KINEROS2-based simulation of total nitrogen loss on slopes under rainfall events

Abstract

Abstract Soil, water and nutrient losses are major causes of environmental pollution, with runoff accompanied by nutrient transport and sediment loss. The existing runoff and erosion models focus on estimating the total amount of pollutants in the long term. There are few studies on the process of nutrient transport during individual rainfall events, and there are still some shortcomings in the mathematical models that describe the nutrient transport process on slopes with consideration of both the dissolved and adsorbed solute in the runoff. In this study, a mathematical model was constructed for describing the nutrient transport process during individual rainfall events by combining a dissolved solute transport model and an adsorbed solute transport model. After adding the nutrient model to the runoff and erosion model KINEROS2, the runoff, sediment yield, and total nitrogen loss on slopes during individual rainfall events were simulated, and the simulation results were verified using a field experiment with different rainfall intensities and different slope lengths. The results showed that the behaviour of the total nitrogen loss was consistent with the runoff and the sediment yield. The values all first increased and then gradually stabilized, and the time to reach steady state was shortened with the increase in rainfall intensity. The runoff and sediment yield simulated by KINEROS2 were consistent with the measured data, indicating that KINEROS2 could successfully simulate the processes of runoff and erosion in runoff plots (NSE\u202f>\u202f0.22; R2\u202f>\u202f0.35). Likewise, the amount of total nitrogen loss at different time points was simulated well (NSE\u202f>\u202f0.36; R2\u202f>\u202f0.54). Therefore, KINEROS2 shows potential for simulating nutrients and has good applicability on the runoff plot scale in the arid and semi-arid regions of China.