HR: 0800h
AN: H21G-0822 [Abstracts]
TI: Probabilistic Impact Assessment of Domestic Rainwater Harvesting in Urban Slums: West Africa Case Study
AU: Cowden, J R
EM: jrcowden@mtu.edu
AF: Michigan Technological University, Department of Civil and Environmental Engineering
1400 Townsend Drive, Houghton, MI 49931, United States
AU: * Watkins, D W
EM: dwatkins@mtu.edu
AF: Michigan Technological University, Department of Civil and Environmental Engineering
1400 Townsend Drive, Houghton, MI 49931, United States
AU: Mihelcic, J R
EM: jm41@mtu.edu
AF: Michigan Technological University, Department of Civil and Environmental Engineering
1400 Townsend Drive, Houghton, MI 49931, United States
AU: Fry, L M
EM: lmfry@mtu.edu
AF: Michigan Technological University, Department of Civil and Environmental Engineering
1400 Townsend Drive, Houghton, MI 49931, United States
AB:
Urban populations now exceed rural populations worldwide, creating unique challenges in providing basic
services, especially in developing countries where informal or illegal settlements grow in peri-urban areas. West
Africa is an acute example of the problems created by rapid urban growth, with high levels of urban poverty and
low water and sanitation access rates. Although considerable effort has been made in providing improved water
access and urban services to slum communities, research indicates that clean water access rates are not
keeping up with urbanization rates in several areas of the world and that rapidly growing slum communities are
beginning to overwhelm many prior water improvements projects.
In the face of these challenges, domestic rainwater harvesting is proposed as a technologically appropriate and
economically viable option for enhancing water supplies to urban slum households. However, assessing the
reliability, potential health impacts, and overall cost-effectiveness of these systems on a regional level is difficult
for several reasons. First, long daily rainfall records are not readily available in much of the developing world,
including many regions of sub-Saharan Africa. Second, significant uncertainties exist in the relevant cost, water
use, and health data. Third, to estimate the potential future impacts at the regional scale, various global change
scenarios should be investigated. Finally, in addition to these technical challenges, there is also a need to
develop relatively simple and transparent assessment methods for informing policy makers.
A procedure is presented for assessment of domestic rainwater harvesting systems using a combination of
scenario, sensitivity, and trade-off analyses. Using data from West Africa, simple stochastic weather models are
developed to generate rainfall sequences for the region, which are then used to estimate the reliability of
providing a range of per capita water supplies. Next, a procedure is proposed for quantifying the health impacts
of improved water supplies, and sensitivity analysis of cost and health data provides an indication of cost-
effectiveness. Climate change impacts are assessed via weather model parameter adjustment according to
statistical downscaling of general circulation model output. Future work involving the interpolation of model
parameters to ungaged sites, incorporation of additional global change scenarios (e.g., population, emissions),
and extension of the procedure to a full Monte Carlo analysis will be discussed as time allows.
DE: 1635 Oceans (1616, 3305, 4215, 4513)
DE: 1807 Climate impacts
DE: 1854 Precipitation (3354)
DE: 1869 Stochastic hydrology
DE: 1884 Water supply
SC: Hydrology [H]
MN: 2007 Fall Meeting