Assessing the Impact of Site-Specific BMPs Using a Spatially Explicit, Field-Scale SWAT Model with Edge-of-Field and Tile Hydrology and Water-Quality Data in the Eagle Creek Watershed, Ohio

Abstract

The Eagle Creek watershed, a small subbasin (125 km2) within the Maumee River Basin, Ohio, was selected as a part of the Great Lakes Restoration Initiative (GLRI) “Priority Watersheds” program to evaluate the effectiveness of agricultural Best Management Practices (BMPs) funded through GLRI at the field and watershed scales. The location and quantity of BMPs were obtained from the U.S. Department of Agriculture-Natural Resources Conservation Service National Conservation Planning (NCP) database. A Soil and Water Assessment Tool (SWAT) model was built and calibrated for this predominantly agricultural Eagle Creek watershed, incorporating NCP BMPs and monitoring data at the watershed outlet, an edge-of-field (EOF), and tile monitoring sites. Input air temperature modifications were required to induce simulated tile flow to match monitoring data. Calibration heavily incorporated tile monitoring data to correctly proportion surface and subsurface flow, but calibration statistics were unsatisfactory at the EOF and tile monitoring sites. At the watershed outlet, satisfactory to very good calibration statistics were achieved over a 2-year calibration period, and satisfactory statistics were found in the 2-year validation period. SWAT fixes parameters controlling nutrients primarily at the watershed level; a refinement of these parameters at a smaller-scale could improve field-level calibration. Field-scale modeling results indicate that filter strips (FS) are the most effective single BMPs at reducing dissolved reactive phosphorus, and FS typically decreased sediment and nutrient yields when added to any other BMP or BMP combination. Cover crops were the most effective single, in-field practice by reducing nutrient loads over winter months. Watershed-scale results indicate BMPs can reduce sediment and nutrients, but reductions due to NCP BMPs in the Eagle Creek watershed for all water-quality constituents were less than 10%. Hypothetical scenarios simulated with increased BMP acreages indicate larger investments of the appropriate BMP or BMP combination can decrease watershed level loads.

Long‐term Variation in Agricultural Edge‐of‐Field Phosphorus Transport during Snowmelt, Rain, and Mixed Runoff Events

“…Modeling suggests that filter strips are the most effective stand‐alone BMP for reducing DRP, whereas cover crops were the most effective stand‐alone BMP for reducing winter DRP loading (Merriman et al, 2018). However, cover crops have been implicated as being sources of DRP, as P from plants can be mobilized in runoff (Lozier et al, 2017).…”

Modeling and Prioritizing Interventions Using Pollution Hotspots for Reducing Nutrients, Atrazine and E. coli Concentrations in a Watershed

“…A number of studies have reported high removal rates of sediment and nutrients in surface flows through the use of filter strips [63,64]. In their study conducted in Iran, Babaei et al [63] found filter strip to be a very effective BMP in reducing total nitrogen load (42.61%), and total phosphorus load (39.57%).…”

Flood Risk Reduction from Agricultural Best Management Practices

“…Previous studies have largely focused on assessment of BMP performance in reducing nutrient and sediment loss and the subsequent impacts on water quality (Parajuli et al 2013;Weissteiner et al 2013;Kladivko et al 2014;Yeo et al 2014;McLellan et al 2015;King et al 2016;Merriman et al 2018) (see also study reviews in Hashemi et al 2016;Liu et al 2017). Previous studies have largely focused on assessment of BMP performance in reducing nutrient and sediment loss and the subsequent impacts on water quality (Parajuli et al 2013;Weissteiner et al 2013;Kladivko et al 2014;Yeo et al 2014;McLellan et al 2015;King et al 2016;Merriman et al 2018) (see also study reviews in Hashemi et al 2016;Liu et al 2017).…”

“…Assessing benefits of agricultural BMPs is challenging due to the multiple impacts on hydrology, nutrient cycling, soil fertility, and other processes. Previous studies have largely focused on assessment of BMP performance in reducing nutrient and sediment loss and the subsequent impacts on water quality (Parajuli et al 2013;Weissteiner et al 2013;Kladivko et al 2014;Yeo et al 2014;McLellan et al 2015;King et al 2016;Merriman et al 2018) (see also study reviews in Hashemi et al 2016;Liu et al 2017). BMPs that slow runoff are effective in reducing sediment detachment and transport (Bosch et al 2013;Mitchell et al 2018), although effectiveness can vary depending on watersheds characteristics, BMPs location, and storm magnitude.…”