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Report Site Map > Monitoring Network for Nine Major Subbasins Comprising the Mississippi-Atchafalaya River Basin > Daily Average Streamflow Data for the Red River at Alexandria, Louisiana

USGS Open-File Report 2007-1080 - Streamflow and Nutrient Fluxes of the Mississippi-Atchafalaya River Basin and Subbasins for the Period of Record Through 2005

Daily Average Streamflow Data for the Red River at Alexandria, Louisiana

The daily average streamflow for the Red River at Alexandria, Louisiana, came from two sources. Streamflow for water years (WY's) 1970 through 1983 was obtained from the USGS NWISWeb database. Streamflow for WY's 1984 through 2005 was obtained from the U.S. Army Corps of Engineers (USACE; Mark Richter, U.S. Army Corps of Engineers, Vicksburg, Miss., written commun., February 22, 2006, and January 5, 2007).

The USACE data had 163 days with missing streamflow. Though most data gaps were 3 days or less in length, there were 6 gaps between 4 and 7 days, and one gap of 23 days (which occurred from 12/15/04 through 1/6/05 due to a temporary obstruction at the gate of the data that resulted in artificially high stages; Mark Richter, U.S. Army Corps of Engineers, Vicksburg, Miss., oral commun., January 11, 2007). Daily average streamflow for gaps of 3 or less days in length were linearly interpolated from streamflows from the day before and the day after the gap. Daily average streamflow for gaps longer than 3 days was estimated using a regression relation developed as a function of the difference between the daily average streamflows of the Atchafalaya River at Simmesport, Louisiana, and the Old River Outflow Channel near Knox Landing, Louisiana. This difference represents the contribution of streamflow from the Red River. Note that there is one significant ungaged tributary (the Black River) that enters the Red River between Alexander, Louisiana, and where the Red River enters the Atchafalaya River.

Regression models were developed for two separate periods because the USACE changed the rating curve (the relation to convert water level stage to streamflow discharge) technique for the Red River at Alexandria, Louisiana, in 2002 (Mark Richter, U.S. Army Corps of Engineers, Vicksburg, Miss., oral commun., January 11, 2007). The new rating curve approach results in slightly higher flows for similar stages. Therefore, the 4- to 7-day gaps were filled in with a regression model developed for the period WY's 1989 through 1999, which encompasses these gaps. The 23-day gap was filled in with a regression model developed for the period WYs 2003 through 2005 which covers the period around this longer data gap and contains streamflow derived only from the new rating curve approach.

In order to account for travel time of Red River streamflow from the Alexandria, Louisiana, station to the Atchafalaya River, the regression model for streamflow at Alexandria was fit to the following day's difference in streamflow between the Atchafalaya River and the Old River. The shift of 1 day provided a somewhat better fit to the two regression models. A 4^th-order polynomial best fit the shape of the relation between the flows for the WY89-99 period. The regression equation is:

where Q_Red is the predicted daily average streamflow for the Red River at Alexandria, Louisiana, and Q_Diff is calculated as the next days daily average streamflows of the Atchafalaya River at Simmesport, Louisiana, minus the Old River Outflow Channel near Knox Landing, Louisiana. Fifty days were not included in the relation (from 4/28/91 to 6/1/91) as these streamflows did not follow the observed relation for the rest of the period. The model R² is 83.9.

A 2^nd-order polynomial best fit the shape of the relation between the flows for the WY03-05 period. The regression equation is:

The model R² is 76.5.

Report Site Map > Monitoring Network for Nine Major Subbasins Comprising the Mississippi-Atchafalaya River Basin> Daily Average Streamflow Data for the Red River at Alexandria, Louisiana