Simulating impact of over-grazing on grassland degradation using GIS: a case study in the Heihe River Basin, China

Abstract. Inland river basins in arid to semi-arid regions are widely distributed in Northwest China, Central Asia, Central Australia, and North Africa, and are often subject to significant human activities. The most distinctive natural feature of such basins is the shortage of water resources, and the pivotal reasons involve less precipitation and heavy evapotranspiration (ET). In recent years, intensive human activities also damage the natural environment of the basins. They result in many problems especially the deterioration of ecological environment which will lead to severe consequences such as desertification, sandstorm, the disappearance of wetlands, reduction of forest and grassland degradation. They prevent us from achieving the goal of sustainable development. How to balance economic development and ecosystem conservation and to realize the sense of sustainability in inland river basins will be vitally important.

The Heihe River is the second largest inland river in the Northwest of China with a long history development by human (Figure 1). Water resources from the river are crucial not only for the ecosystem but also for local human societies. The Heihe River Basin (HRB) is divided into three zones with different landscapes and natural environments. The upstream of HRB is the headstream which generates water resources mainly from glaciers and snow in Qilian Mountain. A large population of nomadic national minorities inhabits here and keeps animal husbandry as the primary production activity. In the early times, the Chinese government encouraged production activities to stimulate economic growth, and significant over-grazing and resultant severe grassland degradation occurred. Grassland is crucial for maintaining water resources especially in arid regions, without grasses most water will quickly evaporate into the air. Therefore, land resource management about grassland and the impact of human activities on the natural environment are of high research value in the HRB.

This research aims to investigate the impact of over-grazing on grassland degradation in the inland ecosystem of the HRB. The changes of grassland distribution were simulated under different over-grazing scenarios to provide a reference for resource management and the related decision-making process and to contribute to the sustainable development of the region.