The Spatial And Temporal Dynamic Changes And Driving Forces In The Surface Area Of Weishan Lake Of Shandong Province

Lake is an important regulator of ecological balance,which can truly reflect regional climate change and socio-economic development.In recent years,great progress has been made in social economy.Human activities in Weishan Lake area are severe,lake ecosystem has been seriously broken,many large lakes are dying out,and some small lakes have disappeared.Therefore,it is of great significance to grasp the dynamic changes of lake area in Weishan Lake area in a timely and accurate manner for the development of fisheries and the indication of local ecological and environmental problems.The continuous improvement of water extraction methods and the continuous progress of remote sensing technology provide a powerful support for remote sensing monitoring of the dynamic change of lake area.This paper focuses on the changes in the Weishan Lake area from 1986 to the 30 th year of 2016,using the Landsat TM and OLI images in the summer of 1986,1996,2006 and 2016,using the supervised classification.The maximum likelihood method is used as a reference,as well as the commonly used normalized water body index model(NDWI)and the modified normalized water body index model(MNDWI).Based on this,combined with the NDVI and NDWI models,a combined water body index is proposed.NCWI),based on the characteristics of NDWI and MNDWI models,proposed the empirical water body index(ENDWI),extracted the water area of Weishan Lake in Shandong,studied the dynamic changes of Weishan Lake in recent years,and made five water body extraction methods.The accuracy is evaluated and the following conclusions are drawn.(1)By summarizing the lake area of Weishan Lake and summarizing the characteristics of the five methods,the results of the four-stage extraction area are used as reference,and the accuracy of the five water body extraction methods is evaluated,and the first three Landsat TM images are obtained.The most suitable model for extracting information from Weishan Lake waters is ENDWI,with an overall accuracy of over 95%.The most suitable method for Landsat OLI images is the NDWI model,with an overall accuracy of over 96%.Combined with the extraction results of Weishan Lake area and the accuracy evaluation results of Weishan Lake watershed,it can be concluded that the two water body index models NCWI and ENDWI are more comprehensive than the other three types in extracting water area,ENDWI ratio NCWI on background other objects The inhibition is high,and the applicability of the four-phase comprehensive extraction of Weishan Lake water area is compared and analyzed.It is found that the ENDWI model is the most suitable method for the extraction of Weishan Lake waters.(2)Using Arc GIS10.1 software to calculate the area extracted by various index models of Weishan Lake in various periods,according to the measured data of Weishan Lake published by Shandong Provincial Surveying and Mapping Institute in recent years,combined with the applicability of five methods,ENDWI Based on the results of the index model extraction,it can be concluded that the area of Weishan Lake has decreased by nearly 60km2 from 1986 to 2016,and the area change is 4.6%.By the end of 2010,the area of Weishan Lake is basically stable at around 1200km2.(3)There are three main factors of natural factors: precipitation,temperature and evaporation.The social factors mainly include population and construction land area.Rainfall presents an unstable trend,and the situation of serious imbalance between evaporation and recharge has led to a decrease in the amount of water entering the lake,which has caused the lake area in Weishan Lake to decrease seriously in the past 30 years.The population of Weishan Lake is affected by administrative planning.The increase and decrease of the population is unstable,but the construction area is increasing year by year.The overall economic level of the construction industry and Weishan Lake area is continuously improving.The expansion of the construction area due to the construction of the lake,the development of a large number of waters and the continuous expansion of the arable land area led to a gradual increase in water demand,which is the reason for the decrease in the area of Weishan Lake.Research on the change of lake area and the reasons that affect its change in Weishan Lake area has important theoretical and practical significance for the protection of lake ecosystem.