Somes-Tisa Watershed Area
Somes-Tisa watershed area is located to the North and North-Western part of the country, being delineated to the North by the natural border – Tisa river with Ukraine on a length of 61 km, to the West by the border with the Hungarian Republic, and on the national territory, it borders on Siret Basin to the East, Mures Basin to the South and Crisuri Basin to the South-West.
Where is it located?
In administrative terms, Somes-Tisa watershed area includes the territory of 7 counties, respectively: Cluj, Salaj, Bistrita-Nasaud, Maramures, Satu Mare, Alba and Bihor. The ratio of the last two is insignificant. The total population is of around 1.95 million inhabitants, the population density being of 87.03 inhabitants/km2.
On the Romanian territory, Somes-Tisa watershed area includes the sub-basin of Tisa (including Turul) with 123 coded water courses (an area of 4540 km2 and the network density of 0.35 km/km2), Somes with 403 coded water courses (an area of 15740 km2 and the network density of 0.35 km/km2) and Crasna with 54 coded water courses (an area of 2100 km2 and the network of 0.34 km/km2). The total water resources of surface water in Somes-Tisa watershed area amount to approx. 6830 mil. m3/year, of which, usable resources are of approx. 1287 mil. m3/year. In Somes-Tisa watershed area, there are 8 important reservoirs (with an area of more 0.5 km2), of complex use and totaling a useful volume of 328.3 mil. m3.
Total water resources
The total area of Somes-Tisa watershed area is of 22451.86 km2, representing a ratio of 9.42% of the country area. The hydrographic network includes 580 surveyed water courses (of which 46 have river basins with an area of less than 10 km2), with a total length of 8387 km and an average density of 0.37 km/km2.
The average multiannual discharges for the main rivers in Somes-Tisa watershed area are: 130 m3/s (Tisa river when exiting the country), 129 m3/s (Somes river in Satu Mare gauge station), 5.83 m3/s (Crasna river in Domanesti station).
Description of existing flood protection works
Structural measurements refer to investment works for making safe the existing ones and for bringing them to the performance parameters stipulated in the Defense Strategy, as well as new investment works both on water courses and on areas of sub-basins making up Somes-Tisa watershed area. The main existing works considered for making them safe are reservoirs and embankment works, especially those defending important socio-economic and administrative centers.
Serious floods, with significant maximum discharges, come from rainfalls recorded on large areas of the basin or from mixed source (snowmelt and rain). The maximum historical flood over the last 50-60 years was that occurred in 1970, having a mixed source. An analysis of the series of floods over around the last 50 years shows that the most significant floods occurred in: 1970, 1974, 1975, 1978, 1979, 1980, 1981, 1989, 1993, 1995, 1998, 2000, 2001, 2005 and 2008.