RAINFALL MONITORING AND DISCHARGE FORECASTING OVER MEDITERRANEAN BASINS IN BULGARIA Eram Artinian, Dobri Dimitrov National Institute of Meteorology and Hydrology of Bulgaria – regional centre Plovdiv, Bulgarian Academy of Science [email protected] The Arda River basin is located in the Southeast part of Bulgaria. Its climate is highly influenced by the Mediterranean. For instance over 70% of the river flow of Arda River at Vehtino village is concentrated in winter-spring period. On the other hand, summer months are very dry with average river flow at basin outlet between 20 and 30 m3/sec. Three large dams forming a cascade are built in 1950s on the river bed – Kardzhaly, Studen Kladenets and Ivaylovgrad. Their total capacity is about 1 billion m3 versus mean annual inflow of about 2 billion m3. Hydrological observations were made since 1950s. There are 7 operating stations by now. The river stages are recorded on paper support by limnigraphs. Once a month the river discharges are measured by using current meters. Discharge rating curve is established for each station. 16 automatic rain gages were 2 installed in 2006 and real-time precipitation data is processed Arda River basin in Bulgaria covers about 5200 km and in every 3 h to produce fields with grid cell size of 8 km. Greece (on the right) about 600 km2. To optimize reservoir management for energy production and for limiting dam overflow an automatic rainfall monitoring network coupled with discharge forecasting system was developed. Forecasted precipitation and air temperature outputs from ALADIN with 72 h lead- time are used. Initialization is done after running the model with real-time precipitation fields. Nash-Sutcliffe coefficient of the comparison of mm the simulated against forecasted discharge series 24h 1.00 depending on forecast lead-time 0.95 t n e i 0.90 c i f f e 0.85 o c h s 0.80 a Arda N 0.75 Varbitsa 0.70 0 24 48 72 forecast lead-time in hours Various data sources used together, operational processing twice a day, diagnosis and forecasts at website Data from 19 manual rain gages and ISBA surface scheme coupled with Diagnostic and forecasted stream 16 automatic rain gages is used to Modcou macro scale distributed flows [m3/sec] are computed for produce precipitation fields with 3h hydrological model is used. Fields of profiles with monitored river flow and time step. Near real-time water level evapo-transpiration, surface runoff, soil in separate additional profiles like measurements, converted to moisture and snow water content are outlets of rivers to the dams. The discharges serve for model stored for each run as well as diagnostic various results are made accessible at verification each day. and forecasted discharge series. an interactive website. Near real-time Model result with use A new 72 h ahead measured of measured input forecast is issued discharge twice a day Conclusion: Short range atmospheric forecasting models’ result may be used for distributed hydrological modeling to produce discharge forecast for up-to 72 h ahead. Statistic scores are higher for periods with advective, long lasting precipitation events. The system can serve to improve flood preparedness, to increase reservoirs efficiency and for research purposes..