Changing the Paradigm: Stormwater Management for the Greater New Orleans Area

Abstract

The Greater New Orleans (GNO) area is often referred to as “a bowl of water surrounded by water;” an indication of the area’s continuous struggle with stormwater management, including the more recent problems of subsidence and sea level rise. To address some of these challenges, the City of New Orleans commissioned the development of an H&H computer model. As envisioned, this evaluation would serve as a baseline, and assess what could be in order that it might either exceed it in level of service or reduction in cost. The model has succeeded in fulfilling its vision and blossomed into more than just a tool for traditional drainage design. The model has been essential in developing plans and proving benefits for several projects in the GNO area, including many green infrastructure projects, and has been used to help prove the benefits of changing the stormwater management paradigm of the GNO area. TRADITIONAL DRAINAGE SOLUTIONS A properly sized and functioning stormwater system is essential to the protection of public, property, and infrastructure of any metropolitan area. This is especially true in the City of New Orleans where the local topography presents a unique challenge for stormwater management. The stormwater drainage and conveyance system in New Orleans falls under the auspices of three different entities: the City of New Orleans, Department of Public Works (NO DPW), the Sewage &Water Board of New Orleans (S&WB), and the U.S. Army Corps of Engineers (USACE). The NO DPW is responsible for the construction and maintenance of roadside ditches and the underground stormwater structures associated with lines smaller than 36inches in diameter. Study Area and System Characteristics The entire City of New Orleans is addressed in the modeled area within Drainage Master Plan. Historically, development of the City has gradually migrated northward and eastward from the “high ground’ area, ridges along