西藏唐北地区湖泊动态及空间格局预测

Dynamics and spatial pattern prediction of lakes in the northern Tanggula Mountains,Tibet,China

本研究评估了西藏唐古拉山以北地区(唐北地区)湖泊动态并预测了湖泊空间格局变化.使用面向对象分类和光谱角向量变化检测方法生成了2000-2015年西藏唐北地区每5年一期的生态系统分布数据.以此为基础,分析了湖泊与其他生态系统之间的转换和空间格局特征,评估了湖泊空间格局的动态及其与相关自然地理因素的关系.通过增强回归树识别了不同因素对湖泊动态的贡献,使用GEOMOD模型预测了湖泊到2030年的空间变化.结果表明:唐北地区在2000-2015年间湖泊增加了14.2%,是唐北地区生态系统变化的主要形式之一.区域内15个面积大于10 km2的湖泊有10个增加,另有5个减少,且缩减量较低.通过空间格局分析发现,唐北地区湖泊斑块表现为面积和数量同时增加,大斑块面积比重略有上升.扩张幅度高的湖泊多分布于海拔高、坡度大、温度低、降水少、距离冰川近的区域.位于现有湖泊周边、温度低、降水少、坡度小的区域转变为湖泊的几率较高.根据过去15年的趋势,到2030年,唐北地区湖泊将继续增加119 km2,主要变化形式从大湖扩张转变为小型水面扩张.

This study assessed the dynamics of lakes in the north Tanggula Mountains in Tibet(NT area)and predicted the spatial changes.We used object-oriented classification and a spectral-angle vector change detection method to generate ecosystem distribution data for the NT area at five-year interval between 2000 and 2015.Based on this dataset,we measured the spatial pattern of lake dynamics and related geophysical and meteorological factors.A boost regression tree model was used to examine the contribution of these variables to lake area change,which were further used in a GEOMOD model to predict the distribution of lakes in 2030.The results showed that the area of lakes increased by 14.2%between 2000 and 2015,which was one of the main forms of ecosystem change in the NT area.In the study region,the area of 10 lakes out of the total 15 lakes with an area greater than 10 km2 increased and that of another five lakes decreased with a relatively low shrinkage ratio.Both the mean site area and site number of lakes increased,and the percentage of large lake sites increased slightly.Lakes located in areas with high altitude,high slope,low tempe-rature,low precipitation,or near glaciers had a higher probability of size increase.Locales near the current lake sites with low temperature,precipitation,and slope tended to become new parts of extant lakes.Following the trend of the last 15 years,lakes in the NT area would increase by 119 km2 by 2030,with the main form of lake expansion changing from inundation of area around large lakes to area around smaller sites.