Water for people.pdf - WHO Thailand Digital Repository

S E N E G A L R I V E R B A S I N , G U I N E A , M A L I , M A U R I T A N I A , S E N E G A L / 4 5 9■ education, by favouring collaboration between stakeholders;■ technology, by reassessing the situation (diagnosis of the entirebasin) and defining the strategic orientations and measuresrequired to establish sustainable resource management practices;■ legislation, by ensuring that regulatory actions carried out in allof the member states are coherent; and■ finances by focusing funding on future OMVS programmes.Moreover, the May 2002 effective date of the Senegal RiverWater Charter and the start-up of environmental monitoring bythe Observatory represent golden opportunities for increasing theinvolvement of representatives of the various stakeholders in theresource management decision making process. This participatoryapproach will be reinforced by the launching of the Master Plannext year.Identifying Main ProblemsDegradation of ecosystemsThe flood plain ecosystems have been most affected by damconstruction. In less than ten years, the degradation of theseenvironments and the consequences on the health of the localpopulation have been spectacular.Upstream of Diama, the functioning of regularly floodedwetlands, lakes and ponds, such as the Djoudj, Guiers Lake andLake Diawling, has been seriously disrupted. After 1986, Diama damblocked seawater intrusion. The water above the dam is now freshyear-round, creating ecological conditions favouring the proliferationof freshwater plants (Typhas, Pistia startioles, Salvinia molesta andvarious alga species). These are very invasive and eutrophicationhas begun at some places in the valley and the delta. Downstreamof the Diama dam, perturbations in the functioning of ecosystemstakes the form of an increase in salinity and/or a drying-up duringpart of the year (Ndiael wetlands) due to the reduction of floodingor the destruction of water inflow channels during construction ofthe development works (dikes, irrigated areas). Anthropogenicpollution is caused by the discharge of industrial and agriculturalchemicals into these environments.Other problems arise from increased competition for agricultural landand firewood. As marginal land on slopes and river banks is cleared,there is increased erosion. In addition, large areas of the basin havebeen denuded due to overgrazing. As was shown in table 20.3, a bigpercentage of the population is pastoral and therefore must compete forland, increasing competition between agriculture and pastoralism.Public healthThe degradation of the basin’s ecosystems has affected the riparianpopulation to various degrees. For example, there has been a dropin productivity in some economic areas (agriculture, fishing,livestock-raising) compared to productivity during the first yearsafter the dams were filled, which has led to a decrease in incomeand, therefore, a decrease in the standard of living.The most serious problem that the basin has had to face since1993/4, however, is the impact of the dams on public health. Therehas been not only a rapid increase in the prevalence of water-bornediseases that were already present in the area (malaria, urinaryschistosomiasis, diarrhoea, intestinal parasitic diseases), but also theappearance of intestinal schistosomiasis, a much more dangerousform of the disease.MalariaMalaria is a major public health problem in the basin. Indeed, it isthe primary reason for consultations in health clinics and the primarycause of death. It causes 90 percent of the cases of fever. It iscaused by Plasmodium falciparum, the most deadly species ofPlasmodium, carried by the anopheles mosquito Anopheles gambiae.DiarrhoeaSurveys done recently by the OMVS in the three member statesindicate a diarrhoea prevalence of 15 to 30 percent around Podor(Senegal). This rate is estimated to be about 25 percent in Mauritaniaand 15 percent in Mali. Many factors favour the appearance ofdiarrhoea, but in the Senegal River basin, aside from general hygiene,the primary cause is the abusive use of agricultural fertilizers andpesticides, which, at the end of the hydrological cycle, end up in thehuman food chain.Schistosomiasis (bilharzia): urinary and intestinalIn the OMVS area of the basin, there are two types of humanschistosomiasis: urinary and intestinal. Intestinal schistosomiasis wasunknown in the region before the dams were built, but today is rampantin the valley and delta. The blocking of saltwater intrusion upstream hasallowed the snails that host the parasite (Schistosoma mansoni) toproliferate in the desalinated river and irrigation canals. Humans arecontaminated when the parasite penetrates the victim’s skin.Surveys conducted in 2000 by OMVS health services in themember states indicated a prevalence of urinary schistosomiasisdisease in about 50 percent of the region around Saint Louis. InMauritania, in the Trarza, the average infestation is estimated to beat 25 percent, with places where the increase in prevalence is quitespectacular. For example, in Lexeiba, the infestation rate increasedfrom 8 to 50 percent in only a few years. In Mali, urinaryschistosomiasis is highly present, with a rate of 64 percent.