From Flood Risk to Financial Losses: Assessing the Impacts of Projected Inland Subsidence with Future Development in the Spring Creek Watershed, Southeast Texas, USA

In southeast Texas, groundwater extraction has caused irreversible aquifer compaction that results in land subsidence. As this region continues to experience population growth and increased water demand, the evaluation of projected subsidence impacts is crucial for effective water resource planning. This study presents a scenario-based framework for investigating future flood hazards and quantifying economic damages associated with inland subsidence in the Spring Creek Watershed, Texas, United States (US). A 2D pluvial hydrologic and hydraulic (H&H) model, Hydrologic Engineering Center’s River Analysis System (HEC-RAS) 6.6, simulated flooding using two rainfall conditions for a Baseline scenario, containing 2020 conditions, and a subsidence with future development (SFD) scenario with projected 2070 conditions to assess flood risk. Modeling results for the 100-year event SFD scenario included expansion of the floodplain by over 1700 acres, increased streamflow, flood depth increases over 30 cm, and over 3700 flooded structures, the majority being residential. The greatest flood impacts were experienced downstream in the watershed rather than within the area of most projected subsidence. Economic losses were analyzed using the Go-Consequence tool and revealed the SFD scenario had over half a billion US dollars in additional losses for a single 100-year flood event relative to the Baseline. This work highlights the importance of long-term planning to minimize future flood damages in a flood-prone region.