Rainwater harvesting for Addis Ababa city; a Case of Jemo Condominium site
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Date
2015-05
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Addis Ababa University
Abstract
The main objective of this thesis is to assess the potential of rain water harvesting practice to solve
problems of both increasing water demand and storm water in Addis Ababa city. The research is
carried out based on case-study of Jemo condominium site, from November 2014 to May 2015 that is
found in the south western part of Addis Ababa city. The site has about 337 residential blocks with an
average roof area of 286m2 and 50 communal blocks with an average roof area of 216m2 roof area
and serves for about 9,800 households in which they serve for about 42,140 population.
A descriptive quantitative study was carried out in order to achieve the objectives of the study. A
monthly rainfall data, catchment characteristics, roof material, population data, water consumption
and water demand data were collected from primary and secondary sources. People's attitude and
practice towards rainwater was also assessed. The collected data was analyzed using different tools
including samsamwater RWH model, Google earth, rainwater harvester, AutoCAD, MS Excel spread
sheets and etc. Calibration and validation of the finding was carried out using appropriate
instruments.
Based on the findings the total annual rainfall in an average year is 1219mm. A 6 months of water
consumption data of Jemo I collected from AAWSA Mekanisa branch shows that only 30% of the
demand is supplied to residents by the municipality at private water pipes. The average annual RWH
potential at Jemo I condominium site is not enough to fulfill the total water demand at this site.
However, it might still be worthwhile to construct a rainwater harvesting system. With a storage
reservoir of 113400 litres (113.4 m3) for a single building a rainwater harvesting system could
provide about 36% of non-potable demand and RWH can reduce water demand problems by 36% for
only non-potable demands and 10% for all domestic demands based on the current AAWSA standard.
The total cumulative runoff generation from this site throughout the year is 723,450m3 and the
amount of water that RWH system only from roof tops can harvest could be 90,290.2m3. With this
estimation RWH from roof tops at Jemo condominium site can reduce runoff by 12%. This
contributes for sustainable storm water management and best management practices. Therefore
RWH has many benefits once it is applied for any building for sustainable alternative water supply
and sustainable storm water management. The big problem here will be the size of storage tank
should be big enough since the rainfall is concentrated for limited months which will not be cost
effective but related to other interventions RWH is more cost effective and sustainable than other
options.
Key words: Rainwater, Harvesting, water demand, Stormwater, Alternative source, Non potable,
Jemo, Domestic, Urbanization, Condominium, Addis Ababa, Ethiopia
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Keywords
Rainwater, Harvesting, Water demand, Stormwater, Alternative source, Non potable, Jemo, Domestic, Urbanization, Condominium, Addis Ababa, Ethiopia