| The change of water area in Shenwu irrigation area of Hetao irrigation area has important influence on maintaining the ecological balance of irrigation area.This paper takes the land classification of long time series in Shenwu irrigation area as the starting point,one of its underlying surfaces is analyzed from the perspective of LUCC(Land-Use and Land-Cover Change)—long time series variation of water area.This paper focuses on the analysis of the long time series changes and driving factors of the total water area and the areas of Jinma lake,Nalin lake,Guyuechen lake and Zhuanzhaojing haizi natural lakes.At the same time,the water depth of four natural lakes was inverted and the water volume was estimated.The main conclusions are as follows:1.The land classification of Shenwu irrigation area was carried out by stratification classification,supervised classification and mask technology.The results showed that the area of water area,cultivated land,forest and grass land and urban and rural construction land in the study area continued to increase,and the area increased by 25.13km,485.18km,223.12km and 19.81km respectively in 34 years,while the unused land area showed a continuous decrease trend in 34 years,with a total decrease of 753.24km.The classification accuracy was greater than the Kappa coefficient was greater than 0.94,and the drawing accuracy and user accuracy were more than 88%.LUCC from 1986 to 2019 was analyzed through the change confusion matrix.It is concluded that the irrigation area of Shenwu is mainly cultivated land,forest and grassland and unused land alternations.2.The total water area and natural lake area in Shenwu irrigation area from 1986 to 2019 were analyzed.It is concluded that the dynamic change process of the total water area over time has experienced the continuous expansion-continuous shrinkage-wave expansion phase.The four natural lakes(Jinma lake,Nalin lake,Guyuechen lake and Zhuanzhaojing haizi)in the irrigation area all experienced the stage of continuous expansion-wave shrinkage-wave expansion.3.By analyzing the driving factors of climatic factors(annual evaporation,annual precipitation,annual average temperature and annual average wind speed),human activities factors(autumn irrigation diversion,total diversion,ecological replenishment,total population,urban and non-urban population,gross domestic product,added value of the first,second and third industries),the dynamic change of water area in the study area is analyzed.The results show that the evolution of the total water area and the natural lake area in the irrigation area are produced under the joint influence of climatic factors and human factors.In the general environment of climatic factors,the contribution of human factors cannot be ignored.4.Based on the remote sensing data,depth inversion models of different variables were constructed for four natural lakes,and the optimal model was selected for depth inversion.The optimal model of Jinma lake is a non-logarithmic model with five variables,the average absolute error of water depth inversion model of Jinma lake is between 0.15m and 0.25m,the average relative error ranges from 6%to 12%.The optimal models for water depth inversion of Narin lake,Guyuechen lake and Zhuanzhaojing haizi are all five variable logarithmic models,the average absolute error of the three lakes depth inversion models is between 0.41m and 0.62m,the average relative error is between 21%and 40%.5.Based on the inversion of natural lake depth,ENVI software was used to estimate the volume of water in four natural lakes,VNarin lake>VZhuanzhaojing haizi>V Jinma lake Guyuechen lake.The results of this study provide technical support for the maintenance of water ecological balance and protection in Shenwu irrigation area,and provide theoretical basis for the appropriate amount of water from the Yellow River in the irrigation area... |
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