Nonpoint source modeling of Indian Run Watershed /

Abstract

The problem of soil erosion and sediment runoff in the Indian Run watershed (area 11, 277 acres), a major tributary to Mill Creek, is of serious concern to the Mill Creek Metroparks management and the Youngstown metropolitan area community. Mill Creek is primarily responsible for sediment deposition in Lake Newport that continues at an alarming rate. A nonpoint source simulation was performed for the Indian Run watershed using the Agricultural Nonpoint Source Pollution Model (AGNPS) water quality model with a focus on the problems of soil erosion and sediment yield. Four hypothetical storm conditions were simulated: (i) 3 in. precipitation of 6 hour duration, (ii) 2 in. precipitation of 4 hour duration, (iii) I in. precipitation of 1 hour duration, and (iv) 1 in. precipitation of 12 hour duration. Sensitivity of the results to changes in P, C, and K factors in the Universal Soil Loss Equation was evaluated. Using the model results, the mean flow, erosion and sediment yield for the watershed outlet on a yearly basis were estimated to be on the order of 0.944 cfs/sq. miles, 13.4 tons/acre, and 1100 tons, respectively, which compare favorably with the field measurements. The AGNPS simulation identifies five cells (each 179 acres in area) that are primarily responsible for the problems of soil erosion, and sediment deposition in the entire Indian Run watershed. The sediment deposition and the flow rate predictions are within 10% of measurements reported [MBR-HER, 1994]. The AGNPS simulation of the watershed provides information that could be of considerable help in formulating management decisions to address the problem of sediment deposition in Lake Newport.