Vulnerability of Mojo Drinking Water Supply Well Aquifer to Anthropogenic Development

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Addis Ababa University


Ethiopia’s Water Resources Management Policy of 1999 gives highest priority to supply drinking water as a national wide. Accordingly MoWE called attention to solve problems associate to unstable states of deficient supplies and increasing demands. Mojo Town with rapid incremental population, the former existing water supply scheme found inadequate to meet the increasing demands of water for domestic uses. Hence, new water supply project for the Mojo town has been executed and its works of construction on progress so far to alleviate such escalating demands for the potable water due to advancing developments. The Mojo water supply scheme depends on groundwater as the sole resource of drinking water from boreholes at Mojo well field. This well field system is designed containing of three deep boreholes where development for each closer to Mojo Perennial River. All over again, this river is basically apprehensive of contaminants because of existences of more than seventeen factories of tanneries, oil factories, waste disposal site and six depots in which roughly all have established at about the brink of this river and most of the factories have not been facilitated with waste treatment plants so that these can be considered as the main sources of potential threats. Therefore; this research paper was primarily initiated attributable to these conditions and was been conducted. As a return of this study, the maximum radius of influences was established fixing to be 3853m considering the entire pumps in the boreholes were assumed working at once under case scenario of the wells operation with aquifer maximum transimissivity and minimum storativity and with the designed pumping rates. The minimum length of the plume position which existing at closest distant from well head is discovered at 2034m at the downstream of the well field. So the contaminant plume is circumscribed in the influence zone of the pumping when the boreholes will start functioning. It also elaborates the particular radii of influences as results of operating boreholes and realizes that the cones of depressions are interacting with the Mojo perennial River and this river is suspicious agents of the potential threats of contaminants sites as previously described. Capture zone was also delineated at mean distance of 110m from the wells head considering case scenario when the boreholes are all simultaneously operating, visualizing that this may supportive in deciding remedying measures to protect the potential threatening of the contaminants from admittances into the boreholes at time when pumps in boreholes will be under equipped to operation. In determinations of differentiating influences of the long term operating boreholes, the superposed drawdown for groups and individual boreholes under varying aquifer parameters was approximated and noticed the intersecting of cones of depressions arrangements and thus in this coincidence it recognized the happenstances of well interference at the Mojo well field while the boreholes are operating.



Water Resources Management