SWAT parameterization for the identification of critical diffuse pollution source areas under data limitations

• Published in: Ecological modelling Vol. 222; no. 19; pp. 3500 - 3512
• Main Authors: Panagopoulos, Y., Makropoulos, C., Baltas, E., Mimikou, M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 10.10.2011; Elsevier
• Subjects: Animal, plant and microbial ecology; Biological and medical sciences; Catchments; cost effectiveness; Critical areas; Data limitations; Diffusion; environmental law; Freshwater; Fundamental and applied biological sciences. Psychology; General aspects. Techniques; geographic information systems; Methods and techniques (sampling, tagging, trapping, modelling...); Model parameterization; nitrogen; Nutrients; Parametrization; phosphorus; Pollutants; pollution; Pollution abatement; pollution control; risk; runoff; seasonal variation; Sediments; soil; Soil (material); Soil and Water Assessment Tool model; surface water; SWAT; Water pollution; watersheds; Europe; SWAT; Data limitations; Nutrients; Model parameterization; Sediments; Critical areas; Nonpoint pollution; Pollution source; Nutrient; Models; Parameterization
• ISSN: 0304-3800; 1872-7026
• DOI: 10.1016/j.ecolmodel.2011.08.008

► We demonstrated a justified SWAT model parameterization under data limitations. ► We provided guidance on taking advantage of the limited data for modeling. ► High risk areas of pollution were identified facilitating catchment management. ► Particular modeling issues were discussed increasing the acceptance of the outcome. For lowering sediment, nitrogen (N) and phosphorus (P) pollution of surface water bodies at the catchment scale, environmental legislation require programs of pollution abatement measures. To be able to ensure the cost-effectiveness of such programs we first need to identify high risk areas, which give rise to increased pollutant runoff. Process-based GIS models provide the opportunity to identify such critical areas and hence better target diffuse pollution abatement actions. However, these models are data intensive and their spatially-distributed parameterization in poorly monitored catchments is not feasible without extensive input data pre-processing and significant simplifying assumptions. This study implements the widely-used SWAT river basin model (Soil Water Assessment Tool) to study a medium-sized Greek catchment with the typical data limitations met at the national level, in order to identify critical diffuse pollution source areas that may serve as the key areas for meeting the objective of ‘good ecological status’ of water bodies set by the European Water Framework Directive (WFD). Model parameterization and evaluation are presented along with the decisions made to overcome problems related to data representation in the catchment, in an effort to provide guidance on SWAT modeling in areas with similar characteristics. The results show that sediments and nutrients could be adequately reproduced in large time steps (monthly or seasonal) and that even with the current data limitations, the seasonal variation and the most critical areas of pollutant losses to waters could be adequately identified. The study proposes a transparent modeling approach under data limitations without neglecting possible deficiencies; however, it maintains that the SWAT model, if appropriately parameterized with respect to the land-use and soil differentiation within a limited-gauged catchment, can still facilitate the selection and placement of suitable practices across the landscape for a cost-effective diffused pollution management.