Streamflow regime change and ecological response in the Lake Chad basin in Nigeria

Three major factors account for the streamflow regime change in the Komadugu-Yobe river system. The combined effects of the Sahelian drought and the partial conversion of flood flows to dry-season releases by Tiga Dam reservoir has decreased the contribution from the Hadejia to the Komadugu-Yobe River since 1974. Blockages by weed growth and siltation in the Hadejia have also jointly contributed to the decline in river flow. The change in the flood regime has directly impacted certain components of the Yobe basin ecosystems including plant and fish species diversity and quality. A certain minimum flood extent is required in the Jama'are and Hadejia rivers to sustain their rich wetland ecosystems at reasonable level, particularly areas of high biodiversity such as the Dagona water fowl sanctuary, the Gorgoram forest reserve and the fish resources.