Temporal Information Entropy And Its Application In The Evaluation Of Ecological Environment Quality In Yanhe Watershed

The ecological environment quality of watershed is closely related to human survival and development.Remote sensing technology has the advantages of timeliness,wide coverage and repeated observation,so it plays a great role in the study of ecological problems of the watershed.Remote sensing data is a new data source,it provides a new observation angle.At the same time it means we need new ways to dig the laws that traditional methods cannot find.Since the long time series of remote sensing images can record the change process of ecological environment,extracting environmental parameters' temporal and spatial change characteristics will provide more objective information for the research of ecological environment quality in watershed.In this paper,viewing remote sensing data as the main data source and based on temporal and spatial information analysis,we aim to study the evaluation of ecological environment quality in watershed.The current studies mainly focus on the evaluation of regional ecological environment quality of a specific time,however,discuss less on its temporal and spatial change characteristics.And the common method is mainly based on the difference between the results of two periods' ecological environment quality,which cannot adequately reflect the change characteristics of its time dimension.Considering this problem,by introducing information theory,temporal information entropy and its computational formula have been proposed to extract the temporal and spatial change information of key environmental parameters.Then the change evaluation index system of ecological environment quality is built based on these change characteristics.At the same time,through introducing the concept of mutual information,the improved entropy weight method is proposed to determine the weight of evaluation indexes,which can eliminate the inter-correlation of evaluation indexes,so the evaluation results are more scientific.Taking Yanhe watershed as the study area,combined with the main ecological environment problems in this region,this paper uses temporal information entropy method to extract the temporal and spatial change characteristics of key ecological factors-vegetation coverage and land surface temperature based on long time series of remote sensing data.And taking the change detection of vegetation coverage in Yanhe watershed from 2000 to 2010 as an example,compared with the traditional regression analysis method,temporal information entropy method can be more objectively in reflecting the change characteristics of vegetation coverage.Based on these temporal and spatial change information of key ecological parameters,this paper also uses improved entropy weight to determine the weight of evaluation indexes.And then completes the change evaluation of ecological environment quality in Yanhe watershed from 2000 to 2010.At the same time,this paper calculates the ecological environment quality of Yanhe watershed in 2010 based on the "Technical Standard for Evaluation of ecological environment"(HJ192-2015).Considering both the status and change characteristics of ecological environment quality in the study area,this paper gets the comprehensive governance map so as to provide advices for the protection and management of the ecological environment in this region more objective and scientific.