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Levee Repair - Geomorphologic Assessments

DWR Levee Repairs Program
Department of Water Resources

3310 El Camino Avenue,
Suite 140
Sacramento, CA 95821

Mailing Address:
P. O. Box 219000
Sacramento, CA 95821-9000

For public comments or questions e-mail:

Geomorphology looks at the processes that shape and alter the surface features of the land. By studying landforms, including their origin and patterns, scientists attempt to comprehend landscapes' history and dynamics. In so doing, they can better understand the types and extents of deposits directly beneath the existing levees through field observation, detailed mapping, and stratigraphic models (which study rock layers).

A 1937 aerial photo (left) shows Sutter Bypass levees overlying Gilsizer Slough stream channel deposits. A 2006 satellite image (right) shows modern conditions in the same area, including substantial cultivation of adjacent agricultural lands.
For the levee evaluation program, experts are preparing a comprehensive surficial geologic map of the project areas based on analyses of:

  • Vintage aerial photos
  • Vintage topographic maps
  • Historical and modern soil maps
  • "Landsat" (satellite) imagery
  • Field reconnaissance observations

Results of this effort will help program specialists assess available data on site-specific conditions, leading to a better understanding of the geomorphic processes (e.g., erosion, deposition) responsible for the materials directly beneath the levees. For example, looking at vintage aerial photos and topographic maps gives us a snapshot of what the land features looked like before large-scale agricultural operations and flood-control systems dramatically changed the landscape, providing important information about the deposits that were likely present at the ground surface prior to construction of the levees. Meanwhile, satellite imagery can be used to identify unusual land and vegetation features.

Ultimately, the information gathered during these evaluations will be used to assess the current conditions affecting the levees and in critical decisions to identify boring locations and drilling depth and techniques.