Analysis of Lakes Area Change and Their Influencing Factors in Gansu Province in Recent 30 Years

Abstract

Inland lakes can truly and sensitively reflect the climate change in the region， are important indicators of climate change.The analysis of temporal and spatial evolution and causes of lake area changes is of great scientific value not only for the water resources utilization and water resources management， but also for revealing regional climate change and reflecting the impact of human activities.In this study， seed growth method （object-based image analysis， OBIA ） was used to extract the area changes of 7 typical lakes in Gansu Province from 1986 to 2017， among the tail type lakes， Dasugan Lake has the largest area， with an area of more than 60 km2 from 1986 to 2017； Qingtu Lake has a maximum area of more than 20 km2， the area of Xiaosugan Lake remains between 11~12 km2， with relatively stable changes.The area of Ganhaizi Lake is less than 2 km2， with large fluctuations.In the river source lakes， the area of Gahai Lake is 2.9~12.56 km2， with large area fluctuation.The areas of Delenoer Lake and Tianchi Lake are less than 2 km2， among which the area fluctuation of Delenoer Lake is large and the area fluctuation of Tianchi Lake is relatively small.Based on the cluster analysis method， seven typical lakes were divided into two types according to the changing characteristics of lake area.The first category included Gahai Lake， Qingtu Lake and Dasugan Lake， and the lake area showed an overall increasing trend.The second category includes Delenore Lake， Xiaosugan Lake， Tianchi Lake and Ganhaizi Lake， the lake area is decreasing as a whole.Through correlation analysis， it can be seen that the lake area changes of Delenoer Lake， Gahai Lake， Tianchi Lake， Qingtu Lake and Ganhaizi Lake have a significant correlation with some climate factors.In addition， the area changes of Dasugan Lake and Xiaosugan Lake have a certain correlation with climate factors， but not significant.Through principal component analysis， it can be concluded that among the climate impact factors， average temperature and relative humidity， precipitation and ET0 are the main climate impact factors of lake area change， average temperature and relative humidity are the main impact factors of Delenoer Lake area change， and ET0 and average temperature are the main climate impact factors of Gahai Lake area change， relative humidity and precipitation are the main climatic factors affecting the change of Tianchi Lake area.

Keywords

• gansu province
• lake area change
• seed growth method
• influencing factors