Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Master → Kenya → 1997 → SOME ASPECTS OF DROUGHT IN THE LAKE VICTORIA BASIN, KENYA

Moi University (1997)

SOME ASPECTS OF DROUGHT IN THE LAKE VICTORIA BASIN, KENYA

Olwero, Jotham Nasser G

Titre : SOME ASPECTS OF DROUGHT IN THE LAKE VICTORIA BASIN, KENYA

Auteur : Olwero, Jotham Nasser G

Université de soutenance : Moi University

Grade : Masters 1997

Résumé
Droughts were identified in the Lake Victoria basin by the Herbst et al.(1966) method employing monthly rainfall data. The onset and termination dates, durations, intensities and Severity indices of droughts were determined by running the Herbst procedure in a QBASIC program. The stations were compared with respect to the severity indices and a severity map developed. Further spatial analysis of drought was carried out using GIS overlay of the map obtained from the above procedure, a classified soil map, a map of coefficients of variation and a classified annual rainfall map. The result of this overlay produced finely defined areas which were interpreted as areas of greatest drought vulnerability. The frequency of droughts was examined by investigating the probability density functions (pdf) of the severity indices. This revealed that the severities fitted lognormal distribution. The frequencies were then investigated by normalizing the lognormal pdf which allowed the use of the normal probability tables. It was discovered that a drought of severity index 36 (severe) occurs about once in 100 years and that of 15 (not severe) once in 10 years. The study also investigated the impacts of droughts in the area by use of questionnaires and interviews. Impacts identified from this were mainly crop failure, depletion of water resources and lack of pasture. Drought was also found to limit the access to water hence causing use of water of poor quality. Agriculture records were examined to identify trends in crop yields. It was noted that the yields varied in the various divisions following approximately the trend of droughts identified above and the yields seemed to have gone so low in 1993 just as was observed from the interviews. The physical methods used to identify drought were seen to tie well with the Herbst et al. (1966) method. This therefore qualifies the latter method satisfactory for use in the study area. The characteristics of drought identified here are deemed useful for planners, managers and environmentalists

Présentation (Research Kenya)

Page publiée le 10 décembre 2013, mise à jour le 28 mars 2018