The effects of land use change on gully erosion in the Mullah Ahmad watershed of Ardebil province

Water erosion is one of the most important soil loss factors that accelerated by land use change in many regions of the world. Gully erosion is the most severe type of water erosion that caused to wasting a large amount of soil, land degradation and producing a large amount of sediments. In this research, the effect of land use change from rangeland to farming on the severity of gully erosion in the Mullah Ahmad watershed of Ardebil province investigated. The watershed was located at 48 degrees, 12 minutes to 48 degrees, 21 minutes longitude, and 38 degrees, 4 minutes to 38 degrees and 6 minutes latitude and has an area of 4700 hectares. With the interpretation of the aerial photos of 1963 in Ardebil region and the satellite images of google earths and Landsat8 for 2013, the area of the main land uses of the watershed as well as the gully density at the watershed was determined over a period of 50 years. According to the survey, it has been determined that over the past 50 years, about 960 hectares of watershed area have been changed from rangeland to farming, and now there are 2,430 hectares of agricultural land. Also found that the density of gullies in 1963 was 0.42 km / sq. Km, while in 2013 it was 0.74 km / sq. Km, indicating 87% increase in gully density. Therefore, it is observed that as land use changes in the watershed, the severity of gullies expansion increased. By land use change from rangeland to agriculture, natural vegetation and soil permeability decreases, which leads to increased runoff production in the watershed. This caused more runoff production and increase of gully erosion.

کلیدواژه ها:

Runoff ، Gully ، Land degradation