Research On Ecological Environment Quality Of Surface Water Source Based On Remote Sensing Technology

As urbanization continues to increase with an accelerated pace in China,human activities have caused severe damage to the surface environment.At the same time,deteriorating environmental quality becomes a serious threat to ecological security.Analyzing the quality of the regional ecological environment is the basic method to determine environmental quality.It can not only provide reference data for the relevant government departments during decision-making,but also help establish sustainable development policies.The surface water source of Laolongkou Reservoir in Hunchun is vital to the safety of the local residents.It not only is the major source of daily drinking water for residents,but also plays an important role in improving the local ecological environment.The accelerated urbanization process has been creating an unprecedented amount of ecological and environmental quality problems.The research and management of the ecological environmental quality in this area is urgently needed.This study selected the surface water source of Laolongkou Reservoir in Hunchun as the research object and used Landsat remote sensing image data captured in 2002,2009,2013 and 2017.ENVI 5.3 and Arc GIS10.2 platforms were used to process remote sensing data,create data mapping and run data analysis.Through data processing,four indicators--Greenness Index(Normalized Difference Vegetation Index,NDVI),Humidity Index(Wet),Land Surface Temperature(LST),and Dryness Index(Normalized Difference Build and Soil Index,NDBSI)were extracted from remote sensing images,and were combined to determine the Remote Sensing Based Ecological Index(Remote Sensing Based Ecological Index,RSEI).A suitable method for assessing the ecological environment quality at surface water source areas was determined and used to conduct research and analysis.SPSS software program combined with a variety of analysis methods was used to determine the factors that affect the quality of the ecological environment.As a result of this study,recommendations and countermeasures to issues that affect healthy development of the ecological environment were proposed.The main discoveries made through this study are as follows:(1)This study extracted four indicators from the remote sensing image data: NDVI,Wet,LST,and NDBSI,and analyzed their variation in 2002,2009,2013,and 2017.In the four sets of data,the NDVI remained relatively stable,varying within the range of 0.7-0.8.It was consistent with the environment of low-rise buildings and high vegetation,with a general upward trend.The Wet increased by 0.068 from 2002 to 2017.Low humidity records were mainly concentrated in urban areas,and high humidity records in areas with low number of buildings and low population density.From 2002 to 2017,the LST had been on the rise.High temperature was mostly found in major urban areas and denselypopulated areas,and low temperature was mostly found in the mountains and areas with extensive forest cover.The NDBSI showed an overall downward trend.Generally speaking,if an area has dense buildings,or has exposed soil,its NDBSI would be higher than that of an area with vegetation.(2)The principal component transformation method was used to perform principal component analysis on the four indicators obtained.The first principal component and the second principal component contained most of the information regarding the ecological environment quality.They eventually formed the RSEI.When the NDVI and the Wet are both greater than 0,it means the quality of the ecological environment has improved with the increase of the NDVI and the Wet.When the LST and the NDBSI are lower than 0,it means the quality of the ecological environment has deteriorated with the increase of the LST and the NDBSI.The study showed that the areas with good ecological environment quality were mostly found in the northeast region of the study area of surface water sources.The areas with poor ecological environment quality were mostly found in the southwest region of the study area,where the urban core was located.In addition,the areas with Good or Excellent quality grades were found to be increasing every year.The increase of forest cover and the reduction of cultivated land area had effectively improved the quality of the ecological environment.(3)Through a variety of statistical analysis methods,it was found that from 2002 to2017,the area where the quality of the ecological environment deteriorated was 221.407km2,the area where the quality of the ecological environment remained generally unchanged was 1,156.42 km2,and the area where the quality of the ecological environment improved was 2499.909 km2.Through linear regression analysis,it was found the NDVI and the Wet are positively correlated with the RSEI,while the LST and the NDBSI are negatively correlated with RSEI.This is consistent with the principal component analysis results.Finally,the gray correlation analysis method was used to combine the indices of effecting factors with the RSEI and derived the correlation between each index and the RSEI.The indices,from the most effecting the RSEI to the least is as follows: primary sector gross output,cultivated land,sulfur dioxide emissions,tertiary sector gross output,secondary sector gross output,total population,precipitation.