Environmental suitability evaluation for human settlements in an arid inland river basin: A case study of the Shiyang River Basin

Abstract

The study employs slope, aspect, relief degree of land surface, land use, vegetation index, hydrology and climate, as evaluation indexes to set up the Human Settlements Environmental Index (HEI) model to evaluate the environmental suitability for human settlements in the Shiyang River Basin. By using GIS spatial analysis technology, such as spatial overlay analysis, buffer analysis and density analysis, the environmental suitability of the human settlement spatial situation and spatial pattern are established to analyze their spatial distribution. The results show that the index of suitability for human settlements in the Shiyang River Basin is between 17.13 and 84.32. In general, suitability for human settlements decreases from the southwest to the northeast. Seen from an area pattern, the suitable region is mainly distributed in the Minqin oasis, Wuwei oasis and Changning basin, which are about 1080.01 km² and account for 2.59% of the total area. Rather and comparatively suitable region is mainly distributed around the counties of Gulang, Yongchang and north of Tianzhu, which is about 1100.30 km². The common suitable region is mainly distributed outside the counties of Yongchang, Jinchuan and most parts of Minqin County, which are about 23328.04 km², accounting for 56.08% of the total area. The unsuitable region is mainly distributed upstream and to the north of the river, which is about 9937.60 km², accounting for 23.89% of the total area. Meanwhile, the least suitable region is distributed around the Qilian Mountains, which are covered by snow and cold desert and lie in the intersecting area between the Tengger Desert and Badain Jaran Desert. The total area is about 6154.05 km², accounting for 14.79% of the total area. Suitable regions for human habitation are mainly distributed around rivers in the form of ribbons and batches, while others are scattered. The distribution pattern is identical to the residential spatial pattern. In addition, the relationships between HEI and other factors have been analyzed. There is a clear logarithmic correlation between the residential environment and population, that is, the correlation coefficient between the evaluation value and population density reaches 0.851. There is also a positive correlation between the residential environment and economy, which reaches an evaluation value of 0.845 between the residential environment and GDP. Results also show that the environment is out of bearing with the existing population in Shiyang River Basin. Spatial distribution of population is profoundly affected by severe environmental problems, such as the expanded deserts, the hilly terrain and the changing climate. Surface water shortage and slow economic growth are bottlenecks for suitable human settlement in the Shiyang River Basin. Combining these problems with planning for construction of new country and the exploitation of local land, some residential areas should be relocated to improve the residential environment.