Abstract

The Gonaives Plain lies in northern Haiti at the head of the Gulf, of Gonaives. Ground water in the plain is used widely for domestic and stock purposes but so far to only a limited extent for irrigation. The future agricultural development of the plain will depend in large measure on the proper utilization of available ground-water supplies for irrigation.The rocks of the region are Upper (?) Cretaceous, Eocene and Oligocene, and Pleistocene and Recent. The structural depression occupied by the Gonaives Plain was formed in post-Miocene time by the dislocation of Oligocene and older rocks along normal faults and by the tilting of the adjacent crustal blocks. The lower parts of the depression contain a Pleistocene and Recent alluvial fill deposited by streams tributary to the plain.The Upper (?) Cretaceous rocks include andesite and basalt lava flows locally intercalated with some beds of tuff and agglomerate. These rocks are generally dense and impervious, but locally small springs rise from fractures and bedding planes or from weathered zones.The Eocene rocks are hard thin-bedded cherty limestones with some beds of massive chalky limestone. Considerable ground water circulates through joints and openings along bedding planes, some of them solutionally enlarged, giving rise to important springs such as Sources Madame Charles. The Sources Madame Charles discharge at the rate of about 110 liters per second. The Oligocene rocks include limestone, shaly limestone, limy sandstone, marl, and shale. The limestone beds contain solution passages and other openings and these may afford capacity for the circulation of ground water, but no springs were observed.The Quaternary alluvial fill of the plain is composed of interbedded lenses of clay, silt, sand, and gravel. These deposits contain a zone of saturation whose upper limit is marked by a water table at a depth from less than 1 m to about 20 m; in most places it is less than 15 m. Where present in the zone of saturation the coarse, well-sorted sand and gravel beds of the alluvium probably will yield moderate to large supplies of water to wells and infiltration galleries. The individual yields of existing wells range from a few liters to about 60 liters per second.The most favorable part of the plain for ground-water prospecting and development lies 5 to 10 km northeast of Gonaives. In this area yields of 10 to 50 liters per second could be obtained from the alluvium in single wells drilled to depths of about 35 to 45 m. Additional information on the yield and physical character of aquifers in the alluvium would be provided by test wells drilled to depths of 40 to 60 m.

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