Abstract. General circulation models (GCMs) have been widely used to simulate current
and future climate at the global scale. However, the development of
frameworks to apply GCMs to assess potential climate change impacts on
regional hydrologic systems, ability to meet future water demand, and
compliance with water resource regulations is more recent. In this study
eight GCMs were bias-corrected and downscaled using the bias correction and
stochastic analog (BCSA) downscaling method and then used, together with
three ET0 methods and eight different water use scenarios, to drive an
integrated hydrologic model previously developed for the Tampa Bay region in
western central Florida. Variance-based sensitivity analysis showed that
changes in projected streamflow were very sensitive to GCM selection, but
relatively insensitive to ET0 method or water use scenario. Changes in
projections of groundwater level were sensitive to both GCM and water use
scenario, but relatively insensitive to ET0 method. Five of eight GCMs
projected a decrease in streamflow and groundwater availability in the future
regardless of water use scenario or ET method. For the business as usual
water use scenario all eight GCMs indicated that, even with active water
conservation programs, increases in public water demand projected for 2045
could not be met from ground and surface water supplies while achieving
current groundwater level and surface water flow regulations. With adoption
of 40 % wastewater reuse for public supply and active conservation four
of the eight GCMs indicate that 2045 public water demand could be met while
achieving current environmental regulations; however, drier climates would
require a switch from groundwater to surface water use. These results
indicate a high probability of a reduction in future freshwater supply in the
Tampa Bay region if environmental regulations intended to protect current
aquatic ecosystems do not adapt to the changing climate. Broad interpretation
of the results of this study may be limited by the fact that all future water
use scenarios assumed that increases in water demand would be the result of
intensification of water use on existing agricultural, industrial, and urban
lands. Future work should evaluate the impacts of a range of potential land
use change scenarios, with associated water use change projections, over a
larger number of GCMs.
Assessing the Utility of Rainfall Forecasts for Weekly Groundwater Level Forecast in Tampa Bay Region, Florida