Sediment Data Portal Guide

Video demonstrations of the portal

Video 1: Purpose and navigation of the portal

Video 2: Instructions for selecting sites and downloading data

Video 3: Information on data downloaded from the portal

Data provided in the portal

The sediment portal displays the location of sites in which discrete and (or) daily suspended sediment data have been collected in the United States. The U.S. Geological Survey National Water Information System (NWIS) is the original source for all suspended-sediment data provided in the portal. Daily suspended-sediment data are retrieved directly from NWIS; discrete suspended-sediment were retrieved from NWIS in July 2017 and have been screened to only those data thought to best represent particular sampling sites and to sites with data potentially adequate to compare among sites or compute loads.

Daily suspended-sediment data

USGS mean daily, time-weighted suspended-sediment concentration (USGS parameter code 80154), suspended-sediment load (USGS parameter code 80155), and streamflow data (USGS parameter code 00060) are retrieved directly from the U.S. Geological Survey National Water Information System (NWIS). Daily-record sediment data are daily mean estimates of suspended-sediment concentration and (or) load, and are computed at sites in which suspended-sediment concentration samples are collected approximately daily or more frequently.  It is important to note that these daily computations can be moderately to highly dependent on human interpretation of the relation between streamflow and sediment transport.  Daily streamflow, suspended-sediment and other water quality data from NWIS can be found at  http://waterdata.usgs.gov/nwis/sw.   Daily sediment data field abbreviations, definitions, and units provided by the portal can be found in  Table 3 in the User Manual.   Note that unlike discrete data, different daily sites are separated by site-specific header information which may redefine column designations.

Discrete suspended-sediment data

Discrete, periodically-collected suspended-sediment data were retrieved from NWIS in July of 2017. These data were screened and augmented with available daily and instantaneous streamflow information before being uploaded to the sediment portal.   Data were screened from the sediment portal if:

  • They were quality control samples, lake or reservoir samples, and or were samples thought not to represent the width of the stream cross-section.
  • They were collected at sites not colocated with (or verfied to be adjacent to) a daily streamflow station.

More specifics on the methods used to screen and augment discrete suspended-sediment data can be found in the sediment portal user guide and in  USGS Data Report 776.  Discrete sediment data field abbreviations, definitions, and units can be found in the  Table 2 in the User Manual.   Note that prior to the July 2017 update only sites with 15 or more discrete suspended-sediment samples were able to be viewed and downloaded.  The July 2017 update removed that restriction.

For information on quality assurance tests of the accuracy and reliability of discrete, U.S. Geological Survey suspended-sediment analyses, please visit the USGS  Sediment Laboratory Quality Assurance Project .

Viewing the portal

The sediment portal is best viewed in Google Chrome, Mozilla Firefox, or Internet Explorer version 8 or newer. The portal also works in Safari, but testing has been limited and bugs may occur.

Site Legend

A legend on the lower right-hand side of the map indicates which sites have discrete (blue) and daily (red) suspended-sediment data.  The size of each dot is proportional to the number of discrete samples or length of daily record.  To minimize the site legend, click on the blue "Site Legend" box.

Window size

The size of the map and the filters do not adjust automatically to the screen size of you monitor.  To adjust the portal to the desired size, hold the control key and use the mouse to scroll forward or backward to increase or decrease the size of the map and data filters. Alternatively, if you are using google chrome, you can adjust using the zoom option located under the "Customize and control google chrome" option located to the right part the address bar.  

Zoom/Pan

To zoom in on (or out from) a portion of the map, either (1) double click on the area of interest, (2) use the mouse to scroll or (3) use the zoom bar located on the left-hand side of the map. The "+" and "-" keys located at the top and bottom of the bar can be used to zoom in or out one level (respectively).  The "-" symbol located on the bar indicates the current zoom level.  Users can click on a specific zoom level, use the "+" or "-" keys,  or use the mouse scroll bar to zoom in or out on the map.  To pan the map, users can either left click on the mouse and pull the map to the right or left or use the arrow keys located above the zoom bar.

How to inspect a data point

Selected data attributes can be inspected by left-clicking on single or groups of dots that represent suspended-sediment sampling sites.   Upon left-clicking a sampling site, a table appears that shows the station name, the USGS streamgage identifier, drainage area in square miles, the period of discrete sampling and/or daily record (depending upon the site type), the number of discrete samples, and the number of years in which daily data are available.  Click again on the map to make the site inspection table to disappear.

How to use/change base layers and overlays

Various background layers are available to help place sediment sampling sites in context with spatial boundaries (political, environmental, or basin boundaries) and landscape characteristics.  A full list of backgrounds is listed open opening the portal; this list can be minimized by clicking on the "+" tab located on the upper-right hand corner blue overlay box. Background layers are characterized as base layers and overlays.  

How to filter data

Data filters are designed to allow users to identify and get data for sites of interest. Daily and discrete sediment sampling sites can be filtered using available information on geospatial boundaries, data characteristics, and sampling site characteristics.  Filters can to be used to progressively narrow the population of sediment sampling sites.  For example if a data filter is applied to limit sites to those with 0-50% agricultural land use and by 0-25% urban land use, only those sites are returned with both 0-50% agricultural and 0-25% urban land use.  The tab key or a left-mouse click can be used to enter data in a particular filter. To apply a filter, click the "Apply Filter" button located on the top-right of the map or press the "enter" key on your keyboard.  To reset applied filters, click the "Clear Filter" button located on the top-right of the portal.  To return the portal to the initial, default view, click the refresh button on your browser.

Downloading data

Three types of data are available to download, (1) site characteristics, (2) daily data, and (3) discrete data. To download data, first use filters to identify sites of interest (or apply no filters to download the entire dataset) and then click the "Download Data" button located on the top-right hand side of the portal.

Once the "Download Data" button is clicked, a pop-up screen will appear that lets the user choose which data to download, the format of the data, and how the data will be delivered.   The user is given the option to download daily flow and sediment data from the U.S. Geological Survey National Water Information System (NWIS) and (or) discrete sediment and related data from the sediment portal.  Information on sampling site characteristics is provided with either of these data downloads by default.  If users select to download discrete sediment data, an option is provided to "Include Daily Flow" box.  Selection of this box will add the daily flow time series from the discrete suspended-sediment data to the daily data file (meaning that the "Daily Flow and Sediment Data" box must also be checked).  A time series of daily flow data is provided along with daily sediment data by default.

Additionally, if users desire only information on sampling site characteristics, they should pick one (or both) of the daily or discrete sample data and select the box labeled "Site Attribute Information Only".  If this checkbox is not selected, users will get both the sample and site characteristic data.   Data can be downloaded in .csv or .tsv format by selecting from the drop down menu next to the “File Format” button.  Users can also have data sent directly to their email by placing an email address in the "Email Address" box.  This is especially useful when large numbers of data/sites are selected for download.  If no email address is entered, data will be downloaded directly through the web browser.  For more information on any of these options, hover over the "?" located to the right of each option. 

A complete list of fields, field abbreviations, units, and data sources of site characteristic data can be accessed via this  link.  Daily data are a daily time series of mean daily streamflow, mean daily suspended-sediment concentration, and mean daily suspended-sediment data; a complete list of fields, field abbreviations, and of daily sediment data can be accessed via this  link. Discrete data represent periodically collected suspended-sediment and associated data;  complete list of fields, field abbreviations, and of discrete sediment data can be accessed via this link .

USGS Data Report 776

More information on methods used to produce the sediment portal can be found in USGS Data Report 776  or in the  Sediment Portal User Manual.