University of Khartoum

Assessment of Groundwater Resources Ineltaity Area, South of Dongola, North State- Sudan

Assessment of Groundwater Resources Ineltaity Area, South of Dongola, North State- Sudan

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Title: Assessment of Groundwater Resources Ineltaity Area, South of Dongola, North State- Sudan
Author: Eltai, Mohamed Abuagla
Abstract: The main goal of this study is to construct a conceptual model describing the groundwater characteristics in the study area. Hence, the detailed objectives could be summarized as follows:To delineate aquifer/aquitard system, to envisage aquifer physical parameters, to determine the groundwater flow pattern and to assess the groundwater quality. A combined methodology have been followed. It includes: the collection of data during field work, analysis and interpretation of the collected samples and materials which have been done via modern techniques and software. The study area is located in the North State – Sudan, between latitudes 180 46` 15.0``N and 180 50` 00.0``N and longitudes 300 11` 36.4`` E and 300 29` 12`` E, covering an area of approximately 400 km2(about 10 km wide and 40 km long). The area is characterized by a desert climate and is generally flat with scattered small outcrops. For the purpose of the study, the study area has been divided into two sub areas; the detailed investigated part of the study area and QaabElbab area. A total of 28 deep high capacity wells were constructed in the former, while the later has been studied using data gathered from only two hand-dug wells. Three main lithological units were regionally identified, these are: Precambrian basement rocks; Cretaceous sedimentary strata and the Quaternary superficial deposits. The water bearing zone is represented by a single, free water table, aquifer. It is composed entirely of sandstone, with which mudstone lenses of variable depths are placed. The thickness of the aquifer has never been determined through the present work, since the deepest borehole (270m) has not reached any basement rock or other impervious layer. The hydraulic parameters (transmissivity, hydraulic conductivity and storage coefficient) were calculated from the available pumping test data based on Theis’s and Logan’s methods. Based on Theis’s method, the average hydraulic conductivity is 0.86×10 m/day, the average transmissivity is 1.8×103 m2/day and the average storage coefficient is 2.1×10-2. The local groundwater flow was found to be of two directions (NW and NE), though the regional flow direction is NW. However, the groundwater flow velocity is estimated to be 0.06m/day. The results of the chemical analysis of water samples revealed that the groundwater in the study area is within the permissible limits for drinking usage. The highest concentrations of total dissolved solids, electrical conductivity and total hardness are shown by QaabElbab samples. While these parameters show lowest concentration at the northern and northwestern sides of the detailed investigated part of the study area, and relatively higher concentrations are recorded at the southeastern side of the study area. The highest pH value was also recorded at QaabElbab area. The major ions (Ca+2, Mg+2, Na+, K+, SO4-2, Cl- and HCO3-) were analyzed and represented by spatial variation maps. Then these ions have been plotted on Piper trilinear diagram, and groundwater has been classified as [Ca+2 - HCO3-] type. Sodium Adsorption Ratio (SAR) has been calculated. It is in the range of 0.56 to 1.44. Then these values have been plotted on the Wilcox diagram which indicates that the groundwater in the study area is excellent for irrigation purposes.
Description: 157 Pages
URI: http://khartoumspace.uofk.edu/handle/123456789/19494
Date: 2016-02-29


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