Comprehensive Ecological Risk Assessment And Driving Force Analysis Of Karst Mountain Basin

Due to the weak natural environment,strong human activities,soil erosion,rocky desertification and other environmental problems in karst mountain areas,the contradiction between plowland and human in the river basin is prominent and the economic development is restricted in the karst mountainous areas.This study considers the karst mountain landscape succession process,the process of soil erosion and desertification of the ecological risk,constructs the comprehensive ecological risk evaluation model of watershed landscape,with 324 as evaluation unit of small watershed in the Wujiang river basin,the comprehensive ecological risk assessment of river basin,and analysis of river basin ecological risk space-time evolution characteristics and use of the geographical probe to detect the change of space drivers.The purpose of this paper is to provide a reference for the management and restoration of ecological environment,the construction of ecological security pattern and the early warning of ecological risks in the Wujiang River Basin(Guizhou section).And the research results are of great significance to the management and sustainable development of the basin’s social economic ecological environment system.The results show that:1)(1)from 2000 to 2015,under the influence of human activities,the changes of landscape types and landscape patterns in the basin showed that the proportion of forest land,grassland,artificial surface and wetland landscape types increased by 2.87%,1.03%,0.49%and.021%respectively,and the proportion of cultivated land area decreased to 4.7%.According to the change characteristics of landscape pattern indexes,the landscape pattern of the basin has changed significantly in the past 15 years.As a whole,the landscape pattern of the basin is becoming more and more optimized and stable.(2)Under the influence of a series of integrated projects of soil and water loss and rocky desertification,the soil erosion modulus of Wujiang River Basin decreased from 9.80 in 2000 to 6.03 in 2015 T/(hm~2·a),Wujiang River Basin belongs to mild erosion;among them,the soil erosion modulus of the upper and lower reaches of the basin is larger than that of the middle reaches,and the spatial difference of the change amount of the soil erosion modulus of the basin in 15 years is large,which shows that the change of the lower reaches of the basin is the largest,the middle reaches is smaller,and the upper reaches is the smallest.(3)In the past 15 years,the area proportion of non karst areas in the basin has remained basically unchanged,while the area proportion of different rocky desertification grades in karst areas has shown different trends,among which the area proportion of extremely severe and severe rocky desertification does not protrude,the area proportion of moderate rocky desertification has gradually increased,the area proportion of light rocky desertification has gradually decreased,and the area proportion of non rocky desertification has gradually increased Gradually.The areas of extremely severe and severe rocky desertification in the basin are mainly distributed in the upper and lower reaches of the basin,and some of them are scattered in the middle reaches.2)During the period of 200-2015,the ecological risk based on the process of landscape succession showed a growing trend,while the ecological risk based on the process of soil erosion and rocky desertification showed a declining trend;the average value of comprehensive ecological risk of the basin was 0.58,0.61,0.66 and 0.31,respectively,and the ecological risk of the basin increased in some periods,but decreased in the whole;high-level risk area It is mainly distributed in the upstream and downstream areas of the basin,and the low-level risk areas are distributed in the middle reaches.3)The comprehensive ecological risk and related influencing factors are analyzed by graph and geographical detector.The results show that the temporal and spatial variation characteristics of the comprehensive ecological risk are controlled by natural factors,and human activities are the main influencing factors.The explanatory power of the human activity factors in the basin is greater than that of the natural factors,and the maximum and minimum explanatory power of the human interference factors are respectively 83%,38%.In conclusion,human activities are the main driving factors for the dynamic change of comprehensive ecological risk.