Water reservoirs and the risk of accidental flood occurrence. Case study: Stanca–Costesti reservoir and the historical floods of the Prut river in the period July–August 2008, Romania

In the summer of 2008 the Prut river recorded a historical flow of 7140 m³/s at its entrance into Romania. This flow was the highest ever recorded of any Romanian river. The high value was generated by high amounts of rainfall recorded first on the territory of Ukraine and then in Romania. Unfortunately, there were some discrepancies between the data transmitted and intercepted from the Meteorology National Agency and Hydrology and Water Management National Agency. This is why the amount of precipitation which fell over the territory of Ukraine could not be monitored in time and punctually. Nor could the high flood wave moving rapidly from the upper basin to the lower basin. The high flow of the upper Prut caused the accumulation of an immense quantity of water in the Stanca–Costesti reservoir. Under the conditions of precipitation occurring in the lower river basin as well, the levels reached the flood quota and the reservoir reached the maximum accepted capacity, with 0·1% insurance. The release of supplementary water quantities from the reservoir would have produced catastrophic floods downstream. Keeping the water in the reservoir could have broken it and the flooding, through backwater eddies, or the riverbank settlements. In such a case, it would have produced the greatest tragedy in the hydrological history of Europe. The most significant damage was produced upstream of the barrage, next to the localities of Radauti Prut and Baranca–Hudesti, as well as in the area of the reservoir, as a result of the phenomenon known as ‘remuu’, or backwater eddies. The floods of the Prut river occurred between the end of July and the end of August. Copyright © 2011 John Wiley & Sons, Ltd.