IDENTIFYING POTENTIAL LEVEE SEEPAGE BLOWOUT LOCATIONS USING MODERN GEOSCIENCE TOOLS

A geomorphology study was performed for the Dallas County reach of the Trinity River in Dallas, Texas. The complex system was characterized with geospatial tools such as ArcGIS and Google Earth. Geomorphic data, soil borings, cone penetrometer test (CPT) data, and historical information were incorporated into a geospatial database. The final result was a highly detailed geomorphic map, which was used to identify areas of potential levee blowouts. Continuous clean sands or gravels under a levee can allow high velocity water flows to instigate a blowout. The digitally generated geomorphologic map documents wide zones for potential sandbar deposits (i.e. potential clean sands and gravels). CPT data was used to delineate actual sandbar deposit locations. Soil borings were used to confirm the underlying stratigraphy of the area. This data was also used to further differentiate the geologic boundaries previously mapped by the United States Geological Survey (USGS). This integrated procedure creates a more comprehensive analysis of potential risk. Unlike other hazard maps, this geomorphic map is the next step towards a better risk assessment of levee failures.