Elevation of the Pantanal ranges from above sea level. Annual rainfall over the flood basin is between , with most rainfall occurring between November and March. Annual average precipitation ranged from 920 to 1,540 mm in the years 1968-2000. In the Paraguay River portion of the Pantanal, water levels rise between two meters to five meters seasonally; water fluctuations in other parts of the Pantanal are less than this. Flood waters tend to flow slowly ( per second) due to the low gradients and high resistance offered by the dense vegetation.