Modeling the impacts of best management practices (BMPs) on pollution reduction in the Yarra River catchment, Australia

Abstract

Pollution of a watershed by different land uses and agricultural practices is becoming a major challenging factor that results in deterioration of water quality affecting human health and ecosystems. Sustainable use of available water resources warrants reduction of Non-Point Source (NPS) pollutants from receiving water bodies through best management practices (BMPs). A hydrologic model such as the Soil and Water Assessment Tool (SWAT) can be used for analyzing the impacts of various BMPs and implementing of different management plans for water quality improvement, which will help decision makers to determine the best combination of BMPs to maximize benefits. The objective of this study is to assess the potential reductions of sediments and nutrient loads by utilizing different BMPs on the Yarra River watershed using the SWAT model. The watershed is subdivided into 51 sub-watersheds where seven different BMPs were implemented. A SWAT model was developed and calibrated against a baseline period of 1998–2008. For calibration and validation of the model simulations for both the monthly and annual nutrients and sediments were assessed by using the Nash–Sutcliffe efficiency (NSE) statistical index. The values of the NSE were found more than 0.50 which indicates satisfactory model predictions. By utilizing different BMPs, the highest pollution reduction with minimal costs can be done by 32% targeted mixed-crop area. Furthermore, the combined effect of five BMPs imparts most sediments and nutrient reductions in the watershed. Overall, the selection of a BMP or combinations of BMPs should be set based on the goals set in a BMP application project.

Physical and Biological Stream Health in an Agricultural Watershed after 30+ Years of Targeted Conservation Practices

“…This is not an atypical observation after BMP implementation in large (>1500 hectares) watersheds [23]. Modeling studies on large watersheds suggest that BMPs can be used to improve stream health, but 50% or more of watershed agricultural lands may need to be in BMPs to produce an observable effect [35,44]. If such a BMP implementation threshold is realistic and applicable to other large watersheds, the Whitewater River subwatersheds would need to at least double the areal coverage of BMPs before widespread improvements in stream health might be observed.…”

“…Even with new rules protecting stream riparia within the Whitewater watershed, total areal coverage of BMPs within the watershed likely will remain well below the possible 50% threshold [35,44] needed to truly protect stream systems from agricultural activities. Consequently, successful conservation management of watershed lands leading to improved stream health probably will require that future efforts focus on targeting BMPs within remaining problem areas and continuing maintenance of already existing BMPs.…”

Monitoring, Modeling and Planning Best Management Practices (BMPs) in the Atwood and Tappan Lake Watersheds with Stakeholders Engagements

“…Water quality problems due to total nitrogen (TN) and total phosphorus (TP) have become increasingly critical over the past few decades as a result of anthropogenic influences including point and non-point sources [1][2][3][4][5] resulting in serious water quality issues in lakes and reservoirs [6,7]. Several past studies reported that non-point sources from agricultural activities [8,9], especially due to the nutrient loading from the agricultural field, is one of the major contributors to water contamination in the United States [10][11][12].…”