Tucson Urban Runoff

As a collaborative project between Purdue University, University of Arizona and Arizona State, we are studying the effects of urbanization on the coupled hydrologic and nitrogen biogeochemical processes in xeric ecosystems. The main objectives of this research is to determine: how urbanization impacts delivery of nitrate, the main sources of nitrate, and how wash substrate type changes in-stream/wash processing of nitrate. This will be achieved through a series of investigations of source, transport, and processing of nitrate using natural abundance, stable isotopes, and geochemical tracers throughout a range of urbanizing watersheds in Tucson and Phoenix, AZ.

Runoff samples collected by

automated ISCO samplers as well as siphon samplers .

Catchments showing different wash substrates: gravel (middle) and grass (left) and a mixed density catchment that drains into the Rillito River (right).