Evaluation of the instrinsic vulnerability of the Mingosso watershed (Yaounde region) by parametric methods DRASTIC, SI and GOD

The Mingosso watershed is located at periurban zone. It was influenced by high rate of occupation of space by the dwellings. This occupation of space has an impact on the groundwater quality exploited by the wells and the springs. These groundwaters make it possible to make up the deficit due to the lack of the distribution network of water. This water is also threatened by pollution rising from the anthropic activities. In order to protect groundwaters from the Mingosso watershed against pollution, the study on the evaluation of the intrinsic vulnerability in the aquifers of this watershed was carried out by applying methods DRASTIC, SI and GOD coupled with a Geographical Information System. The aim had by this study is to chart the zones likely to be more at the risk of contamination due to an activity coming from the soil surface. Three classes of degree of vulnerability similar to pollution are highlighted by methods DRASTIC, SI and GOD. They are the classes of low, average vulnerability (or moderate) and strong (or significant). The low class of degree vulnerability is most dominant, covering the surfaces respectively of 53,82%; 67,46% and 71,80% for these methods. This low degree vulnerability is due to low permeability, an average infiltration and average slopes. The rate of coincidence of the values of mineralisation of groundwaters with the definite zones of vulnerability is 37%, 18,5% and 25,9% respectively for methods DRASTIC, SI and GOD. Of this rate of coincidence, approach DRASTIC seems to better reflect reality on the ground and could be adequate for the tracing of the vulnerability in the Mingosso watershed.