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Assessing runoff changes is of great importance especially its responses to the projected future climate change on local scale basins because such analyses are generally done on global and regional scales which may lead to generalized conclusions rather than specific ones. Climate change affected the runoff variation in the past in the upper Daqinghe Basin, however, the climate was mainly considered uncertain and still needs further studies, especially its future impacts on runoff for better water resources management and planning. Integrated with a set of climate simulations, a daily conceptual hydrological model (MIKE11-NAM) was applied to assess the impact of climate change on runoff conditions in the Daomaguan, Fuping and Zijingguan basins in the upper Daqinghe Basin. Historical hydrological data (2008–2017) were used to evaluate the applicability of the MIKE11-NAM model. After bias correction, future projected climate change and its impacts on runoff (2025–2054) were analysed and compared to the baseline period (1985–2014) under three shared social economic pathways (SSP1-2.6, SSP2-4.5, and SSP5-8.5) scenarios from Coupled Model Intercomparison Project Phase 6 (CMIP6) simulations. The MIKE-11 NAM model was applicable in all three Basins, with both R2 and Nash-Sutcliffe Efficiency coefficients greater than 0.6 at daily scale for both calibration (2009–2011) and validation (2012–2017) periods, respectively. Although uncertainties remain, temperature and precipitation are projected to increase compared to the baseline where higher increases in precipitation and temperature are projected to occur under SSP2-4.5 and SSP5-8.5 scenarios, respectively in all the basins. Precipitation changes will range between 12%–19% whereas temperature change will be 2.0°C–2.5°C under the SSP2-4.5 and SSP5-8.5 scenarios, respectively. In addition, higher warming is projected to occur in colder months than in warmer months. Overall, the runoff of these three basins is projected to respond to projected climate changes differently because runoff is projected to only increase in the Fuping basin under SSP2-4.5 whereas decreases in both Daomaguan and Zijingguan Basins under all scenarios. This study's findings could be important when setting mitigation strategies for climate change and water resources management. [ABSTRACT FROM AUTHOR]

Mountain glaciers are considered natural indicators of warming and a device for climatic change. In addition, it is also a solid reservoir of freshwater resources. Along with climate change, clarifying the dynamic changes of glacier in the Aksu River Basin (ARB) are important for hydrological processes. The study examined the variations in glacier area, elevation, and their reaction to climate change in the ARB between 1990 and 2022. The glacier melt on the runoff is explored from 2003 to 2020. This investigation utilized Landsat and Sentinal-2 images, ICESat, CryoSat, meteorological and hydrological data. The findings suggest that: (1) The glacier area in the ARB retreated by 309.40 km2 (9.37%, 0.29%·a−1) from 1990 to 2022. From 2003 to 2021, the ARB glacier surface elevation retreat rate of 0.38 ± 0.12 m·a−1 (0.32 ± 0.10 m w.e.a−1). Comparison with 2003–2009, the retreat rate is faster from 2010 to 2021. (2) From 1990 to 2022, the Toxkan and the Kumalak River Basin's glacier area decreases between 61.28 km2 (0.28%·a−1) and 248.13 km2 (0.30%·a−1). Additionally, the rate of glacier surface elevation declined by −0.34 ± 0.11 m·a−1, −0.42 ± 0.14 m·a−1 from 2003 to 2021. (3) The mass balance sensitivities to cold season precipitation and ablation-phase accumulated temperatures are +0.27 ± 0.08 m w.e.a−1(10%)−1 and −0.33 ± 0.10 m w.e.a−1 °C−1, respectively. The mass loss is (962.55 ± 0.57) × 106 m3 w.e.a−1, (1087.50 ± 0.68) × 106 m3 w.e.a−1 during 2003–2009, 2010–2021 respectively. Warmer ablation-phase accumulated temperatures dominate glacier retreat in the ARB. (4) Glacier meltwater accounted for 34.57% and 41.56% of the Aksu River's runoff during the ablation-phase of 2003–2009 and 2010–2020, respectively. The research has important implications for maintaining the stability of water resource systems based on glacier meltwater. [ABSTRACT FROM AUTHOR]

The impacts of the accelerated glacier retreat in recent decades on glacier runoff changes are still unknown in most Andean catchments, increasing uncertainties in estimating water availability. This particularly affects the outer tropics and Dry Andes, heavily impacted by prolonged droughts. Current global estimates overlook climatic and morphometric disparities, which significantly influence model parameters, among Andean glaciers. Meanwhile, local studies have used different approaches to estimate glacier runoff in a few catchments. Improving 21st-century glacier runoff projections relies on calibrating and validating models using corrected historical climate inputs and calibrated parameters across diverse glaciological zones. Here, we simulate glacier evolution and related runoff changes between the periods 2000–2009 and 2010–2019 across 786 Andean catchments (11 282 km2 of glacierized area, 11° N to 55° S) using the Open Global Glacier Model (OGGM). TerraClimate atmospheric variables were corrected using in situ data, getting a mean temperature bias by up to 2.1 °C and enhanced monthly precipitation. Glacier mass balance and volume were calibrated, where melt factor and the Glen A parameter exhibited significant alignment with varying environmental conditions. Simulation outcomes were validated against in situ data in three documented catchments (with a glacierized area > 8 %) and monitored glaciers. Our results at the Andes scale reveal an average reduction of 8.3 % in glacier volume and a decrease of 2.2 % in surface area between the periods 2000–2009 and 2010–2019. Comparing these two periods, glacier and climate variations have led to a 12 % increase in mean annual glacier melt (86.5 m3s-1) and a decrease in rainfall on glaciers of - 2 % (- 7.6 m3s-1) across the Andes, with both variables comprising the glacier runoff. We confirmed the utility of our corrected regional simulations of glacier runoff contribution at the catchment scale, where our estimations align with previous studies (e.g., Maipo 34° S, Chile) as well as provide new insights on the seasonal glaciers' largest contribution (e.g., La Paz 16° S, Bolivia) and new estimates of glacier runoff contribution (e.g., Baker 47° S, Chile). [ABSTRACT FROM AUTHOR]

Located in the central part of the arid regions of Northwest China, the Heihe River Basin (HRB) plays an important role in wind prevention, sand fixation, and soil and water conservation as the second largest inland river basin. In the context of the warming and wetting climate observed in Northwest China, the situation of the ecological environment in the HRB is of significant concern. Using the data from meteorological observation stations, grid fusion and hydrological monitoring, this study analyzes the multi-scale climate changes in the HRB and their impacts on runoff. In addition, predictive models for runoff in the upper and middle reaches were developed using machine learning methods. The results indicate that the climate in the HRB has experienced an overall warming and wetting trend over the past 60 years. At the same time, there are clear regional variabilities in the climate changes. Precipitation shows decreasing trends in the northwestern part of the HRB, while it shows increases at rates higher than the regional average in the southeastern part. Moreover, the temperature increases are generally smaller in the upper reaches than those in the middle and lower reaches. Over the past 60 years, there has been a remarkable increase in runoff at the Yingluo Gorge (YL) hydrological station, which exhibits a distinct "single-peak" pattern in the variation of monthly runoff. The annual runoff volume at the YL (ZY) hydrological station is significantly correlated with the precipitation in the upper (middle) reaches, indicating the precipitation is the primary influencing factor determining the annual runoff. Temperature has a significant impact only on the runoff in the upper reaches, while its impact is not significant in the middle reaches. The models trained by the support vector machines and random forest models perform best in predicting the annual runoff and monthly runoff, respectively. This study can provide a scientific basis for environmental protection and sustainable development in the HRB. [ABSTRACT FROM AUTHOR]

Climate change has resulted in an increase in extreme rainstorm events, posing the challenges of urban waterlogging and runoff pollution. Low Impact Development (LID) is widely used to address the issues above, but its effectiveness is unknown in mountainous areas. Due to a flash flood and high flood peak, storage pumping stations are also needed to drain. Thus, a framework composed of storage pumping stations and Low Impact Developments (LIDs) was proposed based on the topography and the regional upstream and downstream relationships. The water quantity in this framework is applied to YI County in Hebei Province, China. The results showed that individual LIDs effectively reduced runoff volume, with the implementation area being more crucial than the location. Combining storage pumping stations with LIDs significantly reduces peak outflow and delays it by 5 to 51 min. The combined downstream implementation of storage pumping stations and LIDs yielded the most effective results. These findings offer important insights and management strategies for controlling waterlogging in mountainous cities of developing countries. [ABSTRACT FROM AUTHOR]

In the past decades, land use pattern and climate conditions of Shaying River Basin have changed significantly, which will inevitably have a significant impact on the river hydrological situation. Therefore, in order to study the response of the hydrological cycle process of the Shaying River Basin to land use and climate changes, this paper constructed the Soil and Water Assessment Tool (SWAT) hydrological model of the Shaying River Basin based on historical meteorological and hydrological data, and conducted parameter calibration and model verification to quantitatively explore the response of the runoff of the Shaying River Basin to different land use and climate change scenarios. The results showed that: (1) In calibration and verification periods, the determination coefficients (R2) were 0.80 and 0.83 respectively, the Nash–Sutcliffe efficiency coefficients (NSE) were 0.77 and 0.73 respectively, and the percentage deviation (PBIAS) was within ± 25%. (2) Setting different combinations of land use and climate changes into four scenarios S1, S2, S3, and S4, the simulated runoff depths were 257 mm, 298 mm, 259 mm, and 301 mm, respectively. The impacts of land use and climate changes on the annual runoff of Shaying River were 0.9% and 16.1% respectively. (3) In the scenario with 4 °C reduction and 20% precipitation increase and scenario 4 °C increase and 20% precipitation reduction, the maximum and minimum annual runoff were increased by 81.9% and decreased by 70.9% compared with the baseline period, respectively. (4) Under the seven scenarios, the precipitation, temperature and runoff in the middle and late 21st century showed an increasing trend, and precipitation will be the main controlling factor affecting runoff. The annual runoff depth showed an increasing trend, and the change of runoff depth in the lower reaches of the basin will be the most obvious. [ABSTRACT FROM AUTHOR]

Nature-based solutions (NbSs) are considered to form an innovative stormwater management approach that has living resolutions grounded in natural processes and structures. NbSs offer many other environmental benefits over traditional grey infrastructure, including reduced air pollution and climate change mitigation. This review predominantly centers on the hydrological aspect of NbSs and furnishes a condensed summary of the collective understanding about NbSs as an alternatives for stormwater management. In this study, which employed the CIMO (Context, Intervention, Mechanism, Outcome) framework, a corpus of 187 NbS-related publications (2000–2023) extracted from the Web of Science database were used, and we expounded upon the origins, objectives, and significance of NbSs in urban runoff and climate change, and the operational mechanisms of NbSs (including green roofs, permeable pavements, bioretention systems, and constructed wetlands), which are widely used in urban stormwater management, were also discussed. Additionally, the efficacy of NbSs in improving stormwater quality and quantity is discussed in depth in this study. In particular, the critical role of NbSs in reducing nutrients such as TSS, TN, TP, and COD and heavy metal pollutants such as Fe, Cu, Pb, and Zn is emphasized. Finally, the main barriers encountered in the promotion and application of NbSs in different countries and regions, including financial, technological and physical, regulatory, and public awareness, are listed, and future directions for improving and strategizing NbS implementation are proposed. This review gathered knowledge from diverse sources to provide an overview of NbSs, enhancing the comprehension of their mechanisms and applications. It underscores specific areas requiring future research attention. [ABSTRACT FROM AUTHOR]

The occurrence of scour around bridge elements due to the transportation of bed material during flood events can cause serious structural damage and loss of life. Increased uncertainties in precipitation and runoff predictions due to climate change make this phenomenon more complex and dangerous. Bridge scour countermeasures should thus be more focused on decreasing scour formation around bridge elements. In this study, abutment scour under clear-water conditions with constant flow intensity was conducted and collars were tested as scour countermeasures around semi-circular end bridge abutments. The experimental study was performed in a rectangular channel with an almost uniform cohesionless bed material for 3 h with and without collars. Collars of various lengths located at different elevations around the abutments were tested to investigate the effect of collars on scour development. The results of the study showed that the scour depth decreased with increasing collar width and when the collar was placed below the bed level for a given abutment length. The results were compared with those of similar earlier studies to show the effect of abutment shape, size of the bed sediment and test durations on the development of scour depth around abutments. [ABSTRACT FROM AUTHOR]

Valid simulation results from global hydrological models (GHMs), such as WaterGAP3, are essential to detecting hotspots or studying patterns in climate change impacts. However, the lack of worldwide monitoring data makes it challenging to adapt GHMs' parameters to enable such valid simulations globally. Therefore, regionalization is necessary to estimate parameters in ungauged basins. This study presents new regionalization methods for WaterGAP3 and aims to provide insights into selecting a suitable regionalization method and evaluating its impact on the simulation. Our results suggest that machine learning-based methods may be too flexible for regionalizing WaterGAP3 due to a significant performance loss between training and testing. In contrast, the most basic regionalization method (using the concept of spatial proximity) outperforms most of the developed regionalization methods and a pre-defined benchmark-to-beat in an ensemble of split-sample tests. The method selection, whether spatial proximity-based or regression-based, has a greater impact on the regionalization than the specific details on how the method is applied. In particular, the descriptor selection plays a subsidiary role when at least a subset of selected descriptors contains relevant information. Additionally, our research has shown that regionalization causes spatially varying uncertainty for ungauged regions. For example, India and Indonesia are particularly affected by higher uncertainty. The impact of regionalization in ungauged areas propagates through the water system, e.g., one water balance component changed by approximately 2400 km3 yr-1 on a global scale, which is in the range of inter-model differences. The magnitude of the impact of regionalization depends on the variability in regionalized values and the region's sensitivity for the analysed component. [ABSTRACT FROM AUTHOR]

Baseflow plays a crucial role in sustaining the alpine ecosystem during rainless or cold periods. Despite its importance, information on how and why baseflow has changed in the source region of the Yangtze River (SRYR) is sparse. In our study, statistical analysis and the elastic coefficient method were used to identify the dynamic characteristics of baseflow and the underlying causes. The results show that monthly baseflow contributed 62-97% of runoff with a mean value of 75%, and they followed remarkable increasing trends from 1957 to 2020. The contributions of precipitation, temperature, evapotranspiration, and ecological conservation programs (ECPs) on baseflow variations were 86, 53, ~15, and ~24%, respectively. However, their contributions differed across months. During the warm months of May to September, precipitation played a dominant role, followed by evapotranspiration. In contrast, during other colder months, temperature was dominant; meanwhile, the effect of precipitation was almost absent. Moreover, climatic change had a hysteretic effect on baseflow variation, with a maximum lag time of 10 months. Our results highlighted critical roles of both precipitation and temperature, and indicated that climate change, rather than ECPs, dominated the variation in baseflow in the SRYR. [ABSTRACT FROM AUTHOR]

To achieve sustainable development goals in Huangshui River Basin (HRB), strengthening adaptive water resources management under the dual impact of climate change (CC) and human interventions (HI) is of great significance. Multiple mathematical and statistical methods were employed to determine the runoff trend and breakpoint in HRB. The elasticity of CC and HI on the runoff decline and their contributions were quantitatively discerned based on the Budyko hypothesis, complementary method, and SWAT hydrological model. The results show that (1) the runoff showed a decreasing trend, with a runoff breakpoint in 1990; (2) the elasticity coefficients indicated a 1% increase in P, ET0, and n, leading to a 2.19% increase, a 1.19% decrease, and a 1.52% decrease in the runoff, respectively; (3) the Budyko framework determined the contribution of CC and HI to runoff decline in HRB to be 37.98-41.86% and 58.14-62.02%, respectively, and that estimated by SWAT hydrological model to be 38.72 and 61.28%, respectively; (4) HI were the primary factor for runoff decline in HRB, where direct anthropogenic disturbances such as water withdrawals and water conservancy project construction were the main drivers. The findings have important scientific significance for water resources planning and management in HRB. [ABSTRACT FROM AUTHOR]

The impact of global climate change on water resources is a pressing concern, particularly in arid and semi-arid regions, where water shortages are becoming increasingly severe. Rainwater harvesting (RWH) offers a promising solution to address these challenges. However, the process of selecting suitable RWH sites is complex. This paper introduces a comprehensive methodology that leverages various technologies and data sources to identify suitable RWH locations in the northern region of Iraq, considering both historical and future scenarios. The study employs remote sensing and geographic information systems to collect and process geospatial data, which are essential for the site selection process. AHP is utilized as a decision-making tool to assess and rank potential RWH locations based on multiple criteria, helping to prioritize the most suitable sites. The WLC approach is used to combine and weigh various factors, enabling a systematic evaluation of site suitability. To account for the uncertainty associated with future climate conditions, a stochastic weather generator is employed to simulate historical and future precipitation data for period (1980–2022) and (2031–2100). This ensures that the assessment considers changing climate patterns. Historical precipitation values ranged from 270 to 490 mm, while future projections indicate a decrease, with values varying from 255 to 390 mm. This suggests a potential reduction in available water resources due to climate change. The runoff for historical rainfall values ranged from 190 mm (poor) to 490 mm (very good). In the future projections, runoff values vary from 180 mm (very poor) to 390 mm (good). This analysis highlights the potential impact of reduced precipitation on water availability. There is a strong correlation between rainfall and runoff, with values of 95% for historical data and 98.83% for future projections. This indicates that changes in precipitation directly affect water runoff. The study incorporates several criteria in the model, including soil texture, historical and future rainfall data, land use/cover, slope, and drainage density. These criteria were selected based on the nature of the study region and dataset availability. The suitability zones are classified into four categories for both historical potential and future projections of RWH zones: very high suitability, covering approximately 8.2%. High suitability, encompassing around 22.6%. Moderate suitability, constituting about 37.4%. Low suitability, accounting for 31.8% of the study region. For the potential zones of RWH in the future projection, the distribution is as follows: very high suitability, approximately 6.1%. High suitability, around 18.3%. Moderate suitability, roughly 31.2%. Low suitability, making up about 44.4% of the study region. The research's findings have significant implications for sustainable water resource management in the northern region of Iraq. As climate change exacerbates water scarcity, identifying suitable RWH locations becomes crucial for ensuring water availability. This methodology, incorporating advanced technology and data sources, provides a valuable tool for addressing these challenges and enhancing the future of water management to face of climate change. However, more investigations and studies need to be conducted in near future in the study region. [ABSTRACT FROM AUTHOR]

Urban transformations change land use, permeability, and morphology of the areas involved in the evolution process; this, consequently, modifies the impact produced by the precipitation phenomena and increases the risk of flooding or uncontrolled runoff in different areas.The proposed watershed hydrologic approach enables us to consider the morphology of the territory together with the transformations implemented by human activities, and this allows us to evaluate the effects of each area on neighboring areas, emphasizes the hydrological roles of upper, intermediate, and lower parts, and reveals urban and non-urban connections. This elucidates hydromorphic complexities in urban transformations and assesses climate change adaptability. The suggested methodology has been implemented in the urban district of "Sasso Caveoso" within the city of Matera. This application facilitates a quantitative synthesis of the contextual response, allowing for an analysis across various scenarios and offering decision-support tools of practical utility. [ABSTRACT FROM AUTHOR]

Environment change alters hydrological rhythms and affects utilization of water resources for a river basin. The Lancang-Mekong River is a transboundary river in Southeast Asia originated in the Southwestern China. It is of significance to scientifically quantifying runoff change attribution of the Langcang River for supporting water benefits share between countries which the Lancang-Mekong River runs across. Based on the recorded runoff data series from 1961 to 2020 gauged at the Yunjinghong hydrometric station on the Langcang River, the variability characteristics of runoff series and the impact of climate change and human activities on runoff change as well as its seasonal distribution were investigated by using statistical methods and hydrological simulation methods. The results show that: ① The measured annual runoff at Yunjinghong station showed a significant decrease trend from 1961 to 2020, with an increase in runoff during the period from January to May and a decrease in runoff in period from June to December. The abrupt change of the measured annual runoff series was occurred in 2008. ② The RCCC-WBM model performs well for monthly natural discharge simulation in the baseline period of 1961-2008 with relative error of less than 1. 0%. The simulated natural annual runoff in the human-disturbance period of 2009-2020 is about 371. 8 mm, which is 6. 8% less than that in baseline period. The reduction is induced by climate change. ③ Reservoirs construction and operation is the utmost human activity in the Langcang River. Human activities are the main reason of runoff decrease in the reservoir impoundment period of 2009-2013, while climate change is principal driver of runoff reduction in in the reservoir operation period of 2014-2020, which contribution is about 61. 7% of total runoff reduction. ④ The reservoirs operation makes runoff decrease by 44. 3% in flood season from June to November and increase by 134. 3% in dry season from December to May for period of 2014-2020. The regulation function of reservoirs on the Langcang River for decreasing flood discharge and increasing low flow has been guaranteeing security of water supply and flood control for the middle and lower reaches of the Mekong River. [ABSTRACT FROM AUTHOR]

This study aims to estimate the surface runoff and examine the impact of climate change on water resources in the Upper Kabul River Basin (UKRB). A hydrological model was developed using the Soil and Water Assessment Tool (SWAT) from 2009 to 2019. The monthly calibration was conducted on streamflow in six stations for the period from 2010 to 2016, and the results were validated from 2017 to 2018 based on available observed data. The hydrological sensitivity parameters were further prioritized using SWAT-CUP. The uncertainty of the model was analyzed by the 95% Prediction Uncertainty (95PPU). Future projections were analyzed for the 2040s (2030–2049) and 2090s (2080–2099) compared to the baseline period (1986–2005) under two representation concentration pathways (RCP4.5, RCP8.5). Four Regional Climate Models (RCMs) were bias-corrected using the linear scaling bias correction method. The modeling results exhibited a very reasonable fit between the estimated and observed runoff in different stations, with NS values ranging from 0.54 to 0.91 in the calibration period. The future mean annual surface runoff exhibited an increase in the 2040s and 2090s compared to the baseline under both RCPs of 4.5 and 8.5 due to an increase in annual precipitation. The annual precipitation is projected to increase by 5% in the 2040s, 1% in the 2090s under RCP4.5, and by 9% in the 2040s and 2% in the 2090s under RCP8.5. The future temperature is also projected to increase and consequently lead to earlier snowmelt, resulting in a shift in the seasonal runoff peak to earlier months in the UKRB. However, the shifts in the timing of runoff could lead to significant impacts on water availability and exacerbate the water stress in this region, decreasing in summer runoff and increasing in the winter and spring runoffs. The future annual evapotranspiration is projected to increase under both scenarios; however, decreases in annual snowfall, snowmelt, sublimation, and groundwater recharge are predicted in the UKRB. [ABSTRACT FROM AUTHOR]

Climate change is expected to significantly affect countries in Southern Europe and the Mediterranean Basin, causing higher-than-average temperature increases, considerable reductions in rainfall and water runoff, and extreme events such as heatwaves. These pose severe threats to local energy systems, requiring a reliable and quantitative risk analysis. A methodological approach is thus proposed which covers both energy supply and demand, utilizing the latest climate projections under different greenhouse gas emissions scenarios and an appropriate scale for each energy form. For energy supply technologies, risks are assessed through statistical regression models and/or mathematical equations correlating climatic parameters with energy productivity. To analyze climate risks for energy demand, bottom–up models were developed, integrating both behavioral and policy aspects which are often considered in a very limited way. The results show that climate change will mainly affect electricity generation from hydroelectric and thermal power plants, with variations depending on the plants' locations and uncertainties associated with precipitation and runoff changes. The climate risks for solar and wind energy were found to be low. Energy consumption will also be affected, but the range of risks depends on the ambition and the effectiveness of measures for upgrading the thermal performance of buildings and the intensity of climate change. [ABSTRACT FROM AUTHOR]

This study presents a framework to attribute river runoff variations to the combined effects of reservoir operations, land surface changes, and climate variability. We delineated the data into natural and impacted periods. For the natural period, an integrated Long Short-Term Memory and Random Forest model was developed to accurately simulate both mean and extreme runoff values, outperforming existing models. This model was then used to estimate runoff unaffected by human activities in the impacted period. Our findings indicate stable annual and wet season mean runoff, with a decrease in wet season maximums and an increase in dry season means, while extreme values remained largely unchanged. A Budyko framework incorporating reconstructed runoff revealed that rainfall and land surface changes are the predominant factors influencing runoff variations in wet and dry seasons, respectively, and land surface impacts become more pronounced during the impacted period for both seasons. Human activities dominate dry season runoff variation (93.9%), with climate change at 6.1%, while in the wet season, the split is 64.5% to 35.5%. Climate change and human activities have spontaneously led to reduced runoff during the wet season and increased runoff during the dry season. Only reservoir regulation is found to be linked to human-induced runoff changes, while the effects of land surface changes remain ambiguous. These insights underscore the growing influence of anthropogenic factors on hydrological extremes and quantify the role of reservoirs within the impacts of human activities on runoff. [ABSTRACT FROM AUTHOR]

Recent climatic changes and anthropogenic activities considerably affect regional water resources, particularly in water‐scarce regions. The present study, therefore, aims to understand the changes in monsoon rainfall, potential evapotranspiration (PET), surface runoff, dam storage and groundwater in the drought‐prone region of Maharashtra. The analyses of trend and step‐change were carried out using standard parametric tests. The results were verified with the application of non‐parametric statistical techniques. Notably, monsoon rainfall and runoff were observed to be declining. Exceptionally, the Yerala Basin witnessed significant increase in rainfall along with heavy rainfall events. Contradictorily, Agrani and Man Basins registered a notable decline in rainfall and runoff. As vulnerability to hydrological disasters is high, these basins should be carefully monitored. Although surface water harvesting brought a positive change in post‐monsoon groundwater level, it was the main reason for a decline in runoff volume at downstream reaches, which led to intra‐basin water disparity. The study area witnessed significant increase in groundwater extraction. Unfortunately, the misuse of government‐subsidized schemes exacerbates groundwater exploitation and stockpiling of water resources. Moreover, the increasing rate of PET augments hydrological losses and amplifies water distress. Interestingly, almost all the hydrological changes were notably experienced during the post‐2000 period. To cope with present and future water scarcity problems, it is therefore necessary to restrict irrational use and allocation of available limited water resources. The findings that emerge from this investigation may help to formulate judicious water policies and plans which could be implemented by the government, agronomists, water resource managers and farmers. [ABSTRACT FROM AUTHOR]

Land use changes are one of the main factors in the amount of surface runoff changes in watersheds. Therefore, it is necessary to investigate it to reduce the damages (human and financial) caused by floods and to modify watershed management. The watershed of Nahre Azam is located in the north of Shiraz city and a lot of loss of life and money to the residents of Shiraz due to floods has occurred in previous years. The present research was conducted to investigate the relationship between land use change and runoff in the Nahre Azam watershed in Shiraz using the SWAT model in the period of 2004-2020. The model was calibrated using data from 2004 to 2014 and validated for 2015 to 2020. These images were classified into 6 main land uses using the supervised classification method after performing necessary preprocessing, and a land use map was prepared for 2040 using the Markov chain method. Then, the effect of the land use change in 2003 and 2040 on the amount of simulated runoff was evaluated with the recalibrated model. The calibration results of Nahre Azam watershed for the values of statistical parameters in the calibration step for the coefficient of determination, P-Facor and R-Facor are 0.77, 0.72, and 2.43, respectively, and for the validation step we obtained 0.69, 0.65, and 2.3 respectively. The analysis of the land use map showed that the main land use change in the region related to the conversion of pastures to agricultural land and urban land, which caused a decrease in pastures. Also, the results of the model simulation using the land use maps of 2003 and 2040 indicated that the amount of runoff decreased. The results revealed that if all the uncertainties are minimized, the calibrated SWAT model can produce acceptable hydrological simulation results for the user, which is useful for water resource and environmental managers and politicians as well as city managers of Shiraz. [ABSTRACT FROM AUTHOR]

This study evaluated the potential effects of long-term land use and climate change on the quality of surface runoff and the health risks associated with it. The land use change projection 2030 was derived from the main changes in land use from 2009 to 2019, and rainfall data was obtained from the Long Ashton Research Station Weather Generator (LARS-WG) model. The Long-Term Hydrological Impact Assessment (L-THIA) model was then utilized to calculate the rate of runoff heavy metal (HM) pollutant loading from the urban catchment. It was found that areas with heavy development posed a significantly greater public health risk associated with runoff, with higher risks observed in high-development and traffic areas compared to industrial, residential, and commercial areas. Additionally, exposure to Lead (Pb), Mercury (Hg), and Arsenic (As) was found to contribute significantly to overall non-carcinogenic health risks for possible consumers of runoff. Carcinogenic risk values of As, Cadmium (Cd), and Pb were also observed to increase, particularly in high-development and traffic areas, by 2030. This investigation offers important insight into the health risks posed by metals present in surface runoff in urban catchment areas under different land use and climate change scenarios. [Display omitted] • Long-Term Hydrologic Impact Assessment was used to calculate runoff pollutant. • Long Ashton Research Station and Land-use Change Model predicted rainfall and land. • Human health impacts of runoff from different land uses were assessed. • Lead had the highest ingestion exposure, followed by Mercury, Arsenic and Cadmium. • Arsenic emerged as primary contributor to carcinogenic health risks from runoff. [ABSTRACT FROM AUTHOR]

• Four types of models quantified anthropogenic changes and climate variability. • SEM for the attribution analysis of runoff changes was constructed. • SEM quantifies runoff change attribution better than traditional models. • Human activities are the dominant factor of runoff change in Shiyang River Basin. • The contribution rate of water withdrawal to runoff reduction was 50 % during 1961–2020. Recently, with the increasing global warming and intensity of human activities, runoff has significantly decreased. This has had a severe impact on water resources development and utilization, as well as ecological and environmental construction. To understand hydrological cycles and promote sustainable utilization of water resources, it is crucial to conduct attribution analysis of runoff changes. This study employed traditional models, including empirical statistics, elasticity coefficients, hydrological modeling, and introduced a simple and efficient model – structural equation modeling (SEM) – to quantify the impact of various factors on runoff changes. The findings revealed a notable decreasing trend in natural runoff in the Shiyang River from 1960 to 2020, while precipitation, snowmelt, potential evapotranspiration (ET0), and temperature exhibited increasing trends. The integrated the results from multiple models highlighted that human activities emerged as the primary driver influencing runoff changes. From 1972 to 2020, the factors contributing to runoff reduction were ranked in the order: water withdrawal (50 %) > LUCC (20 %) > ET0 (16 %) > temperature (8 %). Factors contributing to runoff increase were ranked: precipitation = water diversion project (20 %) > snowmelt (6 %). The impact of reservoir regulation on runoff initially exhibited a negative correlation (impact rate of 10 %) and later turned positive (impact rate of 6 %). The SEM model, employed for runoff change attribution analysis, demonstrated a good fit and was consistent with results obtained from the SWAT model. Compared to traditional methods, SEM not only allowed for quantitative analysis of the factors' impact on runoff but also explored the interactions between factors and the direct and indirect effects of factors on runoff. This study introduces innovative methods for the attribution analysis of runoff changes, offering valuable insights crucial for the ecological sustainable development of water resources in arid and semi-arid regions. [ABSTRACT FROM AUTHOR]

• Nationwide streamflow projections for Australia informed by CMIP5 and CMIP6. • Vast majority of CMIP5 and CMIP6 GCMs project less winter rainfall across Australia. • Lower winter rainfall translates to a significant reduction in annual runoff. • Modelled median projection of runoff shows a 50% reduction in far southwest Australia. • Modelled median projection of runoff shows a 20% reduction in far southeast Australia. Projections of streamflow under future climate are essential for developing adaptation strategies in the water and related sectors. This paper presents nationwide streamflow projections for Australia informed by climate change signals in CMIP6 GCMs and compares the projections with those from CMIP5 GCMs. The modelled future runoff projections driven by CMIP5 and CMIP6 GCMs are relatively similar for far southern Australia. The median projection is a 50% reduction in mean annual runoff in far southwest Australia and 20% reduction in far southeast Australia by 2046–2075 relative to 1976–2015 under the high SSP5-8.5/RCP8.5 global warming scenario. The vast majority of CMIP5 and CMIP6 GCMs project less winter rainfall across Australia. As most of the runoff in far southern Australia occurs in winter and spring, the lower winter rainfall translates to a significant reduction in annual runoff. It is therefore prudent to plan and manage for a reduction in future water resources, particularly in the densely populated and important agricultural regions in southeast Australia. There is less agreement between GCMs in the summer rainfall projection, with the CMIP6 GCMs generally projecting a wetter future (or smaller decrease in rainfall) than the CMIP5 GCMs. The modelled median projection for mean annual runoff is a 10% reduction in the south-east coast, 5% reduction in the north-east coast and little change in northern Australia. More GCMs project an increase rather than a decrease in the interannual variability of rainfall, and this would further amplify multi-year hydrological droughts. [ABSTRACT FROM AUTHOR]

• Analysis of 17 years of stream hydrochemistry for an upland catchment in Scotland. • Low flows dominated by weathering products, high flows by soil/atmospheric solutes. • Determinand concentrations were typically correlated with stream water age. • 2018 & 2022 droughts changed the stream to more chemodynamic behaviour. • Associated ecosystem services likely to be impacted with ongoing climate changes. We used data from 17 years of routine stream flow sampling to characterise hydrochemical dynamics in the Girnock Burn, an internationally important long-term catchment monitoring site. We combined hydrochemical time series analysis with hydrological modelling to understand short- and long-term dynamics in relation to dominant runoff processes. Isotopic tracer data employed within the model enabled flux tracking of water as it transited the catchment, facilitating water age estimates. The stream drains an upland 31 km2 catchment with complex topography and variable geology, which influences soil distributions; peaty soils dominate valley bottoms which receive drainage from more permeable podzolic soils on steeper slopes. Short-term hydrochemical dynamics largely reflect the relative dominance of hydrological sources: summer low flows are dominated by alkaline groundwater high in weathering products (Ca2+, Mg2+, SiO 2) whilst high flows generated by overland flow from peaty soils are more acidic, DOC enriched, and dominated by atmospheric solutes (Na+, Cl-, SO 4 2-). Baseflows are dominated by older groundwater (>∼3years) in contrast to storm runoff dominated by younger (<∼0.5 years), near-surface, waters. Usual seasonal distributions of stream flows, with high flows in winter and summer low flows, result in strong seasonality in most solutes. However, coupled effects of hydroclimatic variability and catchment heterogeneity dictates marked scatter in flow-concentration relationships for most determinands. A long-term decreasing trend was evident for SO 4 2-concentrations, reflecting continuing effects of reductions in atmospheric deposition of pollutants from coal burning. Reductions in large storm event frequency post-2016 and protracted periods of low flows in the droughts of 2018 and 2022 have resulted in the catchment becoming dominated by low flows, derived from older groundwater with more alkaline chemistry for longer periods. Changing climatic conditions and stream flow responses seem likely to continue to cause changes in stream water quality and associated ecosystem services of the Girnock Burn and similar upland catchments. [ABSTRACT FROM AUTHOR]

[Display omitted] • Climate change affects the stormwater quality due to variation in climatic parameters. • Scientific interventions with strong database should be geared up in developing nations. • Emerging pollutants needs more attention by undertaking systematic research. • Groundwater recharge with stormwater may raise groundwater level and reduce pollution. The problem of water logging and deteriorating water quality of surface water bodies has been witnessed in and around the urban centers owing to rapid population growth, urbanization, industrialization and climate variability. The stormwater runoff management is the need of the hour, and with increasing public and political awareness and rapid economic growth, it is receiving due attention. In the climate-change scenario, it needs to be addressed with scientific interventions as changes in pattern of precipitation affects the runoff volume and movement of pollutants including nutrients. This paper discussed and critically reviewed the stormwater runoff characterization, modelling, relationship between runoff and water quality, first flush phenomena, runoff treatment in changing climate scenarios. Researchers have used regional climate models (RCMs) to project future precipitation and then incorporated in various hydrologic and hydraulic models such as SWMM, SWAT, HSPF, SUSTAIN and MUSIC etc to study the impact of climate change and its adaptation. The flooding and water quality problem can be combatted with adopting green infrastructure practices. Many works on stormwater management have been carried out in developed countries, but efforts need to be geared up in the developing countries, particularly for runoff characterization and effective management. Emerging pollutants need to be paid more attention by undertaking systematic research. Future studies should include measurements and quantification of ecosystem services and integration of stormwater management into environmental policy. This review suggests intriguing future research avenues at the nexus of stormwater management and ecological services. [ABSTRACT FROM AUTHOR]

About 70% of water withdrawals in the Yellow River Basin (YRB) are used for irrigation, and deeply explanation of the effects of climate change on runoff in the YRB provides a guarantee for agricultural production. Analysis and prediction of climate change were implemented according to the meteorological and hydrological data from 1967 to 2016, and the responses of the catchments of the six hydrological stations on the Yellow River to the different combinations of precipitation and temperature change conditions were explored adopting the Budyko framework, then the results based on the climate scenario simulation and climate elasticity were compared. Our results revealed that the precipitation in the YRB indicated a downward trend (p>0.05) while the temperature showed a upward trend (p<0.01), both which were predicted to climb in the future; the sensitivities of upstream, midstream and downstream runoff to climate change were gradually increased and the catchment characteristics acted a decisive role in determining sensitivities rather than climatic factors, generally, the runoff of different catchments increased by 17.1–30.2% with only 10% increase in precipitation and decreased by 4.2%-12.4% with only 1℃ increase in temperature; compared to the climate elasticity, the climate scenario simulation tend to be more accurate as it captured the changes in sensitivities when climate change. The results of this study provide a foundation for the regional development and utilization of water resources in the YRB under the influences of climate change. • Seasonal climate change in the Yellow River Basin was explored in spatial. • Budyko framework was used to assess the runoff responses to climate change. • Runoff responses to climate change were nonlinear. • Middle and lower reaches were more sensitive to climate change. [ABSTRACT FROM AUTHOR]

• Snowmelt Runoff Model well simulates monthly streamflow in a cold-arid headwater catchment. • Meltwater runoff and rainfall runoff contribute to 42% and 31% of streamflow, respectively. • Total runoff and rainfall runoff are respectively controlled by snow cover and precipitation. • Meltwater runoff is jointly controlled by precipitation, ET, and NDVI. Streamflow is increasingly vulnerable to climate change over cold-arid regions. To understand the underlying mechanisms of streamflow changes, it is essential to distinguish streamflow components and identify their drivers due to various meltwater and rainfall runoff processes. This study combines the conceptual temperature-index Snowmelt Runoff Model (SRM) and wavelet coherence analysis to unravel the impacts of environmental factors on streamflow and its components over the semiarid-and-cold headwater catchment of the Manas River in Northwest China during 2001–2015. Our results show that SRM reproduces monthly observed streamflow with determination coefficients of > 0.91, Nash-Sutcliffe Efficiency of > 0.82, and absolute relative error of < 5 % during SRM calibration (2001–2007) and validation (2008–2015) periods. The meltwater runoff and rainfall runoff contribute to 42 % and 31 % of the total streamflow, respectively. The wavelet-based spectral analysis, partial wavelet coherency analysis, and multiple-wavelet coherence together demonstrate that total streamflow (rainfall runoff) is predominantly influenced by snow cover area (precipitation) at a scale of 32 (4–16) months. But the meltwater runoff is simultaneously controlled by precipitation, potential evapotranspiration, and normalized difference vegetation index on scales of 4–16 and > 32 months. Our study provides technical support for streamflow partitioning and controlling factors identification, and has implication to sustainable water resources management in cold and arid regions. [ABSTRACT FROM AUTHOR]

Quantitative fertilization and straw mulch play a pivotal role in regulating runoff nitrate- (NO 3 -N) and ammonium‑nitrogen (NH 4 -N) losses from sloping croplands. However, the directions and magnitudes of these effects remain largely elusive at the plot scale. This study investigated the effects of decreased and/or increased fertilizer combined with straw mulch on NO 3 -N and NH 4 -N runoff losses under different rainfall categories. Conventional fertilizer (CK), decreased fertilizer (DFT) and its combination with straw mulch (DFT + SMT), increased fertilizer (IFT) and its combination with straw mulch (IFT + SMT) were assigned at four sites with runoff plots in the purple soil sloping croplands, southwest China. Runoff depth, the concentrations and losses of total nitrogen (TN), NO 3 -N and NH 4 -N as well as NO 3 -N/TN and NO 3 -N/NH 4 -N molar ratios in runoff were determined in the wet season in 2019. Results showed that runoff depth significantly increased as elevated rainfall amount in the plots with straw mulch. TN concentration was significantly different among different rainfall categories for the treatments of IFT and IFT + SMT, showing 9.12–132.91% and 2.56–102.33% higher in the heavy rain than that in other rainfall events, respectively. Higher NO 3 -N and NH 4 -N concentrations were found in the treatment of IFT in the high rainfall amount. The changes in TN, NO 3 -N and NH 4 -N losses had trends similar to runoff depth, indicating that the N runoff loss was dominantly affected by the runoff rather than the concentration. NO 3 -N/TN and NO 3 -N/NH 4 -N were markedly higher in the light rain than that in other rainfall events, but were not differed by the varied applications of fertilizers and their combinations with straw mulch. The results suggest that NO 3 -N and NH 4 -N runoff losses are mostly affected by the rainfall rather than the quantitative fertilization and straw mulch in a short-term experimental period. Our results have great significance for identifying the effective measures to control the nitrogen runoff loss in sloping croplands. [Display omitted] • Runoff depth increases as the increased rainfall amount in mulched plots. • Increased fertilizer and high rainfall events lead to high runoff N concentration. • TN, NO 3 -N and NH 4 -N losses are more sensitive to runoff than their concentrations. • NO 3 -N loss accounts for most TN lost relative to NH 4 -N in the light rain events. • Fertilization and straw mulch alter the links between runoff and N concentration. [ABSTRACT FROM AUTHOR]

Water erosion, a notorious major threat to food security and ecosystem sustainability, is strongly conditioned by spatial and temporal scale effects. This paper systematically reviews the scale issues in runoff and sediment delivery (SIRSD) as a research field by integrating the traditional review approach and bibliometric analysis. This review summarises SIRSD's roots and the scale effect on runoff and sediment delivery. Then, we provide quantitative insights into the SIRSD domain's development history, thematic structure, geographic distribution, international cooperation, and methodologies. Findings show that: i) SIRSD arises from the gap between the non-linearity of runoff and sediment delivery across scales and our ability to measure it. Point-based and short-term measurements cannot capture the non-linearities from the spatio-temporal heterogeneities and cross-scale interactions of factors or processes. ii) Previous literature provides evidence that the spatial scaling of specific runoff (r), soil erosion (SE), sediment yield (SSY), or sediment delivery ratio (SDR) with drainage area (A) or slope length (L) exhibits contrasting patterns due to distinct mechanisms. Infiltration-excess and saturation-excess processes account for inverse and positive r - A relations, respectively. Interrill-erosion and rill-erosion cause inverse and positive SE-L relations. Hillslope-erosion and channel/bank-erosion explain inverse and positive SSY-A relations. Downstream increasing deposition and additional sediment inputs drive inverse and positive SDR-A relations. These scaling relationships can be nonlinear or complex due to spatial heterogeneities in land use, vegetation, topography, climate, lithology, and soil characteristics. Hence, applying an empirical scaling equation developed from the region with distinct environmental contexts is not recommended. Furthermore, the existing scaling patterns or equations may require updating given global climate and land use change. iii) SIRSD is a complex and multidisciplinary issue investigated by scientists from 93 countries since 1928. International research has substantially facilitated the understanding of SIRSD; still, more collaboration should focus on less-developed countries with high soil and water loss risks and urgent conservation needs, such as those in Africa and South America under cropland expansion. iv) Scale mismatch and scale break have discredited large-scale erosion and sediment assessments. Incorporating gully and bank erosion into modelling, extending the scale range of the L factor, and expanding the sediment scaling scope from watershed to slope may make a difference. Therefore, more research with nested design incorporating multiple scales is necessary for cross-scale analysis and scalable modelling. Addressing global climate change requires improving real-time urban flood forecasting and integrating downscaled climate models with hydrology, erosion, and sediment transport models. • A bibliometric review of the global SIRSD research for the first time. • SIRSD is rooted in the gap between natural nonlinearity and our measuring ability. • Scaling of specific runoff, erosion, sediment yield, and SDR has diverse patterns. • Scale mismatch and scale break discredit large-scale modelling and assessments. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ten multi-model combination methods (MMCMs) are created from 29 models in 50 basins. • MMCMs improve some performance indicators, especially the Granger-Ramanathan method. • MMCMs do not improve performance in reproducing distributions of hydrological signatures. • Application with series of targeted signatures does not improve MMCM performance. • MMCM performance is improved by selecting more robust candidate models for ensembles. Multi-model combination (averaging) methods (MMCMs) are used to improve the accuracy of hydrological (precipitation-runoff) outputs in simulation or forecasting/prediction modes. In this paper, we examined if the application of MMCMs can improve model performance in reproducing distributions of hydrological signatures, such as annual maxima or minima of varying durations. To this end, ten MMCMs were applied to 29 bucket-type models to simulate runoff in 50 high-latitude catchments. The MMCMs were evaluated by comparing the resulting simulated flows to the reference (i.e., best-performing) individual model, considering various commonly used performance indicators, as well as model performance in reproducing the distributions of signatures. Additionally, we analysed whether (1) the selection of the candidate models, or (2) targeting specific signatures, such as annual maxima or minima, can improve performance of the model combinations. The results suggest that the application of MMCMs can improve accuracy of runoff simulations in terms of traditional performance indicators, but fails to improve performance in reproducing the distributions of signatures. Neither excluding poor-performing models nor applying the MMCMs with the targeted signatures, improves this aspect of model performance. These findings clearly reveal the need for further research aiming at enhancing model performance in reproducing the distributions of hydrological signatures, which is essential for climate-change impact studies. [ABSTRACT FROM AUTHOR]

• Understanding future change with the aspects of runoff and hydroclimatic conditions. • Source region of Yangtze River will be warmer and wetter in the future. • Runoff will increase by around 15% with highly spatial heterogeneity. Exploring the future hydroclimatic conditions of source region of Yangtze River (SRYaR), an alpine affected by climate change significantly, is essential for basin water resources management and development ss global climate change intensifies and the process of climate warming and humidification in Northwest China. This study proposed a practical framework for assessing water resource response to the context of climate changes in alpine catchments from the respective of both runoff and hydroclimatic conditions. Utilizing Grid-RCCC-WBM driven by corrected climatic forcing from the global climate models, this study estimate the prospective overall warmer and wetter pattern in the source region of Yangtze River. The key results indicated that: (1) Under all future scenarios, both temperature and precipitation within the catchment exhibit a significant upward trend. Projections from multi-model ensembles (MME) suggest that during the mid-term period (2041–2060, MT), temperatures are expected to rise by [0.74 °C, 3.08 °C] compared to the baseline period (1995–2014), with precipitation changes ranging from [4.8%, 21.4%]. (2) Future runoff within the catchment exhibits a consistent increase, with a linear trend rate of 1.1 mm/decade. runoff changes in MT compared to the baseline period vary from [−5.1%, 33.7%]. Runoff decreases in the northern part of the catchment, while notable increases occur in the southeastern and western regions. (3) In the future, the ratio of catchment evaporation capacity to precipitation decreases in comparison to the baseline period with an augmentation in soil moisture, enhancing its capacity for water retention and reducing the conversion of precipitation to evaporation, resulting a wetting trend of the catchment. (4) The future snowpack in the catchment continues to decrease, with a significant reduction in both the proportion of snowfall relative to total precipitation and the proportion of snowmelt runoff relative to total runoff, the risk of water resources crisis in the watershed is escalating. [ABSTRACT FROM AUTHOR]

The Island of Rhodes, located in the Eastern Mediterranean Sea, is affected by an active convergent plate boundary. In this context, marine sediments of Plio-Pleistocene age have been uplifted and are outcropping along the eastern coast of Rhodes. These archives provide an excellent opportunity to unravel the hydrological and climatic changes of the region during the late Pliocene. Our results provide new evidence for a more humid climate and an increased precipitation on the island during times of Northern Hemisphere summer insolation maxima and related sapropel formation in the Mediterranean deep sea. The periodic occurrence of eutrophic conditions at the shelf and upper slope off Rhodes is indicated by the recurrent dominance of eutrophic indicator species (of the genera Bolivina , Eubuliminella and Rectuvigerina), simultaneously with a decline in diversity and oligotrophic indicator species. These conditions resulted from higher primary productivity, triggered by local effects, such as enhanced precipitation and river run-off, which consequently favors the appearance of eutrophic taxa. The ∆δ13C records of the epibenthic foraminifera Cibicidoides pseudoungerianus and the shallow infaunal species Uvigerina peregrina indicate a slight productivity decrease towards younger times. • We investigated a Pliocene sediment section of the Lindos Bay Formation on Rhodes. • We found a recurrent and periodic dominance of eutrophic benthic foraminifera. • A periodic increase in nutrient supply and primary production is indicated. • The changes are likely triggered by enhanced local precipitation and river run-off. • The distinct periodicity suggests a relation to precession-induced climate changes. [ABSTRACT FROM AUTHOR]

The growing incidence of urban flood disasters poses a major challenge to urban sustainability in China. Previous studies have reported that climate change and urbanization exacerbate urban flood risk in some major cities of China. However, few assessments have quantified the contributions of these two factors to urban flood changes in recent decades at the nationwide scale. Here, surface runoff caused by precipitation extremes was used as the urban flood hazard to evaluate the impacts of climate change and urbanization in China's 293 major cities. This study assessed the contributions of these drivers to urban flood hazard changes and identified the hotspot cities with increased trends under both factors during the past four decades (1980–2019). The results showed that approximately 70% of the cities analyzed have seen an increase of urban flood hazard in the latest decade. Urbanization made a positive contribution to increased urban flood hazards in more than 90% of the cities. The contribution direction of climate change showed significant variations across China. Overall, the absolute contribution rate of climate change far outweighed that of urbanization. In half of the cities (mainly distributed in eastern China), both climate change and urbanization led to increased urban flood hazard over the past decade. Among them, 33 cities have suffered a consecutive increase in urban flood hazard driven by both factors. [Display omitted] • A nationwide study on the impacts of climate change and urbanization on flood hazard. • The absolute contribution rate of climate change outweighed that of urbanization. • Urbanization promoted hazards, whereas the impact of climate change varied. • A consecutive increase in hazards driven by both factors was found in 11% of cities. [ABSTRACT FROM AUTHOR]

[Display omitted] • The impact of the uncertainties on the attribution of runoff changes was quantified. • A method was improved to analyze non-monotonic trends in wet, normal, and dry years. • The breakpoint was the main uncertainty source for runoff change attribution. Quantifying the contributions of climate change (CC) and human activities (HAs), which are important drivers of the hydrological cycle, to runoff change by CC and HAs under uncertainty is crucial for water resource management, especially in karst basins. In this study, we adopted the climate elasticity method to assess the impacts of CC and HAs on runoff change in Chengbi River Basin during 1970–2019. Furthermore, the main sources of uncertainty (Budyko formula, breakpoint, and underlying surface characteristics) in runoff change attribution were quantified via analysis of variance method. The improved innovative trend analysis based on the Fisher optimal partition method was first used for the non-monotonic trend analysis. The groundwater storage change obtained through the abcd model was used to obtain the effective precipitation for the Budyko hypothesis. The results indicated that the runoff and precipitation exhibited an increasing trend in wet and normal years, whereas they exhibited a decreasing trend in dry years after 1995 compared with 1970–1994. Furthermore, potential evapotranspiration exhibited no significant trend. The climate elasticity method based on the Budyko formula was effective, and the Choudhury-Yang formula was found to be more suitable than the Fu formula for the basin. The impact of water storage change was not negligible, and water storage change needs to be considered in runoff change attribution. Effective precipitation played a dominant role in runoff change, with a mean contribution rate of 87.85%, whereas the mean contribution rates of potential evapotranspiration and underlying surface characteristics were 22.55% and −10.40%, respectively. The breakpoint was the main source of uncertainties in runoff change attribution and demonstrated the highest contribution to the uncertainties (85.93%). The simultaneous breakpoint of the runoff coefficient was suggested as a reference to determine the confident breakpoint of runoff. The findings of this study are expected to provide a scientific basis for water resource management and contribute to the development of the climate elasticity method. [ABSTRACT FROM AUTHOR]

As non-point source pollution has emerged as a significant global and regional concern, climate change (CC), land use/cover transformation (LUCT), and management practices (MP) play vital roles in addressing nutrient pollution. However, current studies lack comprehensive quantification and consistent conclusions on the response to these factors, especially for management practices. To quantify and elucidate the impact of representative environmental factors on rapidly urbanizing regions, this study focused on the Shenzhen River, which serves as the most typical urbanizing watershed. Using a process-based distributed hydrological model with a factor-controlled simulation method, we identified significant differences in nutrient concentrations and the impacts of climate variability, land use/cover changes, and anthropogenic interventions from 2003 to 2020. Moreover, effective measures greatly improved water quality in the Shenzhen River during study period, as evident from trend and cluster analysis. However, ecological water supplements implemented since 2016 have led to a slight reduction in simulated runoff performance, and CC may amplify the synergistic effects of precipitation and temperature on the river system. While the implemented practices have been effective in reducing total nitrogen (TN) and total phosphorus (TP) loads, strong TN pollution control is still needed in rapidly urbanizing areas due to the results of land use/cover type changes. Our findings emphasize the intricate interplay among CC, LUCT, and MP in shaping water quality and hydrological processes in rapidly urbanizing watersheds, and clarify the independent effects of these factors on nutrients. This study contributes to a better understanding of the complex interactions between multiple factors in watersheds and provides guidance for sustainable watershed management. [Display omitted] • Independent effects of climate, land use/cover, and management were clarified. • Urbanization increased nutrient loads, especially total nitrogen. • Vegetative filter strips effectively reduced nutrient loads. [ABSTRACT FROM AUTHOR]

In China, sloping farmland accounts for one-third of its total farmland, supporting ~330 million mountain people's livelihoods. Despite its long history of using soil conservation measures for reducing soil loss on sloping farmland, no comprehensive evaluation has ever been performed on their effectiveness. In this study, we reviewed the soil conservation measures on sloping farmland in China from ~2500 years ago to the present and examined their effectiveness under current and projected climate change scenarios based on 6909 plot-scale observations. For the sloping farmland across China, the average soil loss rate is 14.47 Mg ha−1 yr−1, with a quarter of the observed values exceeding the maximum tolerable soil loss rate (10 Mg ha−1 yr−1). Soil conservation measures can reduce soil loss by ~80%, with the highest effectiveness for the combination of biological and engineering measures (reduced by ~86%), followed by biological measures (reduced by ~84%) and engineering measures (reduced by ~82%) separately. However, the effectiveness of soil conservation measures shows a significant decrease in the farmland with a slope above 15° or a single rainfall event >25 mm. The effectiveness of currently applied soil conservation measures was also compared under the Shared Socioeconomic Pathways (SSP) 1, 2, and 5 in 2050, and their effectiveness is expected to decrease on over 27% of the sloping farmland. In particular, under the SSP1 scenario, the effectiveness of soil conservation measures is projected to diminish in 70%, 54%, and 54% of sloping farmland in Northeast China, Sichuan Basin and surrounding regions, and Yunnan-Guizhou Plateau, respectively, due to changes in rainfall, highlighting the need to consider the impact of climate change when implementing soil conservation measures. Overall, this study provides useful information for scientific strategies on the construction, management, and maintenance of soil conservation measures to control soil loss on sloping farmland. [ABSTRACT FROM AUTHOR]

[Display omitted] • Framework to select appropriate methods for quantifying the contribution of human and climatic factors to runoff changes. • Comparative analysis of different approaches and methods of trend determination, homogeneity and breakpoints detection and quantification of the contribution of climatic and human factors. • Quantitative assessment of methods for determining the contribution of climate and human effects by validation against real evidence. Planning for reducing climate changes impacts and human interventions on river discharge relies on determining the extent to which factor has contributed to the observed changes. However, the diversity of approaches and methods proposed for assessing the impact of human and climatic factors, coupled with limitations in data and time, necessitate the careful selection of suitable methods. This study aims to address these challenges by providing a reliable framework to reduce uncertainty and select appropriate methods for quantifying the contribution of human and climatic factors to runoff changes using available information. To achieve this goal, a comparative analysis of different approaches and methods was conducted in three stages: trend determination, assessment of homogeneity and breakpoints of the meteorological and hydrological watershed, and quantification of the contribution of climatic and human factors, followed by validation against real evidence. Subsequently, these methods were employed to evaluate the contribution of climatic and human factors in the Boukan watershed, enabling a quantitative comparison of the results. The findings revealed an upward trend in temperature, a downward trend in precipitation and runoff, and significant changes in annual runoff in 1997. The results obtained from various methods exhibited a range of variations, attributing human factors to 35% to 85% of the reduction in runoff, while climatic factors accounted for 15% to 64%. In general, the box plot analysis indicated that human factors contributed approximately 57% on average, whereas climatic factors contributed around an average of 47%. Additionally, the examination of land use changes, resource utilization, and consumption patterns further supported the notion of human factors playing a more substantial role in the regional runoff reduction. Based on the available evidence, the double-mass curve methods, the water balance model, and the SWAT are identified as the most suitable approaches for this watershed, displaying a better fit to reality. Therefore, given the wide range of results, adopting multiple methods with different methodologies becomes crucial to reduce uncertainty. In this context, the proposed framework can serve as a valuable guide for selecting appropriate methods and decision-making processes. [ABSTRACT FROM AUTHOR]

One of the strategies to manage and reduce the problems caused by floods is to use different Low-Impact Development (LID) systems. Due to the existence of different types of LID systems, it is difficult to choose the best combination of them. The purpose of this research is to rank different LID systems and choose the best combination or arrangement of them under climate change using TODIM multi-criteria decision making method, which has not been done so far, in the northernmost of Tehran city (Iran), which also includes part of Tehran municipality districts 1 and 3 and it is adjacent to Tehran municipality district 6. Previously by the authors, surface runoff in the near future (2030–2047) and far future (2048–2065) under three scenarios of Representative Concentration Pathway (RCP2.6), (RCP4.5), and (RCP8.5) with the Storm Water Management Model (SWMM) was simulated (Dougaheh et al., 2023). Next the LID systems, including Vegetative Swale, bio-retention cell, infiltration trench and permeable pavement, are optimized with Multi-Objective Harris Hawks Optimization (MOHHO) algorithm. Then, using the Pareto Fronts obtained from the optimization algorithm, seven combinations of different LID systems were extracted as final alternatives. Then, the objective functions of the optimization algorithm, including the minimization of the volume of outflow runoff of the basin and the minimization of the cost of construction and maintenance of LID, are determined as problem criteria and weighted by the Entropy-Shannon method. The results show that the volume of urban runoff with the use of LID systems, in all future time periods under RCP2.6, RCP4.5, and RCP8.5 scenarios, will decrease by an average of 54% compared to the baseline time period, and the maximum percentage of volume reduction of the flood is related to the baseline period. In the future research, taking into account the qualitative parameters, the performance of the urban runoff collection system can be evaluated qualitatively in addition to quantitatively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Continued erosion is expected to occur in the sandy shores. • Equilibrium relationship between sediment supply and hydrodynamic forces has been severely disrupted. • Global climate change-induced sea level rise has a small effect on erosion in the short term. • Human activities are the critical effect on the erosion. • Reduced seaward sediment transport by coastal surface runoffs is a new factor. Most sandy shores (SSs) are currently experiencing erosion to various degrees due to the combined impact of increasing climate change and human activities. In order to reveal the evolution of the SSs in the Shandong Peninsula (SP), shoreline and elevation changing data are obtained from 29 SSs and results show that most (27 of 29) of the SSs exhibited erosion. The length of the SSs has decreased by 241.4 km from 2010 to 2020, and the average shoreline recession rate was found to be 1.0 m/a and the downward erosion rate was in the range of 0.05 to 0.10 m/a. Climate change-induced sea level rise has a smaller effect on the erosion in the short term and the construction of massive coastal engineering structures has become a major cause of local coastal erosion. The coastal erosion rate caused by river damming and sand mining in the early years has abated and reduced seaward sediment transport induced by the expansion of the built-up area has become a new factor of coastal erosion. In the past decade, the 672 km2 net increase in land area mainly originated from human activities, has occupied the original space for hydrodynamic energy dissipation, which has severely disrupted the balance between sediment supply and the hydrodynamic environment and the system then rebalance itself by eroding unprotected SSs. Therefore, with the increase in hydrodynamic forces caused by climate change and the scarcity of sediment supply caused by human activities, continued erosion is expected to occur in the SSs. [ABSTRACT FROM AUTHOR]