integrating system dynamics and remote sensing to estimate future water usage and average surface runoff in lagos, nigeria

the goal of this study was twofold; first analyze the patterns of water consumption in lagos, nigeria and use them in a system dynamics (sd) model to make projections about future demand. the second part used remote sensing to quantify the contribution of extensive land use/cover change to urban flooding. land use/cover dynamics over the past decade was analyzed using satellite imagery provided by landsat thematic mapping (tm). unsupervised classification was performed with false color composite using the iterative self-organizing data analysis (isodata) technique in a geographic information systems (gis). the study area was divided into four different land use types during image classification: bare land, built-up area, water bodies, and vegetation. for water demand, two different scenarios of population growth including 5.5% and 2.75 % annual increase were considered. the results showed that water demand dropped by 67% of its current value when losses in distribution were reduced by 20% and population annual growth rate kept at 2.75% over the study period. bare land and water bodies lost 1.31% and 1.61% of their current area respectively while built-up area grew by 1.11%. these changes in land use/cover changes led to a 64% increase in average surface runoff, mostly attributable to increasing surface imperviousness and the absence of an adequate urban drainage system.