Low-Flow Characteristics

Science Center Objects

Streamflow data collection and analysis are a necessary component of effective water resource management and planning.  Low-flow statistics are needed to safely allow withdraws from and discharges to surface waters in the State of New Jersey.  Operating streamflow gaging stations at every water use location would be ideal but is cost prohibitive. Statistics help extend the utility of available data and provide reliable information for a fraction of the cost of operating streamgages.

Estimates of various flow statistics at un-gaged locations are available from USGS web applications such as “StreamStats”, in which regional equations based on physical basin characteristics are used to transfer flow information from long-term continuous gages. These flow estimates are based on streamgage data that are considered to be un-impacted by water use or regulation, and are considered “natural”. The low-flow statistics needed for water management in the context of this project do require inclusion of the effects of water use and regulation. A vast network of partial-record sites in New Jersey reflects these altered flows, and makes it possible to estimate “actual” rather than a presumed “natural” condition. The estimates are site specific and attempt to represent at-site conditions as much as the available data allow.

 

Methods used for the calculation of the low-flow statistics at ungaged sites are documented in the reports, “Streamflow Characteristics and Trends in New Jersey, Water Years 1897-2003” (U.S. Geological Survey Scientific Investigations Report 2005-5105) and “Implementation of an R Script to Implement MOVE.1, Censored MOVE.1, and Piecewise MOVE.1 Low-Flow Regressions with Applications at Partial-Record Streamgaging Stations in New Jersey” (U.S. Geological Survey Open File Report 2018-1089).

 

To provide a publicly available, citable repository of the computed low flow statistics at ungaged locations in New Jersey, the pertinent information of each estimate is made available in an annual data release in Science Base (https://www.sciencebase.gov/catalog/item/5b4cd524e4b06a6dd17aca26). The data releases include the stream name, location, method, and intended use of the low-flow statistics computed during the specified water year. The data are provided as both a plain text file and an ArcGIS shapefile format.

 

This project is made possible through cooperative agreements between the New Jersey Department of Environmental Protection (NJDEP) and USGS.