Geomorphic Aspects of China's Desertification Problem and De-Desertification Efforts.
Abstract
The extremely arid sandy deserts of northwest China lie in intermontane basins or lowlands in the rainshadow of high mountains, which deprive these areas of precipitation and create environments conducive to the development of barren sand dunes and stony (gobi) plains. A legacy of Pleistocene glaciation in these high mountains is a thick cover of sand, silt, and gravel deposited in the lowlands by meltwater streams. The presently much-diminished flow of these streams, and the arid to extremely arid climate of the basins, have allowed desert winds to rework the finer particles from dried-up riverbeds, lakes, and floodplains into loess blankets, sand sheets, and dunes. With the deflation of finer alluvial particles, the coarser gravels and cobbles are let behind, armoring the gobi plains. An end product of the sorting proficiency of desert winds is the concentration of particles in sand sheets and in 'sand seas' of dunes that consist of loose, noncohesive mineral and rock grains, mostly quartz. By 'eolian depedogenesis', most of the nitritive silt and clay soil particles in these deposits have been winnowed and blown away as dust. Today the surrounding mountains are reservoirs for ice and snow that provide abundant fresh water to irrigate the desert margins during all but the winter months. The unusual geomorphic setting of the Chinese arid lands thus provides a partial remedy for their climatic deficit, and for their desertification problem.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1984
- Accession Number
- ADA153251
Entities
People
- C. S. Breed