Role of Watershed Subdivision on Modeling the Effectiveness of Best Management Practices With Swat

Abstract

Distributed parameter watershed models are often used for evaluating the effectiveness of various best management practices (BMPs). Streamflow, sediment, and nutrient yield predictions of a watershed model can be affected by spatial resolution as dictated by watershed subdivision. The objectives of this paper are to show that evaluation of BMPs using a model is strongly linked to the level of watershed subdivision; to suggest a methodology for identifying an appropriate subdivision level; and to examine the efficacy of different BMPs at field and watershed scales. In this study, the Soil and Water Assessment Tool (SWAT) model was calibrated and validated for streamflow, sediment, and nutrient yields at the outlet of the Dreisbach (623 ha) and Smith Fry (730 ha) watersheds in Maumee River Basin, Indiana. Grassed waterways, grade stabilization structures, field borders, and parallel terraces are the BMPs that were installed in the study area in the 1970s. Sediment and nutrient outputs from the calibrated model were compared at various watershed subdivision levels, both with and without implementation of these BMPs. Results for the study watersheds indicated that evaluation of the impacts of these BMPs on sediment and nutrient yields was very sensitive to the level of subdivision that was implemented in SWAT. An optimal watershed subdivision level for representation of the BMPs was identified through numerical simulations. For the study watersheds, it would appear that the average subwatershed area corresponding to approximately 4 percent of total watershed area is needed to represent the influence of these BMPs when using the SWAT model.

Desempenho Do Modelo Swat Para Diferentes Critérios De Geração De Unidades De Resposta Hidrológica

“…Diversos estudos têm sido desenvolvidos visando investigar os efeitos do critério para definição de HRUs sobre os resultados das simulações com o modelo SWAT, podendo-se destacar HAVERKAMP et al (2002); MACHADO, VETORAZZI e CRUCIANI (2003);JHA et al (2004); ARABI et al (2006); GASMANN et al (2007); GITHUI e THAYLAKUMARAN (2011) e MELO NETO et al (2014). Contudo, os resultados são dependentes das escalas espacial e temporal trabalhadas, processos simulados, saídas objeto da modelagem, entre outros.…”

Quantifying Soil Moisture Distribution at a Watershed Scale

“…This study used a watershed scale hydrologic model, called Soil and Water Assessment Tool (SWAT) (Arnold et al 1998), to quantify long-term variation in spatial distribution of soil moisture on a medium-size watershed located in Midwestern USA. SWAT has been shown to perform well on both large river basins and small watersheds in terms of annual water and sediment yield (Arabi et al 2006, Gitau et al 2004, Spruill et al 2000, and Jha et al 2011, among may other studies). Gassman et al (2007) has reviewed over a hundred of peer-reviewed SWAT related peerreviewed publications, which speaks of the magnitude and reliability of model use for hydrology and water quality analyses.…”

Hydrological Modeling and Runoff Mitigation in an Ungauged Basin of Central Vietnam Using SWAT Model

“…Smith et al [47] presented BMPs to conserve agricultural lands. Arabi et al [48] used four BMPs types in different land use classes in order to reduce sediment and nutrients loads in the watershed.…”