1896-2006 Sahelian annual rainfall variability and runoff increase of Sahelian Rivers

摘要: Updated rainfall data to 2006 confirm that the Sahelian has increased since end of 1990s, but annual average is still as low during drought 1970s. The decrease higher in Northwest and lower Southeast Sahel. increase temperature over West Africa 20th century induced an Potential Evaporation, which might reduce runoff. However, joint effect climate change human activities on land cover more than three decades responsible for runoff coefficients African Rivers 1970s, despite shortage same period, revealed by analysis from Mauritania, Burkina-Faso Niger. have regions with less 750 mm rainfall, under subdesertic climates, leading flood peaks, occurring earlier season. Even if it difficult separate part this coefficient due alone or impact cover, highest values are observed most inhabited areas, where dominated cultivated areas. This climatic/human so huge changed hydrological regimes Rivers, small watershed largest one, such Niger River at Niamey.