Attribution Analysis of Runoff Variation in the Yue River Watershed of the Qinling Mountains

In recent decades, global climate change, especially human activities, has led to profound changes in the hydrological cycle and hydrological processes in watersheds. Taking the Yue River watershed in the Qinling Mountains in China as the study area, the Mann–Kendall test and Pettitt mutation test method were used to analyze the various characteristics of hydrological and climatic elements from 1960 to 2018. Then, the elastic coefficient method based on the Budyko framework was used to estimate the elastic coefficient of runoff change on each influencing factor. The results showed that the annual runoff decreased at a rate of 0.038 × 108 m3/a ( P > 0.05 ), and a significant abrupt change occurred in 1990. The annual precipitation and potential evapotranspiration (ET0) increased and decreased, with change rates of 0.614 mm/a and −0.811 mm/a ( P > 0.05 ), respectively. The elasticity coefficients of precipitation, ET0, and the underlying surface were 1.95, −0.95, and −0.85, respectively, indicating that annual runoff was most sensitive to the change in precipitation, followed by the change in ET0, and had the lowest sensitivity to the change in the underlying surface. Underlying surface change is the main factor of runoff decrease; the contribution is 89.07%. The total contribution of climate change to runoff change is 10.93%, in which the contributions of precipitation and ET0 are 17.59% and −6.66%, respectively. The NDVI reflecting underlying surface change has been increasing since 1990, which is an important reason for the runoff decrease.

Evaporation in Hydrological Models Under Rising CO2: A Jump into The Unknown

Many hydrological models use the concept of potential evaporation (PE) to simulate actual evaporation. PE formulations often neglect the effect of carbon dioxide (CO2), which challenges their relevance in a context of climate change and rapid changes in CO2 atmospheric concentrations. In this work, we implement three options from the literature to take into account the effect of CO2 on stomatal resistance in the well-known Penman–Monteith PE formulation. We assess their impact on future runoff using the Budyko framework over France. On the basis of an ensemble of Euro-Cordex climate projections using the RCP 4.5 and RCP 8.5 scenarios, we show that taking into account CO2 in PE formulations largely reduces PE values but also limits projections of runoff decrease, especially under an emissive scenario, namely, the RCP 8.5. Whereas the classic Penman–Monteith formulation yields decreasing runoff projections over most of France, taking into account CO2 yields more contrasting results. Runoff increase becomes likely in the north of France, which is an energy-limited area, with different levels of runoff response produced by the three tested formulations. The results highlight the sensitivity of hydrological projections to the processes represented in the PE formulation.

Quantifying the Impacts of Coal Mining and Soil-Water Conservation on Runoff in a Typical Watershed on the Loess Plateau, China

Coal mining and soil-water conservation are the two major human interventions on the Loess Plateau in China. Analyzing their impacts on hydrological processes is of great significance for sustainable water resource management. Using hydrological simulation (Soil and Water Assessment Tool, SWAT) and a data-driven method (double mass curve, DMC), the contributions of these two human activities and climate change to the runoff decrease were analyzed in the upper Fenhe River. The runoff in the three affected periods (1967–1987, 1988–1994, and 1995–2017) decreased by 7.5%, 28.2%, and 24.1%, respectively, compared with the base period (1957–1966). In the first affected period (1967–1987), the amount of coal mining activities was small, human activities had little impact on runoff. In the second (1988–1994) and third (1995–2017) periods, as the coal mining and soil-water conservation intensified, their contributions to the runoff decrease rapidly increased. Due to the uncertainties in the model structure and parameters, in addition to the impact of the data accuracy, the results obtained from the two methods were different, but the proportions and the trends of the contribution rates in the different periods were consistent.

Evaluation of Infiltration Rainwater Drainage (IRD) System with Fully 3-D Numerical Simulation Approach

Water scarcity can mean scarcity in availability due to physical shortage, or scarcity in access due to the failure of institutions to ensure a continuously regular supply or due to a lack of adequate infrastructure. Water scarcity will be exacerbated as rapidly growing urban areas place heavy pressure on water resources. To solve these problems, various solutions have been applied, but a fundamental solution has not been applied. Recently, a researched and developed infiltration rainwater drainage (IRD) system is being applied with consideration of its applicability. In this study, features of surface runoff and infiltration according to various flow patterns were analyzed using a three-dimensional CFD (Computational Fluid Dynamics) model for calculating water flow in the IRD system. To estimate the optimal setup, a permeability test and scaled model simulation were performed. The runoff characteristics of the IRD system with respect to rainfall intensity and duration were analyzed with dimensionless variables. With the prototype model, the drainage characteristics of the IRD system were analyzed over time using the hydrological curves. From the simulated results, it was found that the IRD system analyzed in this study was appropriate in the field by comparative analysis with the existing system based on peak runoff, internal storage, and lag time. Therefore, by applying the IRD system in the future, it is expected that the IRD has benefits, such as delayed lag time, surface runoff decrease, and an attenuation of the peak runoff.

Review and decision support of options for the removal, treatment and disposal of stormwater sediments

Stormwater management (SWM) ponds are a widely used option to control runoff, decrease flooding potential, reduce erosion rates in receiving waters and improve water quality. Although dredging and disposal are accepted practices, there is a need to consider alternative removal techniques, since 1) overall costs for a single pond can be substantial, and 2) a large number of ponds are approaching their operational capacity. It is evident that numerous remedial and beneficial reuse options are more economically viable and environmentally stable than current options. The intent of the current research was to develop guidance for municipalities and operators when faced with contaminated stormwater sediments. This paper presents a review of potential removal, treatment, disposal and beneficial use options and offers a simple decision support methodology to aid in the selection of options.

Review and decision support of options for the removal, treatment and disposal of stormwater sediments

Stormwater management (SWM) ponds are a widely used option to control runoff, decrease flooding potential, reduce erosion rates in receiving waters and improve water quality. Although dredging and disposal are accepted practices, there is a need to consider alternative removal techniques, since 1) overall costs for a single pond can be substantial, and 2) a large number of ponds are approaching their operational capacity. It is evident that numerous remedial and beneficial reuse options are more economically viable and environmentally stable than current options. The intent of the current research was to develop guidance for municipalities and operators when faced with contaminated stormwater sediments. This paper presents a review of potential removal, treatment, disposal and beneficial use options and offers a simple decision support methodology to aid in the selection of options.

Avaliação da esteira de turbulência gerada por um parque eólico teórico na região do Pampa Gaúcho utilizando o modelo WRF

The main objective of this study is to analyze the influence of a wind farm on the variables that control the flow in the atmospheric boundary layer. The simulated period was the whole year of 2008, using a control simulation performed with the Weather Research and Forecasting model (WRF), and the wind farm model (the WRF model with the module Fitch, which parameters the influence of wind turbines on atmospheric flow). Both simulations using the Yonsei-University (YSU) boundary layer parameterization. From the control simulation is made the validation of the model, using observational data collected in two automatic stations of the National Institute of Meteorology (INMET) in the cities of Alegrete-RS and Quaraí-RS. The wind farm idealized in this work has 100 wind generators of 3 MW of power with 120 m in height and with rotor measuring 125 m in diameter. Although the wind speed responds adequately, the temperature and turbulence of near-surface runoff decrease. Analysis of the dependence of near-surface turbulence with vertical stability indicates that the turbulence being generated by the turbines is not reaching the surface. This problem may be related to the chosen boundary layer parameterization.

Separating the effects of revegetation and sediment-trapping dams construction on runoff decrease in a semi-arid watershed of the Loess Plateau

<p>Runoff decrease as was triggered or exacerbated by human activities over the past decades on the Loess Plateau has grown to be a hot spot increasingly drawing nationwide concerns; distinguishing human-induced runoff-altering factors from one another is of great significance to decision-making on maintaining regional water, ecological and economic security. Sediment-trapping dams (STDs) construction and revegetation are the two major soil conservation practices regarded to have also caused runoff reduction, whose hydrologic effects on the basin scale have not been separated quantitatively. Our study, choosing the Huangfuchuan River Basin as the study area and based on analyses of its hydrologic, climatic and underlying condition changes, proposed a physically-based attribution framework which is able to account for the hydrological effects of STDs, revegetation, land use change and climate change simultaneously, and attributed runoff decrease of the basin among factors including climate change, STDs construction, revegetation and land use cover change. The model-based attribution results indicate that STDs construction caused a 45% (48%) runoff reduction from 1976-1988 to 1989-2000 (2001-2014) and revegetation was responsible for a 30% runoff decrease from 1976-1988 to 2001-2014, with daily simulation implying that the hydrologic effect of revegetation to affect flow magnitudes more consistently than that of STDs. Our study demonstrates that STDs construction is the prime contributor to runoff decrease in the study area and suggests that STDs should be taken into account in similar studies on the Loess Plateau in the future.</p>

Trends of Runoff Variation and Effects of Main Causal Factors in Mun River, Thailand During 1980–2018

Mun River is the largest tributary of the Mekong River in Thailand and provides abundant water resources not only for an important agricultural area in Thailand but also for the lower Mekong River. To understand how the runoff of Mun River responds to climate change and human activities in recent decades, this study performed a detailed examination of the characteristics of runoff variation based on measurements at two hydrological gauging stations on the main stem of Mun River during 1980–2018. Using the Mann-Kendall test, Morlet wavelet transform and Double Cumulative Curve methods, this study identifies that the variation of annual runoff of Mun River encountered an abruption in 1999/2000, with an increased trend taking place since then. Furthermore, a detailed assessment of the effects of the variations in rainfall, temperature, evaporation, and land use types extracted from remote sensing images at the basin scale reveals that a significant reduction in forest area and slight reductions in evaporation and farmland area taking place since 1999 can lead to an increase in the runoff of Mun River, while the dramatic increase in garden area since 1999 tends to make the runoff decrease.