Hydrological models are recognized as valid scientific tools to assess water balance and provide support for the integrated management and planning of water resources. Calibrating and validating hydrological models in ungauged basins are complex due to the lack of reliable data, uncertainty in representing the hydrological processes and the physical features of a river catchment in a simulation model. In the present study an innovative approach is presented which couples a semi-distributed hydrological model called Distributed model for Runoff, Evapotranspiration, and Antecedent soil Moisture simulation (DREAM) with the FAO’s Crop Water Productivity Simulation Model (AQUACROP). The main objective of the study is to calibrate and validate the Dream model by assessing an accurate estimation of soil water content using AquaCrop model. The study area is "Lama San Giorgio", a basin located in a wadi area in the central part of the Apulia region
. The calibration process regards a specific parameter of the water balance: the subsurface flow coefficient that controls the lateral flow and assumes a constant value in time and space.