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A COMPARISON OF THE SALINITY REGIME ALONG THE TEXAS COAST WITH TERRESTRIAL VEGETATION GREENNESS AND WATER USE IN THE GALVESTON BAY WATERSHED USING REMOTING SENSING
Citation:
Keith, D J. AND H A. Walker. A COMPARISON OF THE SALINITY REGIME ALONG THE TEXAS COAST WITH TERRESTRIAL VEGETATION GREENNESS AND WATER USE IN THE GALVESTON BAY WATERSHED USING REMOTING SENSING. Presented at Transactions Of The American Geophysical Society Spring Meeting, Boston MA, June 1-4, 1999.
Description:
Variability in vegetation greenness was determined for the Galveston Bay watershed using biweekly Normalized Difference Vegetation Index (NDVI) data derived from the Advanced Very High Resolution Radiometer (A VHRR) flown on NOAA satellites. NDVI variability was compared with regional climatological data for coastal Texas, gaged flows and ungaged runoff within the Galveston Bay watershed, and salinity changes in the Galveston Bay estuary during 1985 thru 1991.
Statistical comparisons indicate that a weak correlation (r2 = 0.33) exists between salinity variation in Galveston Bay and gaged freshwater inflow from the Trinity River, which supplies 83% of the freshwater to the estuary. However, a stronger relationship
(r2 = 0.52) exists between Galveston Bay salinity and NDVI with variation in vegetation greenness preceding salinity change by several months. Results also indicate that variability in ungaged runoff from freshwater diverted for agricultural and municipal (i.e., diverted flow) uses shows a strong relationship with evaporation rates (r2 = 0.54). Diverted flow also covaries with variability in the satellite-derived NDVI, and Galveston Bay salinity tim.e series.
The results suggest that channelized flows and non-channelized runoff may be of equal importance in characterizing freshwater inflow to estuaries and in modifying the coastal salinity regime. In addition, a satellite-derived NDVI may be useful in predicting change in the salinity of estuarine waters in response to climate variability and water use. These relationships, derived for coastal Texas, may have utility in other arid coastal areas.