Investigation temporal variation of surface runoff and its relation with soil properties in semi-arid soils

Surface runoff is the main factor eroding soil which causes sheet and interrill erosion in gentle slopes. It started when water infiltration would be lower than rainfall intensity during rainfall event. Soil properties can vary amount and rate of surface runoff during rainfall. This study was carried out to investigate the role of soil properties in amount of surface runoff generation and its temporal variations in different soil textures. Eight soil textures placed in 1 m × 1.2 m plots were exposed under seven simulated rainfalls with 60 mm h-1 in intensity for 60 min. Runoff samples were collected for 5-min intervals during each event. Results indicated that various soil physicochemical properties are different among the soils. Surface runoff varied among the soils and the highest runoff (55.51 mm) was in clay, while sand didn’t produce any runoff during rainfall. Surface runoff production rate temporally increased during rainfall and reached to a pick after about 30-50 min. Time to pick was very short (30 min) in fine textured soils. The correlation analysis showed that surface runoff is significantly affected by sand, silt clay, bulk density, gravel, hydraulic conductivity, calcium carbonate, gypsum and ESP. With an increase in soil hydraulic conductivity, surface runoff was inversely differed. Linear regression analysis showed that sand percentage is the most important factor controlling surface runoff in semi-arid soils. Controlling surface runoff in the soils with lower percentage of sand as well as hydraulic conductivity is essential to prevent sheet and interrill erosion in semi-arid soils.