About 45% of our country is lowland area, one quarter of which is a low-lying flat area from which water does not flow naturally. Without the drainage structures, these areas would be permanently or periodically covered by the accumulated runoff from snowmelt and rainwater for a long time. A very significant part of Hungary, 45,000 km2 is lowland area, 60% of it is significantly threatened by inland water.
Excess water inundation
Excess water pumping
In areas of low slopes, the speed of the water flowing on the surface is very low, the water flow is slowed down and it is difficult to drainage it. In such places, under natural conditions, the water remains in the hollows and it can be only drained by artificial means and facilities. Damaging excess water occurs in the upper layer of the soil when free pores of the soil are saturated with water, it is characterized by the fact that it is formed locally as a result of unfavourable meteorological and hydrological factors: from sudden snowmelt, precipitation but it can also appear because of high groundwater level, when groundwater escapes to the surface.
Regarding the elaboration of excess water hazard mapping methodology, several concepts have been created in different research workshops, the most well-known map covering a significant part of the country, is the Pálfai’s excess water vulnerability map.
According to the Pálfai’s index, the areas of Hungary endangered by inundation are classified as I.-IV. category. The Pálfai’s vulnerability index (in %) is a relative indicator that numerically indicates the excess water vulnerability of any defined area. The excess water hazard index can be determined by weighting the size of areas flooded with different frequencies.
Hydromechanization dredging (Szarvasi-oxbow)