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Analysis of trends in selected streamflow statistics for the Concho River Basin, Texas, 1916-2009

Scientific Investigations Report 2012-5193

Prepared in cooperation with the Texas Water Development Board
By:
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Abstract

The Concho River Basin is part of the upper Colorado River Basin in west-central Texas. Monotonic trends in streamflow statistics during various time intervals from 1916-2009 were analyzed to determine whether substantial changes in selected streamflow statistics have occurred within the Concho River Basin. Two types of U.S. Geological Survey streamflow data comprise the foundational data for this report: (1) daily mean discharge (daily discharge) and (2) annual instantaneous peak discharge. Trend directions are reported for the following streamflow statistics: (1) annual mean daily discharge, (2) annual 1-day minimum discharge, (3) annual 7-day minimum discharge, (4) annual maximum daily discharge, and (5) annual instantaneous peak discharge. The South Concho, Middle Concho, and North Concho Rivers drain the upper part of the Concho River Basin. The North and South Concho Rivers converge in San Angelo, Tex., to form the Concho River. The Concho River flows east from San Angelo to its confluence with the Colorado River east of Paint Rock, Tex. The trend analyses principally focused on application of the nonparametric Kendall's Tau statistical test to detect monotonic trends (dependency) in streamflow with time; in other words, Kendall's Tau is a test of temporal independence of streamflow with time. A positive Tau indicates an upward monotonic streamflow trend; conversely, a negative Tau indicates a downward monotonic streamflow trend. Hence, the trend analysis reported here is limited to direction and not magnitude of streamflow change. Six U.S. Geological Survey streamflow-gaging stations were selected for analysis. Streamflow-gaging station 08128000 South Concho River at Christoval has downward trends for annual maximum daily discharge and annual instantaneous peak discharge for the combined period 1931-95, 2002-9. Streamflow-gaging station 08128400 Middle Concho River above Tankersley has downward trends for annual maximum daily discharge and annual instantaneous peak discharge for the combined period 1962-95, 2002-9. Streamflow-gaging station 08128500 Middle Concho River near Tankersley has no significant trends in the streamflow statistics considered for the period 1931-60. Streamflow-gaging station 08134000 North Concho River near Carlsbad has downward trends for annual mean daily discharge, annual 7-day minimum daily discharge, annual maximum daily discharge, and annual instantaneous peak discharge for the period 1925-2009. Streamflow-gaging stations 08136000 Concho River at San Angelo and 08136500 Concho River at Paint Rock have downward trends for 1916-2009 for all streamflow statistics calculated, but streamflow-gaging station 08136000 Concho River at San Angelo has an upward trend for annual maximum daily discharge during 1964-2009. The downward trends detected during 1916-2009 for the Concho River at San Angelo are not unexpected because of three reservoirs impounding and profoundly regulating streamflow.

Geospatial Extents

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Analysis of trends in selected streamflow statistics for the Concho River Basin, Texas, 1916-2009
Series title:
Scientific Investigations Report
Series number:
2012-5193
Year Published:
2012
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
Texas Water Science Center
Description:
iv, 15 p.
Country:
United States
State:
Texas
County:
Coke;Concho;Crockett;Glasscock;Howard;Irion;Midland;Reagan;Runnels;Schleicher;Sterling;Tom Green;Upton
City:
San Angelo
Other Geospatial:
Concho River Basin
Datum:
North American Datum of 1983
Projection:
Albers Equal Area
Scale:
2000000