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For much of Kordofan Province, surface-water supplies collected ani stored in hafirs, fulas, and tebeldi tr•~es are almost completely appropriated for present needs, and water from wells must serve as the base for future econo-nic and cultural development. This l'eport describes the results of a reconn"'issance hydrogeologic investigation of the Province and the nature and distribution of the groundwater resources with respect to their availability for deve~opment. Kordofan Province, in central Sudan, lies within the White Nile-Nile River drainage basin. The land suri'ace is largely a plain of low relief; jebels (hills) occur sporadically, and sandy soils are common in most areas except in the south where clayey soils predominate. Seasonal rainfall, ranging from less than 100 millimeters in the north to a bout 800 millimeters in the south, occurs almost entirely during the summer months, but little runoff ever reaches the Nile or White Nile Rivers. The rocks beneath the surficial deposits (Pleistocene to Recent) in the Province comprise the basement complex (Precambrian), Nawa Series (upper Paleozoic), Nubian Series (Mesozoic), laterite (lower to middle Tertiary), and t1 ~ Umm Ruwaba Series (Pliocene to Pleistocene). Perennial groundwater supplies in the Province are found chiefly in :five hydrologic units, each having distinct geologic or hydrologic characteristics. These units occur in Nubian or Umm Ruwaba strata or both, and the sandstone and conglomerate beds form the principal aquifers. The water is generan~ under slight artesian head. and the upper surface of the zone of saturation ranr-~s from about 50 meters to 160 meters below land surface. The surficial deposits and basement rocks are generally poor sources of ground water in most of the Province. Supplies from such sources are commonly temporary and may dissipate entirely during the dry season. Locally, however, perennial supplies are obtain~d from the surficial deposits and from the basement rocks. Generally, water from Nubian aquifers is satisfactory for most uses and is of better quality than that obtained from Umm Ruwaba aquifers. The relatively high mineralization of water from the Umm Ruwaba, especially in the eastern part of the Province, makes the water unsuitable for many municipal and industrial uses. The water is generally usable, however, for domestic and rvestock purposes. Jl J2 HYDROLOGY OF AFRICA AND THE MEDITERRAN:"AN REGION Some 175 drilled wells located at 75 water yards yield an averag~ of about 1,000 imperial galLons per hour per well from Nubian or Umm Ruwabf. aquifers. Generally the water y•ards provide sufficient water for minimUJm dor•1estic and livestock requirements throughout the year. Commonly, however, the water yards are widely separated and, hence, not always properly spaced for good range management or for serving the needs of the dispersed rural popnlation. In 1962, withdrawals from Nubian and Umm Ruwaba aquifers in the Province were approximately 600 million gallons annually. This rate of draf:•; could probably be cont...

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Lyon County is in southwestern Minnesota, about 150 miles southwest of Minneapolis and St. Paul. The basement rocks in the area consist of granite and quartzite of Precambrian age. These materials are in turn overlain by shale and sandstone of Cretaceous age, glacial drift of Pleistocene age, and alluvium of Recent age. Ground water is available primarily from aquifers in Pleistocene and Cretaceous strata from depths ranging from 15 to 500 feet below the land surface. The county is divided into areas of groundwater availability based on the quality and quantity of ground water available from the different geologic units. The glacial drift which covers all of the area, yields very hard water from sands and gravels occurring in melt-water channel deposits or as small, isolated melt-water bodies. Wells in the drift commonly yield from 2 to 30 gpm (gallons per minute), but sustained yields of as much as 500 gpm are obtained in areas where thick melt-water channel deposits occur. Cretaceous strata underlie about two-thirds of the county and yield water from poorly consolidated sandstone. The water ranges in hardness from soft to very hard and is sometimes high in chloride content. Wells in Cretaceous strata commonly yield from 2 to 7 gpm; however, in areas where the sandstone is in contact with" the underlying weathered granite, sustained yields of as much as 75 gpm are obtained. The geographic and stratigraphic distribution of the geologic units suggests that additional water supplies may be available from Pleistocene and Cretaceous strata in areas not yet fully explored.