Modeling of conservation practices on a HUC-12 watershed scale using Hydrological Simulation Program -- FORTRAN

Conservation practices are frequently used to try and restore the natural resilience of the landscape to retain water, decrease nutrient loads, and mitigate flooding. Quantifying the potential benefits of conservation practices can inform stakeholders and improve the effectiveness of watershed planning. To this end, an existing Hydrological Simulation Program --- FORTRAN (HSPF) model of the English River was enhanced to enable detailed modeling of conservation practices. Using site-specific nutrient removal wetlands and water and sediment control basins (WASCOBs) derived from the Agricultural Conservation Planning Framework (ACPF) two 12-digit hydrologic unit code (HUC-12) watersheds within the English River, Headwaters North English River and Gritter Creek, were selected for modeling. Wetlands drain much larger areas than ponds that currently exist in the two watersheds. Average flood peak reductions are over 50% near the wetland sites, and diminish moving downstream to a few percent or less at the watershed outlets. Many WASCOBs exist in the two watersheds, but WASCOB use is minimal in other areas of the state. WASCOBs provide slightly more flood storage than ACPF wetlands but the storage isy distributed throughout the watershed. As a result the simulations show that the peak reduction is greater than for wetlands at many locations.