| Abstrakt: |
Africa numerous floodplain wetlands provide a host of hydrologic, ecological, economic, and social benefits. They play a fundamental rolein supporting significant human populations. In common with all wetlands, the hydrology of Africa floodplains is central to their functioning and in turn plays a key role in determining the benefits that they provide. The timing and extent of wet-season inundation are major influences upon the temporal and spatial distribution of floodplain resource use. Using results from intensive hydrologic surveys, supplemented by analyses of river flow data and flood extent maps, this paper delineates areas within the Hadejia Nguru Wetlands of northeastern Nigeria according to their hydrologic characteristics. This delineation is used in combination with a land-use map derived from aerial andfield surveys to examine the impacts of hydrology upon human activities and land use. The timing of different cultivation practices in the wetlands is shown to be in tune with the annual flood cycle. Rice is cultivated in inundated areas that are then planted with other crops after the floods recede. The intensity of fishing and cattle grazing also varies with the pattern of rising and falling water levels. The distribution of major land uses is strongly influenced by spatial variations in hydrologic characteristics. The location of rice cultivation and small-scale irrigation is determined by water availability in the wet and dry seasons, respectively. Extensive flood rice farms are found along the JamaOare River, which contributes over 70% of the river inflow to the wetlands. Within the Hadejia River system, important flood rice areas are the Madachi Swamp and the Marma Channel. Theprimary area of small-scale irrigation is along the Burum Gana Riverin which small, but year round, flows are maintained by return flowsfrom upstream irrigation schemes. This area, which covers only 13% of the land-use map, contains 48% of the area of small-scale irrigation. Ex [ABSTRACT FROM AUTHOR] |
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