Modelling the water budget and the riverflows of the Maritsa basin in Bulgaria

摘要

A soil-vegetation-atmosphere transfer model coupled with a macroscaledistributed hydrological model was used to simulate the water cyclefor a large region in Bulgaria. To do so, an atmospheric forcing was builtfor two hydrological years (1 October 1995 to 30 September 1997), at an eight kmresolution. The impact of the human activitieson the rivers (especially hydropower or irrigation) was taken into account.An improvement of the hydrometeorological model was made: for better simulation of summerriverflow, two additional reservoirs were added to simulate the slowcomponent of the runoff. Those reservoirs were calibrated using the observeddata of the 1st year, while the 2nd year was used for validation.56 hydrologic stations and 12 dams were used for the model calibration while41 river gauges were used for the validation of the model. The results comparewell with the daily-observed discharges, with good results obtained overmore than 25% of the river gauges. The simulated snow depth was compared todaily measurements at 174 stations and the evolution of the snow waterequivalent was validated at 5 sites. The process of melting and refreezingof snow was found to be important in this region. The comparison of thenormalized values of simulated versus measured soil moisture showed goodcorrelation. The surface water budget shows large spatial variations due tothe elevation influence on the precipitation, soil properties andvegetation variability. An inter-annual difference was observed in the watercycle as the first year was more influenced by Mediterranean climate, whilethe second year was characterised by continental influence. The energy budgetshows a dominating sensible heat component in summer, due to the fact thatthe water stress limits the evaporation. This study is a first step for theimplementation of an operational hydrometeorological model that could beused for real time monitoring and forecasting of water budget components andriver flow in Bulgaria.