Urban stormwater tracing with the naturally occurring deuterium isotope

Measurements of naturally occurring deuterium isotope (delta D) assist in t racing water components during wet weather flows in an urban watershed. A t ransect 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 s ources such as direct runoff, bank seepage, and groundwater flow to a strea m channel. Isotope hydrograph separation indicates that groundwater or vado se water predominantly contributed to the volume of stream water compared t o direct surface runoff during a storm event. Significant differences in de lta D in the subsurface suggest that multiple flow components exist beyond the time period of a storm event. Deuterium measurements are helpful for mo deling leaks and seepage and refining mass balances of flows in urban water sheds.