In Sibilu dam catchment geomorphological, geological hydrological and engineering geologicalrnstudies were conducted 10 characterize the lim itat ion and importance of the area for the new d:unrnconstruction.rnUsing main ly Ihe, aerial photos and lopo-maps of the area relief and landform, s lope andrngeomorphological maps of the catchment afC produced at the sca le of I :50,000. Topographic featuresrnclearly show that all s urfncc water converges to the reservoir. Hydrological eva luati ons also indi caternthat there is no out now of groundwater from Ihe catchment through other rou les, whi ch is in fa vor ofrnthe reservoir conditionrnGcologlcal 11l3pS of Sibi lu catchment and reservoir area arc produced al the scale of 1.50,000 andrn1 12,500 lespecti veiy. Basalt. trachyte, pyrocl astic depOS its, rhyolit e, ignimbrite and recentrnQuatern ary deposits arc exposed III the area The sln/ctmal featu res of the catchment arc mappedrnfrom aerial photograph in terpretations. Th ~ NV-SE alld NE-SW ll11e:unents arc found to he thernd0l111113nt lineaments in the catchment Bul the meas urcments and int erpretation of the Jomt setsrnorient atIons in the reservoir area, conformed that the N-S and E-W arc the dominant jOint sets overrnNW-SE and NE-SW. Bes ide their concentrat ion th ese Joint sets, especial[y the E-W, nrc op..:n andrncont inuollsrn-n le rock and so ils IIni ts of the reservOIr were described usi ng the ir lithology and genetic type a.