ASSESSMENT OF THE POTENTIAL IMPACT OF CLIMATE CHANGE UPON SURFACE WATER RESOURCES IN THE IALOMITA RIVER BASIN FROM ROMANIA.

The warming of the global climate caused by the greenhouse effect can induce essential changes in the hydrological regime and water resources at a different time and space scale. Water balance modelling with regard to climate change scenarios can give substantial information on changes in the hydrological situation in the future. Water-balance models are especially useful for identifying the regional hydrologic consequences of changes in temperature, precipitation, and other climatic variables [1]. The aim of the present research is the determination of the impact of possible climatic changes in the 21st century upon surface water resources in the Ialomita river basins, using the WatBal (water balance) model. The analyzed river basin covers an area of 10 309 km² and is located outside the curvature of the Carpathian Mountains, in an area where the altitude varies between 50 m and 2500 m. In accordance with the altitude, the annual precipitation varies from 450 mm/year in the plain area to over 1000 mm/year in the mountain area and the evaporation-transpiration between 850 mm/year in the plain area to 500 mm/year in the high areas. On the other hand, due to a very high variability of weather conditions, droughts, as well as excessive humidity periods, may occur during the year. WatBal is an integrated water balance model developed for assessing the impact of climate changes on a river basin runoff. This model has essentially two main modelling components. The first is the water balance component that uses continuous functions to describe water movement into and out of a conceptualized basin. The second component is the computation of the potential evaporation-transpiration processes. The model input components are: precipitation, air temperature, relative air humidity, wind speed, sunshine duration, net radiation, albedo and historic discharges (only for calibration of model parameters). The output components are: effective precipitation, potential evaporation-transpiration, total modelled runoff (direct, surface, subsurface runoff and base flow) and relative depth of water reserves in the basin [2]. Monthly data series recorded at 8 weather stations and 1 runoff gauging-station during the 1961-2007 period have been used for the calibration of the WatBal model to the local conditions of the area. Finally, the paper focuses on the values of the mean monthly discharges at Tandarei gauging station on the Ialomita River, estimated in the above-mentioned hypotheses. The paper analyses the influence of potential climatic changes, expressed by a wide range of climatic scenarios, upon the average water resources in the Ialomita river basin. We have also taken into consideration the average-low water resources, expressed by the minimum monthly average liquid discharges and characteristic to low-water periods as well as the average-maximum water resources, expressed by the maximum monthly average liquid discharges and characteristic to high-water periods. [ABSTRACT FROM AUTHOR]