scholarly journals Analysis of the Spatial and Temporal Changes of NDVI and Its Driving Factors in the Wei and Jing River Basins

2021 ◽  
Vol 18 (22) ◽  
pp. 11863
Author(s):  
Chenlu Huang ◽  
Qinke Yang ◽  
Weidong Huang
Keyword(s):  
Soil Moisture ◽  
Random Forest ◽  
River Basin ◽  
Water Conservation ◽  
Human Activities ◽  
Driving Factors ◽  
Positive Effects ◽  
Wei River ◽  
Soil And Water ◽  
Measurement Period

This study aimed to explore the long-term vegetation cover change and its driving factors in the typical watershed of the Yellow River Basin. This research was based on the Google Earth Engine (GEE), a remote sensing cloud platform, and used the Landsat surface reflectance datasets and the Pearson correlation method to analyze the vegetation conditions in the areas above Xianyang on the Wei River and above Zhangjiashan on the Jing River. Random forest and decision tree models were used to analyze the effects of various climatic factors (precipitation, temperature, soil moisture, evapotranspiration, and drought index) on NDVI (normalized difference vegetation index). Then, based on the residual analysis method, the effects of human activities on NDVI were explored. The results showed that: (1) From 1987 to 2018, the NDVI of the two watersheds showed an increasing trend; in particular, after 2008, the average increase rate of NDVI in the growing season (April to September) increased from 0.0032/a and 0.003/a in the base period (1987–2008) to 0.0172/a and 0.01/a in the measurement period (2008–2018), for the Wei and Jing basins, respectively. In addition, the NDVI significantly increased from 21.78% and 31.32% in the baseline period (1987–2008) to 83.76% and 92.40% in the measurement period (2008–2018), respectively. (2) The random forest and classification and regression tree model (CART) can assess the contribution and sensitivity of various climate factors to NDVI. Precipitation, soil moisture, and temperature were found to be the three main factors that affect the NDVI of the study area, and their contributions were 37.05%, 26.42%, and 15.72%, respectively. The changes in precipitation and soil moisture in the entire Jing River Basin and the upper and middle reaches of the Wei River above Xianyang caused significant changes in NDVI. Furthermore, changes in precipitation and temperature led to significant changes in NDVI in the lower reaches of the Wei River. (3) The impact of human activities in the Wei and Jing basins on NDVI has gradually changed from negative to positive, which is mainly due to the implementation of soil and water conservation measures. The proportions of areas with positive effects of human activities were 80.88% and 81.95%, of which the proportions of areas with significant positive effects were 11.63% and 7.76%, respectively. These are mainly distributed in the upper reaches of the Wei River and the western and eastern regions of the Jing River. These areas are the key areas where soil and water conservation measures have been implemented in recent years, and the corresponding land use has transformed from cultivated land to forest and grassland. The negative effects accounted for 1.66% and 0.10% of the area, respectively, and were mainly caused by urban expansion and coal mining.

scholarly journals Effects of water and soil conservation works on runoff and sediment variation in the areas with high and coarse sediment yield of the middle Yellow River

2018 ◽  
Vol 38 ◽  
pp. 01033
Author(s):  
Wei Ying Sun ◽  
Pan Zhang ◽  
Li Li ◽  
Jiang Nan Chen
Keyword(s):  
Sediment Yield ◽  
Water Conservation ◽  
Human Activities ◽  
Soil Conservation ◽  
Yellow River ◽  
Soil And Water Conservation ◽  
Contribution Rate ◽  
Rainfall Variation ◽  
Runoff Reduction ◽  
Soil And Water

The areas with high and coarse sediment yield of the middle Yellow River is well known for its severe erosion, high sediment yields. Since 1982 when the 8 key soil and water conservation harnessing regions has been built, the ecological environment has been gradually improved and the amount of sediment and runoff entering the Yellow River has been reduced continuously. Some researchers considered that it was owing to the water and soil conservation works (WSCW), while others believed that it was caused by the rainfall variation, but this has not been quantified for the effect respectively. This paper deals with the effects of WSCW on runoff and sediment variation. The study has been carried out in the Sanchuanhe River watershed, where was listed as one of the 8 key soil and water conservation harnessing regions. The results show that the contribution rate of human activities was 80.2% after 1st harnessing stage (1970-1979), 43.0% after 2nd harnessing stage (1980-1989), in 3rd harnessing stage (1990-1996) it reached 98.4%, and was 44.8% after 4th harnessing stage (1997-2006). With regard to the influence on runoff reduction in the watershed, the contribution rate of human activities was 62.5% compared with the natural factors after 1st harnessing stage (1970-1979), 28.4% after 2nd harnessing stage (1980-1989), in 3rd harnessing stage (1990-1996) it reached 69.6%, and was 37.0% after 4th harnessing stage (1997-2006). The results revealed that human activities exerted the largest effects on the sediment reduction and explained 66.6% of the variation in the specific sediment yield. This study suggests that a combination of human activities and rainfall variation effectively reduces runoff and sediment delivery of the Loess Plateau. Generally The runoff reduction and contribution of rainfall variation to runoff reduction in this area were as large as human activities. After many years' harnessing the great benefit have been obtained in water and soil loss control in this watershed.

Integrated framework for soil and water conservation in Kosi River Basin

2018 ◽  
Vol 35 (4) ◽  
pp. 391-410 ◽  
Author(s):  
Rajani Kumar Pradhan ◽  
Prashant K. Srivastava ◽  
Swati Maurya ◽  
Sudhir Kumar Singh ◽  
Dhruvesh P. Patel
Keyword(s):  
River Basin ◽  
Water Conservation ◽  
Soil And Water Conservation ◽  
Integrated Framework ◽  
Soil And Water

scholarly journals Changes in streamflow regimes and their response to different soil and water conservation measures in Loess Plateau watersheds

2021 ◽  
Author(s):  
Shuyu Zhang ◽  
Guangju Zhao ◽  
Xingmin Mu ◽  
Peng Tian
Keyword(s):  
Loess Plateau ◽  
Water Conservation ◽  
Human Activities ◽  
Soil And Water Conservation ◽  
Low Flow ◽  
Hydrological Change ◽  
River Watershed ◽  
Daily Streamflow ◽  
Conservation Measures ◽  
Soil And Water

Investigating the changes in streamflow regimes is useful for understanding the mechanisms associated with hydrological processes in different watersheds and for providing information to facilitate water resources management. In this study, we selected three watersheds, i.e., Sandu River, Hulu River, and Dali River on the Loess Plateau, to examine the changes in the streamflow regimes and to determine their responses to different soil and water conservation measures (terracing, afforestation, and damming). The daily runoff was collected continuously by three hydrological gauges close to the outlets of the three watersheds from 1965 to 2016. The eco-surplus, eco-deficit, and degree of hydrological change were assessed to detect hydrological alterations. The Budyko water balance equation was applied to estimate the potential impacts of climate change and human activities on the hydrological regime changes. Significant decreasing trends (P < 0.05) were detected in the annual streamflow in the Sandu and Dali River watersheds, but not in the Hulu River watershed where afforestation dominated. The annual eco-surplus levels were low and they decreased slightly at three stations, whereas the eco-deficit exhibited dramatic increasing trends in the Sandu and Dali River watersheds. In the Sandu River watershed (dominated by terraces), the runoff exhibited the most significant reduction and the eco-deficit was the highest among the three watersheds. The integral degrees of hydrological change were higher in the Sandu River watershed than the other two watersheds, thereby suggesting substantial variations in the magnitude, duration, frequency, timing, and rate of change in the daily streamflow. In the Dali River watershed (dominated by damming), the changes in the extreme flow were characterized by a decreasing number appearing in high flow. In these watersheds, human activities accounted for 74.1% and 91.78% of the runoff reductions, respectively. In the Hulu River watershed (dominated by afforestation), the annual runoff exhibited an insignificant decreasing trend but with a significant increase in the low flow duration. Rainfall changes accounted for 64.30% of the runoff reduction.

scholarly journals Causes of Variations in Sediment Yield in the Jinghe River Basin, China

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jinliang Zhang ◽  
Yizi Shang ◽  
Jinyong Liu ◽  
Jian Fu ◽  
Shitao Wei ◽  
...  
Keyword(s):  
River Basin ◽  
Sediment Yield ◽  
Water Conservation ◽  
Yellow River ◽  
Soil And Water Conservation ◽  
Water Diversion ◽  
Sediment Discharge ◽  
Jinghe River Basin ◽  
Jinghe River ◽  
Soil And Water

Abstract The Jinghe River remains the major sediment source of the Yellow River in China; however, sediment discharge in the Jinghe River has reduced significantly since the 1950s. The objective of this study is to identify the causes of sediment yield variations in the Jinghe River Basin based on soil and water conservation methods and rainfall analyses. The results revealed that soil and water conservation projects were responsible for half of the total sediment reduction; sediment retention due to reservoirs and water diversion projects was responsible for 1.3% of the total reduction. Moreover, the Jinghe River Basin has negligible opportunity to improve its vegetation cover (currently 55% of the basin is covered with lawns and trees), and silt-arrester dams play a smaller role in reducing sediment significantly before they are entirely full. Therefore, new large-scale sediment trapping projects must be implemented across the Jinghe River Basin, where heavy rainfall events are likely to substantially increase in the future, leading to higher sediment discharge.

The Impacts of Different Land Use Patterns on Water Volume in the Xixian Watershed, China

2015 ◽  
Vol 737 ◽  
pp. 728-731 ◽  
Author(s):  
Yuan Yuan Han ◽  
Tao Cai
Keyword(s):  
Land Use ◽  
Time Series ◽  
Land Use Change ◽  
River Basin ◽  
Water Conservation ◽  
Swat Model ◽  
Water Volume ◽  
Huaihe River Basin ◽  
Huaihe River ◽  
Soil And Water

In this study, Soil and Water Assessment Tool (SWAT) model was used to simulate land-use change effects on water quantity in the upper Huaihe river basin above the Xixian hydrological controlling station with a catchment area of 10,190 km2 by the use of three-phase (1980s、1990s、2000s) land-use maps, soil type map (1:200000), 1980 to 2008 daily time series of rainfall from the upper Huaihe river basin. On the basis of the simulated time series of daily runoff, land-use change effects on spatio-temporal change patterns of runoff coefficients and runoff modules were investigated. The results revealed that under the same condition of soil texture and terrain slope the advantage for runoff generation and the sensitivity of rainfall-runoff relationship to rainfall descended by farmland, paddy field, woodland.The outputs could provide important references for soil and water conservation and river health protection in the upper stream of Huaihe river.

Study on Off-Stream Ecological Water Demand of Fu River Basin

2014 ◽  
Vol 641-642 ◽  
pp. 92-96
Author(s):  
Fa Lei Wang ◽  
Wei Hu
Keyword(s):  
River Basin ◽  
Water Conservation ◽  
Water Demand ◽  
Green Space ◽  
Sewage Treatment ◽  
Scientific Basis ◽  
Soil And Water Conservation ◽  
Ecological Water Demand ◽  
Public Green Space ◽  
Soil And Water

According to researches on mechanism and concept of off-stream ecological water demand, off-stream ecological water demand of Fu River Basin is consist of ecological water demand for soil and water conservation and for urban public green space, considering the current situation and planning objectives of off-stream ecological water demand of Fu River Basin. Directly calculation method is employed in this study. Choosing 2005 as the current year in this study, indicators of public green space and soil erosion data are obtained. Then the ecological water demand of urban public green space in Fuzhou City is determined as 0.438×108m3 and the water demand for off-stream soil and water conservation in Fu River Basin is determined as 0.3159×108m3 in virtue of quota method. The off-stream ecological water demand in the Basin (2005 as the current year) is about 0.359×108m3. The determination of the off-stream ecological water demand in the basin provide a scientific basis on taking a variety of water-saving measures, improving the recovery rate of sewage treatment and increasing the off-stream ecological water consumption. Results of this study will make the ecological environment of this area to achieve a healthy state, and shall greatly improve regional water resources and water environmental situation.

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