Assessing the Impact of Best Management Practices in a Highly Anthropogenic and Ungauged Watershed Using the SWAT Model: A Case Study in the El Beal Watershed (Southeast Spain)

Abstract

Best management practices (BMPs) provide a feasible solution for non-point source pollution problems. High sediment and nutrient yields without retention control result in environmental deterioration of surrounding areas. In the present study, the soil and water assessment tool (SWAT) model was developed for El Beal watershed, an anthropogenic and ungauged basin located in the southeast of Spain that drains into a coastal lagoon of high environmental value. The effectiveness of five BMPs (contour planting, filter strips, reforestation, fertilizer application and check dam restoration) was quantified, both individually and in combination, to test their impact on sediment and nutrient reduction. For calibration and validation processes, actual evapotranspiration (AET) data obtained from a remote sensing dataset called Global Land Evaporation Amsterdam Model (GLEAM) were used. The SWAT model achieved good performance in the calibration period, with statistical values of 0.78 for Kling–Gupta efficiency (KGE), 0.81 for coefficient of determination (R2), 0.58 for Nash–Sutcliffe efficiency (NSE) and 3.9% for percent bias (PBIAS), as well as in the validation period (KGE = 0.67, R2 = 0.83, NS = 0.53 and PBIAS = −25.3%). The results show that check dam restoration is the most effective BMP with a reduction of 90% in sediment yield (S), 15% in total nitrogen (TN) and 22% in total phosphorus (TP) at the watershed scale, followed by reforestation (S = 27%, TN = 16% and TP = 20%). All effectiveness values improved when BMPs were assessed in combination. The outcome of this study could provide guidance for decision makers in developing possible solutions for environmental problems in a coastal lagoon.

A Soil Water Assessment Tool (SWAT) Modeling Approach to Prioritize Soil Conservation Management in River Basin Critical Areas Coupled With Future Climate Scenario Analysis

“…High erosion class from the coverage of 53.61% in future scenarios was brought to 0%, 13.55%, 18.25%, 18.25%, 34.48% after recharge structure, filter strip of 6 m, contour farming, gully plugs, and two tillage operations, respectively. These percentage reductions are within the percentage reduction of sediment yield as obtained by a different researcher, such as 71% reduction by the implementation of contour farming (López-Ballesteros et al, 2019); up to 37.2% reduction with the recharge structure (Tuppad et al, 2011), 51% reduction by the gully plugs (Park et al, 2014); 5.4%-6.8% reduction in case of conservation tillage and zero tillage, respectively (Himanshu et al, 2019); 25% reduction by the application of filter strip (Parajuli et al, 2008).…”

Prioritization of Sub-Watersheds to Sediment Yield and Evaluation of Best Management Practices in Highland Ethiopia, Finchaa Catchment

“…In this context, watershed models are widely used for the long-term prediction of BMPs applications on the watershed. Several studies have shown that the Soil and Water Assessment Tool (SWAT) model is considered as a versatile model that integrates multiple processes which support effective watershed management across the globe [2,13,[25][26][27]. All of these studies indicated that the SWAT model is good enough to study the representation of agricultural BMPs.…”

Evaluating the Effectiveness of Best Management Practices On Soil Erosion Reduction Using the SWAT Model: for the Case of Gumara Watershed, Abbay (Upper Blue Nile) Basin

“…Globally, several studies evaluated the effectiveness of BMPs to reduce sediment load and agricultural nutrients to freshwater ecosystems (e.g., Uniyal et al 2020;Briak et al 2019;Park et al 2014;Bosch et al 2013;Arabi et al 2008). However, majority of these studies were undertaken in North America (e.g., Lamba et al 2016;Bosch et al 2013;Arabi et al 2008), Europe (e.g., López-Ballesteros et al 2019;Engebretsen et al 2019;Lam et al 2011) and Asian continents (e.g., Uniyal et al 2020;Himanshu et al 2019;Park et al 2014). There are only few studies that evaluate BMPs in Africa (e.g., Briak et al 2019 in Morocco;Gathagu et al 2018 in Kenya; Betrie et al 2011 in Ethiopia).…”