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

polluted due to overgrazing, and certain foragesare “weak” due to excessive animal pressure 135 .The Dinka of the Sudan look at the quantity ofmanure left by livestock in order to detect overuseof the range (FAO CF Note 4, 1990).The building of small barrages and dams has beenobserved among a few pastoral groups. “Hafirs” orsmall stone walled barrages are common in northernSudan, Somalia, and among the Zaghawa ofChad. Unfortunately not much has been writtenon their management such as organization of theconstruction and management tasks, design andlocation. The use of surface catchment basins appearsto be more widespread in North Africa andelsewhere than in Sub-Saharan Africa. For example,in Tunisia many different types of waterharvesting systems are used to irrigate crops andforage, to recharge aquifers, and to create stockponds and reservoirs (FAO CF Note 4, 1990).ENSURING THE KNOWLEDGE BASEBox 16.1: Indigenous Knowledge on Soil TypesThe Bambara agropastoralists of Mali have one of the most complete soil classification systems. They distinguish7 major soil types, which very regularly correspond to western soil texture types. The level of classification is notequally detailed for all soil groups. The most detailed division is for the sandy soil, due to the fact that these are usedfor cultivation. They also distinguish soil colour - not just hue but also greyness/brightness and darkness/lightness(similar to formal science). They also classify soils according to their inundation potential, ease of cultivation andpotential for certain crops.Indigenous Knowledge on Vegetation TypesThe Maasai of Kenya differentiate between pastures and the “wilderness” (the former used for grazing, the latterfor hunting), and divide pastures into lowland (wet season) and highland (dry season) areas. The Fulani of northernBurkina Faso recognize 4 major vegetation communities, each divided into different range types. The Zaghawadistinguish many different range types, depending on their forage value (coarse, tender, salty, poisonous, etc.) andeffect on livestock (constipating, irritating, nutritious, etc.). The Mbozi of Southern Tanzania have several broad vegetationtypes, but in the same type will have different names according to the density of vegetation. The Wodaabecategorize plants according to the type of soil they grow on and in which they are best suited to. The Twaregdistinguish many different woodlands, e.g. “efei” is a large area with big trees, “afara” is an area with a mixture oftrees, bushes and herbs, “taferfera” is a dense thicket, “agoras” is a line of riparian trees, “abatol” is a small, isolatedwooded area, “amesekni” is an isolated, remarkable tree in the middle of grassland/desert, or an isolated tree ofone species in the middle of a forest which is used as a point of reference.Source: FAO CF Note 4, 1990 Community Forestry: Herders’ Decision-Making in Natural Resources Management in Arid and Semi-aridAfrica301