In 1981, flooding in the Walnut Creek Basin resulted in two deaths, widespread property damage and disruption of city services. In subsequent years, flood damage continued to occur despite structural improvements and the participation of the City of Austin in the National Flood Insurance Program. Because of its uneven distribution over space and time, land use change appears to be the major factor affecting vulnerability in this basin. This study uses HEC-HMS (U.S. Army Corps of Engineer’s Hydrologic Modeling System) to evaluate the impact of land use change on the magnitude of flood peaks in the Walnut Creek Basin between 1960 and 1990. Census tract data and historiographic analysis are then used to examine the interplay of physical and social factors that create vulnerability, as well as the relationship between risk and mitigation that contributes to the process by which certain groups become vulnerable to a hazard. This study will identify the processes that result in the current “riskscape” and their cumulative effect over time.