Coefficients of Imperviousness

Land Cover Coefficients Using Town Planimetric Data

Reference: Determining Impervious Surfaces for Watershed Modeling Applications. 2000. Prisloe and Giannotti.



The planimetric data were then overlain with our 30 meter pixel, 1995 satellite derived 28-category Connecticut land use/land cover (LULC) database (right). This allowed us to produce LULC-specific impervious surface coefficients.

There was good consistency among the LULC impervious surface coefficients for the three suburban towns, however; the impervious surface coefficients for the one urban town were significantly higher. In other words, the % impervious surface for the “high density residential” class, for example, was similar for three of the test towns, but in the more urban West Hartford the coefficient was higher.

Thus, our results suggested that there was a need to develop different sets of impervious surface coefficients based on town “type,” (urban, suburban, rural), or possibly population. This led us to a follow-up study examining the relationship of population density to impervious surface. See our reference paper for more information.


Planimetric data showing outlines of impervious features (roads in gray, driveways in blue, roof in black), with grid of 30-meter land use/land cover in the background. An impervious surface coefficient for each LULC category can then be calculated.