Hydrological Processes最新文献

This paper focuses on the hydro-climatic dimension of climate modelling, emphasising how methodological advances translate into implications for water resources and adaptive governance. Moving beyond a general review, it consolidates the link between climate science and hydrology by examining how improvements in model design, process representation and uncertainty management inform practical water strategies. The analysis highlights key developments within the Coupled Model Intercomparison Project (CMIP), including the integration of biogeochemical cycles, refined parameterisations and expanded socio-economic scenarios. Persistent challenges remain in simulating precipitation and cross-scale feedbacks, which directly constrain hydrological projections. Innovative approaches—such as high-resolution modelling, emulators and machine learning (ML)—are presented as promising tools to refine process fidelity and bridge global-to-local scales. By situating these technical frontiers within governance debates, the paper clarifies how uncertainty informs adaptive strategies and decision-making. This interdisciplinary perspective advances the understanding of hydrological processes within the climate system while charting actionable pathways for sustainable and resilient water management.

While there have been recent advancements in synthetic aperture radar (SAR)-based snow water equivalent (SWE) retrievals, obtaining accurate estimates of SWE requires knowledge of the amount of liquid water content (LWC) in the snowpack given its strong impact on radar velocity. Recent studies have utilised Sentinel-1 SAR to identify snowmelt runoff onset in complex, high-elevation terrain based on a seasonal minimum backscatter time-series; however, detailed investigations into the snowpack state before and after snowmelt runoff onset are lacking. In this study, we integrated repeat field measurements at five sites, SNOw TELemetry (SNOTEL) station data (n = 260) from across the Western United States, and paired Sentinel-1 SAR estimates of snowmelt runoff onset to (1) assess the snowpack state prior to and after Sentinel-1 SAR-derived runoff onset estimates, and (2) evaluate Sentinel-1 SAR estimates of runoff onset with SNOTEL-derived estimates of melt output via soil moisture ‘pulses’. We found that on the date of minimum backscatter, the snowpack was isothermal at three of the five field sites, and snow pit-measured LWC was increasing at all field sites relative to previous survey dates. SNOTEL soil moisture pulses preceded Sentinel-1 SAR estimates of snowmelt runoff onset by a median of 3 days (standard deviation = ±25.3 days) and post-dated peak SWE by a median of 3 days (standard deviation = ±18.2 days). Snow density and the number of positive degree days on soil moisture pulse date increased with latitude and longitude and decreased with elevation. Although satellite-based estimates of snowmelt runoff onset provide a promising approach for improving spaceborne retrievals of SWE, local climatological conditions exert significant influence on meltwater runoff onset signal clarity for both in situ and satellite-based estimates.

India's agricultural sector increasingly relies on groundwater for irrigation, leading to depleting groundwater resources in various parts of the country. Historically, surface water storage structures known as ‘tanks’ were used for millennia in India to store rainwater for irrigation. Their use declined over time and due to the increased groundwater pumping in the 20th century, but recent revitalisation efforts aim to improve water availability and support sustainable livelihoods. Despite this resurgence, the role of irrigation tanks in recharging groundwater is not yet fully understood. This study aims to evaluate the effectiveness of tanks in facilitating groundwater recharge using numerical modelling with Hydrus 2D. Time series for tank water levels were reconstructed using satellite images from Planet Labs. The findings confirm that irrigation tanks contribute to groundwater recharge, particularly when constructed in a cascade system. As the cascade of tanks, where water flows from upstream to downstream tanks, is supplied by rivers, both tanks are almost constantly filled with water. This causes recharge throughout the year, except on some days in the dry season. Recharge rates strongly depend on both the aquifer's hydraulic conductivity and the characteristics of the tank floor. The results show the effect of measures such as the removal of accumulated sediments and thus provide insights to optimise the tanks' dual function as reservoirs for irrigation as well as aquifer recharge structures.

Coastal wetlands, some of the most productive ecosystems on Earth, provide critical ecosystem services, including support of biodiversity, carbon sequestration and flood protection. In recent decades, these ecosystems have experienced extensive coastal wetland loss. Coastal wetland restoration provides a beacon of hope, offering a chance to reclaim these important habitats. However, even with billions of dollars invested worldwide in restoring coastal wetlands, we still lack comprehensive knowledge about the effectiveness of these restoration efforts in recovering wetland ecosystem functions and how future climate change may affect these efforts. The ability to evaluate how these ecosystems will function in the future is vital for examining current investments and developing future protection and management plans. We selected Elkhorn Slough, a tidal estuary, in California, to investigate the impact of wetland restoration and sea level rise (SLR) on coastal hydrology using the process-based coastal hydrologic model, Advanced Terrestrial Simulator (ATS), informed by site-specific data. We designed a novel modelling workflow for incorporating wetland restoration features into land cover and soil properties for the model parameterization. The validation results demonstrate a strong agreement between modelled and observed data. We studied the characteristics of coastal watershed hydrology, then focused on the surface water dynamics at two wetland sites within Elkhorn Slough, a reference site and a restored site. Our simulation results indicate that the restored site successfully maintains surface elevation, resulting in reduced surface inundation. We also examined the impact of wetland restoration under expected SLR over the next few decades. The low-lying Yampah Marsh, the reference site, is likely to be inundated due to future SLR when highest tides arrive, while a higher percentage of Hester Marsh, the restored site, would retain marsh vegetation in coming decades, regardless of tidal conditions. Our study provides important information for examining the outcome of restoration practices that include surface elevation in tidal wetlands under climate changes.

Chloride is a natural ion and widely used tracer in hydrological and ecological studies. Tree canopies possess a natural filtration capacity that enables them to effectively capture aerosols, leading to potentially higher rates of ion deposition beneath the canopies compared to open areas. Therefore, understanding the spatial and temporal variability of chloride deposition in throughfall is crucial, particularly in coastal areas where chloride deposition exhibits significant variation. This study aims to estimate chloride throughfall deposition and analyze its distribution among different vegetation types on a small island, while concurrently comparing deposition rates in vegetated sites and open areas. The monitoring network consisted of 17 throughfall collectors positioned beneath the primary vegetation types. The findings demonstrate that vegetation plays a substantial role in enhancing chloride deposition by effectively intercepting marine aerosols, resulting in total deposition values among throughfall sites ranging from 8% to 3742% higher than nearby open sites over a ~ 2-year period. Norfolk pines, white oak, and hardwood forest exhibit significantly elevated chloride deposition in throughfall compared to a shrub stand (Hawaiian holly) and a mixed palm forest. Notably, isolated Norfolk pine sites exhibit exceptionally high chloride deposition. Key factors contributing to the spatial variation of chloride deposition in throughfall include vegetation type, leaf area index (LAI), and exposure to wind and marine aerosols. Additionally, temporal analysis using multiple regression reveals the considerable influence of rainfall depth and wind gust speed on the temporal distribution of chloride deposition in throughfall. The relatively high chloride deposition recorded on Norfolk Island highlights the significant role of vegetation in shaping total chloride deposition in small islands or coastal environments with extensive canopy cover. These findings add to the limited global evidence that neglecting vegetation effects in hydrological studies can underestimate chloride inputs, with implications for chloride mass balance and related methods.

The MESH hydrological model, driven by a 10 km meteorological reanalysis, was deployed to simulate the Saskatchewan River Basin (SRB), a 406 000 km² cold-region basin in Western Canada with diverse climate zones and extensive human regulation. The model was validated using multi-source observation and enabled detailed assessment of the basin's water balance components, runoff generation processes and irrigation impacts on hydrology. The model achieved Kling-Gupta Efficiency values of 0.35–0.85 across 23 streamflow stations (2005–2016), indicating reliable capture of observed flow regimes and reservoir regulation effects. Simulated evapotranspiration correlated strongly with satellite estimates (GLEAM, r = 0.98), and the model realistically reproduced seasonal snowpack dynamics and GRACE-derived water storage variations, with minor underestimation of peak snow water equivalent. Glacier diagnostics revealed that total runoff from glacier-covered areas contributes ~2.9% of SRB's mean annual runoff, of which 0.75% is glacier ice melt. Glacier ice melt runoff contributions varied by sub-basin, with the highest proportions from high-elevation regions: 1.96% to the North Saskatchewan near Edmonton, 1.14% to the Bow near its mouth, 0.66% to the Oldman and 0.32% to the Red Deer. A negative glacier mass balance trend strongest in southern sub-basins, signals declining ice reserves and the long-term vulnerability of glacier-fed water supplies. Diagnosis of runoff processes revealed significant variability in runoff generation, particularly in mountain headwaters and identified snowmelt as the dominant contributor, involved in 84.2% of runoff generation, broken down as snowmelt 43.4%, rain-on-snowmelt 10.2% and mixed events 30.6% of the SRB's annual runoff. Rainfall events contributed 15.8% and events with rainfall involved totalled 56.6% of annual runoff. This highlights the complexity of runoff generation processes in the SRB and the substantial role of snowmelt in sustaining the basin's hydrology. The impact of irrigation on evapotranspiration and streamflow was significant, with irrigation increasing mean annual evapotranspiration by 26.4% and reducing streamflow in key locations by up to 11%. Overall, this study provides a comprehensive and validated understanding of the SRB's hydrology and water resources, emphasising the influence of interactions between natural processes and human interventions. The insights from this research can inform water management strategies, particularly those aimed at adapting to future environmental changes. The findings underscore the importance of MESH as a robust tool for coupled hydrological and water resources modelling in managed, diverse, cold-regions basins.