Use of hydrological models at the catchments scale to predict the effect of different land management practices and point source pollution

Action plans to reduce water pollution is a strategic task of European Countries, mostly in Mediterranean areas, where water demand is steadily increasing, while water resources are limited. Contamination levels in water bodies, both ground and surface waters, are found to be increasing and local and regional authorities are now facing this awkward environmental problem. Most of the nutrients that enter water are from the agrozootechnical and the industrial compartments. Consideration of the physical processes associated with water movement, crop growth, and nutrient cycling can be essential to evaluate the gradual build up of pollutants due to alternative land management practices on downstream water bodies, e.g. rivers and coastal lagoons. In this framework, models can give support to identify, among alternative choices, those that will not lower the integrity and sustainability of the ecosystems. In this study, the SWAT model is used to estimate the effect of point and diffuse source of pollution on the 520 kmq S. Sperate basin, South western part of Sardinia, Italy. High levels of P, NH4 and COD, etc. are found in the two monitoring gages located on the Flumini Mannu of S. Sperate river within the basin. This contamination is assumed to be due to the civil and industrial compartment as well as to the agro-zootechnical compartment. Objective of this work is to apply the physically based hydrological model, SWAT 2000, to predict the impact of alternative land management practices and of point source of pollution on water bodies. To this end a statistical analysis of the climatic data has been carried out and daily rainfall data downscaled from monthly pluviometric records in order to generate weather daily inputs for the SWAT model. The resulting model input data along with the watershed and hydrologic response unit, HRU, spatial discretization criteria are carefully checked to ensure global consistency at the overall scale. The calibration and validation of the model outputs have been performed against monthly measured stream flows of the period 1922 1992. SWAT performance has been then compared with the result of the black box export coefficient model. This comparison is used to improve identifying methods, tools, and indicators at each scale that reflect critical ecosystem processes or state variables related to the integrity and sustainability of those ecosystems.

@InProceedings{CCC05a,
  author       = {Contu, I. and Carucci, A. and Cau, P.},
  title        = {Use of hydrological models at the catchments scale to predict the effect of different land management practices and point source pollution},
  booktitle    = {3rd International Swat Conference},
  year         = {2005},
  editor       = {EAWAG},
  keywords     = {SWAT, DSS, Sardinia},
  url          = {https://publications.crs4.it/pubdocs/2005/CCC05a},
}