Orange River Basin Evaporation in Average Year

In the Orange river basin there is a clear east west divide in evaporation with the dry western section of the basin consistently showing low evaporation levels. From October to March when rainy period occurs evaporation in the basin is higher with the eastern portion showing more elevated levels than the western section. During the dryer months of May to September there is little evaporation but inter annual variability does exist with 1988 and 1996 differing by experiencing higher evaporation levels, presumably due to increases in rainfall which occurred with La Nina conditions.