marshes as pastures in the dry season and thereafter they go back to their habitats in the interior of the basin. During the high flood stage, flood waters arriving at the lake are reported as . This was absorbed in the vast lake, as storage, and the out flow from the lake is thus moderated to only when it reaches Niamey, the capital city of Niger. Since 1962, even a extra flow from the lake could now cause increase of water level in the Niamey area by , rising to the level . Climate The lake in the Sahel, just south of the Sahara desert, has climatic conditions which are reported to be a transitional zone of humid Guinean climate in the south to a dry climate at border with the Sahara. The rainy season in the south lasts from July to October, with an average annual rainfall of . However, the rainy season in the north lasts from July to September, with an average annual precipitation recorded at . Temperatures vary with strong seasonal emphasis. The average maximum temperature recorded in May at Tombouctou is and at Mopti is . The cooler climatic season is from December to January with temperatures dropping to a mean minimum of to in the northern part of the delta. Lake Débo during high flow season when it has the maximum dimensions of water spread, is from Mopti on its upstream, on the southern end, and from Timbuktu at its downstream, on the north-eastern end. It is the largest of many such seasonal wetlands and lakes which form the Inner Niger Delta, and the largest lake within Mali. Its size is largely reduced during the dry season of September to March. Vegetation The inundated Lake Débo and Walado Débo (Inner Niger Delta in Mali) form the pasture lands which are collectively known as the flooded forest savannah with aquatic herbaceous and two dominant species of acacia. These pastures are known locally as bourgou grass. Palms like Hyphaene thebaica, and Borassus aethiopum are also reported on the fringes of the lake. There are three types of pasture lands, defined on the basis of its management. These are: Resident Fulani's pastures which are controlled by the Amiro (the chief Joro); the "Harima" (meaning: a local convention) with the chief of village and other members responsible for its usage; and the several small holdings (within the bourgou)