Affected by climate variability and human activities, the changes of basin environment have altered runoff, posing new challenges to water resources and land use management strategies, especially in ...areas with limited water resources. The purpose of this study is to quantify factors that drive the changes in runoff components. Annual runoff data from six hydrological stations in the Weihe River Basin, China and sixteen meteorological stations data from 1961 to 2015 were used. The Mann-Kendall test and Pettitt method were used to diagnose the runoff sequence and detect its abrupt-point. The period before the abrupt-point of annual runoff was taken as the base period (Period I), while the period after the abrupt-point was taken as the calculation period (Period II). The elasticity coefficient of runoff (Q) was deduced based on the Budyko hypothesis, including climate variabilities such as precipitation (P) and potential evapotranspiration (Ep), and the catchment characteristics representing land surface changes (n). The elasticity coefficient was the smallest for Ep ranging from −1.210 ~ −2.847, intermediate for n ranging from −1.602 ~ −2.964, and greatest for P ranging from 2.210–3.847. Runoff exhibited a significant downward trend throughout the Weihe River Basin, where the land surface change is the main cause of runoff reduction, accounting for 75% at the largest Linjiacun hydrological station, with the smallest being 40.36% at the Zhuangtou hydrological station. Adaptive water resource management measures are necessary to cope with future environmental change and water resource scarcity.
•The analytical method based on coupling water balance and the Budyko hypothesis on the elasticity coefficient is applied.•Runoff showed a total reduction at six hydrological stations in the Weihe River Basin.•Overall, the change of land surface is the main factor of runoff decrease in the Weihe River Basin, followed by precipitation, and the potential evapotranspiration was less affected.
In this study, a semi-distributed hydrologic model Soil and Water Assessment Tool (SWAT) has been employed for the Karnali River basin, Nepal to test its applicability for hydrological simulation. ...Further, model was evaluated to carry out the water balance study of the basin and to determine the snowmelt contribution in the river flow. Snowmelt Runoff Model (SRM) was also used to compare the snowmelt runoff simulated from the SWAT model. The statistical results show that performance of the SWAT model in the Karnali River basin is quite good (
p
-factor = 0.88 and 0.88, for daily calibration and validation, respectively;
r
-factor = 0.76 and 0.71, for daily calibration and validation, respectively). Baseflow alpha factor (ALPHA_BF) was found most sensitive parameter for the flow simulation. The study revealed that the average annual runoff volume available at the basin outlet is about 47.16 billion cubic metre out of which about 12% of runoff volume is contributed by the snowmelt runoff. About 25% of annual precipitation seems to be lost as evapotranspiration. The results revealed that both the models, SWAT and SRM, can be efficiently applied in the mountainous river basins of Nepal for planning and management of water resources.
A high‐quality daily runoff time series of the Lake Como inflow and outflow, the longest for Italian Alps, was reconstructed for the 1845–2016 period in the Adda river basin. It was compared with ...contemporary monthly precipitation and temperature observations and estimated potential evapotranspiration losses. Trend analyses were conducted for daily flow maxima and 7‐day duration minima of inflows into the lake showing a non‐significant decrease and a significant increase, respectively. Although the annual precipitation time series exhibits a non‐significant decrease, annual runoff volumes decrease with a rate of −136 mm⋅century−1, with a significance level of 5%. Possible causes of variability of rainfall and runoff as North Atlantic Oscillation (NAO), Atlantic Multidecadal Oscillation and Western Mediterranean Oscillation indexes and sunspot activity were also explored. Wavelet spectra analyses of monthly precipitation and runoff show some changes in the energy both at small and large scales and are effective in pointing out phenomena as droughts and the effects of dams' regulation. Conversely, wavelet coherence spectra indicate a weak correlation of NAO and sunspots with precipitation. In addition, the analysis of temperature and potential evapotranspiration tendencies suggests that the decrease of runoff has to be ascribed mostly to anthropogenic factors, including water ion for irrigation and increased evapotranspiration losses due to natural afforestation and, only in part, to climatic variability.
The article presents the reconstructed daily runoff series of the Lake Como inflow and outflow for the 1845–2016 period in the Adda river basin, which is the longest runoff record of Italian Alps. It was investigated for trend and variability over different time scales and compared with the basin precipitation record presented in the companion paper. Annual runoff volumes show a significant decrease, ascribing mostly to increasing evapotranspiration losses and anthropic factors.
Close to one-half of all Americans live in coastal counties. The resulting flood of wastewater, stormwater, and pollutants discharged into coastal waters is a major concern. This book offers a ...well-delineated approach to integrated coastal management beginning with wastewater and stormwater control.The committee presents an overview of current management practices and problems. The core of the volume is a detailed model for integrated coastal management, offering basic principles and methods, a direction for moving from general concerns to day-to-day activities, specific steps from goal setting through monitoring performance, and a base of scientific and technical information. Success stories from the Chesapeake and Santa Monica bays are included.The volume discusses potential barriers to integrated coastal management and how they may be overcome and suggests steps for introducing this concept into current programs and legislation.This practical volume will be important to anyone concerned about management of coastal waters: policymakers, resource and municipal managers, environmental professionals, concerned community groups, and researchers, as well as faculty and students in environmental studies.
The rise in temperatures over the Himalayan regions due to climate change have shown profound effects on the seasonality and long‐term availability of snow melt runoff and glacier melt runoff. As per ...the sixth assessment report by the Intergovernmental Panel on Climate Change, the Himalayan glaciers are retreating and the fraction of precipitation falling as snow is altering. This study analyses the effect of snow‐glacier changes on the melt runoff (1986–2020) over the Upper Ganga river basin (up to Rishikesh) using a fully distributed model namely, Spatial Process in Hydrology (SPHY), which governs by Temperature Index Model approach with varying degree‐day factors. This study performs the two‐step calibration approach for model parameterization and to evaluate the snow and glacier melt runoff utilizing the observed discharge and real time satellite datasets. The SPHY derived snow cover was compared with the Moderate Resolution Imaging Spectroradiometer (MODIS) derived snow covers. Results show that the SPHY modelled fractional snow covers found comparable to MODIS derived snow covers (~70%–90% correlation). The R2 based comparison of SPHY modelled runoff (Q) and observed Q at two gauges namely, Maneri (~0.85) and Rishikesh (~0.80) found reasonable. For the assessment of glacier changes and corresponding melt runoff, temporal glacier maps (i.e., for years 1990, 2000, 2010, 2020) were prepared utilizing the Landsat imageries. Results showed a noticeable reduction in the glacier areas (~5% mass reduction in 30 years) and an increase in glacier melt runoff at different stations (e.g., at Bhojwasa ~3%–4% and at Rishikesh ~1%–2%). Similarly, a decrease in snow melt runoff (~3%–4%) and an increase in rainfall runoff (~3%) were computed. A month wise percent of change analysis has shown significant fluctuations in the magnitude and seasonality of all runoff components (i.e., snow Q, glacier Q, base Q and rainfall induced Q) in the Himalayan Upper Ganga basin.
Computation of snow melt and glacier melt runoff in upper Ganga river basin. Separation of snowmelt, glacier melt and other runoff components. Analysing the effect of glacier changes on melt runoff. Percentage of change analysis in different runoff components under varying cryospheric characteristics.
The solution of many practical water problems is strictly connected to the availability of reliable and widespread information about runoff. The estimation of mean annual runoff and its interannual ...variability for any basin over a wide region, even if ungauged, would be fundamental for both water resources assessment and planning and for water quality analysis. Starting from these premises, the main aim of this work is to show a new approach, based on the Budyko's framework, for mapping the mean annual surface runoff and deriving the probability distribution of the annual runoff in arid and semiarid watersheds. As a case study, the entire island of Sicily, Italy, is here proposed. First, time series data of annual rainfall, runoff, and reconstructed series of potential evapotranspiration have been combined within the Budyko's curve framework to obtain regional rules for rainfall partitioning between evapotranspiration and runoff. Then this knowledge has been used to infer long‐term annual runoff at the point scale by means of interpolated rainfall and potential evapotranspiration. The long‐term annual runoff raster layer has been obtained at each pixel of the drainage network, averaging the upstream runoff using advanced spatial analysis techniques within a GIS environment.
Furthermore, 2 alternative methods are here proposed to derive the distribution of annual runoff, under the assumption of negligible interannual variations of basin water storage. The first method uses Monte Carlo simulations, combining rainfall and potential evapotranspiration randomly extracted from independent distributions. The second method is based on a simplification of the Budyko's curve and analytically provides the annual runoff distribution as the derived distribution of annual rainfall and potential evapotranspiration. Results are very encouraging: long‐term annual runoff and its distribution have been derived and compared with historical records at several gauged stations, obtaining satisfactory matching.
Accurate and reliable runoff prediction is of great significance to water resources management, disaster monitoring and rational development and utilization of water resources. In this paper, a ...metaheuristic evolutionary deep learning model based on Temporal Convolutional Network (TCN), Improved Aquila Optimizer (IAO) and Random Forest (RF) is proposed for rainfall-runoff simulation and multi-step runoff prediction. In this study, the influence of various input variables on the prediction accuracy is discussed. First of all, in order to avoid the dimensional disaster problems and reduce the calculation time, RF is used to calculate the correlation between the input variables and the prediction object, and the data with high correlation is selected as the final inputs. Then, the filtered data are sent to the TCN model, and the parameters of the TCN model are optimized using the IAO algorithm, and the final prediction results are obtained. In this study, the rainfall and runoff data of five stations in the middle reaches of Jinsha River, China were selected, and the runoff of Panzhihua station was simulated and predicted by establishing multiple models. By analyzing and comparing the predictive results of several models, it shows that the models and improvements proposed in this study are effective.
Purpose
Soil degradation is a widespread problem and currently one of the biggest challenges in modern-day agriculture. The partial adoption of conservation agriculture, such as no-till management, ...does not provide adequate erosion control, and the hydrology dynamics on hillslopes under no-till management remain poorly quantified. This study examines the hydrology of agricultural hillslopes under no-till management, with and without terraces in southern Brazil.
Materials and methods
Water and soil losses were measured in two paired, zero-order catchments (2.4 ha) under no-till cultivation, with and without broad-based retention terraces. Rainfall, surface runoff, and suspended sediment concentrations were monitored during major rainfall events. Analysis of hydrographs and sedigraphs was used to derive the peak flow, runoff duration, and sediment yield values and the hysteresis between surface runoff and the suspended sediment concentration during different seasons.
Results and discussion
The results show higher soil and water losses in the catchment without terraces. Terracing reduced peak flow rates by 79%, sediment yield from 0.44 to 0.16 t ha
−1
, and the total surface runoff from 3943 (126 mm) to 855 m
3
(36 mm) during 31 events over 16 months. The no-till system without terraces was unable to adequately control surface runoff and soil erosion. Surface runoff and sediment yield were higher under no-till without terraces than under no-till with terraces.
Conclusions
The difference in terms of surface runoff volume and sediment yield indicates an important difference in the hydrology and soil erosion in the catchment without terraces, which is represented by high-surface-runoff coefficient values observed during the rainfall-runoff events. The short lag time and steep rising limb of the hydrographs indicate high-surface-runoff responsivity to rainfall in no-till without terraces.
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