Most of the basins in the Mediterranean Region are characterized by a large spatial gradient in rainfall and temperature and heterogeneity in lithology, soil, and land use. Such environmental factors determine a specific hydrological regime that generally includes periods of absence of flow and flash flood events. Lithological and geological features are important factors affecting the flow regime, playing a crucial role in groundwater and surface-water interaction and water exchange for which the flow may appear and disappear along with the river network. In such a complex environment, the hydrological model set up and run may be a challenge. This work, through a case study, aims at testing different options in simulating hydrology in Mediterranean basins with karst areas. The Soil and Water Assessment Tool (SWAT) was applied to the Canale d’Aiedda (Puglia, Italy), a temporary karst river basin under the Mediterranean climate and with limited data availability. Different watershed delineations and model parameterization were adopted to simulate the hydrological processes in the study area that include: (i) a GIS elaboration consisting of the cut-off of the karst areas (Configuration A); (ii) basin set-up including the karst areas (Configuration B) and (iii) a model parameterization considering a specific bypass flow function activated in karst sub-basins (Configuration C). SWAT showed great adaptability in the three configurations. The statistical performances were satisfactory for the configurations B and C and good for A. In particular, A and C slightly underestimate (PBIAS +5.1) and overestimate (PBIAS -2.0) daily streamflow, respectively, and B overestimated streamflow (PBIAS +25.4). Differences in water balance components were detected among the three configurations. Rainfall ranged from 732 mm to 745 mm due to the different number of weather stations included in the three model configurations. Configuration C showed lower values of surface runoff and actual evapotranspiration compared to configurations A and B, meanwhile, the values for total water yield and deep aquifer recharge were higher. Configuration B showed mean monthly flow lower than A and C, except for July. During the wet months (from October to February), configuration C showed mean monthly streamflow higher than A and B and also than measured streamflow. From May to July, Configuration C presented the best fit compared to the measured monthly streamflow. This study showed that the choice of the best approach depends on the final aim of the work since all the configurations provided acceptable performances.
Simulating streamflow in a karst river basin: comparing different approaches
Marco Centanni;Giovanni Francesco Ricci;Francesco Gentile
2022-01-01
Abstract
Most of the basins in the Mediterranean Region are characterized by a large spatial gradient in rainfall and temperature and heterogeneity in lithology, soil, and land use. Such environmental factors determine a specific hydrological regime that generally includes periods of absence of flow and flash flood events. Lithological and geological features are important factors affecting the flow regime, playing a crucial role in groundwater and surface-water interaction and water exchange for which the flow may appear and disappear along with the river network. In such a complex environment, the hydrological model set up and run may be a challenge. This work, through a case study, aims at testing different options in simulating hydrology in Mediterranean basins with karst areas. The Soil and Water Assessment Tool (SWAT) was applied to the Canale d’Aiedda (Puglia, Italy), a temporary karst river basin under the Mediterranean climate and with limited data availability. Different watershed delineations and model parameterization were adopted to simulate the hydrological processes in the study area that include: (i) a GIS elaboration consisting of the cut-off of the karst areas (Configuration A); (ii) basin set-up including the karst areas (Configuration B) and (iii) a model parameterization considering a specific bypass flow function activated in karst sub-basins (Configuration C). SWAT showed great adaptability in the three configurations. The statistical performances were satisfactory for the configurations B and C and good for A. In particular, A and C slightly underestimate (PBIAS +5.1) and overestimate (PBIAS -2.0) daily streamflow, respectively, and B overestimated streamflow (PBIAS +25.4). Differences in water balance components were detected among the three configurations. Rainfall ranged from 732 mm to 745 mm due to the different number of weather stations included in the three model configurations. Configuration C showed lower values of surface runoff and actual evapotranspiration compared to configurations A and B, meanwhile, the values for total water yield and deep aquifer recharge were higher. Configuration B showed mean monthly flow lower than A and C, except for July. During the wet months (from October to February), configuration C showed mean monthly streamflow higher than A and B and also than measured streamflow. From May to July, Configuration C presented the best fit compared to the measured monthly streamflow. This study showed that the choice of the best approach depends on the final aim of the work since all the configurations provided acceptable performances.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
