Analysis of the factors affecting abandoned terraces in mountainous areas from the perspective of engineering design

Abstract: This study mainly analyzes some influence factors for the large-scale abandonment of cultivated land in mountainous areas using the method of remote sensing and field investigation. Four counties were selected, including Linzhou city, Yishui, Xundian and Huachi county in the northwest of China. In each county, several sampling areas were selected to identify the abandoned terraces in the mountainous areas by remote sensing interpretation and field research. The geoscience factors of the abandoned terraces in mountainous areas were finally analyzed from the perspective of geosciences. The main results are as follows: 1) Extracted information from terraced field wastes in the sampling area shows that there are varying ratios of the abandoned fields in the four counties. Specifically, the average area rates of the abandoned terraces in the sampling areas of Huachi, Xundian, Yishui county and Linzhou city were 4.11%, 7.68%, 9.46% and 24.03%, respectively; 2) The width of the terraced field was the main factor for the wasteland of terraces. The narrow width of the terraced area was easy to be abandoned according to the relationship between the terraced abandonment rate and the width of terraced fields in Yishui, Linzhou and Xundian. When the terraced width was wide enough, the abandonment rate was not obvious in Huachi county; 3) In rocky mountain areas, the slope of ground and the thickness of the soil layer are the main factors for the width of the terraces. As the slope of the ground increases, the width of the terraces becomes narrow. As the thickness of the soil layer decreases, the width of the terraces becomes narrow. In soil mountainous areas, the slope of the ground was the main factors for the width of terraces, where the width of terraces becomes narrower as the slope increases; 4) The construction of terraces in mountainous areas should consider the local conditions. Most of the newly-built terraces are the so-called unused land from past developments, where the desertification more possibly occurs due to the exhausting natural resource. Therefore, the construction of mountain terraces can mainly refers to the local natural geographical conditions. In the areas with thin soil layers and large slopes, it is not cost-saving to build terraces. This finding can provide a theoretical guidance for the optimization of mountain terraces from the perspective of engineering design.