察汗淖尔湖泊面积变化及其对气候的响应分析

LAKE AREA CHANGE OF CHAHANNUR LAKE AND ITS RESPONSES TO CLIMATE CHANGE

以察汗淖尔流域为研究对象,基于1990—2020年Landsat遥感影像,通过归一化水体指数(MNDWI)结合人工目视解译的方法提取察汗淖尔31年的丰水期湖泊面积并分析其演化规律。选取化德、尚义和商都3个气象站点的月气温、降水、蒸发量和相对湿度数据,采用线性倾向估计法和Mann-Kendall检验法分析了气候要素的变化趋势,并利用主成分分析和相关性分析法综合说明了察汗淖尔湖泊面积对气候因子的响应关系。结果表明:1)31年间,察汗淖尔流域呈气温上升、降水量下降、蒸发量上升的暖干化趋势;2)1990—2020年察汗淖尔湖泊面积经历稳定、减少、增长、再减少,4个变化阶段,湖泊面积于1991年达到最大49.72 km^(2),于2005年达到最小0.074 km^(2),整体呈下降趋势;3)湖泊面积对气候的响应迅速,夏季降水量和夏季蒸发量为影响丰水期湖泊面积的主要因素,同时也是造成湖泊季节性变化明显的主要因素。

The Chahannur lake Basin was taken as the research object of this paper.By extracting the lake areas of the Chahannur during the wet season of 31 years from 1990 to 2020 using Landsat images by modified normalized difference water index(MNDWI) combined with the method of visual interpretation,the evolution law of the lake area was obtained.Based on the monthly temperature,precipitation,evaporation and relative humidity data of Huade,Shangyi and Shangdu meteorological stations,the linear trend estimation method and Mann-Kendall test method were used to analyze the changing trend of climate factors.Principal component analysis and correlation analysis were used to explain the response of the lake area to climate factors.The results showed that:1) In the past 31 years,the Chahannur lake Basin has presented a warming and drying trend of rising temperature,decreasing precipitation and increasing evaporation;2) the area of the Chahannur lake experienced four stages of stability,decrease,increase,and decrease again,and the water surface area of the Chahannur lake showed a downward trend as a whole between 1990 to 2020.During the 31 years,the lake area was 49.72 square kilometers at its maximum and 0.074 square kilometers at its minimum;3) lake area respond quickly to climate.The increase of evaporation and decrease of precipitation in summer resulted in a significant decrease in relative humidity,which was the main factor affecting the lake area in the wet season and causing the obvious seasonal variation of the Chahannur lake.