StreamStats in New Jersey Active

2022 Update

New Jersey StreamStats database has been updated with improved base elevation information and stream centerlines (see Data tab). Prior to the update it was based on 10-meter horizontal-resolution elevation data and 1:24,000-based hydrography. It is now based on 10-foot horizontal-resolution elevation data and 1:2,400 scale hydrography. In both cases, this is the best resolution/scale of any StreamStats state-wide project to date. New functionality was also developed to provide average watershed land slope based on the lag method in addition to 10-85 channel slope.  

Sources/Usage: Public Domain.

With this accuracy, New Jersey StreamStats can be used for watershed analysis to much smaller basins than is currently possible for any other StreamStats project. It has a tighter fit with elevations along the channels to support future automated floodplain, bankfull, and culvert analysis. More accurate river morphology analysis could also be considered with this level of detail. 

StreamStats for New Jersey can be used to estimate instantaneous flood discharges and monthly flow-duration and monthly low-flow frequency statistics for ungaged streams. All peak and low flow equations have remained the same for this StreamStats update. Streamflow statistics and basin characteristics produced by this version may deviate slightly from those generated previously. These deviations were not found to differ significantly among state regions and were distributed normally. Work has begun to develop new statewide equations to estimate flood discharges. These are planned to be integrated into New Jersey StreamStats when available.   

Use 

StreamStats for New Jersey can be used to estimate instantaneous flood discharges with exceedance probabilities of 0.5, 0.2, 0.1, 0.04, 0.02, 0.01, and 0.002 for ungaged, unregulated or slightly regulated, non-tidal streams in New Jersey. These exceedance probabilities correspond to recurrence intervals of 2-, 5-, 10-, 25-, 50-, 100-, and 500-years, respectively.

StreamStats for New Jersey also can be used to estimate monthly flow-duration and monthly low-flow frequency statistics for ungaged streams in Coastal Plain and non-coastal regions of New Jersey for baseline and current land- and water-use conditions. The equations were developed to estimate 87 different streamflow statistics, which include the monthly 99-, 90-, 85-, 75-, 50-, and 25-percentile flow-durations of the minimum 1-day daily flow; the August–September 99-, 90-, and 75-percentile minimum 1-day daily flow; and the monthly 7-day, 10-year (M7D10Y) low-flow frequency.

Documentation

The reports (Publications tab) present the regression equations used to estimate the noted streamflow statistics, describe the errors associated with the estimates, and describe the methods used to develop the equations and to measure the basin characteristics used in the equations. Users should familiarize themselves with the reports before using StreamStats to obtain estimates of streamflow statistics for gaged and ungaged sites.

NOTE 1: Although 1990 population density was used for the development of the regression equations in SIR 2009-5167, the New Jersey StreamStats application uses the more current 2000 population-density data.

NOTE 2: Watson and McHugh (2014) provide two sets of regression equations for flow duration and low-flow frequency statistics, intended to reflect conditions for a “base” and a “current” period. The “base” period is defined as the years a streamgage had little to no change in development and water use. The “current” period is defined as the 1989–2008 water years (Oct. 1, 1988 to Sept. 30, 2008). The base period of record is representative of a period when the basin was unaffected by change in development. The current period is representative of more recent increased development.