Bathymetry, topography, and acoustic backscatter data, and a digital elevation model (DEM) of the Cache Slough Complex and Sacramento River Deep Water Ship Channel, Sacramento-San Joaquin Delta, California

This data release presents bathymetric and topographic data from surveys performed between 2017 and 2018 in the Cache Slough Complex and the Sacramento River Deep Water Ship Channel (DWSC), northern Sacramento-San Joaquin Delta, California. The shallow, highly vegetated aquatic habitats of this region necessitated a variety of survey platforms and techniques. In the deeper channels, swath bathymetry data were collected using a 234.5 kHz interferometric sidescan sonar pole-mounted to the 26-ft R/V San Lorenzo. In smaller channels and shallow areas not accessible with the larger survey vessel, swath bathymetry data were acquired with Kelpfly, a personal watercraft (PWC) equipped with a 468 kHz interferometric sidescan sonar. Two PWCs equipped with 200 kHz single-beam sonars were primarily used to survey the large, gently sloping flooded agricultural tracts and areas with dense submerged vegetation. Topographic data were collected by hiking over the land surface, with global navigation satellite system (GNSS) receivers mounted on backpacks. However, this method was largely ineffective in marshes because of the difficulty in traversing the dense, tall vegetation. The combination of these techniques resulted in good coverage of the main channels and shallow, open water embayments.

These new bathymetric and topographic data were merged with existing recent datasets to produce seamless digital elevation models (DEMs) of the Cache Slough Complex and of the DWSC with a grid resolution of 1 m. Funding for these surveys and generation of the DEMs was provided by the U.S. Bureau of Reclamation in support of ongoing field experiments and numerical modeling to improve our understanding of habitat quality, the influence on various landscape features on ecosystem function, and the effects of restoration actions in the Sacramento-San Joaquin Delta.