Modeling Phosphorus Transport in Grass Buffer Strips

Abstract

An event‐based computer model, GRAPH, was developed to simulate phosphorus (P) transport in grass buffer strips (GBS) by incorporating submodels into SEDIMOT II, a stormwater and sediment transport model developed for strip mine reclamation. GRAPH considers the effects of advection processes, infiltration, biological uptake, P desorption from the land surface to runoff, adsorption of dissolved P to suspended solids in runoff, and the effects of changes in sediment size distribution on P transport. Required input data include: rainfall intensity and duration, an inflow hydrograph, a sediment graph, sediment size distribution, GBS dimensions and hydraulic characteristics, inflow graphs for dissolved P, P desorption and adsorption reaction coefficients for soil and plant matter, and the P content of each soil particle size class. GRAPH simulates time varying infiltration, runoff discharge, sediment yield, particle size distribution, and dissolved and sedimentbound P discharge along with sediment and P trapping efficiencies in GBS. GRAPH was verified using data from experimental field plots. Model predictions and observed P transport in the GBS compared favorably.