Abstract: Surface runoff is the main factor causing water loss and soil erosion. Controlling water loss and soil erosion and maximizing rainfall utilization are key factors for agricultural sustainable development in semiarid regions. In this paper, the sensitivity of SCSCN model parameters (runoff curve number (CN) and initial loss coefficient (λ)) was analyzed based on runoff data collected from microrunoff observation experiment, combined with underlying surface and rainfall data. Effects of different ridgefurrow ratios and different mulching materials on the model parameters were studied. Meanwhile, the model parameters were modified and verified with the data collected from the microridgefurrow rainwater harvesting system. The results indicated that λ was the main factor in the model, and the effect of ridgefurrow ratios on model parameters was not distinct. There was good consistency between the runoff simulated by the model and the actually measured value. The validity coefficients of common plastic film, biodegradable mulch film and compacted soil were 0.864, 0.988 and 0.947, respectively, showing that this model was relatively reasonable in determining the parameters and could accurately predict runoff in the microridgefurrow rainwater harvesting system, thus providing scientific methods for controlling water loss and soil erosion and maximizing rainfall utilization in semiarid regions.

Key words: temperate steppe, carbon, nitrogen and phosphorus., nitrogen deposition, soil pH