A Partnered Approach to Design of ‘‘Natural'' Wash Corridors in an Urbanizing Pseudo-Alluvial Fan Area in Northeast Phoenix, Arizona

The goal of this project was to preserve and restore natural washes and provide flood protection to the existing and future developments in rapidly urbanizing northeast Phoenix. The developmental pressures, unplanned nature of past land use practices and developments and concern for the remaining pristine undisturbed areas necessitated a holistic approach involving many stakeholders. The partnering stakeholders included city, state and federal agencies, the developer, the community and engineering and environmental consultants. The task was especially challenging in the semi-arid Sonoran desert environment where relatively uncontrolled flooding occurs and numerous varying sized washes flow overland — many of them beginning and disappearing over short distances. In spite of the ephemeral nature of flows, these washes support significant riparian habitats and native wildlife. Another significant issue was the sediment laden/flowing nature of the washes (channels) which can be a maintenance nightmare if not considered. This paper presents the approach adopted by the project's partners for the design of "natural" flood control channels using hydraulic, sediment transport, environmental/landscape and community based criteria and procedures.