Bathymetric survey and digital elevation model of Little Holland Tract, Sacramento-San Joaquin Delta, California

Abstract

The U.S. Geological Survey conducted a bathymetric survey in Little Holland Tract, a flooded agricultural tract, in the northern Sacramento-San Joaquin Delta (the "Delta") during the summer of 2015. The new bathymetric data were combined with existing data to generate a digital elevation model (DEM) at 1-meter resolution. Little Holland Tract (LHT) was historically diked off for agricultural uses and has been tidally inundated since an accidental levee breach in 1983. Shallow tidal regions such as LHT have the potential to improve habitat quality in the Delta. The DEM of LHT was developed to support ongoing studies of habitat quality in the area and to provide a baseline for evaluating future geomorphic change. The new data comprise 138,407 linear meters of real-time-kinematic (RTK) Global Positioning System (GPS) elevation data, including both bathymetric data collected from personal watercraft and topographic elevations collected on foot at low tide. A benchmark (LHT15_b1) was established for geodetic control of the survey. Data quality was evaluated both by comparing results among surveying platforms, which showed systematic offsets of 1.6 centimeters (cm) or less, and by error propagation, which yielded a mean vertical uncertainty of 6.7 cm. Based on the DEM and timeseries measurements of water depth, the mean tidal prism of LHT was determined to be 2,826,000 cubic meters. The bathymetric data and DEM are available at http://dx.doi.org/10.5066/F7RX9954.

Wetland geomorphology and tidal hydrodynamics drive fine-scale fish community composition and abundance

“…Thus, we considered that bed and water elevations would each contribute to the overall effect of instantaneous volume of available habitat, which in tidal wetlands is inherently a combination of both features and is a known driver of fish distribution (Kneib and Wagner 1994;Silver et al 2017;Colombano et al 2020). Bed elevation associated with each sample was obtained from digital elevation models of the study areas (Snyder et al 2016;Fregoso et al 2020). Water elevation was obtained for each net using the median time of the sample and the associated reading from USGS streamgage 11455167 located in the study area (Fig.…”

“…Because the figure is static, only variation in the two spatial geomorphic characteristics could be visualized (i.e., distance from a main waterway connection and bed elevation) and the temporally variable characteristic (water surface elevation) was kept constant at the mean value for the sampling period. We used raster datasets of bed elevation (Snyder et al 2016;Fregoso et al 2020) and distance from main waterway to generate zonal statistics for a grid of 30 m 2 cells for each wetland, thus creating a spatially explicit grid of model covariates. We then used this grid to generate multiple (n = 1000) model predictions for a stage equivalent to the mean stage for all samples.…”

“…It is now a broad, shallow, intertidal embayment with a surface area of 292 ha fringed with emergent marsh plain and vegetation (primarily Schoenoplectus). Mean bed elevation of the intertidal basin relative to sea level is − 0.70 m (standard deviation = 1.42 m; NAVD88; Snyder et al 2016), with sampled depths ranging from 0.5 to 3.1 m. On average, 78% of the intertidal basin's water volume exchanges with surrounding channels during each complete tidal cycle (Snyder et al 2016), resulting in a substantial area of the intertidal basin completely dewatering at low tides and exposing the bed to air.…”

“…The dendritic wetland consists of a network of shallow, subtidal dendritic channels embedded in intertidal marsh plain. Mean bed elevation of the dendritic wetland relative to sea level is − 0.68 m (standard deviation = 0.87 m; NAVD88) (Snyder et al 2016;Fregoso et al 2020). There are no published quantitative measurements of tidal exchange; based on water elevation data and field observations, the primary channel in the dendritic wetland remains inundated at low tides.…”

Application of Integration Measurement Technologies in Inventory of Bagry Water Body

“…This also refers to the underwater part, which has not been studied in detail or cartographically documented. According to [15], bathymetric data contains key information that can enable us to start habitat studies and classifying various zones of the water body to define their economic or environmental functions. In the case of Bagry, no cartographic documents were preserved to allow us to make conclusions about the morphological characteristic of the water body, which is very important for the safety of visitors in terms of recreation (finding the areas of safe swimming and sailing).…”