Boundaries and Characteristics of Arid Regions in Mountain Valleys in Southwestern China

Arid regions in valleys of southwestern China have steep topography and fragile ecosystems, making them a critical and challenging management issue in this region. A substantial amount of the research on these arid regions in valleys took place in the 1980s; less work has been done since the start of the 21st century. Knowledge of the boundaries of arid lands within these valleys can provide basic data and a scientific foundation, and comparing and analyzing the characteristics of different valleys will help policymakers match management regimes to local conditions, assuring sustainability in these fragile areas. Using remote-sensing data, we extracted the boundaries of the arid regions within these valleys. We then calculated land cover, elevation, slope, and aspect data for the study area. Our results describe the basic features of these valleys; they occur between 23°23′ and 33°19′N and between 97°03′ and 104°43′E, with a total area of 33,391.60 km2 at elevations between 254 and 5707 m. The arid regions in valleys have slopes ranging from 0 to 87.17°, with a mean of 25.77°, and a slightly greater area and proportion of sunny aspects than of shady aspects. The main land covers in the arid regions in valleys are grasslands and shrublands. Our results indicate that (1) the arid regions within these valleys have expanded significantly, and their vegetation consists largely of grasses or shrubs; (2) the study area consists of interlaced mountains and valleys, with a terrain consisting of diverse slopes and aspects; and (3) the land cover gradually transitions from grassland to shrub, and elevation and slope decrease from northwest to southeast.