Land Use/Cover And Landscape Pattern Changes In Shaying River Basin And Ecological Impact

With the increase in population,economic development,and the increased intensity of land resource utilization,regional soil erosion and water pollution problems continue to emerge.As the main drainage channel of the Huaihe River Basin in Henan Province,the Shaying River Basin currently has different levels of pollution,and the ecological environment is under great pressure.It is urgent to strengthen the research on the dynamic changes of land use and landscape pattern in the basin.This paper is based on the land use data of the Shaying River Basin from 2000 to 2018,with the aid of Arcgis and Fragstate4.2 software and the non-point source pollutant output coefficient model,to the five prefecture-level cities in the basin such as Zhengzhou,Luohe,Pingdingshan,Xuchang,and Zhoukou Land use/cover change and landscape pattern evolution and their impact on the ecological environment were studied.The conclusions are as follows:(1)From 2000 to 2018,the main types of land in the study area were cultivated land and urban-rural construction land,both of which accounted for about 85%of the total area of the study area.During the study period,the cultivated land area in the watershed decreased by 1351.72km2,and the urban and rural construction land area increased by 1409.23km2.The average annual growth rate of industrial and mining transportation land from 2000 to 2018 was 10.21%,and the average annual decrease of grassland was the largest at 1.33%;the comprehensive dynamic index of watershed showed a trend of increasing first,then decreasing and then increasing,among which the dynamic of watershed was from 2005 to 2010.The change is the most dramatic;Zhengzhou has the largest comprehensive dynamic index in 2010,reaching 5.19%.The main types of spatial conversion of construction land in the early stage are concentrated in the cultivated land around the circular area centered on the main urban area,and the transferred areas are concentrated;in the later period,they are outwardly diffused and scattered,and the types of transfer out are concentrated outside the rural construction land.Converted to cultivated land.In the early stage,the transfer of cultivated land was mainly concentrated in the central urban areas of various cities,and in the later period,it was expanded outward and scattered.The transfer of cultivated land is mainly concentrated in the woodland and grassland in the suburbs of the city and a small amount of construction land and water land in the urban area.The forestland and grassland are spatially distributed in the northern regions of Zhengzhou,Pingdingshan and Xuchang.Be used for cultivated land and construction land.(2)At the patch level,the dominant patch in the watershed is cultivated land,accounting for 70%of the landscape,but the proportion of cultivated land in the landscape decreased by 3.86%from 2000 to 2018;the number of patches of urban and rural construction land increased by 3017 from 2000 to 2018 The landscape is the most fragmented.The maximum patch index of cultivated land,grassland and industrial and mining land in the watershed decreased,and the shape index of the patch increased,and the three land types developed towards fragmentation;the connectivity of each land type in the watershed was relatively strong.At the landscape level,the density of landscape patches in the entire watershed was bounded by 2010,and then increased first and then decreased.The maximum value was 0.95/km2 in 2010,indicating that patches as a whole changed from scattered to concentrated.The shape index of the landscape in the watershed increased from 98.54 to 111.43,indicating that the entire area was affected by man-made,the dominant patches were separated,and the shape of the patches tended to be irregular.The overall Shannon Diversity Index and Shannon Evenness Index of the watershed have increased,from 0.91 and 0.47 in 2000 to 0.98 and 0.50 in 2018,respectively,and the diversity of land use has gradually increased.The minimum index of land use uniformity in Zhoukou City is only 0.30.There are dominant patches mainly on cultivated land,and the direction of regional land development is uneven.(3)From 2000 to 2018,the increased values of TP and TN loads in the entire basin were 238.31t and 8173.88t,respectively.Among them,Zhoukou City's TP and TN contributed the most,accounting for 40%of the total.The main factor affecting regional non-point source pollution emissions is the area planted,with a contribution rate exceeding 90%.During the study period,the load of TN/TP in Zhengzhou and Xuchang decreased year by year,and Pingdingshan increased year by year.The main reason is that the fertilizers and pesticides exceeded the standard seriously.Space Zhoukou and Pingdingshan are high-value areas of TN/TP load,Zhengzhou and Xuchang are medium-value variable areas,and Luohe is a low-value area.