As prime contractor to the US Army Corps of Engineers (USACE), Los Angeles District, we prepared three economic analyses under individual delivery orders for water resource projects in Southern California and in Arizona. All were prepared in conformance with USACE guidance for National Economic Development (NED) account evaluations for civil works projects.
RDN’s first project was an economic analysis of flood control alternatives in the Tortolita Drainage Area in the Pima and Pinal Counties in Arizona. The purpose of this project was to provide a reconnaissance-level study of the benefits and costs of alternative fan-wide flood control projects in the drainage area. Rapid population growth in the region had increased the demand for buildable land, leading to proposed measures to enhance flood protection. Six flood-control solutions were analyzed, each with different NED benefits and costs – reductions in flood-proofing costs, inundation damages, maintenance costs for existing transportation infrastructure, costs for proposed transportation improvements, flood-induced traffic delays, improved access for emergency vehicles, and flood insurance administrative costs. Additional benefits were evaluated for recreation, open space, and riparian habitat management. Benefit estimates were based on local real estate development projections.
RDN’s second project under this delivery order was an economic analysis of flood control alternatives for the Whitewater River Basin in Riverside County, California. This study provided a feasibility-level flood inundation analysis for a portion of the basin, documenting flood-proofing savings due to development of a proposed flood control system. We estimated expected annual inundation damages under without-project conditions over a 50-year period using the Hydrologic Engineering Center’s EAD model. We assessed existing development from county appraiser records on parcel numbers, ownership, size, land use, type and value of improvements, structure age, and structure size. We conducted a field survey to determine first floor elevations of the improvements and to confirm structure sizes and types for a sample of existing structures. Additionally, we prepared forecasts of future development based on the Riverside County General Plan, compilation of data from state and local agencies, and developer interviews.
RDN’s final project under this delivery order was an economic analysis of recreation benefits in the Hansen Dam Recreation Area in Los Angeles, California. We prepared a feasibility-level study for a proposed flood control project affecting recreational activities at the Hansen Dam Recreation Area in the City of Los Angeles. Our analysis was used to assist in determining the economic feasibility of the proposed project and in preparing the EIS. Several recreation sites were more likely to become inundated with the addition of a water conservation function and alternative operating plans. To assess the differences among alternatives, we forecast future activity and then estimated the number of foregone visitor-days under each alternative based on the probability of inundation.