Posted on 09/14/2016 2:52:41 PM PDT by SandRat
SIERRA VISTA — A multi-year study examining over a dozen indicators of groundwater discharge into the San Pedro River and riparian area indicates, that in some areas, streamwater and groundwater levels along the river are in decline.
The study, conducted by the U.S. Geological Survey, analyzed a series of data sets—including aquifer water levels, streamflow permanence, June wet-dry status of the river and spring discharge—collected over a 10-year span ending in 2012.
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https://www.facebook.com/fspraz/ (local river group)
Some original source materail:
A STATISTICAL ANALYSIS OF LOW FLOWS ON THE SAN PEDRO RIVER, ARIZONA1
Richard Koehler2 and George Ball3
1 Paper presented at the 11th Annual Symposium of the Arizona Hydrological Society, Tucson, September 23-26, 1998.
2 Cochise County Highway and Floodplain Department, 1415 W. Melody Lane, Bisbee, AZ 85603, USA; tel: 520-432-9674, fax: 520-432-9645; email: hydro@theriver.com
3 School of Renewable Natural Resources, Advanced Resource Technology Group, University of Arizona Tucson, AZ 85721, USA; tel: 520-621-7255; fax: 520-626-7401; email: gball@nexus.srnr.arizona.edu
A statistical analysis of season low flow characteristics for the San Pedro River was completed for data from the USGS gaging station at Charleston, Arizona. The 7-day annual and winter (December through February) low flows were used as an approximation of baseflow using data from 1935 to 1996.
Multivariate regression shows that for the 7-day low annual series that La Niña episodes, El Niño episodes and previous winter 7-day low flow values are statistically significant beyond the 95% confidence interval. The regression slope indicates an annual decline of 0.04 ± 0.01 cubic-feet per second (cfs)/year in the annual series. The adjusted r2 of the regression was 0.66 with an RMS of 0.65. The winter 7-day low flow series shows no significant trend over time but does have more variability than the annual series.
Additionally, daily values were used in an analysis of spring decreases and fall increases to the baseflow. Results show both spring and fall values ranged from 0.1 to 0.2 cfs/day with no detectable trend over time.
Ya gotta love the math.
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