African Water Development Report 2006 - United Nations Economic ...

African Water Development Report 2006are normally linked to the fluctuations in frequency-magnituderelationship of the climaticfluxes over the subregion, attributed to the anomalousbehaviour of the ITCZ and SST’s over theIndian Ocean, induced by the El Niño SouthernOscillation (ENSO). El Niño /La Niña eventscommence 8-10 months prior to changes in theAtlantic and Indian Oceans and this can providesome long-range forecasting lead-time.La Niña appears to have the greatest influence onrainfall in Southern Africa and wet episodes tendto occur throughout the subcontinent during thefirst few months of the post-La Niña year. Thestrongest La Niña signals occur in Southern Africaand in extra-tropical North Africa. Some influencealso appears along the Guinea. Strong positiveanomalies occur toward the end of the La Niñayear and/or the beginning of the post-La Niñayear and the positive anomaly is evident throughouta six to eight-month period. This is roughly thetiming of the maximum negative anomaly in theseregions during the El Niño cycle.Unlike the positive anomalies, the negativeanomalies are generally relatively weak and arenot temporally persistent. The strongest negativeanomalies generally occur toward the end of theLa Niña year or the end of the year preceding it.As with El Niño, the La Niña signal is strongestduring the second half of the episode (i.e. thecold phase), but in contrast to El Niño, rainfall isabnormally high. La Niña’s influence on rainfalloccurs most consistently in southwestern Africa(Namibia and western South Africa, from 15°Sto 32°S), with increased rainfall occurring in thefirst few months of the post-La Niña year in 14of 17 events. Further east, in a sector stretchingfrom southern Tanzania (10°S) to South Africa(32°S), positive anomalies occur at roughlythe same time but less consistently. In the twonorthern African sectors, positive anomalies occurredin this same season just as consistently,but were generally weak. In the western highlandsof equatorial Africa positive anomalies alsooccurred in the second half of La Niña episodes,but during the summer season.Potential Hazards in AfricaThe people of Africa are exposed to a wide rangeof disasters that ahve seriously aggravated theContinent’s economic situation. Economic lossesand human sufferings from floods, drought,desertification, locust infestation, infectiousdiseases, epidemics, and armed conflicts are thedominant disasters that the people in the Africancountries face, and they have rendered the peopleutterly vulnerable. Disasters have aggravated Africa’seconomic situation. The cumulative effectof disasters include loss of property, injury, death,mounting food import bills, health hazards, environmentaldegradation, backward economicdevelopment, displaced people, refugees, and nutritionaldeficiency. Today, 175 million Africansout of a total population of 744 million (23.5 percent) are suffering from chronic hunger; this isan increase of 50 per cent from 25 years ago. Inmany African countries, up to half of the populationsuffers from absolute poverty. It is projectedthat Africa will be the only Continent to remainat the current level of poverty for another decade.More than 50 million Africans have beenaffected by disasters such as drought, floods, fire,war, epidemics, industrial and transport accidentsduring the last decade. The main naturaldisasters, Africa-wide, are related to climaticextremes. Droughts are endemic in both SouthernAfrica and the Sahelian region of westernand northern Africa. In some cases droughts areexacerbated by human-induced changes in landcover. “Climate change is projected to increasethe risk of drought over much of Southern Africain the 21st century, partly through alteringthe frequency of El Niño events,” Floods canoccur in arid areas as well as humid areas. Intropical, near-coastal regions, they generally resultfrom cyclones that can drop a year’s worthof rainfall in a day. Because coastal zones are flatand densely populated, and cyclones are large inextent, hundreds of people can be affected. Africais generally not very windy, but tropical cyclonescan have a destructive force, and severeconvective storms sometimes generate tornadoesin the humid interior. “Dust storms are a feature234