Influence of climate change on salt lakes in Qinghai Province and their mineral resources exploitation in the past forty years: A case study of Xiao Qaidam Lake
Qinghai is the main area with extensive distribution of salt lakes which are rich in mineral resources. The authors extracted information of all salt lakes each of which has an area larger than 10 km2 (excluding dry salt lakes) in Qinghai from Landsat of five periods, i.e., the 1970,s, the 1990's, around 2000, from 2008 to 2009 and from 2013 to 2014,based on RS and GIS, and then analyzed dynamic changes of these salt lakes. On the whole, the total area of these salt lakes increased except in the period around 2000; more specifically, in the period around 2000, salt lakes whose areas decreased were mainly distributed in the Qaidam Basin,whereas in all other periods salt lakes tended to expand. In the background of the global climate warming, the authors analyzed annual mean temperature, annual rainfall and annual evaporation data from 11 meteorological stations of Qinghai, and have reached some conclusions based on the data obtained : in the past forty years, the climate in Qinghai has tended to change into warm wet, especially since 2002. Finally, with the Xiao Qaidam Lake as an example, the influence of lake desalination and mineral resources impoverishment on mineral resources exploitation was analyzed :① it has caused higher cost and more difficulties, even some salt lakes at the critical-grade level for industrial development will lose their exploitation value; ② under the condition of salt lake desalination, effective extraction technologies of mineral resources such as lithium require development urgently;③ such a situation may have some impact on the government s policy-decision for mineral resources development, and the establishment of the pre-warning and monitoring system of salt lakes in Qinghai is necessary. Remote sensing with its unique advantages is effective in the investigation and evaluation of salt lake resources in Qinghai under the conditions of bad traffic, fragile ecological environment and high cost of surveying.