The effects of subsurface water harvesting system application and its impact on soil quality and soil erosion control in low yield rainfed lands

Soil degradation and erosion caused by human factors is the main threat to the functions of soil resources. The consequences of this phenomenon are reducing the sustainability and quality of production as well as environmental problems. Also, moisture stress, especially in rainfed lands, is a major limitation to improve productivity in these lands. The use of subsurface water harvesting is one of the options that is prevalent in Zagros provinces, due to topographic and geological conditions. This research was designed to evaluate the effectiveness of the operation of the traditional system of land use change of dryland to grape, almond and alfalfa cultivation with supplementary irrigation using subsurface water harvesting system in improving soil permeability and inhibition of soil degradation and erosion in the Razin Watershed of Kermanshah Province. To do this, after selecting the study area, some of the diagnostic features of selected area including the soil permeability with the disk permeameter and the soil degradation and erosion condition with GLADIS method were measured by field measurements in the study area as well as the control area. In the laboratory, soil texture, bulk density, saturation percentage, lime, acidity, salinity, nutrient concentration and organic carbon storage were measured the soil samples collected in the operation and control area. The results showed that the hidden form of erosion, the gradual washing of fine particles and the coarse grains of gravel and pebbles remaining known as Armor, is the most important form of erosion in the region. In the long term, the construction of this system was able to remove this form of erosion and loss of soil from the region. Also, exploitation of the underground dam system and extraction of subsurface water harvesting within its scope, in addition to enhancing all soil quality indicators (including its organic carbon accumulation), resulted in a 23% increase in soil permeability capacity and soil erosion has inhibited 5.56 tons per hectare.