mid-time drawdowns, while greater aquitard K decay limits vertical leakage and decreases aquitard and upper aquifer drawdowns. Compared with a homogeneous aquitard K, increasing dimensionless decay exponent of K from 1.5 to 2.5 reduces stable-stage leakage rates by 45% to 86%. Aquifer anisotropy intensifies vertical hydraulic gradient contrasts and promotes drawdown accumulation. Variable pumping induces nonlinear leakage responses and transient flow reversals. Boundary conditions significantly influence stable-stage leakage rates: compared to the constant-head boundary, the leakage rate at the aquifer-aquitard interface is 3% lower under the water table boundary and 10% lower under the no-flux boundary. The model offers a robust tool for evaluating leakage-driven risks to groundwater quality in complex, vertically heterogeneous hydrogeologic systems such as glacial and alluvial basins.
{"title":"Semi-analytical modeling of transient flow to a partially penetrating variable-discharge well in a complex aquifer-aquitard system","authors":"Yabing Li , Zhifang Zhou , Ning Zhang","doi":"10.1016/j.jhydrol.2026.134967","DOIUrl":"10.1016/j.jhydrol.2026.134967","url":null,"abstract":"<div><div>Accurate prediction of transient flow and vertical leakage in multilayer aquifer systems is critical for sustainable groundwater management and contaminant risk assessment. Conventional groundwater models often simplify subsurface conditions by assuming homogeneous aquitards, isotropic aquifers, constant pumping rates, and idealized boundary conditions, limiting their applicability in realistic field settings. This study develops semi-analytical solutions for three-dimensional transient flow toward a partially penetrating well under variable discharge in a complex aquifer-aquitard system. The model incorporates aquifer anisotropy and vertical heterogeneity in aquitard hydraulic conductivity (<em>K</em>) and specific storage (<em>S<sub>s</sub></em>). It considers representative upper boundary conditions: constant head, water table with delayed drainage, and no-flux. Solutions are derived in the Laplace-Hankel domain and numerically inverted to quantify drawdown and leakage response. Results show that stronger aquitard <em>S<sub>s</sub></em> decay enhances early- and mid-time drawdowns, while greater aquitard <em>K</em> decay limits vertical leakage and decreases aquitard and upper aquifer drawdowns. Compared with a homogeneous aquitard <em>K</em>, increasing dimensionless decay exponent of <em>K</em> from 1.5 to 2.5 reduces stable-stage leakage rates by 45% to 86%. Aquifer anisotropy intensifies vertical hydraulic gradient contrasts and promotes drawdown accumulation. Variable pumping induces nonlinear leakage responses and transient flow reversals. Boundary conditions significantly influence stable-stage leakage rates: compared to the constant-head boundary, the leakage rate at the aquifer-aquitard interface is 3% lower under the water table boundary and 10% lower under the no-flux boundary. The model offers a robust tool for evaluating leakage-driven risks to groundwater quality in complex, vertically heterogeneous hydrogeologic systems such as glacial and alluvial basins.</div></div>","PeriodicalId":362,"journal":{"name":"Journal of Hydrology","volume":"668 ","pages":"Article 134967"},"PeriodicalIF":6.3,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145962385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Understanding fluid flow through rough rock fractures is essential in numerous geoscientific and engineering applications. Surface roughness introduces enhanced viscous dissipation and inertial effects, thereby amplifying nonlinear flow behavior. Accurate reconstruction of rough fracture geometries, followed by their integration into nonlinear flow models, is crucial for capturing these effects with higher accuracy. This study presents a Discrete Fractal Set (DFS) method for reconstructing rough fracture surfaces and evaluating their influence on nonlinear flow. The approach segments rough profiles into Basic Rough Cells (BRCs), which are then grouped into ordered segments based on a peak ratio criterion. The Weierstrass–Mandelbrot (W–M) function is subsequently applied to each segment for localized fractal refinement. Sensitivity analysis reveals that a peak ratio threshold of 1.0 achieves an optimal balance between reconstruction accuracy and robustness. The DFS method, validated against standard JRC profiles and natural fracture surfaces, outperforms the conventional W–M approach in reconstruction quality, achieving MSE values consistently below 0.11 compared with values often exceeding 0.7 for the W–M equation. To characterize flow behavior, the generated aperture and hydraulic aperture fields are incorporated into the Forchheimer equation, yielding the DFS–Forchheimer equation. Comparative validation against both experimental and numerical results demonstrates that the proposed model improves outlet flow rate prediction accuracy by approximately 4.15% and reduces prediction variability, confirming its enhanced reliability in nonlinear flow simulation.
{"title":"A Discrete fractal set (DFS) method for high–accuracy reconstruction and nonlinear flow simulation in rough rock fractures","authors":"Jinjie Liu, Long Xu, Fusheng Zha, Shan Wu, Qiao Wang, Yuan Zhang","doi":"10.1016/j.jhydrol.2026.135001","DOIUrl":"10.1016/j.jhydrol.2026.135001","url":null,"abstract":"<div><div>Understanding fluid flow through rough rock fractures is essential in numerous geoscientific and engineering applications. Surface roughness introduces enhanced viscous dissipation and inertial effects, thereby amplifying nonlinear flow behavior. Accurate reconstruction of rough fracture geometries, followed by their integration into nonlinear flow models, is crucial for capturing these effects with higher accuracy. This study presents a Discrete Fractal Set (DFS) method for reconstructing rough fracture surfaces and evaluating their influence on nonlinear flow. The approach segments rough profiles into Basic Rough Cells (BRCs), which are then grouped into ordered segments based on a peak ratio criterion. The Weierstrass–Mandelbrot (W–M) function is subsequently applied to each segment for localized fractal refinement. Sensitivity analysis reveals that a peak ratio threshold of 1.0 achieves an optimal balance between reconstruction accuracy and robustness. The DFS method, validated against standard JRC profiles and natural fracture surfaces, outperforms the conventional W–M approach in reconstruction quality, achieving MSE values consistently below 0.11 compared with values often exceeding 0.7 for the W–M equation. To characterize flow behavior, the generated aperture and hydraulic aperture fields are incorporated into the Forchheimer equation, yielding the DFS–Forchheimer equation. Comparative validation against both experimental and numerical results demonstrates that the proposed model improves outlet flow rate prediction accuracy by approximately 4.15% and reduces prediction variability, confirming its enhanced reliability in nonlinear flow simulation.</div></div>","PeriodicalId":362,"journal":{"name":"Journal of Hydrology","volume":"668 ","pages":"Article 135001"},"PeriodicalIF":6.3,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146025917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：