Soil erosion is the most widespread form of soil degradation in Europe. European policies (PAC 2014-2020) aimed at reducing soil erosion are increasingly directed to the application of Best Management Practices (BMPs). Indeed, European states and, consequently, regions have foreseen in their development policies many funds to counteract this problem. This work aimed at (i) quantifying sediment yield; (ii)identify critical areas where interventions to reduce soil erosion are needed; (iii) identify specific Best Management Practices (BMPs) for reducing erosion. The Soil and Water Assessment Tool (SWAT) was applied in a southern Europe watershed, the Carapelle (Puglia, Southern Italy) to quantify sediment yield at basin and subbasin scale and to simulate BMPs scenarios. The model was calibrated and validated, manually and with SWAT-CUP, both for runoff and sediment load at daily time scale for a five years period (2007-2011). Performances were evaluated using the Nash and Sutcliffe efficiency coefficient (NSE), the Percent Bias (PBIAS) and the coefficient of determination (R2). Statistics showed generally a satisfactory efficiency. In particular, for the runoff calibration NSE, R2 and PBIAS were 0.6, 0.6 and +10.8 respectively, while for validation were 0.5, 0.5 and -17.1. Regarding the sediment load, for the calibration, NSE, R2, and PBIAS were 0.5, 0.5 and -2.8, whilst, for the validation were 0.5, 0.5 and +5.1, respectively. On the basin scale, average annual sediment load was estimated to be 6.8 t ha-1 yr-1. At subbasin scale a gradient of sediment yield was found, characterized by a large difference among the upper (from 7 to 13 t ha-1 yr-1), central and lower parts (<1 t ha-1 yr-1) of the basin. The results show that in the Carapelle the soil erosion is irreversible as soil losses are higher than the soil formation rate. To reduce economic and environmental impacts, specific measures are needed, especially in the upper part of the basin. Subsequently, based on the regional policies, three different scenarios of BMPs were implemented: (i) contour planting, (ii) no-tillage and (iii) reforestation. A threshold of sediment yield greater than 10 t ha-1 yr-1 was selected to discretize the target areas in which apply the BMPs. Among these, the first scenario was applied in areas with a slope < 20% (risk of the overturning of tractor), the second in areas devoted to the winter wheat production and the third in all the abandoned lands. The comparison of the different scenarios will be useful for the watershed management in order to select and prioritize the interventions in the Carapelle watershed.
Modelling management practices to reduce soil erosion in an agricultural watershed in Southern Europe
Ricci G. F.;Gentile F.;
2018-01-01
Abstract
Soil erosion is the most widespread form of soil degradation in Europe. European policies (PAC 2014-2020) aimed at reducing soil erosion are increasingly directed to the application of Best Management Practices (BMPs). Indeed, European states and, consequently, regions have foreseen in their development policies many funds to counteract this problem. This work aimed at (i) quantifying sediment yield; (ii)identify critical areas where interventions to reduce soil erosion are needed; (iii) identify specific Best Management Practices (BMPs) for reducing erosion. The Soil and Water Assessment Tool (SWAT) was applied in a southern Europe watershed, the Carapelle (Puglia, Southern Italy) to quantify sediment yield at basin and subbasin scale and to simulate BMPs scenarios. The model was calibrated and validated, manually and with SWAT-CUP, both for runoff and sediment load at daily time scale for a five years period (2007-2011). Performances were evaluated using the Nash and Sutcliffe efficiency coefficient (NSE), the Percent Bias (PBIAS) and the coefficient of determination (R2). Statistics showed generally a satisfactory efficiency. In particular, for the runoff calibration NSE, R2 and PBIAS were 0.6, 0.6 and +10.8 respectively, while for validation were 0.5, 0.5 and -17.1. Regarding the sediment load, for the calibration, NSE, R2, and PBIAS were 0.5, 0.5 and -2.8, whilst, for the validation were 0.5, 0.5 and +5.1, respectively. On the basin scale, average annual sediment load was estimated to be 6.8 t ha-1 yr-1. At subbasin scale a gradient of sediment yield was found, characterized by a large difference among the upper (from 7 to 13 t ha-1 yr-1), central and lower parts (<1 t ha-1 yr-1) of the basin. The results show that in the Carapelle the soil erosion is irreversible as soil losses are higher than the soil formation rate. To reduce economic and environmental impacts, specific measures are needed, especially in the upper part of the basin. Subsequently, based on the regional policies, three different scenarios of BMPs were implemented: (i) contour planting, (ii) no-tillage and (iii) reforestation. A threshold of sediment yield greater than 10 t ha-1 yr-1 was selected to discretize the target areas in which apply the BMPs. Among these, the first scenario was applied in areas with a slope < 20% (risk of the overturning of tractor), the second in areas devoted to the winter wheat production and the third in all the abandoned lands. The comparison of the different scenarios will be useful for the watershed management in order to select and prioritize the interventions in the Carapelle watershed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
