Prior to canalization, the Plain of Reeds was seasonally flooded with standing water for continuous periods of up to seven months per year. Since canalization, floodwaters drain more rapidly, and the national park is flooded for less than six months per year. Water levels in the canals begin to rise in June, at the beginning of the rainy season. Between September and December, the national park is inundated to a depth of 2 to 4 m, with a peak in October.
 
Since the mid-1980s, 53 km of dykes fitted with sluices have been constructed around the national park, with the aim of impounding floodwater for longer, and reducing the lowering of the water table during the dry season. The national park is fragmented by canals into five management zones; the water level of each can be managed separately