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Spatial and Temporal Variations in Streamflow, Dissolved Nitrate, and Total Phosphorus in the Rio Grande from Del Norte, Colorado, to El Paso, Texas, 1993-95. By Stephanie J. Moore and Scott K. Anderholm. National Water Quality Assessment Program NAWQA. Overview.
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Spatial and Temporal Variations in Streamflow, Dissolved Nitrate, and Total Phosphorus in the Rio Grande from Del Norte, Colorado, to El Paso, Texas, 1993-95 By Stephanie J. Moore and Scott K. Anderholm National Water Quality Assessment Program NAWQA
Overview • Describe spatial and temporal variations in streamflow and nutrient concentrations. • Use variations in streamflow to evaluate affects of inflows and diversions? • Use variations in nutrient concentrations to evaluate affects of inflows and instream processes?
Data Monthly water-quality samples -- collected from 1993 to 1995 Daily mean streamflow data -- calculated from continuous data
Rio Grande Valley Study Unit Areas of ground-water inflow Agricultural areas Rio Grande Floodway and Conveyance Channel Elephant Butte And Caballo Reservoirs
2,400 Increasing streamflow Decreasing streamflow 2,200 2,000 1,800 1,600 1,400 1,200 Decreases by 650 ft3/s 1,000 800 600 400 2 + T = Sum 200 0 Spatial variations in streamflow 1993 1994 1995 Annual mean streamflow (ft3/s) RGDelN RGTrinch Conejos Sum1 RGLob RGTJB Chama Sum2 RGOtowi Convey RGFldwy Sum3 RGLeasb RGElP 1 2 T Sum 3 4 T Sum 5 T 7 Sum 8 9
9,000 Temporal variations in streamflow 8,000 Otowi 7,000 6,000 5,000 Daily mean streamflow (ft3/s) 4,000 Rio Chama Taos Jxn 3,000 2,000 1,000 0
Convey vs. Floodway Reservoir effects Increase Above El Paso Increase between Otowi and Isleta Little change above Otowi 2.2 Spatial variations in dissolved nitrate concentrations 2.0 1.8 1.6 1.4 Dissolved nitrate (mg/L) 1.2 1.0 0.8 0.6 0.4 0.2 0 1 2 T 3 4 T 5 6 T 7 8 9
*RGOtowi RGIsleta Temporal variations in dissolved nitrate concentrationsbetween Otowi and Isleta 3 2 Dissolved nitrate (mg/L) 1 0 • Generally, smaller nitrate concentrations during snowmelt. • Smallest increases (between sites) during snowmelt. • Larger concentrations during low flow. • (Otowi: Dec – Feb; Isleta: Aug – Sept)
RGIsleta RGConvey RGFldwy Temporal variations in dissolved nitrate concentrationsbetween Isleta and Elephant Butte (San Marcial) 3 2 Dissolved nitrate (mg/L) 1 0 • Isleta to Floodway at San Marcial: little change. • Isleta to Convey: decrease in nitrate concentrations. • Convey: largest concentrations in Aug-Sept
Convey vs. Floodway Reservoir effects Increase between Otowi and Isleta Increase Above El Paso Little change above Otowi 1.8 Spatial variations in total phosphorus concentrations 1.6 1.4 1.2 Total phosphorus (mg/L) 1.0 0.8 0.6 0.4 0.2 0 1 2 T 3 4 T 5 6 T 7 8 9
*RGOtowi RGIsleta Temporal variations in total phosphorus concentrationsbetween Otowi and Isleta 1.0 Total phosphorus (mg/L) 0.5 0 • Seasonal pattern at Otowi is typical: • Largest concentrations during snowmelt. • Isleta: Smallest concentrations during snowmelt.
RGIsleta RGFldwy Temporal variations in total phosphorus concentrationsbetween Isleta and Elephant Butte 2.0 Total phosphorus (mg/L) 1.0 0 • Isleta and Floodway: smallest concentrations during snowmelt. • Floodway: large concentrations during monsoon and early snowmelt.
Spatial variations in nutrient concentrations, streamflow, and nutrient loads
