Lei Wu

Northwest A & F University · Institute of Water Resources and Hydropower Research

Changing the soil and underlying surface conditions is a key practice for realizing irrigation on‐site storage and infiltration. However, biochar addition and grass planting effects on soil infiltration and water retention capacity remain unclear. The effects of 0% biochar (C1), 1% biochar (C3), 2% biochar (C4), 3% biochar (C5) under ryegrass and 0...

Low resolution of input data and equifinality in model calibration can lead to inaccuracy and insufficient reflection of spatial differences, thereby increasing model errors. However, the impact of input data accuracy, catchment threshold area, and calibration algorithm on model uncertainty reduction has not yet been well understood. The sequential...

In hydrological studies, satellite and reanalysis precipitation products are increasingly being used to supplement gauge observation data. This study designed the composite simulation index (COSI), considering two factors: F1 (data accuracy assessment) and F2 (hydrological simulation performance), to compare the performance of the latest satellite-...

Water conservation is highly important for a successful desert grassland ecosystem, but there was no comprehensive view on how to assess influencing factors in managing and addressing water yield and water conservation in desert steppe. The Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model, which is specifically used for the...

The management of basin water and soil resources greatly benefits from investigating the spatial changes and primary determinants of hydrological and sediment connectivity from perspectives of topographic features, vegetation characteristics, structural features of river networks. However, quantifying the effects of influencing factors and their in...

Critical source area (CSAs) identification and subzone delineation could aid in streamlining watershed management. However, how to build a comprehensive evaluation index system based on the identification of CSAs is the key to solving the problem of management zoning, and this issue has not been fully reported yet. We applied the soil and water ass...

Quantitative identification of the covariation between sediment connectivity and soil erosion can contribute to provide the key information for watershed sediment management. However, this covariation and its spatiotemporal response mechanisms are still unclear, especially whether this covariation can be used as a basis for identifying critical sou...

Climate and land-use change significantly impact hydrological processes and water resources management. However, studies of runoff simulation accuracy and attribution analysis in large-scale basins based on multi-source data and different scenario projections are limited. This study employed the Soil and Water Assessment Tool (SWAT) model in conjun...

Calibration methodologies must extract as much information as possible from available data, but it is not well understood in investigating the multi-objective synchronous calibration strategy by using multiple sources of information and by exploiting the data in better ways. The non-dominated sorting genetic algorithm II (NSGA-II) is introduced to...

Detention pond is a key storm water management measure employed both to attenuate surface runoff and to regulate depression storage, yet the effects of aquaculture ponds and reservoirs on runoff coefficient are not well quantified in a subtropical humid monsoon climate zone, China. Here, a set of six subcatchments ranging in size from 0.7 hm² to 10...

Climate and underlying-surface changes give rise to governance challenges in water resource management in arid and semi-arid regions, and knowledge of the spatiotemporal patterns of water yield is critical in policy and stakeholder engagement. The Soil and Water Assessment Tool (SWAT) model was integrated using spatial autocorrelation analysis, emp...

Modelling tools are commonly used for predicting non-point source (NPS) pollutants and it is timely to review progress that has been made in terms of the development of NPS models. This paper: (1) proposes a systematic description of model framework and generalizes some commonly used models; (2) identifies the common challenges in model structure a...

Efficient best management practices (BMPs) must be both economically and technically feasible; however, designing adequate BMP planning by considering the trade-offs between efficacy and cost-effectiveness is considerably challenging for reducing the environmental impact of soil erosion. To comprehensively evaluate and screen the efficacy and cost-...

In large‐scale watersheds, only the calibration of parameters for the outlet may ignore spatial heterogeneity and fail to meet the simulation accuracy of local areas. Based on the runoff observation data of three hydrological stations (Qingyang, Yangjiaping, and Zhangjiashan) in the Jinghe River Watershed, single‐ and multi‐site calibration strateg...

Many options for reducing nitrogen (N) losses from agriculture rely on changing the surface pathways of N runoff in one way or another, but the runoff N mechanism by agricultural interventions such as biochar, grass, and cross-ridge is not well understood. Herein, 12 artificial simulated rainstorms by three biochars (0%, 3%, and 6%), two planting m...

The phenomenon of "equifinality for different parameters" limits the link between parameters and catchment characteristics; however, solving the equifinality problem is a major challenge in the development, generalization, and application of a model. This study focused on the Yanhe River Watershed to investigate the time-varying characteristics of...

Agricultural interventions such as biochar, grassing, and different planting modes affect the migration and transformation of soil phosphorus (P). However, the effect of different management practices on the mechanism of runoff P fractions and possible tradeoffs associated with consecutive rainstorms is not well understood. This study aggregated ma...

Nitrogen (N) is one of the most common macronutrients applied to soil to promote crop productivity, but no more information can be found in the effect of different management practices on the surface pathways of N loss in the process of drying-rewetting alternation. In this study, the laboratory intermittent rainstorms were adopted to quantify the...

Water erosion is one of the main types of soil degradation, but few quantitative estimates have been done in the soil erosion intensity grades of different landscape scaling characteristics in a large-scale ecological restoration watershed. This study comparatively illustrates the utility of high-resolution data and geospatial technique, particular...

Slope and rainfall intensity are important factors affecting runoff phosphorus (P), but the dynamic mechanism of their coupled influence on P fractions in loessial bare sloping lands is not completely understood. The critical slope and critical rainfall intensity are thresholds associated with significant changes in runoff, erosion, and/or nutrient...

The sediment delivery ratio (SDR) is a key link between slope erosion and river sediment transport but the accurate quantification of sediment yield in different catchments has been hampered by a lack of dynamic multi-scale information on SDR. A dynamic multi-scale SDR algorithm was innovatively applied in the modified sediment yield model to quant...

Sloping farmland is widely distributed in Chinese loess hilly regions but the coupling mechanism between slope gradient and sediment yield was not clear in a large-scale ecological restoration watershed. A piecewise sediment delivery ratio (SDR) algorithm was embedded in the Revised Universal Soil Loss Equation (RUSLE) to identify the spatiotempora...

Land use structure is an important factor affecting soil nutrient loss but the influencing mechanism of land use change on particulate nutrient loss is still unclear in large-scale ecological restoration regions. In this study, an integrated, physically-based modeling framework was put forward to identify the dynamic effects of land use change on p...

Vegetation is an important factor affecting nutrient enrichment ratio in runoff sediments but few studies have been examined in the effects of different vegetation scenarios on the monthly evolutions of particulate nitrogen (N) and phosphorus (P) loss. In this study, a vegetation correction coefficient was innovatively embedded in a dynamic particu...

Nonpoint source (NPS) pollution has been studied for many years but it exhibits random, widespread, complex uncertainties which make it difficult to manage and control. We employ group decision-making utilizing the fuzzy comprehensive evaluation method (FCE) and the analytic hierarchy process method (AHP) and comparatively evaluate the optimal allo...

Soil and nutrient loss is a common natural phenomenon but it exhibits unclear understanding especially on bare loess soil with variable rainfall intensity and slope gradient, which makes it difficult to design control measures for agricultural diffuse pollution. We employ 30 artificial simulated rainfalls (six rainfall intensities and five slope gr...

Land-use change is one of the important topics of regional ecological restoration research, but it exhibits high interdependencies in social-ecological systems which make it difficult to predict spatiotemporal variability and identify the main drivers. We employ long-term dynamic predictions utilizing an integrated cellular automata–Markov (CA–Mark...

The pulsed events of rainstorm erosion on the Loess Plateau are well-known, but little information is available concerning the characteristics of superficial soil erosion processes caused by heavy rainstorms at the watershed scale. This study statistically evaluated characteristics of pulsed runoff-erosion events based on 17 observed rainstorms fro...

Soil erosion is a universal phenomenon on the Loess Plateau but it exhibits complex and typical mechanism which makes it difficult to understand soil loss laws on slopes. We design artificial simulated rainfall experiments including six rainfall intensities (45, 60, 75, 90, 105, 120 mm/h) and five slopes (5°, 10°, 15°, 20°, 25°) to reveal the funda...

The Guanzhong region is one of the water resources shortage areas and also an important food producing area in Chinese Loess Plateau. The unreasonable application of irrigation and pesticide not only reduces the utilization rate of pesticides, but also is a potential threat to aquatic environments. In order to explore the reasonable application pat...

Chinese Loess Plateau is considered as one of the serious soil erosion regions in the world. Nutrient loss through runoff and sediment in highly erodible areas not only decreases soil fertility, but also creates many environmental problems. In this study, an integrated modelling framework for the distributed coupling of hydrological process, soil e...

The watershed sediment delivery ratio (SDR) reflects the transport status of eroded soil in a watershed, and it is an important parameter in studying the relationship between basin erosion and sediment yield of rivers. This review study mainly focuses on China. Based on existing studies of the SDR, this study reviews and summarizes the definition,...

Air temperature changes are one of the main factors that cause variability in the natural landscape and living environment. In this study, spatio-temporal evolutions in temperature in the Yellow River basin were statistically interpolated by the partial thin plate smoothing spline method for the period 1981–2013. Results indicate that: (1) the inte...

The pollution load of urban runoff is boosted due to the washing away of road-deposited sediment (RDS). Therefore, a source-oriented mitigation strategy is essential to integrated stormwater management. This study showcases the influence of land use dependent source apportionment and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in RDS...

Soil erosion is the main pathway of nutrients to fresh water in highly erodible regions. In this study, a dynamic erosion-type nonpoint source (NPS) pollution model was proposed to investigate spatiotemporal characteristics of adsorbed NPS total nitrogen (TN) load before and after returning farmland. Results indicate that: 1) the erosion-type NPS T...

A GIS-based dynamic sediment yield model based on the USLE equation was established to investigate sediment yield evolutions in an easily- eroded watershed of the Loess Plateau from 1995 to 2012. Results indicate that: 1) the dynamic model considering annual changes of precipitation and land management can be used as an effective tool to evaluate s...

Soil erosion not only results in the destruction of land resources and the decline of soil fertility, but also contributes to river channel sedimentation. In order to explore the spatiotemporal evolution of erosion and sediment yield before and after returning farmland in a typical watershed of the hilly and gully region (Chinese Loess Plateau), a...

Soil erosion not only results in the destruction of land resources and the decline of soil fertility, but also makes river channel sedimentation. In order to explore spatiotemporal evolution of erosion and sediment yield before and after returning farmland in a typical watershed of hilly and gully region, Chinese Loess Plateau, a distributed, dynam...

The quantitative estimation of nonpoint source (NPS) pollution load in large river basins is one of the important issues in watershed modeling. This study focuses on Beiluohe River watershed and takes Johnes export coefficient model as a starting point to establish three kinds of modified export coefficient model and estimate NPS total nitrogen (TN...

Loss of nitrogen and phosphorus in the hilly and gully region of Chinese Loess Plateau not only decreases the utilization rate of fertilizer but also is a potential threat to aquatic environments. In order to explore the process of erosion-type non-point source (NPS) pollution in Majiagou watershed of Loess Plateau, a distributed, dynamic, and inte...

The partial thin plate smoothing splines method was applied to evaluate spatiotemporal trends of precipitation in the Yellow River basin from 1981 to 2013 by considering the basin's digital elevation model. Results indicate the following. (1) The spline method can greatly improve the spatial interpolation accuracy of meteorological data and can be...

Rainfall erosivity is considered as one of the most important factors in the universal soil loss equation (USLE) or its revised form (RUSLE); it can directly reflect the potential of soil erosion caused by rainfall. In this study, the simple algorithms of rainfall erosivity including the Wischmeier model and the half-month model are selected and us...

Soil erosion is one of the most important environmental concerns in the hilly and gully region of the Chinese Loess Plateau. In this study, a distributed soil erosion model considering the shallow gully erosion (ephemeral gully erosion) was used to simulate and track soil erosion changes in an easily-eroded watershed from 1985 to 2010. Results indi...

The surface water of 10 major river systems across China has been under intermediate pollution with striking eutrophication problems in major lakes (reservoirs). More data from the Ministry of Environmental Protection of China showed that underground water in 57% of monitoring sites across Chinese cities was polluted or extremely polluted. Rural wa...

Chinese Loess Plateau is considered as one of the most serious soil loss regions in the world, its annual sediment output accounts for 90 % of the total sediment loads of the Yellow River, and most of the Loess Plateau has a very typical characteristic of "soil and water flow together", and water flow in this area performs with a high sand content....

Extensive application of various pesticides preserves high quality in agricultural production, and it is also a potential threat to water and soil environments. In order to explore the transport and fate of insecticides with rainfall and irrigation in canopy-soil systems, an integrated pesticide transport modeling system has been applied for simula...

The demand for assessing both the variability of risk areas and the intensity of pollutant load rates on pesticide transferring to waters in China has been increasingly vigorous in recent decades. Therefore, to explore the transport of linuron with rainfall and irrigation in canopy-soil systems, an integrated pesticide transport modeling system has...

Sequencing batch reactor (SBR) technology has become one of the commonly used treatment systems for municipal and industrial wastewater in the past decades. Cyclic activated sludge technology is one of the newly developed variations of SBR process. In this study, because the water quality situation of effluent under low-temperature and high-load co...

Agricultural nonpoint source (NPS) pollution at the Three Gorges reservoir area in China has been increasingly recognized as a threat to aquatic environment in recent years due to the serious eutrophication problem. Adsorbed NPS pollution is one of the major forms of NPS pollution in mountainous regions, the essential of the adsorbed NPS pollution...

The presence of pesticides via non-point source (NPS) pollution might be a threat to human health and aquatic ecosystems. This study aims to characterize quantitatively the distribution and transport of Linuron in a coupled canopy-soil system by using modelling techniques, viz. an integrated pesticide transport modelling system to simulate three-ph...

Highlights ► B2 climate scenario was coupled with the SLURP hydrological model to evaluate future rainfall runoff. ► The dynamic coefficients into the river were proposed to improve the simulation accuracy of load. ► The dynamic integrated model was presented to study change processes of runoff and load. ► The climate and land-use changes will be t...

The improvement of separation efficiency (SE) and production capacity of a hydrocyclone by introducing a newly-designed structure is a significant challenge when applying Reynolds Averaged Navier Stokes (RANS) turbulence modeling techniques. This study aims to solve the problem that the high content of fine sands in summer in the Chongqing section...

The presence of nonpoint source (NPS) pollution due to agricultural activities at the Three Gorges Reservoir Area in China has been of concern to the public in recent years. Due to the extent of the polluted area and seasonal dispersion mode, sediments have greatly impacted the water quality in the area. Generation and formation of adsorbed NPS pol...

Jialing River, which covers a basin area of 160,000 km2 and a length of 1,280 km, is the largest tributary of the catchment area in Three Gorges Reservoir Area, China. In recent years, water quality in the reservoir area section of Jialing River has been degraded due to land use and the rural residential area induced by non-point source pollution....

Soil erosion model is a foundation for the estimation of adsorbed non-point source (NPS) pollution load at catchment scales. Empirical models are useful for estimating soil erosion, particularly when only limited data are available. In all empirical models, the Universal Soil Loss Equation (USLE) or the Revised Universal Soil Loss Equation (RUSLE)...

Jialing River is the largest tributary in the catchment area of Three Gorges Reservoir, and it is also one of the important areas of sediment yield in the upper reaches of the Yangtze River. In recent years, significant changes of water and sediment characteristics have taken place. The "Long Control" Project implemented since 1989 had greatly chan...

To study non-point source pollution carried by rainfall runoff in the large-scale basins, based on semi-distributed land use runoff processes (SLURP) model, the construction method for prediction models of total phosphorus (TP) and total nitrogen (TN) load, and the future meteorological parameters and land-use map were proposed respectively. By app...

Three batches of water samples were collected from Xiangxi River between March to May 2010, and the L9(34) orthogonal experiments of algae growth were conducted in laboratory. Nutrient concentrations in water, water temperature, light intensity and water flow velocity were selected as environmental factors, and the growth rate of Chla was taken as...

Hydrodynamic conditions are important factors for planktonic algae growth, through introducing two parameters which express the optimal velocity and the velocity range for planktonic algae growth, a new velocity factor was put forward for the formula of growth rate. Therefore, the two-dimensional unsteady ecological dynamic model for algae growth w...

By introducing two parameters which express the optimal velocity and the velocity range for alga growth, a new velocity factor was put forward for the formula of alga growth. The 2-D unsteady ecological dynamic model for algae growth was established to analyze the effects of hydrodynamic condition on algae growth in Chongqing reaches of Jialing Riv...

Xiao-jiang, with a basin area of almost 5,276 km(2) and a length of 182.4 km, is located in the center of the Three Gorges Reservoir Area, and is the largest tributary of the central section in Three Gorges Reservoir Area, farmland accounts for a large proportion of Xiao-jiang watershed, and the hilly cropland of purple soil is much of the farmland...

Xiao-Jiang River is the largest tributary on the north of the middle part in Three Gorges reservoir area, because of predominant hilly cropland with purple soil, the dissolved nitrogen from surface and subsurface runoff caused by raining accounts for most part of the nitrogen pollution in water. This paper develops the annual pollution models based...