Hydrological Processes最新文献

This research, conducted in the mountainous catchment near Abant Lake in the Western Black Sea region of Türkiye, aimed to investigate the spatiotemporal variations of snow depth (SD) and snow water equivalent (SWE) throughout the snow season from December 2019 to March 2020, encompassing both accumulation and melting periods. In total, 14 snow surveys were conducted, covering 58 permanent snow measurement points (PSMP) marked with snow poles. The classification and regression tree (CART) method was employed to statistically analyse their relationships with eight variables: snow period, forest canopy, aspect, slope, elevation, slope position, plan and profile curvature. The root mean square error (RMSE) for SD and SWE was determined to be 0.15 m and 46 mm, respectively. The study findings revealed that mean SD and SWE values were higher in forest gaps compared with under-forest and open areas. Although the snow cover disappeared earliest in under-forest areas, the melting rate was observed to be 43% and 17% slower compared with forest gaps and open areas, respectively. Wind redistribution resulted in minimum snow accumulation on western aspects, upper slope positions and ridges, while maximum accumulation was observed on southern aspects, valleys and lower slope positions. Higher elevations (>1580 meters) experienced faster snow melting rates, leading to earlier disappearance of snow cover. PSMPs located on slopes with lower degrees (<15°) exhibited lesser accumulation and earlier snow disappearance. The CART model identified the snow period as the most significant factor in predicting SD and SWE, based on variations in snowfall and air temperature. Other significant variables included forest canopy, aspect and elevation. The study suggests that the CART method is well-suited for modelling complex snow dynamics, providing valuable insights into spatiotemporal variations in SD and SWE in mountainous regions.

Hydrology has a long history, but is still considered a young science due to its lack of a solid scientific foundation as a natural science. Field experimentation is crucial when investigating hydrological processes and mechanisms, and is essential if hydrology is to have a solid, science-based foundation. Professor Wei-Zu Gu (1932–2022) was an internationally renowned scientist in the field of hydrology and is recognized as the greatest pioneer of experimental hydrology and isotope hydrology in China. He created the Hydrohill experimental catchment, which serves as both a great public facility for experimental hydrology and a valuable legacy for researchers that will enable them to conduct advanced hydrological experiments in the future. This legacy consists of innovative infrastructure that bridges the gap between natural watershed experiments and artificial physical models. The Hydrohill is an intensively instrumented experimental catchment that allows different elements of the hydrological cycle and their tracing indicators to be comprehensively measured. To provide an in-depth understanding of the Hydrohill, this paper presents a short history of the site, its experimental objectives, a site description (including location, construction and instrumentation), site conditions (such as soil, hydrological and meteorological properties), and its contributions to hydrological science. We acknowledge Professor Gu for creating the Hydrohill experimental hydrology facility and enhancing our understanding of hydrological processes and mechanisms. Finally, we hope that Chuzhou Scientific Hydrology Laboratory, along with support from Professor Gu's friends, will ensure the continued growth of the Hydrohill so that it can address unsolved problems in hydrology.

Rainfall infiltration plays a crucial role in the near-surface response of soils, influencing other hydrological processes (such as surface and subsurface runoff, groundwater dynamics), and thus determining hydro-geomorphological risk assessment and the water resources management policies. In this study, we investigate the infiltration processes in pyroclastic soils of the Campania region, Southern Italy, by combining measured in situ data, physical laboratory model observations and a 3D physically based hydrological model. First, we validate the numerical model against the soil pore water pressure and soil moisture measured at several points in a small-scale flume of a layered pyroclastic deposit during an infiltration test. The objective is to (i) understand and reproduce the physical processes involved in infiltration in layered volcanoclastic slope and (ii) evaluate the ability of the model to reproduce the measured data and the observed subsurface flow patterns and saturation mechanism. Second, we setup the model on the real site where soil samples were collected and simulate the 3D hydrological response of the hillslope. The aim is to understand and model the dynamics of hydrological processes captured by the field observations and explain the redistribution of water in different layers during 2 years of precipitation. For both applications, a Monte Carlo analysis has been performed to account for the hydrological parameter uncertainty. Results show the capability of the model to reproduce the observations in both applications, with mean KGE of 0.84 and 0.68 for pressure and soil moisture data in the laboratory, and 0.83 and 0.55 in the real site. Our results are significant not only because they provide insight into understanding and simulating infiltration processes in layered pyroclastic slopes but also because they may provide the basis for improving geohazard assessment systems, which are expected to increase, especially in the context of a warming climate.

Rainfall and sea tides significantly affect the coastal groundwater. The effect of rainfall events and sea tides on groundwater is not fully understood. In this study, groundwater level and electrical conductivity (EC) were simultaneously measured in three monitoring wells to evaluate the behaviour of freshwater in the uplifted atoll island of Zhaoshu, China. We used the water level sensor monitoring the position and variability of freshwater in the island. In the monitoring period, 86 rainfall events (cumulative rainfall above 1 mm) were identified. The fresh groundwater periodically fluctuates with phase lags every 1–2 h following sea tides. The intermittent rainfall increases the volume of fresh groundwater, while groundwater fluctuation is controlled by tides. Multiple regression analysis and cross-correlation analysis were used to analyse the response relationship of groundwater to rainfall and tides. Variation in the groundwater level lags the EC as the temporal fluctuation of the sea tides. Only in case of severe rainstorm (cumulative precipitation of an event above 300 mm), the contribution of rainfall on groundwater level fluctuation is greater than that of sea tide. Four response modes (RRR, RFF, RFR, RRF) decomposition of groundwater have been defined according to the tidal stage and threshold (70.3–301.1 mm) of rainfall. The tidal-induced groundwater effect (TGE) is stronger than the rainfall-induced groundwater effect (RGE) but it is the opposite in the third and fourth modes. These results and mechanisms could be applied to other atoll islands, for our understanding of rainfall infiltration processes with tidal effect, and could be instrumental in estimating groundwater resources.

Anthropogenic activities like overgrazing, deforestation and mismanaged land use accelerate soil erosion (SE), causing nutritional and organic matter loss. In this study, we predicted the annual rate of soil loss in the Salt Range, extending south from the Potohar plateau, Pakistan, using the Revised Universal Soil Loss Equation (RUSLE). The RUSLE model parameters and erosion probability zones were estimated using remote sensing and Geo-Spatial methods. The annual average soil loss rates were calculated by considering five geo-environmental factors, that is, slope length and steepness (LS), rainfall erosivity (R), cover management (C), soil erodibility (K), and conservation practice (P) range from 0–559 527, 1404–4431, 0–1, −0.14 to 1.64, and 0.2–122 $��\left(�t�.�{\mathrm{ha}}^{�-�1�}�.�{\text{year}}^{�-�1�}�\right)�$ respectively. This research determined that the yearly average rate of SE in the Salt Range varies from over 50 to above 350 $��t�.�{\mathrm{ha}}^{�-�1�}�.�{\text{year}}^{�-�1�}�$. The distribution of land area across different SE probability zones reveals that a small portion (2.11%) is classified as High, a moderate portion (7.13%) falls under the category of Moderate, while the majority (90.7%) is classified as Low in terms of proneness towards erosion. The land devoid of vegetation and characterized by steep slopes is especially prone to SE. The Salt Range is highly vulnerable to SE risk due to climatic variation

Rain-on-snow (ROS) is a compound hydrometeorological extreme event that can lead to severe socioeconomic impacts and affect ecosystem function. In high-latitude regions, the percolation of liquid precipitation through snowpack and the associated formation of ice layers can create greater potential for significant runoff and also cause hardship for wintertime ungulate foraging. In this study, we assess the characteristics of ROS events and the corresponding impacts over a large sub-arctic river basin in northwestern Canada. We propose seven indices to assess the projected changes in both major and minor ROS events, defined as instances of 10 and 3 mm/day, respectively, of rainfall occurring on SWE greater than 5 mm, taking into account precipitation intensity and snowpack depth. We use simulations from the variable infiltration capacity hydrologic model driven by a suite of multivariate bias-corrected global climate models from the fifth phase of the Coupled Model Intercomparison Project and assess the ROS changes under the 1.5, 2, 3 and 4°C global warming levels above the pre-industrial period. Overall, ROS events occur more frequently in October–December and January–March (JFM) compared to other seasons. The effects of major and minor ROS events on runoff generation in JAS and OND are considerable at higher elevations, with mean runoff more than 50% greater on ROS days than non-ROS days in many cases. Furthermore, the analyses project notable increases in the frequency of both Major and Minor ROS events in all summer and fall. However, a notable decrease in ROS frequency is present in spring, and in winter, ROS frequency has inconsistent changes. Our comprehensive assessment of ROS events, their projected changes, and associated impacts in a sub-arctic river basin underscore these events' critical role in shaping hydrological patterns and affecting communities, infrastructure and ecosystem dynamics.

With the help of a physically based recharge-groundwater flow model and robust detrended fluctuation analysis (r-DFAn), the effect of local (catchment-scale) forcing on groundwater levels' scaling behaviour in a riparian aquifer in Wallingford, UK, is investigated. The local forcings investigated in this study include the rainfall's temporal scaling behaviour (which is simulated by changing rainfall's intermittency parameter in a β-lognormal multiplicative random cascade model), the aquifer's physical parameters (saturated hydraulic conductivity, specific yield, the empirical coefficients of the water retention curve and the river stage's scaling behaviour). Groundwater level's scaling behaviour was found to be most sensitive to rainfall's fractal behaviour. Additionally, there is preliminary evidence suggesting that changes to the rainfall's local scaling behaviour (i.e., change to the series' scaling that induces crossovers) affects the groundwater's and the recharge's local scaling behaviour.

The addition of crop straw is considered an important measure for sustainable agricultural production. Crop straw when incorporated into the soil affects crop growth and development by changing the hydrothermal conditions of the soil. However, quantitative studies that inform on the mechanisms by which added straw or straw biochar (SSB) affects hydrothermal response of soil and thereby crop productivity in lime concretion black soil (LCBS) are lacking. Moreover, the sustained effects during continuous cropping are less well understood. The impact of SSB on soil properties and crop yields in a typical LCBS area was systematically investigated through field experiments with maize and wheat rotations. Four treatments were set: straw (S), fertilizer (F), straw with fertilizer (SF) and straw biochar with fertilizer (BF). The results indicated that soil water-holding capacity and rainfall storage efficiency were improved in BF and SF treatments. Compared with the F treatment, the soil water storage increased by 80%–98% and the response time of soil water to rainfall was advanced by approximately 4 h in the other three treatments during the maize season. BF and SF treatments only increased soil water storage by 6.8% due to the lack of rainfall during the wheat season. Soil inorganic nitrogen and available phosphorus were significantly increased in SF treatment by 101.1% and 32.9% compared with BF treatment in the wheat season. Considering crop plant height, leaf area index and yield, SF and BF treatments were beneficial to crop growth and improved water use efficiency. They did not increase maize yield significantly, with a maximum increase of 2.1% in BF treatment compared with F treatment. But, SF treatment significantly increased wheat yield by 11.8% and BF treatment increased wheat yield by 6.7%. Overall, this study illustrated the positive effects of SSB additions on the production of LCBS from multiple perspectives. This will provide reference for improving the soil hydrothermal conditions of LCBS and ensure food security.

In the context of expected future melt reductions in the high-Andes, the buffering capacity of non-glacial stores, and especially of high-altitude bofedal wetlands, is of increasing importance. Isotope signatures potentially indicative of water undergoing evaporation on transit through bofedales have been found in the tropics, but end-member uncertainty has so far prevented streamflow separation using this signal. We undertook a stable isotope sampling campaign over the 2022 wet-dry season transition in a 53.6 km², 16% glacierized catchment in southern Peru with a bofedal coverage of 11%. Diurnal proglacial hydrographs and remote sensing were used to interpret seasonal snowmelt dynamics and identify the dry periods when glacial melt and bofedal contributions are assessed to be the two principal components of streamflow. Following the final wet season precipitation event, a rapid ~3 week transition occurs in the main river from a stable isotope signature consistent with dynamic rainfall/snowmelt contributions to one of ice-melt. In both wet and dry seasons, the main river and tributary streams show evaporative enrichment suggesting ongoing supply from water transiting bofedales. A two-component mixing model using lc-excess during the dry season shows the bofedal source contribution varies from 9% to 20% [±9–10%], indicating that streamflow is greatly augmented by the presence of glaciers at these headwater scales. However, applying these proportions to river discharge shows a sustained bofedal contribution of around 0.09 m³/s during the dry season study window whereas the flux of glacial water halves from 0.73 to 0.36 m³/s over this timeframe. The results highlight the important role of bofedales and the connected groundwater system in buffering seasonal declines in streamflow months into the dry season, and suggests the hydrological functioning of bofedales as part of this wider system should be considered when exploring the effectiveness of potential options to sustain baseflows in a post-glacial future.

The Gravity Recovery and Climate Experiment (GRACE) satellite provides valuable data to monitor groundwater variation. This study investigates groundwater dynamics in India during deficit and excess monsoon years. It finds possible interactions by exploring how groundwater levels respond to meteorological and hydrological conditions. Groundwater anomalies (GWA) are estimated using Terrestrial Water Storage Anomalies (TWSA) from GRACE and hydrological parameters from the Global Land Data Assimilation System (GLDAS). The statistical analysis reveals that the standard deviation is higher for hydrological parameters in summer (June to September), whereas it is higher in fall (October to November) for GWA in many parts of India. The modulation in hydrological parameters subsequently impacts GWA during the following seasons. The study reports increased groundwater across many parts of India during fall. However, groundwater decline is closely linked to unsaturated soil moisture from fall to winter (December to February). Groundwater storage is at its lowest levels during the following spring (March to May) over India. Four deficit and three excess summer monsoons occurred from 2002 to 2022. Composite analysis of GWA reveals that there is replenishment (depletion) of groundwater during the following fall and winter in excess (deficit). The analysis based on extreme deficit monsoon years (2002, 2009) and excess monsoon year (2019) reveals that during the deficit years, groundwater recharge is less, and excess monsoon year it is more; and is vice versa for GWA. The study reports decline in GWA during the summer 2019, which is attributed to the hydrological conditions of the preceding year and modulation of the hydrological processes. As climate variability and water scarcity become increasingly pressing issues, understanding the relationships between hydrological factors and groundwater dynamics is essential for ensuring sustainable water use and resilience to extremely varying climate conditions.