Applicability of global public domain data versus local detailed data for distributed hydrological modelling: a study form Gin river basin Sri Lanka

This study investigates the applicability of global public domain data versus local detailed data for distributed hydrological modelling using a case study approach. Major hydrological characteristics in Gin river basin are simulated in the study by applying the distributed hydrological model, YHyM/BTOPMC (University of Yamanashi Distributed Hydrological Model with Blockwise use of TOPMODEL and Muskingum-Cunge method) utilizing the global public domain data sets (Case 1) and local detailed data sets (Case 2). Evaluation of the model outputs for Case 1 and Case 2 shows that the overall hydrological behavior of the Gin river basin is adequately simulated by the model for both Case 1 and Case 2. The simulated average annual discharge volumes in Case 1 and Case 2 at Agaliya during 2002-2006, vary from the observed average annual discharge volume by +4.25 and +1.31 %, respectively. In general, simulated daily discharge in Case 1 shows slightly higher value than that of Case 2 resulting a difference of 0.9 m(3)/s during 2002-2006, on average. The relative differences between the simulated daily discharges in Case 1 and Case 2 become higher during the recession limbs of the flow hydrographs at Agaliya. Reasons for these variations are being discussed in the study. The results of the study give motivation towards the use of global public domain data for hydrologic simulations in data-poor (limited availability of local data) basins.