Taoer River Basin Research Articles

A synergistic framework for dynamic water scarcity assessment: integrated blue and green water

ABSTRACT Dynamic assessment of water scarcity utilising blue and green water can enhance water resource management. The traditional water scarcity assessment mainly considers blue water, ignoring green water, for static evaluation. The improvement objective of this study is dynamically quantifying water scarcity, integrated blue and green water. This study proposed a framework to present an overview of water scarcity within multiple indicators and pinpoint water-stressed areas within an ever-changing process. The framework is based on the theorem of mutual change of quality and quantity to assess the spatiotemporal variability of blue and green water availability and to quantify water scarcity in watersheds. A case study was carried out in Taoer River Basin, a semiarid region of China, to demonstrate the use of the framework. The anthropogenic elements (such as water demand) and natural conditions were combined to quantify water scarcity, as measured by blue and green water scarcity indices. This study also analysed the variation of water scarcity on different spatiotemporal scales. The findings demonstrate that severe water scarcity has been occurring downstream with a tendency towards upstream of the watershed. Collectively, this study provides a useful tool for dynamic water scarcity assessment, helping develop policies to promote sustainable development.

Contribution of Climate Change and Human Activities to Runoff and Sediment Discharge Changes Based on Budyko Theory and Water–Sediment Relationships during 1960–2019 in the Taohe River Basin, China

Variations in runoff and sediment discharge are important characteristic variables for revealing the coupled effects of climate change (including both the natural variability of climate and anthropogenic climate change) and human activities (including soil and water conservation measures, land use changes, and hydraulic engineering construction). Based on the meteorological data from 19 meteorological stations and the hydrological data from the watershed control station of Hongqi Station, the temporal and spatial evolution of runoff and sediment discharge and the water–sand relationship were analyzed, and the response mechanisms of runoff and sediment discharge changes were clarified using Mikhail Budyko’s theory and other qualitative and quantitative methods. The results determined that: (1) The runoff and sediment discharge showed significant downward trends, with linear change rates of −0.28 × 108 m3/a and −46.10 × 104 t/a, respectively. The change points of the runoff and sediment discharge occurred in 1987 and 1996, respectively. (2) The spatial distribution of water and sediment was different, and the upper and middle reaches produced water, while the downstream produced sediment. (3) Comparing potential evapotranspiration and rainfall based on Budyko theory and the regression relationship, runoff is more closely related to rainfall, and runoff changes are more affected by it. The change in sediment discharge is most closely related to sediment concentration, followed by rainfall and potential evaporation. (4) The contribution rates of runoff and sediment discharge changes influenced by climate change were 24% and 3%, respectively, and the contribution rates by human activities were 76% and 97%, respectively. Human activities, including soil and water conservation measures, land use changes, and hydraulic engineering construction were the main influencing factors, and the impacts of human activities increased from 1960 to 2019. The research results are of great significance for erosion control and ecological restoration in the Tao River Basin under the conditions of the changing environment.

A surface and ground‐water integrated investigation of streamflow drying up in semi‐arid regions

AbstractGroundwater exploitations in semi‐arid regions result in significant declines of groundwater levels and streamflow and even trigger seasonal streamflow drying up, which may bring adverse impacts on riparian ecosystems. It is critical to explore future streamflow changes caused by variable climate scenarios and groundwater exploitation intensities; however, a comprehensive assessment of the streamflow drying up frequency remains lacking. Furthermore, the thresholds of controlling factors beyond which streamflow drying up occurs have rarely been explored. Here we develop an integrated surface water‐groundwater model for the Taoer River Basin (TRB), a typical semi‐arid watershed in northeast China. We apply the model to multiple future scenarios to reveal the frequency of potential streamflow drying up and explore the thresholds of controlling factors of streamflow drying up based on a decision tree method. We find that the groundwater level in the lower region of the TRB (LTRB) is hard to recover to the riverbed elevation and the streamflow drying up frequency is still high unless the groundwater exploitation is reduced by 50%. However, this leads to a competition between the ecological and economic objectives. Our results also show that the streamflow drying up frequency in the LTRB is very sensitive to the upstream water inflow that can be regulated through the reservoir operation or inter‐basin water diversion, indicating the importance of a basin scale strategic management. The findings of this paper can help policy makers sustainably exploit water resources in semi‐arid regions.

Quantifying the impact of climate variability and human activities on streamflow variation in Taoer River Basin, China.

Climate variability and human activity are the two driving forces that alter the hydrological cycle and spatiotemporal distribution of water resources. Using the Taoer River Basin (TRB) as an example, this study analyzed the impacts of climate variability and human activities on streamflow discharge in various periods and the resulting hydrological alterations. First, historical streamflow data were divided into four periods (baseline period and altered periods 1, 2, and 3). Based on the proposed basic identification framework, four assessment methods (the hydrological sensitivity method, distributed hydrological model, linear regression model, and runoff restoring computation) are used and provided relatively consistent estimates of streamflow attribution. Climate variability is the driving factor for streamflow changes, and the relative contributions in altered periods 1, 2, and 3 are 81% (+ 50.34mm), 68% (+ 13.37mm), and 53% (-19.23mm), respectively. In addition, climate variability and reservoir construction have different impacts on the hydrological regime at different periods, and reservoir regulation's effect on the hydrological regime depends on climatic conditions. Combined with this case study, we further discuss the necessity of breakpoint selection and period subdivision in the attribution of streamflow changes, and analyze the applicability of different methods with current ideas for improvement. This study not only has practical significance for water resource planning and adaptive policy formulation in the TRB but also provides a useful reference for similar studies.

Quantifying the effects of climate and watershed structure changes on runoff variations in the Tao River basin by using three different methods under the Budyko framework

Quantifying the effects of climate and watershed structure changes on runoff variations in the Tao River basin by using three different methods under the Budyko framework

Separating the contributions of climate change and human activities to regional AET variability by using a developed analytical framework

Actual evapotranspiration (AET) is a key factor in land-atmosphere interactions and a major hydrological cycle component. Variations in AET have resulted from a combination of climate change (CC) and human activities (HA). Quantifying the contributions of these two factors to AET dynamics is essential for better understanding hydrometeorological and ecohydrological processes under both natural and anthropogenic conditions. In this study, an analytical framework was adopted for AET variance analysis, and the influences of CC and HA on regional AET variabilities were separated by using this method. AET variance is determined by the variance in CC ( $${\sigma }_{AETc}^{2}$$ ) and HA ( $${\sigma }_{AETh}^{2}$$ ); the former is estimated through a synthesis of the variance/covariance of potential evapotranspiration (ET0) and precipitation (P), and the latter is determined from the residual between the total AET variance and $${\sigma }_{AETc}^{2}$$ . Based on a 36-year dataset (1980–2015), this framework is applied to the different regions of the Tao River Basin (TRB). The results reveal that climate was the primary factor influencing AET variance in most parts of the basin. Precipitation (P) dominated the $${\sigma }_{AETc}^{2}$$ and had a positive effect, while the interactions between P and ET0 tended to suppress this effect, especially in the semihumid areas of the TRB. The contribution rates of CC and HA to basin AET variance were estimated to be 0.76 and 0.24, respectively. The developed analytical framework and its application are beneficial to the management and exploitation of water resources from the perspective of basin ecohydrology.

Impact of environmental change on runoff in a transitional basin: Tao River Basin from the Tibetan Plateau to the Loess Plateau, China

Quantification of the impacts of environmental changes on runoff in the transitional area from the Tibetan Plateau to the Loess Plateau is of critical importance for regional water resources management. Trends and abrupt change points of the hydro-climatic variables in the Tao River Basin were investigated during 1956–2015. It also quantitatively separates the impacts of climate change and human activities on runoff change in the Tao River by using RCC-WBM model. Results indicate that temperature presented a significant rising trend (0.2 °C per decade) while precipitation exhibited an insignificant decreasing trend (3.8 mm per decade) during 1956–2015. Recorded runoff in the Tao River decreased significantly with a magnitude of −13.7 mm per decade and abrupt changes in 1968 and 1986 were identified. Relative to the baseline period (1956–1968), runoff in the two anthropogenic disturbed periods of 1969–1986 and 1987–2015 decreased by 27.8 mm and 76.5 mm, respectively, which can be attributed to human activities (accounting for 69%) and climate change (accounting for 31%). Human activities are the principal drivers of runoff reduction in the Tao River Basin. However, the absolute influences on runoff reductions by the both drivers tend to increase, from 7.7 mm in 1969–1986 to 24.4 mm in 1987–2015 by climate change and from 20.2 mm to 52.2 mm by human activities.

Quantitative impact of precipitation and human activity on runoff in the upper and middle Taoer River basin

Abstract Improved analysis and usage of water resources in the Taoer River basin requires an evaluation of the contributions of precipitation and human activities to runoff. In this study, we apply an integrated method combining the non-parametric Mann–Kendall trend test and the double-mass curve to analyze runoff data from 1961 to 2010. The major findings are as follows. (1) Annual runoff showed a statistically significant decrease, while precipitation showed no significant trend. (2) An abrupt change point was identified in 1998 at four representative stations, resulting in the study period being divided into pre-change and post-change periods for subsequent analysis. The double-mass curves were approximately linear in the pre-change periods, indicating that the dominant factor was probably climate change. Annual precipitation–runoff curves showed a decreasing trend from 1998, probably because of human activity. (3) The contributions of human activity to runoff in the post-change period for the four selected stations were 58.31%, 17.81%, 37.17%, and 47.66%, and the influence of human activity increased after the abrupt change point.

洮河流域水文水资源研究进展及未来展望

洮河流域水文水资源研究进展及未来展望

Influence of climate variability and human activities on stream flow variation in the past 50 years in Taoer River, Northeast China

Taoer River Basin, which is located in the west of Northeast China, is an agropastoral ecotone. In recent years, the hydrological cycle and water resources have changed significantly with the deterioration of the environment. Many water problems such as river blanking, wetland shrinking and salinization have occurred in this region. All of these phenomena were directly caused by changes in stream flow under climate variability and human activities. In light of the situation, the impact of climate variability and human activities on stream flow should be identified immediately to identify the primary driving factors of basin hydrological processes. To achieve this, statistical tests were applied to identify trends in variation and catastrophe points in mean annual stream flow from 1961 to 2011. A runoff sensitive coefficients method and a SIMHYD model were applied to assess the impacts of stream flow variation. The following conclusions were found: 1) The years 1985 and 2000 were confirmed to be catastrophe points in the stream flow series. Thus, the study period could be divided into three periods, from 1961 to 1985 (Period I), 1986 to 2000 (Period II) and 2001 to 2011 (Period III). 2) Mean annual observed stream flow was 31.54 mm in Period I, then increased to 65.60 mm in Period II and decreased to 2.92 mm in Period III. 3) Using runoff sensitive coefficients, the contribution of climate variability was 41.93% and 43.14% of the increase in stream flow during Periods II and III, suggesting that the contribution of human activities to the increase was 58.07% and 56.86%, respectively. 4) Climate variability accounted for 42.57% and 44.30% of the decrease in stream flow, while human activities accounted for 57.43% and 55.70% of the decrease, according to the SIMHYD model. 5) In comparison of these two methods, the primary driving factors of stream flow variation could be considered to be human activities, which contributed about 15% more than climate variability. It is hoped that these conclusions will benefit future regional planning and sustainable development.

Effects of Climate and Land Use Changes on Water Resources in the Taoer River

The changes of both climate and land use/cover have some impacts on water resources. In the Taoer River basin, these changes have directly influenced the land use pattern adjustment, wetland protection, connections between rivers and reservoirs, local social and economic development, and so forth. Therefore, studying the impacts of climate and land use/cover changes is of great practical significance. The Soil and Water Assessment Tool (SWAT) model is employed in this study. With historical measured runoff data and remote sensing maps of annual land use classifications, we analyzed the impacts of climate change on the runoff of the Taoer River. Based on the land use/cover classifications of 1990, 2000, and 2010, we analyzed the land use/cover change over the last 30 years and the contribution coefficient of farmland, woodland, grassland, and other major land use types to the runoff. This study can provide a reference for the rational allocation of water resources and the adjustment of land use structure for decision makers.

Erosion-Deposition Dataset of the Taoer River Basin in Northeast China

Erosion-Deposition Dataset of the Taoer River Basin in Northeast China

A case study of regional eco-hydrological characteristics in the Tao River Basin, northwestern China, based on evapotranspiration estimated by a coupled Budyko Equation-crop coefficient approach

In a case study in Tao River Basin, China, we derived a high spatial-resolution regional distribution of evapotranspiration (ET) using the single crop coefficient method and Budyko equation. We then further analyzed the spatio-temporal characteristics of this diverse eco-hydrological basin from 2001–2010. The results suggest that the single crop coefficient method based on leaf area index captures better spatial and temporal dynamics of the regional ET than did the Budyko Equation method. The rising temperature was the main reason for the increasing ET in the Tao River Basin during 2001–2010. Areas with high ET efficiency were distributed mainly in the areas where the vegetation coverage was high, and a lower runoff coefficient responded. The estimated spatial patterns of ET allowed an improved understanding of the eco-hydrological processes within the Tao River Basin and the method used might be generalized as a reference for future regional-scale eco-hydrological research.

Sediment Yield Simulation Using SWAT Model for Water Environmental Protection in an Agricultural Watershed

Soil erosion in a catchment has becoming a serious environmental issue for an increasing damage to the surface ecological environment. To quantitatively simulate the sediment yield, the Soil and Water Assessment Tool (SWAT) was introduced in Tao River Basin. The investigation was conducted using a 8-year historical observed sediment data from 2001 to 2008. The performance evaluation shows that the simulated monthly sediment yield matched the observed data satisfactorily, with Re was less than 15%, R2 > 0.9 and Nash-suttclife (Ens)>0.8 for both calibration (2001-2004) and validation period (2005-2008) at two observed stations, indicating the validity of SWAT model for sediment yield simulation in the study area. The results of this study can be helpful for solving the soil erosion issue for water environmental protection.

Regional vegetation dynamics and its response to climate change—a case study in the Tao River Basin in Northwestern China

The 30-year normalized-difference vegetation index (NDVI) time series from AVHRR/MODIS satellite sensors was used in this study to assess the regional vegetation dynamic changes in the Tao River Basin, which cuts across the Eastern Tibetan Plateau (ETP) and the Southwestern Loess Plateau (SLP). First, principal component and correlation analyses were carried out to determine the key climatic variables driving ecological change in the region. Then, regression models were tested to correlate NDVI with the selected climatic variables to determine their predictive power. Finally, Sen’s slope method was used to determine how terrestrial vegetation has responded to regional climate change in the region. The results indicated an average winter season NDVI value of 0.14 in the ETP but only 0.04 in the SLP. Primarily driven by increasing temperature, vegetation growth has generally been enhanced since 1981; spring NDVI increased by 0.03 every 10 years in the ETP and 0.02 in the SLP. Further, results from trend analyses suggest vegetation growth in the ETP shifted to earlier-start and earlier-end dates, however in the SLP, the growing season has been extended with an earlier-start and later-end date. The precipitation threshold for vegetation germination, measured by the cumulative spring rainfall, was found to be 44 mm for both the ETP and SLP.

Estimating Runoff and Environment Protection in Tao River Basin based on Swat Model

The Soil and Water Assessment Tool (SWAT) was used to simulate runoff yield in Tao River Basin on ArcView GIS platform. The main objective was to validate the performance of SWAT and the feasibility of this model as a simulator of runoff in a catchment. The investigation was conducted using a 6-year historical runoff record from 2001 to 2008 (2001-2004 for calibration and 2005-2008 for validation). The simulated monthly runoff matched the observed values satisfactorily, with Re was less than 20%, R2 > 0.78 and Nash-suttclife (Ens)>0.8 for both calibration and validation period at 4 hydrological stations. These indicated that the simulation of runoff was reasonable, reflecting the validity of SWAT model in Tao River Basin.

Optimization of Water Resources Utilization by PSO-GA

The objective of this paper is to present an optimal model to address the water resources utilization of the Tao River basin in China. The Tao River water diversion project has been proposed to alleviate the problem of water shortages in Gansu Province in China. A multi reservoir system is under consideration with multiple objectives including water diversion, ecological water demand, irrigation, hydropower generation, industrial requirements, and domestic uses in the Tao River basin. A multi-objective model for the minimization of water shortages and the maximization of hydro-power production is proposed to manage the utilization of Tao River water resources. An adjustable PSO-GA (particle swarm optimization – genetic algorithm) hybrid algorithm is proposed that combines the strengths of PSO and GA to balance natural selection and good knowledge sharing to enable a robust and efficient search of the solution space. Two driving parameters are used in the adjustable hybrid model to optimize the performance of the PSO-GA hybrid algorithm by assigning a preference to either PSO or GA. The results show that the proposed hybrid algorithm can simultaneously obtain a promising solution and speed up the convergence.

Research on Nitrogen Budgets of Agricultural Fields of the Tao River Basin

Based on a nitrogen (N) budget change model of agricultural fields, nitrogen budget change in each county in Tao River basin was calculated. For the whole basin, N-inputs, N-outputs and N-surpluses were obtained. The results indicated that N-inputs and N-outputs of Tao River from 2006 to 2008 increased obviously. The total N-inputs (N-outputs) in 2006, 2007 and 2008 were 31935 (18109) Tg, 33162 (17982) Tg and 33878 (19048) Tg, respectively. Compared the sources of N inputs, chemical fertilizer accounted for 44.94%, followed by human and animal excreta with 26.06%. For the N-outputs, the percent of crop harvest was biggest with 49.36%. N surpluses were 13826 Tg yr-1 in 2006, 15179 Tg yr-1 in 2007 and 15829 Tg yr-1 in 2008g. Annual growth rates were 9.9% in 2007 related to 2006 and 4.3% in 2008 related to 2007. The N-budgets with positive values showed that it increased significantly. Therefore, it was very urgent to control the non-point source of nitrogen pollution in Tao River basin.

Study on the Non-point Source Pollution in the Upper and Middle Reaches of the Taoer River Basin

Abstract The Taoer River basin is the epitome in the west of Northeast China and it is one of the most fragile and sensitive ecoregions. Thus, protection of water quality of the Taoer River is important. Not only point source pollution but non-point source (NPS) pollution results in deteriorating water quality. In this study, longterm hydrologic impact assessment model was used to evaluate the impacts of land use change impacts on NPS pollution, and the replacement cost method was used to calculate the economic loss caused by NPS pollution. Through analyzing the NPS pollutant loads of different land categories and the economic loss, the article puts forward that there exists a close relationship between landuse types and NPS pollution, and agricultural pollution is the main component of the NPS pollution in this area. The results of this study can provide decision-making basis for agricultural development and land-use change.

Spatial distribution of reference evapotranspiration considering topography in the Taoer river basin of Northeast China

Spatial distribution of reference evapotranspiration (ET0) is essential in water resources planning and management, especially in semi-arid areas. In this paper, a digital elevation model is used in an ‘interpolate-then-calculate’ approach to calculating the spatially distributed ET0 using the physically based Penman–Monteith equation in the Taoer river basin in China. The results show the following. (1) Of 11 interpolation methods, the Inverse Distance Weighting (IDW) method was found to be best for interpolating wind speed and a tri-variate secondary trend surface method was found most suitable for interpolating mean air temperature and relative humidity. Spatial modelling of the radiation environment considered the effects of elevation, slope and aspect. (2) Monthly values in January for the three meteorological variables showed larger spatial variations than in July, and just the reverse of net surface radiation. (3) The resulting ET0 calculated at each grid cell with 200 m resolution and its spatial variation showed strong seasonal variation. Lower ET0 was found in high-elevation southern Great Xingan mountains in the northwest basin, while higher values were located in the plains adjacent to the lower reach. (4) The ET0 distribution by the ‘interpolate-then-calculate’ approach better reflected the effects of topography than that of the ‘calculate-then-interpolate’ approach.