In these other locations, water forces act on levees only during periods of high water or flooding. In the Delta, land elevations are generally much lower than waterway elevations. Because of this difference, the levees function more as earthen dams which act as continuous water barriers. This difference between many Delta levees and levees in other areas has important implications regarding levee design and reconstruction. For example, most of the Delta levees have to remain fully functional during any improvements or rehabilitation.
Levee failures continue to be one of the Delta's primary problems.
Levee failures in the Delta are due to several factors which include instability, overtopping, and seepage. To gain a better understanding of the problems facing the Delta, DWR has undertaken engineering investigations such as a recently completed seismic analysis of the Delta levees. These investigations along with levee improvement projects performed under SB 34 have demonstrated that many difficult Delta levee problems are solvable. SB 34 has provided the necessary focus for coordinated levee engineering investigations and funds for improvement projects that have advanced the state of the art of levee design. These efforts have demonstrated that levees can be engineered to alleviate the unfavorable conditions which continue to threaten this water hub of unique economic and natural value.