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|Title: ||Drought preparedness plan for Kumasi water supply system|
|Authors: ||Antwi, Eric Ofosu|
|Issue Date: ||9-Nov-2005|
|Series/Report no.: ||3887;|
|Abstract: ||Droughts are inevitable consequences of the natural variability of the water cycle and are phenomena driven by complex natural factors that are not well understood or easily predicted. Droughts affect the availability of water resources and ultimately water supply, which is necessary for socio — economic development. Kumasi, the second largest city in Ghana is a nodal city, linking the northern sector to southern sector and a destination point for m any Investors to the country. Water supply to Kumasi is from two surface water sources, which are affected by drought. It is therefore timely and important to plan and prepare to mitigate the effect of drought on a city such as Kumasi.
The objective of this research is to produce an efficient water management (water allocation) plan necessary to meet the water demand with the available water resources during droughts in Kumasi. As such, the drought preparedness plan should reflect the actual situation such that it can be adopted by the utility, the Ghana Water Company.
The research utilizes hydrological drought which is defined as “period during which streamflows are inadequate to supply established uses under a given management system”.
The safe yields of the reservoirs are designed to cater for 25-year drought, therefore droughts with intensity of 25 years and beyond were looked at. The study examined the water demand projection for the city for the next 15 years. Based on past stream flow data and rain fall data the intensity of the historical droughts were studied. The operating yields of the reservoir for the various drought scenarios (25 — 100 year droughts) were estimated from historical streamflow values and other relevant information such as reservoir capacity, evapotranspiration, seepage and leakage in the dam. A 50-year drought will reduce safe yield by 8% whiles a 100-year drought will also reduce safe yield by 15%.
The current water production in Kumasi is only 45% of the demand. Planned production by GWCL will meet 37% — 60% of demand within the study period. The occurrence of drought in Kumasi will affect resource but not production because as planned by GWCL, by 2020 production will be 75% of safe yield which is lesser than operating yield (85% of safe yield). The drought preparedness plan can be effective when water production is affected by drought.
Water demand in Kumasi grows at an exponential rate of 5% with population growth contributing 2.26% and socio-economic growth of Kumasi contributing 2.74%. The water demand of Kumasi will exceed the current safe yield by the year 2007. Alternative sources are needed as an option to meet demand.
The plan identifies areas within Kumasi with good groundwater yield (21.6- 30m3/hour). It is suggested that groundwater be incorporated into the distribution system of these areas to augment supply from the surface water source.
Recommendations are that GWCL should change the production plan by increasing it to meet demand. Water demand management has been suggested as an option to control the increasing water demand.|
|Description: ||A thesis Submitted
To the Board of Postgraduate Studies,
Kwame Nkrumah University of Science and Technology, Kumasi,
In fulfillment of the requirements for the award of Degree of Master of Philosophy
in Civil Engineering, 2005|
|Appears in Collections:||College of Engineering|
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