| With the rapid development of social economy,land use change has became the leading factor of regional environmental change.The shortage of land resources are becoming increasingly serious,which leads to the prominent contradiction between the human and land.Based on the data of 1999?2003?2008?2013 and 2018,this paper takes the land use change along the Yellow River from Zhongwei to Shizuishan in Ningxia as the research object based on the five-year remote sensing image data and GIS technology platform.This paper studies the range,dynamic degree,river evolution characteristics and spatial distribution of land-use change in the study area,which analyzes the driving force of land-use change in the study area from natural?social and economic aspects that preliminarily obtains the following research results:(1)In the past 20 years,the cultivated land area along the Yellow River in Zhongwei Shizuishan of Ningxia has increased slowly year by year,with a change rate of 14.66%.The construction land and industrial land have increased year by year,with a change rate of 6102.74%.The urbanization and industrialization are developing rapidly.The area of water area and beach land is decreasing while the area of other water areas is increasing.(2)1999-2003.In terms of land use change,the largest change area of cultivated land is 83.39 km2 that is reduced by-2.98%.The single land use dynamic degree is-0.75%,which is mainly converted into desertification grassland?beach land and water area.The area of urban land increased,the change range was 541.01%,the dynamic degree of single land use was 135.25%,and the urban land was mainly transformed from cultivated land and desertification grassland.The area of desert decreased,mainly converted into desertification grassland and cultivated land.The area of tidal flat is reduced,which is mainly transformed into water area,cultivated land and desertification grassland.In terms of river channel evolution:erosion in Shapotou section and Huinong section is greater than accumulation,which has an erosion effect on Shapotou section and Huinong section due to the increasing of water area;accumulation in Zhongning section and Qingtongxia section is greater than erosion,which is mainly due to the conversion of water area and other water surfaces into cultivated land,and the increasing of cultivated land?urban land?industrial and mining land area encroaches on a part of river channel,resulting in accumulation.3)2003-2008.In terms of land use change,the largest change area of Desertification Grassland is 505.10km2,with a decrease of-12.73%and a single land use dynamic degree of 2.55%,which is mainly converted into cultivated land?urban land and other water surfaces.The cultivated land area increased by 364.83km2,the change range was 13.45%,and the single land use dynamic degree was 2.69%,which was mainly converted into desertification grassland?urban land and other water surfaces.The area of urban land increased by 82.21km2,with a change range of 90.53%,mainly converted into cultivated land,industrial and mining land and desertification grassland.The area of industrial and mining land increased by 25.09km2.In the aspect of channel evolution,the accumulation of Shapotou and Huinong is larger than erosion,and the erosion of Zhongning and Qingtongxia is larger than accumulation.With the rapid development of economy,the rapid growth of urbanization and industrialization encroaches on the river course.With the rapid development of agriculture and the increase of cultivated land area,the Yellow River irrigation leads to the deposition of river channels.Both man-made destruction and man-made engineering construction are the reasons for increasing erosion.(4)2008-2013.In terms of land use change,the maximum area of Desertification Grassland change is 605.26 km2,and its area is reduced,the change range is-17.49%,and the single land use dynamic degree is-3.05%,which is mainly converted into cultivated land,urban land and beach land.The area of urban land increased by 469.32km2,the range of change was 271.24%,and the dynamic degree of single land use was 54.25%,which was mainly converted into cultivated land,desertification grassland and industrial and mining land.The cultivated land area increased by 137.17km2,the change range was 4.46%,and the single land use dynamic degree was 0.89%,which was mainly transformed into desertification grassland and water area.The area of industrial and mining land increased by 30.47 km2,the change range was 121.47%,the single land use dynamic degree was 24.29%,mainly converted into desertification grassland and urban land.The water area is mainly converted into cultivated land,desertification grassland and beach land.Other water surfaces are mainly transformed into cultivated land and desertification grassland,and deserts are mainly transformed into desertification grassland.The beach is mainly transformed into water area and cultivated land.River course evolution:the accumulation of Shapotou and Huinong sections is greater than erosion,the precipitation of the Yellow River Basin is reduced,the climate is dry,coupled with the significant increase of agricultural irrigation,water resources are in short supply.From 2003 to 2013,the rapid economic development momentum,urban land,industrial and mining land through the occupation of water,beach and other water surface land use types to achieve rapid economic growth.The hardening area and the auxiliary facilities of the river bank are increased,and the erosion rate of the river bank is reduced.The erosion of Zhongning section and Qingtongxia section is greater than accumulation,because the water area and other water surfaces are mainly converted into cultivated land,urban land and industrial and mining land,which occupy part of the river channel.The demand of industrial development for water resources is increasing gradually.While continuous exploitation of groundwater meets its own demand,the groundwater level drops,resulting in the decrease of soil water content and accumulation.(5)2013-2018.Land use change:the urban land use area increased 236.44km2,the change range was 36.81%,the single land use dynamic degree was 7.36%,mainly converted into cultivated land,desertification grassland and industrial and mining land.The desertification grassland area decreased by 146.86km2,the change range was-1.03%,and the single land use dynamic degree was-36.98%,which was mainly converted into cultivated land,desert and urban land.The area of industrial and mining land decreased by 44.94 km2,the change range was-80.88%,the single land use dynamic degree was-16.18%,mainly converted into desertification grassland and urban land.The cultivated land area decreased by 8.66km2,the range of change was-0.27%,and the dynamic degree of single land use was-0.05%,which was mainly converted into desertification grassland,urban land and other water surfaces.Reduction of water area. |
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