HYDROLOGICAL AND GEOCHEMICAL TRENDS AND PATTERNS IN THE UPPER RIO GRANDE, 1975 TO 1999¹

Abstract

Hydrological and geochemical spatial patterns and temporal trends were analyzed using U.S. Geological Survey (USGS) water quality data collected from 1975 to 1999 along the uppermost 600 km of the Rio Grande in Colorado and New Mexico. Data on discharge, specific conductivity (SC), total dissolved solids (TDS), pH, Ca2+, Na+, Mg2+, K+, HCO3−, SO42‐, Cl−, F−, and SiO2 came from six USGS stations ranging from the Colorado‐New Mexico border to below Albuquerque, New Mexico. Linear regression, Kendall's S, and Seasonal Kendall's S’ were used to detect trends, and ANOVA was used to analyze spatial differences between stations. Statistically significant increasing trends occurred in SC, TDS, Ca2+, Na+, Mg2+, K+, Cl−, and F−in the uppermost reaches, and significant decreasing trends of SC, TDS, Ca2+, Mg2+, K+, HCO3−, and SO42‐occurred at the lower stations around Albuquerque. Both fluoride concentrations and pH values increased at and below Albuquerque over the study period. Discharge data show an increasing trend across all stations. Spatially, data for dissolved substances show generally linear upstream to downstream increases in concentrations in the upper four stations, with several notable nonlinear increases at and below Albuquerque (SC, TDS, Na+, Cl−). Significant increases in pH appear at and below Albuquerque, relative to upstream stations, probably due to improved sewage treatment.

Use of a dynamic simulation model to understand nitrogen cycling in the middle Rio Grande, NM.

“…The ephemeral Rio Puerco and Rio Salado and intermittent Jemez River are the three major tributaries within the Middle Rio Grande, however they contribute little water to the river [Moore and Anderholm, 2002]. Annual discharge from the Albuquerque wastewater treatment plant to the Rio Grande makes it one of the largest tributaries in the river's upper basin [Passell et al, 2004].…”

“…We calculated average monthly concentration values for the river and LFCC to compare with the model results using surface water data from the USGS NWIS online database [U.S. Geological Survey (USGS), 2006] (Figure 4). We chose to use data after 1993 based on work by Passell et al, [2004] which suggested that significant improvements were made to the Albuquerque WWTP that reduced nitrate concentrations in the river around this time. Therefore, while the model runs from 1975 -2005, we only compared modeled and observed data between 1993 and 1995.…”

“…Several studies have looked at how nutrient load patterns change downstream and over time [Moore and Anderholm, 2002;Oelsner et al, 2007;Passell et al, 2004;2005]. Results from these studies suggest that wastewater treatment plants are important point sources of nutrients to the river [Oelsner et al, 2007;Passell et al, 2004] and agricultural diversions can remove nitrogen and improve water quality downstream of wastewater treatment plant point sources [Oelsner et al, 2007].…”

“…Previous studies in the Middle Rio Grande have focused on analyzing the spatial and temporal patterns of nutrient concentrations using monitoring and discharge data [Anderholm et al, 1995;Passell et al, 2004;2005]. Several studies have looked at how nutrient load patterns change downstream and over time [Moore and Anderholm, 2002;Oelsner et al, 2007;Passell et al, 2004;2005].…”

Trend analysis of the load and concentration of physical, chemical and biological parameters in the Verde River Basin

“…The evaluation of water quality parameters time series allows the observation of variability in load and concentration over time, which helps to identify the main impact factors and polluting potentials occurring around the area in analysis. Over the last years, many studies have been performed around the world aiming to detect trends and changes in water quality (PASSELL;DAHM;BEDRICK, 2004;CHANG, 2008;CHRISTOFARO;LEÃO, 2009;TABARI;MAROFI;AHMADI, 2011;GOCIC;TRAJKOVIC, 2013;SUN et al, 2013;TRINDADE, 2013;BARBOSA, 2015). The time series studied by these authors vary significantly depending on the availability of data, and some of them call for longer monitoring periods in order to obtain more reliable findings.…”