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Quantifying Evaporation and Evaluating Runoff Estimation Methods in a Permeable Pavement System - abstract
Citation:
Brown, R. AND Mike Borst. Quantifying Evaporation and Evaluating Runoff Estimation Methods in a Permeable Pavement System - abstract. Presented at 2014 ASCE-EWRI World Environmental and Water Resources Congress, Portland, OR, June 01 - 05, 2014.
Impact/Purpose:
Studies on quantifying evaporation in permeable pavement systems are limited to few laboratory studies that used a scale to weigh evaporative losses and a field application with a tunnel-evaporation gauge. A primary objective of this research was to quantify evaporation for a larger scale permeable pavement field application. The measured evaporative losses were less than expected based on laboratory results.
Description:
Studies on quantifying evaporation in permeable pavement systems are limited to few laboratory studies that used a scale to weigh evaporative losses and a field application with a tunnel-evaporation gauge. A primary objective of this research was to quantify evaporation for a larger scale field application. A secondary objective was to quantify abstraction from the impervious asphalt drainage area and evaluate different methods used to calculate runoff. USEPA constructed a 0.4-ha parking lot in Edison, NJ, that incorporated three permeable pavement types. An impermeable liner was installed 0.4 m below the driving surface in four 11.6-m by 4.74-m sections for each pavement type. The liner captures all infiltrating water and routes it to HDPE collection tanks that can fully capture events up to 38 mm. Pressure transducers were installed to measure water level. Level was converted to volume using depth to volume ratios measured for individual collection tanks. Infiltrate volume has been measured for 24 months, and compared to rainfall volume to estimate the losses through evaporation from the permeable pavement and abstraction in the impervious asphalt drainage area. Events were divided into three, four-month categories based on the potential for evaporation using historical pan evaporation records from a nearby site. The data were also divided into groups based on antecedent dry period to evaluate evaporation with time. Evaporation was detected year round. On average, when comparing events with similar antecedent dry periods, an additional 1 mm of evaporation occurred in the months with high potential for evaporation compared to months with low potential. Comparing events with more than five days between events to those with less than one day, about an additional 1 mm of water over the drainage area evaporated. The measured evaporative losses were less than expected based on laboratory results.
