Variations in climate and ephemeral channel recharge in southeastern Arizona, United States

Significant variations in interannual and decadal recharge rates are likely in alluvial basins of the semiarid southwestern United States on the basis of decadal variations in climate and precipitation and correlation of El Nino with high rates of winter precipitation and streamflow. A better unders...

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Bibliographic Details
Published in:Water resources research 2005-11, Vol.41 (11), p.n/a
Main Author: Pool, D.R
Format: Article
Language:English
Subjects:
alluvial plains
climate
climate change
El Nino
El Niño
ephemeral streams
gravity
groundwater
groundwater recharge
hydrology
La Nina
Pacific Decadal Oscillation
precipitation
recharge
seasonal variation
semiarid zones
southeastern Arizona
stream flow
streamflow
temporal variation
water table
wells
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Summary:Significant variations in interannual and decadal recharge rates are likely in alluvial basins of the semiarid southwestern United States on the basis of decadal variations in climate and precipitation and correlation of El Nino with high rates of winter precipitation and streamflow. A better understanding of the magnitude of recharge variations in semiarid and arid regions would reduce water budget uncertainty. Variability of ephemeral channel recharge with climate in southeastern Arizona was investigated through analysis of hydrologic monitoring near three ephemeral streams in southeastern Arizona during the middle to late 1990s and by relating the results to long-term hydrologic and climatic trends. The analysis used precipitation, streamflow, water levels in wells, estimates of groundwater storage change from repeat gravity surveys, and two climatic indicators of El Nino-Southern Oscillation (ENSO), Southern Oscillation index, and Pacific Decadal Oscillation (PDO). Results indicate that variations in winter recharge are related to ENSO. El Nino conditions correspond with a greater probability of high rates of winter precipitation, streamflow, and recharge. La Nina conditions are almost exclusively associated with below-average recharge. Rates of recharge along Rillito Creek near Tucson during 1977-1998, a period of frequent El Nino conditions and positive PDO values, were 3 times recharge rates during 1941-1957, a period dominated by La Nina conditions and low PDO values. Quantification of recharge variability with decadal climate cycles should improve estimates of rates of aquifer drainage and replenishment in the region. Similar methods are applicable to other regions where thick unsaturated zones can accept significant periodic recharge.
ISSN:0043-1397
1944-7973
DOI:10.1029/2004WR003255