What Are The Effects Of Urban Flooding?

Urban flooding is a serious and growing phenomenon affecting both developed and developing countries. In the face of rapid urbanisation, climate change and their corresponding changes in urban hydrology, urban flood events appear to be on the increase (Amoako, 2012). Urban flooding has huge devastating effects on many aspects of urban life especially on the residents, economy and environment (eschooltoday, 2010).

Economic

However, during flooding houses, roads, electricity, schools, hospitals and other infrastructures and facilities in the urban area are affected and destroyed. The make people to be homeless and displaced for some time. In addition, government spent huge economic resources by deploying firemen, police, even the military and

In addition, the total volume of water discharged during a flood tends to be larger for urban streams than for rural streams. For example, stream flow in Mercer Creek, an urban stream in western Washington, increases earlier and more rapidly, has a higher peak discharge and volume during the storm on February 1, 2000, and decreases more rapidly than in Newaukum Creek, a nearby rural stream. As with any comparison between streams, the differences in stream flow cannot be attributed solely to landuse, but may also reflect differences in geology, topography, basin size and shape, and storm patterns (Konrad and Booth, 2002).

The hydrologic effects of urban development often are greatest in small stream basins where, prior to development, much of the precipitation falling on the basin would have become subsurface flow, recharging aquifers or discharging to the stream network further downstream. Moreover, urban development can completely transform the landscape in a small stream basin, unlike in larger river basins where areas with natural vegetation and soil are likely to be

Typically, the annual maximum discharge in a stream will increase as urban development occurs, although the increase is sometimes masked by substantial year-to-year variation in storms, as is apparent in the annual maximum discharge rainfall changes. The effects of development in urban basins are most pronounced for moderate storms following dry periods. For larger storms during wet periods, the soil in rural basins becomes saturated and additional rainfall or snowmelt runs off much as it does in an urban basin.

The effect of urban development in the last half of the 20th century on small floods is evident in Salt Creek, Illinois. With the exception of an unusually large flood in 1987, large floods have increased by about 100 percent (from about 1,000 cubic feet per second to about 2,000 ft3/s) while small floods have increased by about 200 percent (from about 400 ft3/s to 1,200 ft3/s). Nonetheless, even a small increase in the peak discharge of a large flood can increase flood damages (Bailey, et al, 1989 cit. in Konrad,