Nearly one-half (44%) of the length of principal levees (4 180 km) does not meet regulatory standards for levee height. Former flood plains accommodate one third of all arable land, as well as 32% of railroads, 15% of roads, and over 700 settlements with 2.5 million inhabitants. Four extraordinary flood events have happened in the Tisza River Basin area between 1998-2001, causing considerable damage.