One of the problems associated with the increasing world population is the need for housing development projects. Housing projects, as well as other types of development, increase the amount of impervious surfaces, such as paved roads, roofs, and sidewalks. Increasing the amount of impervious surfaces increases the likelihood of flooding problems. This is due to the nature of the impermeable surface which does not allow water, either from precipitation or melting snow, to infiltrate into the ground, thus producing runoff. The impervious surface increases the likelihood of flooding downstream because the runoff flowing into the river is far greater than the amount of water the river can hold. Over the years, many flood-related damages have been reported. In France, floods have killed more than 100 people in the last 10 years. In less than three years, two catastrophic flash floods have hit the south of France. The first flash flood occurred in November 1999 and the second flash flood occurred in September 2002. The two flash floods caused 58 deaths and material damage of approximately 2.3 billion euros (Vinet, 2008 ). In the United States of America, flash floods in June 2001 caused $2 billion in damage to the urban states of Texas (Holder et al., 2002). All of these damages and losses are frightening examples of the threat posed by flooding. Incorporating an effective drainage system and sometimes a retention pond, if the watershed is large, is essential to combat runoff. Researchers and engineers use a computer model of urban stormwater to perform a simulation of the network of urban collection systems. Urban stormwater models play an important role...... middle of paper ......ce Contaminants, « US Environmental Protection Agency, EPAR 2:72-81Schueler, TR, 1987, « Controlling Urban Runoff : A Practical Manual for Planning and Design of Urban BMPs”, Council of Metropolitan Washington Governments, Washington, DCSchueler, TR, 1994, “The Importance of Imperviousness”, Watershed Protection Techniques 3(1): 100-111Shaw, SB, Walter , MT, Steenhuis, TS, 2006, “A physical model of particle leaching from rough impervious surfaces”, Journal of Hydrology 327: 618-626 Sutherland, RC and Jelen SL, 1996, “Sophisticated modeling of stormwater quality worth it,” Advances in Modeling the Management of Stormwater Impacts. 4:1-14White, MD, Greer, KA, 2006, "The Effects of Watershed Urbanization on Stream Hydrology and Riparian Vegetation of Los Peñasquitos Creek, California", Landscape and Urban Planning 74: 125-138