Climate Change Impacts on Water Resources and Ecological Environment of Inland Watersheds in the Hexi Region of West Gansu, China

Abstract

Water resources characteristics in meltwater-fed watersheds of the Qilian Mountains and Hexi region were analyzed with respect to observed changes in climate, extent of glaciation and snow cover, river water yields, groundwater resources, and vegetation during the past 47 years (1960-2006). Results show with global warming, the rate of temperature increase in the Qilian Mountains has exceeded national (0.5℃) and global (0.74℃) rates by about 1.0 ℃ in the last 47 years. Although not spatially uniform, yearly precipitation levels in the Qilian Mountains have generally risen, on average by 28 mm in the past 47 years. Over the same time period, extent of glaciation in the Qilian Mountains has decreased by about 8% from a initial area of 1 619 km 2 in 1956 to 1 489 km 2 in 2000. The extent of snow cover in the eastern to middle portions of the Qilian Mountains decrease from 1997 to 2006 based on the NOAA and EOS/MODIS remote sensing monitoring data, but increase in the western Qilian Mountains. Water yields in the Shiyang River have declined by about 4.5× 108 m 3 over five decades from 1.7× 109 m 3 in the 1950's to 1.25× 109 m 3 in the 1990's; while in the west, in the Shule River system, water yields have increased by about 9.3 × 108 m3 in the 1990's from an initial 8.1 × 108 m 3 in the 1960's. Groundwater resources have decreased by about 46% in the past 50 years from 6.51× 109 m 3 in the 1950's to 3.58 × 109 m 3 in the 1990's. In the past decade (1997-2006), the total vegetated areas in the Shiyang River and Hei River watersheds have decreased as a result of desertification and the remaining vegetation communities have generally undergone compositional changes from tree communities to low-lying shrub complexes. Climate change and unconstrained land use practices have put the ecological environment and sustainable development of the Hexi Corridor at enormous risk. The authors provide recommendations as how to protect the water resources in the Qilian Mountains and inland watersheds of the Hexi Corridor.