Process-Based Modeling of Furrow Irrigation Erosion

Furrow irrigation, one of the most widely used forms of irrigation in the world, may disproportionately contribute to water quality degradation. Accurate furrow erosion models are needed, but no satisfactory model exists. In this paper, we propose a process-based modeling framework by comparing two approaches: (1) the transport capacity (Tc) concept; and (2) a semiempirical approach in which furrow erodibility exponential decreases with length. Furrow erodibility kω was either assumed constant or exponentially decayed with time (dynamic erodibility). The best performance was obtained with the Tc approach when the dynamic kω was used (R2=0.68, Nash–Sutcliffe efficiency [NSE]=0.61, and percent bias [PBIAS]=–14.87% on evaluation data), whereas the semiempirical approach did not show any benefit of the dynamic kω (R2=0.69, NSE=0.65 and PBIAS=–21.93% at evaluation). The inability of the Tc model to account for deposition was found to be a key limitation of this approach. These process-based furrow erosion functions can be directly coupled with furrow flow routing or other hillslope erosion models.