Dependency Between the Total and Effective Imperviousness for Residential Quarters of the Lviv City

Abstract

A detailed hydrologic analysis was performed using geographic information systems and field investigations for thirty residential quarters in the Franko district of the Lviv city, Ukraine. All investigated quarters are located at the territory of the Baltic Sea catchment of the Lviv city, and the surface runoff from this area flows to the Lviv wastewater treatment plant. The total area of the investigated sub-catchment is 348.5 ha, including 58.46 % of impervious covers, 41.17 % of green spaces and 0.37 % of water bodies. The share of total impervious surfaces for each of the 30 analyzed quarters varies from 0.329 to 0.929, and the effective imperviousness – from 0.222 to 0.917. The correlation between the total and effective imperviousness was described by the power law dependency pef=(ptot)n. Two approaches were used to describe the relationship between the total and the effective imperviousness: 1) using all 30 empirical results for each quarter; 2) using the average values of the imperviousness of the total sub-catchment. The obtained values of the power law exponent for these two empirical approaches are n1=1.308 and n2=1.275, respectively or 7.2 % and 9.6 % less, respectively, comparing to the corresponding value n=1.41 in the Livingston's & Veenhuis' approximation, obtained for 14 different highly urbanized quarters of Denver city. On the other hand, the power law exponents are 3.9% and 1.3% higher, respectively, comparing to the corresponding value n=1.259 in the approximation for the 900 km2 semi-urban watershed in Marion County, Georgia, USA.

Keywords

• surface runoff
• total imperviousness
• effective imperviousness
• stormwater modelling