Urban Stormwater Tracing with the Naturally Occurring Deuterium Isotope

Abstract

Measurements of naturally occurring deuterium isotope (δ D) assist in tracing water components during wet weather flows in an urban watershed. A transect of installations in the vadose and saturated zones was completed in the vicinity of a small stream and storm sewer. High‐resolution deuterium mass spectrometry discriminated between storm sewer leaks and other water sources such as direct runoff, bank seepage, and groundwater flow to a stream channel. Isotope hydrograph separation indicates that groundwater or vadose water predominantly contributed to the volume of stream water compared to direct surface runoff during a storm event. Significant differences in δ D in the subsurface suggest that multiple flow components exist beyond the time period of a storm event. Deuterium measurements are helpful for modeling leaks and seepage and refining mass balances of flows in urban watersheds.