Trends and discontinuities in regional rainfall of West and Central Africa: 1951–1989

Abstract

Standardized regional mean annual rainfall series are analysed over the period 1951-1989 from a data set of 891 rainfall stations which covers 23 countries of West and Central Africa. Missing values are estimated by using regionalized indexes computed on the basis of a morpho-climatic delimitation of 44 homogeneous climatic units. Searches for statistical discontinuities in rainfall series show no discontinuity for most units of Central Africa. For several units of West Africa the first discontinuity occurs at the end of the 1950s. The main discontinuity period occurs between 1968 and 1970, followed by a second one at the beginning of the 1980s. Rainfall deficit is greater north of 10°N, and is also important in the Guinean Mountains and on the northern coast of the Gulf of Guinea, west of the Atakora Mountains. Regions leeward of mountainous areas experienced moderate rainfall decrease.

Trends in spatio‐temporal variability in annual rainfall in Ghana (1951‐2000)

“…A great deal of research into the nature and causes of rainfall variability in the subregion has concentrated on the Sahel (Mahe et al, 2001). Nicholson et al (2000) argue that practical difficulties in obtaining data outside the Sahel may be a contributing reason, while on a more practical note Servat et al (1997) conclude that the tragic consequence of drought on the countries in the Sahel explains and justifies the regional focus.…”

The concept of rainfall and streamflow normals in West and Central Africa in a context of climatic variability

“…Initially observed and studied in the Sahelian regions, this drought also appeared in wetter regions, near the Gulf of Guinea (Sircoulon, 1976;Nicholson, 1985;Hubert & Carbonnel, 1987;Nicholson et al, 1988;Hubert et al, 1989;Demarée, 1990;Mahé & Citeau, 1993;Paturel et al, 1997Paturel et al, , 1998Servat et al, 1997a,b;Mahé et al, 2001b;L'Hôte et al, 2002). The rainfall deficit, observed over several consecutive years, has reduced flows of the region (Sircoulon, 1987;Sutcliffe & Knot, 1987;Olivry et al, 1993;Mahé & Olivry, 1991, 1999Aka et al, 1996;Servat et al, 1997c;Fanta et al, 2001).…”

Analysis of mid-twentieth century rainfall trends and variability over southwestern Uganda

“…Such information is still scarce because of the few studies that have analyzed the relationship of climate patterns and water management among others especially in the East Africa region. For example, Kampata et al (2008), New et al (2006), Schreck and Semazzi (2004), Kruger and Shongwe (2004), Mahe et al(2001), King'uyu et al (2000), Nicholson (1996), Ogallo (1993), Beltrando (1990), Rodhe and Virji (1976), and Samson (1952) are among the most recent studies concerning long-term climatological trends that have fo-cused on surface air temperature and precipitation in Africa. From these and other studies, a range of potential climatic impacts on water management for various geo-graphic areas, flood prevention and control, drought man-agement, food and fiber production, etc.…”