Urbanization alters dramatically the hydrological and biogeochemical processes that govern the movement and transformation of materials through ecosystems. Numerous studies have documented elevated runoff volume, peak flow rates, and contaminant loads in storm runoff corresponding to urban development. However, the concomitant roles of urbanization intensity, configuration, and type, and the interaction of urbanization with climate variability in modulating stormwater quality are understudied and poorly understood. In this project, investigators seek to understand these relationships and feedbacks, which are critical to developing science-based strategies for the effective management of stormwater runoff and contaminants in urban environments. Four questions central to this project include: (1) How does urban stormwater infrastructure affect runoff dynamics in a desert city? (2) How does urbanization impact the processes controlling delivery of nitrogen (N) from runoff-generating areas? (3) What are the dominant sources of N in a desert city and what is the extent of internal N processing? and, (4) How do processes controlling the delivery and transport of materials (stormwater, dissolved and particulate matter) change across different spatial scales? To address these questions, a series of nested catchments are instrumented to monitor flow and water quality in the Indian Bend Wash Catchment, Scottsdale, AZ. Catchments range in area from 6 to >17,000 ha, and represent different types and configurations of stormwater infrastructure. Catchments at the smaller spatial scales represent medium-density residential housing, while land cover becomes more heterogeneous at larger spatial scales. Monitoring has been ongoing since summer 2010.