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DatoValore
TitleModeling nutrients in the Rio Mannu River Basin: Scenario analysis
AbstractThe Rio Mannu River Basin (Sardinia, Italy) is experiencing an intensification of agriculture, and correspondingly, irrigation areas are increasing. Like many Mediterranean areas, this basin is characterized by water shortages and diffuse pollution from agricultural sources. It is than important to design, evaluate and adopt adequate management policies to prevent further water quality impairment. The Soil and Water Assessment Tool (SWAT), a model for agricultural watersheds, was applied to simulate hydrological processes and evaluate current and future nutrient loads. Several alternative scenarios were developed through discussions with stakeholders, and four of them were selected and simulated as realistic in consideration of the socio-economical situation in the study area. Scenario A involves agricultural practices that assume a reduction in fertilizer. Scenario B regards the reuse (in three sub-basins) of treated wastewater in fert-irrigation of olive trees instead of discharging it into the river system. Scenario C regards the partial substitution of durum wheat with sugar beet in a subset of the catchment. Scenario D introduces rapeseed and sunflower replacing durum wheat in an other small area. We assessed each option by considering the effects on water balance, water quality, crop yields and economic benefits. The model was able to simulate the hydrologic cycle and water quality notwithstanding an insufficient availability of measured data. This study suggests that a better use of fertilizers could substantially reduce the amount of nutrients flowing into surface waters, but the effects of such a policy on crop yield and farm income are in some cases negative. The reuse of treated effluent can results in a moderate reduction in nutrient load but in a larger reduction in nutrient concentration; it is more efficient in summertime and on soluble compounds (NO3, NH3 and min P); furthermore an application at larger scale of such scenario will result in very great results. The sugar beet scenario is the less competitive scenario: it features slightly higher loads and large increment in water resources usage. In the last scenario the release of several nutrient will increase; maybe a competitive scenario in terms of revenues for farmers coupled with a 6% reduction of water use in irrigation.
Source21ST CENTURY WATERSHED TECHNOLOGY: IMPROVING WATER QUALITY AND ENVIRONMENT CONFERENCE PROCEEDINGS, Univ Earth, Guacimo, COSTA RICA, FEB 21-24, 2010
KeywordsFuture scenariosModelingSWAT modelWater qualityWatershed management
Year2010
TypeContributo in atti di convegno
AuthorsDe Girolamo, Anna Maria; Lo Porto, Antonio
Text372039 2010 Scopus 2 s2.0 79959557949 Future scenarios Modeling SWAT model Water quality Watershed management Modeling nutrients in the Rio Mannu River Basin Scenario analysis De Girolamo, Anna Maria; Lo Porto, Antonio IRSA CNR, Bari The Rio Mannu River Basin Sardinia, Italy is experiencing an intensification of agriculture, and correspondingly, irrigation areas are increasing. Like many Mediterranean areas, this basin is characterized by water shortages and diffuse pollution from agricultural sources. It is than important to design, evaluate and adopt adequate management policies to prevent further water quality impairment. The Soil and Water Assessment Tool SWAT , a model for agricultural watersheds, was applied to simulate hydrological processes and evaluate current and future nutrient loads. Several alternative scenarios were developed through discussions with stakeholders, and four of them were selected and simulated as realistic in consideration of the socio economical situation in the study area. Scenario A involves agricultural practices that assume a reduction in fertilizer. Scenario B regards the reuse in three sub basins of treated wastewater in fert irrigation of olive trees instead of discharging it into the river system. Scenario C regards the partial substitution of durum wheat with sugar beet in a subset of the catchment. Scenario D introduces rapeseed and sunflower replacing durum wheat in an other small area. We assessed each option by considering the effects on water balance, water quality, crop yields and economic benefits. The model was able to simulate the hydrologic cycle and water quality notwithstanding an insufficient availability of measured data. This study suggests that a better use of fertilizers could substantially reduce the amount of nutrients flowing into surface waters, but the effects of such a policy on crop yield and farm income are in some cases negative. The reuse of treated effluent can results in a moderate reduction in nutrient load but in a larger reduction in nutrient concentration; it is more efficient in summertime and on soluble compounds NO3, NH3 and min P ; furthermore an application at larger scale of such scenario will result in very great results. The sugar beet scenario is the less competitive scenario it features slightly higher loads and large increment in water resources usage. In the last scenario the release of several nutrient will increase; maybe a competitive scenario in terms of revenues for farmers coupled with a 6% reduction of water use in irrigation. 9781617823589 Published version http //www.scopus.com/record/display.url eid=2 s2.0 79959557949 origin=inward 21ST CENTURY WATERSHED TECHNOLOGY IMPROVING WATER QUALITY AND ENVIRONMENT CONFERENCE PROCEEDINGS Univ Earth, Guacimo, COSTA RICA FEB 21 24, 2010 Internazionale Contributo Contributo in atti di convegno antonio.loporto LO PORTO ANTONIO annamaria.degirolamo DE GIROLAMO ANNA MARIA MIRAGE Mediterranean Intermittent River Management TA.P04.005.006 Gestione a scala di bacino delle risorse idriche e sostenibilita dell uso irriguo in agricoltura