ABSTRACT

The 1996 study of the Marine Corps Base (MCB) Camp Pendleton3 region used a version of the spatially explicit CASC2D4 model implemented in the GIS software GRASS 4.1 as the r.hydro.casc2d module, to simulate a 25-year flood event on the rivers flowing through or adjacent to the installation. This event is statistically expected to occur once in any 25-year period; it can similarly be understood to have a 4% chance of occurring in any given year. The study used the land cover that existed circa 1990 (referred to as 1990+ in the report). The characteristics of the hydrological elements of the landscape were calibrated with the known spatial and temporal distribution of a rainstorm that generated the discharge of the known 25-year flood. Possible future change was investigated through a Plans Build-Out scenario that fully implemented local land use plans. Additionally, students from the Harvard Graduate School of Design developed five alternative regional land-development designs that were intended to accommodate the 500,000 new residents expected by the year 2020 and to manage for biodiversity. Each alternative was a plausible spatial arrangement of residential, commercial, industrial, agricultural, and other land uses. These alternative plans were simulated with the calibrated CASC2D model to model the new stream flows that would result from the changed land cover. The primary product of each simulation was a hydrograph that graphically displayed the volume of discharge over time.