Ecological Environment Quality Evaluation Of The Watershed System In Luanping County,Heibei

At present,the shortage of water resources and the deterioration of ecological environment have become one important factor of restricting social and economic development of our country.The upper reaches of Miyun reservoir in Chengde is the most important water conservative area and ecological barrier of Beijing and Tianjin,which carries the arduous task of transporting water to downstream.However,in recent days,both the water quantity and quality of Miyun reservoir have been declining fast,which has seriously threatened the drinking safety of residents downstream.It is inseparable from the intensification of rural environment pollution in the upper reaches,the serious soil erosion and degradation of river ecosystem.Therefore,it shows the great practical significance to improve water environment and alleviate the pressure of water resources in capital area by monitoring and evaluating the eco-environment in the upper reaches of Miyun reservoir.This way,we can point out the main limiting factors and put forward countermeasures.In consideration of the difficulties of data acquisition as well as the poor objectivity and reliability of data according to traditional ecological environment evaluation methods,in this research,we use high definition remote sensing images combined with field survey data.The Luanping County watershed system in the upper reaches of Miyun reservoir is taken as the object for study.The evaluation index data are achieved by RS and GIS technology.In addition,AHP and Delphi method are used to establish the comprehensive evaluation index system of ecological environment quality of Luanping County basin and determine the index weights.What’s more,the standardized index data are given to different scores.After the comprehensive evaluation,major conclusions are as follows:(1)The Luanping County watershed system is divided into six sub-watersheds,namely:the northern part of Luanhe watershed,the western part of Chaohe watershed,the Fuyingzi small watershed,the central part of Luanhe watershed,the Laowa small watershed and the Bayingnan small watershed.(2)In view of the location characteristics of Luanping County located in the important water source area of Beijing and Tianjin,the methods of theoretical analysis and expert consultation are used to select the factors influencing the water supply capacity as the evaluation indexes,and to establish the quantitative evaluation model and determine the factors Weights.The quantitative evaluation model is composed of 10 index factors and 4 aspects,including channel characteristics(0.1876),topography(0.1348),living environment(0.1164)and slope state(0.5611).The system goal is clear,operable,and propagable.(3)Using the remote sensing technique to achieve the data of the involved factors,it was found that the average soil erosion modulus is 3308 t/(km2·a)in the study area,and the average vegetation coverage is 65.14%.(4)The overall environmental quality of the Luanping County watershed system is good and the overall score is 5.75(out of 10 points).The area is accountting for 72.6%of the total area with the evaluation score over 5.(5)The ranks of environmental quality of the Luanping County watershed system from high to low:the Laowa small watershed(6.95),the northern Luanhe watershed(6.49),the the western Chaohe watershed(6.03),the Fuyingzi small watershed(5.99),the Bayingnan small watershed(5.38)and central Luanhe watershed(5.04).