Factors on Particulate Phosphorus Loss in Surface Runoff under Simulated Rainfalls

Abstract

Particulate phosphorus loss in surface runoff had special significance compared with total phosphorus loss. We designed 12 stochastic simulated rainfall events with different conditions to find out the key contributing factors on particulate phosphorus loss in surface runoff. There were 6 indices relating to particulate phosphorus loss process were considered, including particulate phosphorus percentage in total phosphorus, particulate phosphorus loss modulus, sediment yield, sediment concentration, runoff coefficient and runoff occurrence time. Four contributing factors were studied, including rainfall intensity, slope, coverage ratio and gravimetric soil moisture content. The studied reveal that runoff occurrence time and runoff coefficient are the key indices to describe the phosphorus loss process. The contributing factors impacted the runoff occurrence time and runoff coefficient to impact the phosphorus loss characteristics. Slope is the most important contributing factor to sediment yield. The gravimetric soil moisture content is the second key contributing factor. Coverage ratio impacted runoff coefficient, while rainfall intensity impacted runoff occurrence time.