Journal of Hydrology-Regional Studies最新文献

Study region

Poyang Lake Plain at the south bank of the middle Yangtze River

Study focus

The dynamics of the groundwater budget, prominently driven by the surface water-groundwater interaction, present significant challenges for water resources and the eco-environment in extensive river-lake-floodplain systems. This research utilizes a groundwater flow model through the application of the MODFLOW-NWT numerical simulator, aiming to explore the patterns of exchange between surface water and groundwater due to intensive seasonal lake inundation, and its consequential impact on the annual and seasonal groundwater storage within the vast Poyang Lake floodplain, China.

New hydrological insights for the region

Simulation results indicate that the change in groundwater storage during the dry year (i.e., –24.96×10⁷ m³/yr in 2022) has decreased by 186.35×10⁷ m³ compared to the wet year (i.e., 161.38×10⁷ m³/yr in 2020). The contribution of surface water infiltration is approximately 45 % of the regional groundwater budget during wet seasons, and groundwater discharge into surface waterbodies accounts for over 60 % of the groundwater budget during dry seasons. The lake infiltration during wet years is approximately 3 times that in dry years, and the flow of infiltrated lake water into plain aquifers is approximately 5 times that in dry years. The present study contributes significant knowledge regarding the impact of intensifying seasonal inundation on variations in regional groundwater budget in large lake-aquifer system.

Study region

Marchfeld region (Austria)

Study focus

A multi-method and multi-scale assessment of the intrinsic groundwater vulnerability to generic pollutants was carried out. At the regional scale, a parametric method, to assess the intrinsic groundwater vulnerability, and a transfer function model, to assess the travel time of a generic and non-reactive pollutant through the unsaturated zone, were applied. At the site-specific scale, the travel time of the peak concentration was evaluated by using a physically-based hydrological model. The comparison of results of different approaches allowed mutual validation and advanced the knowledge about the assessment of groundwater vulnerability.

New hydrogeological insights for the region

To assess the groundwater vulnerability, a detailed hydrogeological map of the study area was reconstructed. A large variability of hydrogeological, morphological and anthropic conditions was recognized. Alluvial aquifers formed by high-permeability deposits hosting shallow groundwater circulation are characterized by the highest groundwater vulnerability. Contrarily, lower groundwater vulnerability was recognized for aquifers formed by low-permeability deposits, favoring a reduction of infiltration processes and a major attenuation of pollutants’ potential effects. The presented multi-method approach revealed how comparing the results of a DRASTIC-like method and two process-based models can deliver hints regarding their suitability, different spatial densities and quality of required inputs, and effectiveness. Finally, the potential strong impact of some agricultural practices was confirmed.

Study region

A legacy underground tungsten mine in a mountainous area, central Japan.

Study focus

We analyzed mining-influenced water (MIW) from mine voids and surface water from rivers to determine the dissolved ion concentrations and water isotopes (δ¹⁸O and δ²H). The results were interpreted using principal components and cluster analyses, as well as Eh-pH (Pourbaix) diagram. By integrating the obtained analytical results with mine-related data, we conducted component separation of MIW and estimation of their origins.

New hydrological insights for the region

The MIW and part of surface water were characterized by the SO₄²⁻ and F⁻ generated via the dissolution of sulfide minerals and fluorite (CaF₂) from the ore deposit. MIW components were successfully separated using these indicators and water isotopes. The results of component separation indicated that the MIW consisted of two components, namely infiltrating water that rapidly passes through upper mine voids to reach the mine void at ground level, and groundwater that undergoes some degree of residence time before flowing into the ground level void from shaft I.

Study region: Six regions in Algeria have been selected as follows: Ain Elhadjel, Msaad, Boussaada, Elkantara, M’sila and M’doukel.

Study focus: This study focused on creating a novel hybrid VMD-ELM approach, established by combining the Variational Mode Decomposition (VMD) technique and the Extreme Learning Machine (ELM) algorithm as a preprocessing technique for predicting future droughts. The first 6 and 12-month SPI values 1, 2, and 3-month lead time values were estimated with the ELM algorithm. After that, meteorological variables and Standard Precipitation Index (SPI) values, divided into subcomponents with VMD, are presented to the ELM model, and a drought forecasting model is developed. Model performances were evaluated according to various visual and statistical criteria.

New hydrological insights for the region: Soft computing techniques have become the preferred method for producing predictions due to their ability to minimize development time, require minimal input, and offer a relatively less complex approach when compared to dynamic or physical models. As a result of the analysis, it has been determined that the highest prediction accuracies are generally obtained in VMD-ELM models and SPI predictions with a 1-month lead time. The study outputs give important ideas to mite donors regarding water resource planning and climate change adaptation strategies in the study area and can be applied to other arid and semi-arid environments.

Study region

The Daliang Mountain region, characterized by its widespread debris flow-pone catchments, is the primary sediment source area for the upper reaches of the Yangtze River, and has experienced intensive human activity over the past half-century.

Study focus

Here, we combined lake deposits with sediment source areas to quantify the sediment source and corresponding sediment yield (SY) in response to recent human impacts in a typical debris flow-prone catchment located in the Daliang Mountain region, Southwest China. The fingerprinting techniques, incorporating geochemical elements and their specific ratios, were used to characterize the sediment provenances and corresponding SY.

New hydrological insight for the region

The results indicated that gully erosion was the major sediment provenance (90.10 %) in the catchment, followed by cultivated land (6.76 %) and forested land (3.14 %) for the studied period. The temporal variations of SY showed two distinctive erosional stages in response to different human activities over the past 70 years, namely 1950−2004 and 2004−2020. Greater SY values, dominated by gully erosion, occurred from 1950 to 2004, implying that both critical national activities and revegetation projects have limited effects on surface sediment generation. In contrast, gully activity and resulting SY have sharply decreased since 2004 following the implementation of check dams. These comparisons indicate a central role of the check dam in reducing gully activity. The findings have important implications for policymakers to optimize the spatial layout of future soil conservation strategies in the region.

Study region: French part of the Moselle catchment

Study focus: By relying on hydrological simulations forced by climate change scenarios, stakeholders can assess the magnitude of future changes in the rainfall–runoff relationship. The inclusion of human influences in water resources modelling in a non-stationary context is a way to improve the accuracy and usefulness of climate change impact studies. Here, we propose a modelling approach that explicitly considers water uses to evaluate adaptation measures for water management at the French Moselle catchment scale.

New hydrological insights for the region: The results highlight the decrease in future low flows but also the change in the balance between demand and supply. Over the Moselle catchment, whatever the water use scenario considered, climate change induces lower water availability both for environmental flows and for human uses. This leads to a potential increase in the duration of water restriction of up to 8 weeks for RCP 8.5 in the long term (2070–2099) compared to 1976–2005. This study could provide water managers with more appropriate climate impact results and potentially help them to design adequate adaptation measures.

Study region

The Shanmei Reservoir Watershed (SRW), Southeast China.

Study focus

This study investigated the climate and hydrological regimes alterations in a subtropical coastal watershed (SRW) during the 21st century in extreme scenarios. The extreme scenarios, i.e., warm-wet and cold-dry climates, were constructed using 18 global climate models (GCMs) from CMIP6 under shared socioeconomic pathways (SSP1–2.6, SSP2–4.5, SSP3–7.0 and SSP5–8.5). The Soil and Water Assessment Tool (SWAT) model and Indicators of Hydrologic Alteration (IHA) were applied to quantify the impacts of climate change on the eco-hydrological regimes during the projected period (2041–2100) compared to the base period (1980–2014).

New hydrological insights for the region

The results show that the average temperature rises by 0.6–3.8 ℃, and the average annual precipitation changes by −21.4 % - 32.4 % by the end of the 21st century under extreme scenarios. Contrasting hydrological regimes are expected in the SRW under extreme scenarios. Under the extreme warm-wet scenarios, the monthly runoff is lower during spring and higher during summer, the minimum flows are significantly higher, and the maximum and minimum flows occurs earlier. Water resource utilization and ecosystem health are expected to improve. However, the opposite holds true in the cold-dry scenarios. The hydrologic regime alteration under future extreme climate scenarios can guide local water planning and ecological restoration strategies.

Study region

The Yarlung Zangbo Basin (YZB) on the Tibetan Plateau, the world's highest river basin, features a significant cryosphere with glaciers and seasonal snow cover crucial to its hydrology. The study focuses on the region between the Nuxia and Dexing river gauging stations, where glaciers cover 15.4 % of the area.

Study focus

The research quantifies the contributions of snow melt (SM) runoff, glacier melt (GM) runoff, rainfall runoff, and baseflow to the total runoff in the YZB. The Spatial Processes in Hydrology (SPHY) model, enhanced with a cryosphere module, was utilized, calibrated with runoff data from the Nuxia station and evapotranspiration data from 2003 to 2014.

New hydrological insights

The study found rainfall runoff to be the primary contributor to annual runoff (66.3 %), followed by snow melt runoff (19.7 %), glacier melt runoff (6.2 %), and baseflow (7.8 %). Snow melt runoff is dominant in early spring, while baseflow prevails in winter. Glacier melt runoff contributes directly to river flow (90.1 %) and replenishes groundwater (9.9 %), which then drains as baseflow. In glacier-rich areas, percolated glacier meltwater significantly recharges groundwater, underscoring its vital role in sustaining river flow in the YZB. This research enhances the understanding of hydrological processes in large alpine river basins and highlights the crucial role of glacier and snow melt in maintaining the Tibetan Plateau's water resources.

Study region

The case study presents Vrana Lake on Cres island in Croatia, which is the largest freshwater resource on the Mediterranean islands. It is used for the public water supply of the residents and tourists who inhabit this island during the summer months.

Study focus

Using the Support Vector Regression (SVR), the influence of future climate changes on the lake surface water temperature (LSWT) was analysed. Input data were monthly air temperatures (AT). Model training and validation were based on measured LSWT and AT in the period 1981–2022. Expected LSWTs for the period 2023–2070 under the RCP8.5 emission scenario were forecast based on climate modelling data of monthly AT for the period 1971–2070.

New hydrological insights for the region

The results showed that the applied SVR model can effectively forecast monthly LSWTs, which was confirmed by a correlation coefficient of approximately 0.99 between the measured and simulated LSWTs. Root mean square errors were lower than 1 °C. The LSWT warming trend in 2023–2070 is expected to be lower than that observed in 1981–2022, and will vary from 0.2 °C dec^-1–0.3 °C dec^-1. The largest increase in LSWT can be expected in spring while the increase in LSWT will be the smallest in the summer months. In approximately 50 years, the expected LSWT could be higher by an average of 1.2 °C.

Study region

Bicol River Basin, Philippines

Study focus

The study investigated the impact of climate change and urbanization on water resources in the Philippines. It used Water Evaluation and Planning (WEAP) software and climate forecasts from eight Global Circulation Models (GCMs) to assess the nation's water balance, focusing on two sensitive watersheds: Libmanan-Pulantuna (LPW) and Quinali (QW). The study projects water availability in these areas by creating climate-urbanization scenarios. Furthermore, our endeavor aims to provide insight into the complexities of hydrological processes within traditionally under-observed regions, serving as a blueprint for future environmental planning and sustainable water management in the Philippines and beyond.

New hydrological insights

The study's simulated streamflow matches observed data (R²: 0.70–0.85, NSE: 0.57–0.67) and indicates warming trends and variable precipitation in both watersheds. Rising water demand in domestic and industrial sectors contrasts with a decline in agriculture due to land conversion. QW faces increased water demands from urbanization, while LPW has lower unmet water demand. Low Land Decline scenarios indicate consistent water scarcity in agriculture, while High Land Decline scenarios predict a decrease by 2100. Urbanization significantly impacts future water stress more than climate change, with reduced agricultural land generally associated with lower water stress. Conversely, climate change exacerbates unmet demand issues in domestic and industrial development cases. Due to diminishing agricultural land, both watersheds are expected to transition from water-deficient to water-surplus regions by the end of the century. However, immediate action is crucial to address current water demands, particularly in the severely water-deficient Quinali Watershed.