ABSTRACT
CONTENTS 17.1 Background.............................................................................................. 353 17.2 Surface Runoff and Impervious Surface Area ................................... 356 17.3 Impervious Surface Area and Water Quality .................................... 359
17.3.1 Evaluating the Regression Equations .................................... 361 17.3.2 An Example ............................................................................... 364
17.4 Concluding Remarks.............................................................................. 365 References ........................................................................................................... 367
Impervious surface area (ISA) affects both water quality and water abundance through its influence on surface runoff. Runoff increases with increasing ISA, a fact that is well known to developers and watershed managers who must estimate the amount of surface runoff to streams and rivers resulting from precipitation events. Localized flooding occurs much more often now in urban areas than before because of development. Most serious urban flooding and surface runoff originate from commercially developed sites such as parking lots or shopping centers. Figure 17.1 shows a large shopping center with considerable impervious surface cover, punctuated by some scattered trees. Runoff from this site, which is a large parking lot, would be considerable.
