Bed sediment properties in Little Holland Tract and Liberty Island, Sacramento-San Joaquin Delta, California, 2014 to 2019 (ver. 3.0, April 2023)

Bed sediments were collected by the USGS Pacific Coastal and Marine Science Center (PCMSC) in two submerged agricultural tracts, Liberty Island and Little Holland Tract, in the northern Sacramento-San Joaquin Delta, California. Samples were analyzed for grain size distribution, bulk density, or both. Analyses were conducted using PCMSC sediment lab standard techniques (see Process Step in metadata). This effort was part of a large interdisciplinary study supported by the U.S. Bureau of Reclamation to investigate how shallow water habitats in the Sacramento-San Joaquin Delta function and whether they provide good habitat for native fish species, including the Delta smelt. Bed sediment properties, including grain size and bulk density, inform studies of sediment resuspension and transport. Suspended sediment is a dominant component of turbidity, and elevated turbidity is a requirement for Delta smelt habitat. Sediment samples were collected at multiple locations in the two tracts during numerous surveys performed between 2014 and 2017. In the summers of 2014 and 2016, surveys were conducted to investigate spatial variability in sediment properties. Sediment cores were collected at 14 to 17 locations in the study area and analyzed for grain size and bulk density at different depths below the sediment-water interface. In addition, during 2015, 2016, and 2017, surface sediment samples were collected repeatedly at several locations to investigate how grain size varied temporally and spatially. The repeat-sample sites were the locations of collection of time-series data of wind-wave properties and suspended-sediment concentration (published separately). Three data sets are available in the Child Items listed below: the 2015 to 2017 surface sediment sample data, the 2014 spatial survey data, and the 2016 spatial survey data. Links to data from other components of this study are provided in the Related External Resources below: time-series data of wind-waves and suspended-sediment, and a digital elevation model of Little Holland Tract.

美国地质调查局（United States Geological Survey，USGS）太平洋海岸与海洋科学中心（Pacific Coastal and Marine Science Center，PCMSC）在加利福尼亚州萨克拉门托-圣华金三角洲北部的两处水下农业区域——自由岛（Liberty Island）与小荷兰水道（Little Holland Tract）采集了河床沉积物样品，研究人员针对样品的粒度分布、容重，或两项指标均开展了分析，测试采用PCMSC沉积物实验室标准流程完成（详见元数据（metadata）中的处理步骤）。本研究是美国垦务局（U.S. Bureau of Reclamation）资助的大型跨学科研究的一部分，旨在探究萨克拉门托-圣华金三角洲浅水生境的功能机制，以及其是否能为包括三角洲胡瓜鱼（Delta smelt）在内的本土鱼类提供适宜栖息环境。河床沉积物特性（包括粒度与容重）可为沉积物再悬浮与输运相关研究提供科学支撑，悬浮沉积物是水体浊度的主要组成部分，而较高浊度是三角洲胡瓜鱼栖息的必要条件。2014至2017年间的多次野外调查中，研究人员在两处水道的多个点位采集了沉积物样品；2014年与2016年夏季，团队开展了针对沉积物特性空间变异的调查，在研究区内14至17个点位采集沉积物岩心，针对沉积物-水界面以下不同深度的样品分析粒度与容重；2015、2016及2017年期间，研究人员在多个点位重复采集表层沉积物样品，以探究粒度特征的时空变化规律，上述重复采样点位同时也是风浪参数与悬浮沉积物浓度时间序列数据的采集站点，相关数据已另行发表。下述子项数据集包含三类可用数据：2015至2017年表层沉积物样品数据、2014年空间调查数据，以及2016年空间调查数据。本研究其他组分的相关数据链接详见下文"相关外部资源"：风浪与悬浮沉积物浓度时间序列数据，以及小荷兰水道的数字高程模型（digital elevation model）。