Thursday, October 25, 2012: 3:45 p.m.
The extreme drought that occurred on the Southern High Plains in 2011 demonstrated that the ground and surface resources in the Canadian River watershed in Texas and New Mexico were unable to supply sufficient water for the region’s water needs. Variations in precipitation parameters (annual rainfall, rainfall volume per event, etc.) within the watershed between 1970 and 2010 and changes in land use from 1981 to 2006 were examined to provide insights as to the origins of the water resources shortfall in 2011 and how the region can adapt to handle future droughts. Analyses of annual rainfall from 36 weather stations located in or adjacent to the watershed indicated that mean annual rainfall from 2001-2010 was significantly less than that from 1971-2000. However, there was no difference in the percentage of rain events that produced more than 12.5 mm of precipitation over time. Simulations using ArcSWAT support the hypothesis that the observed decreases in annual rainfall were sufficient to account for the observed decline in storage from Lake Meredith from 1990 to 2009. Changes in land use were investigated by analyses of the National Land Cover Datasets from 1980 to 2006. In general, both cropland and forested area within the watershed has declined between 1980 and 2006 whereas area as rangeland has increased. However, acres of cropland on the areas of the watershed above the Ogallala Aquifer have not declined since 1980. Groundwater extractions from the Ogallala Aquifer have been relatively constant over the time period. These results indicate that continued pressure will be placed on the region’s ground and surface water resources, especially in times of less than mean rainfall.
