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Report Site Map > Monitoring Network Used to Estimate Delivery of Streamflow and Nutrients to the Gulf of Mexico

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

Monitoring Network Used to Estimate Delivery of Streamflow and Nutrients to the Gulf of Mexico

  Schematic of Mississippi-Atchafalaya River Basin sampling stations for estimating delivery to the Gulf of Mexico
Figure 1. Schematic of Mississippi-Atchafalaya River Basin sampling stations for estimating delivery to the Gulf of Mexico

Nutrient fluxes from the Mississippi-Atchafalaya River Basin to the Gulf of Mexico are calculated as the sum of nutrient loads from the Mississippi and Atchafalaya Rivers. Downstream sampling stations were chosen that had long-term stream discharge and water-quality data so that the load estimates provide both a long-term record and a good measure of the delivery of nutrients to the Gulf. All the stations used in load estimation analysis are shown in figure 1. Water-quality and stream-discharge data are not measured at the same station. However, these stations are located nearby and are considered to reflect similar chemical and flow conditions. Mississippi River nutrient fluxes are estimated using water quality from the station near St. Francisville, Louisiana, and stream discharge from the station at Tarbert Landing, Mississippi. Atchafalaya River nutrient fluxes are estimated using water quality from the station at Melville, Louisiana, and stream discharge from the station at Simmesport, Louisiana. The statistical load estimation procedure for Mississippi River nutrient fluxes also incorporates the flow diverted to the Atchafalaya River via the Old River Outflow Channel as measured at Knox Landing along with flows from two upstream stations, the Mississippi River at Thebes, Illinois, and the Ohio River at Metropolis, Illinois. Water-quality and stream-discharge stations are summarized in table 1 and their relative locations in the hydrologic framework are indicated in figure 1.

Table 1. Summary of information of stations used for nutrient flux estimation.

Station Name   Station ID    Drainage Area 
(km2)
 Data 
Type
 Source 
Mississippi River near St. Francisville, La.1 07373420 2,965,404    quality USGS
    Mississippi River at Tarbert Landing, Miss. 01100 2,913,500    flow USACE
Lower Atchafalaya River at Melville, La.2 07381495 241,690    quality USGS
    Atchafalaya River at Simmesport, La. 03045 226,800    flow USACE
    Old River Outflow Channel near Knox Landing, La. (Total Outflow) 02600 --       flow USACE
Ohio River at Metropolis, Ill. 03611500 526,000    flow USGS
Mississippi River at Thebes, Ill. 07022000 1,847,000    flow USGS
1   =   Flow for this station is measured at Mississippi River at Tarbert Landing, Mississippi.
2   =   Flow for this station is calculated using measurements at Atchafalaya River at Simmesport, Louisiana, and the Old River Outflow Channel near Knox Landing, Louisiana.
USGS   =   U.S. Geological Survey
USACE   =   U.S. Army Corps of Engineers
--   =   Not applicable

Report Site Map > Monitoring Network Used to Estimate Delivery of Streamflow and Nutrients to the Gulf of Mexico

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