University of Khartoum

Appraisal of Ground Water Quality Used for Irrigation in Khartoum State

Appraisal of Ground Water Quality Used for Irrigation in Khartoum State

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Title: Appraisal of Ground Water Quality Used for Irrigation in Khartoum State
Author: Khalifa Elsayed, Fareeda
Abstract: The study was undertaken in Khartoum State, which lies between latitudes 15º 8`- 16º 39`N and longitudes 31º 36`- 34º 25`E in the semi-desert tropics. Water and soil samples (0-30 cm depth), were collected from 50 randomly-selected farms widely scattered in Khartoum State, during March-April 2006. The objective of the study was the appraisal of the ground water quality used for irrigation in these fifty farms and the evaluation of the impact of these waters on the irrigated soils. The measurements of water quality parameters (pH, electrical conductivity, Na+, Ca2+, Mg2+, K+, Cl−, HCO3 −, SO4 2−) were carried out. The USSL, (1954) classification system revealed that the groundwater salinity, as represented by electrical conductivity (ECw), ranged from medium salinity (C2) to very high salinity (C4). The sodium adsorption ratio (SAR) varied from low (S1) to very high (S4) sodicity. Most of the water samples belonged to the high salinity – low sodicity (C3–S1) class (48%), medium salinity – low sodicity (C2–S1) class (30%) and high salinity – medium sodicity (C3–S2) class (12%). The mean ECw of the different wells ranged from 0.4 – 4.8 dS/m with a CV of 71%. Results showed that there is a high variation in depth of wells, age of wells, age of farms, irrigation intervals, The pooled data did not give significant multiple correlation between ECw and each of the individual factors with the exception of irrigation interval. The results showed that ECw increased significantly (p=0.05; r=0.286) with increase of irrigation interval. Almost all water (98%) samples were none-sodic. Only one water sample gave an SAR value equal to 19.1 and the remaining samples gave SAR values ranging between 1.1 and 9.4. However, all water samples have SAR values greater than those of the river Nile system. The CV of the SAR values of the water samples were 72%. The results showed a highly significant correlation between ECw and SAR (r=0.648); there was a highly significant linear increase in SAR with increase in ECw. Ninety six percent of the water samples gave negative RSC values and 4% had RSC values within the safe level. The well waters were predominantly SO4 -2 = Cl- waters. It is evident that these well waters had lower quality than the well waters studied by Mustafa (1983). The results showed that the electrical conductivity (ECe) of 26% of the irrigated soil samples increased four fold, 68% ware leached, and 6% were not affected by irrigation with the ground water.
Description: 97 Pages
URI: http://khartoumspace.uofk.edu/handle/123456789/9468
Date: 2015-04-26


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