Projecting surface water in the Southeastern U.S. under three climate
and development scenarios
Abstract
Water resources are important to both natural ecosystems and human
societies. Surface water is the most readily accessible water resource
and provides an array of ecosystem services. Water stress, the ratio of
water demand to supply, is a global concern as water resources are
stressed by changes in climate, land cover, and population size.
Understanding current and projected spatial and temporal factors of
surface water dynamics is key to better managing our water resources and
limiting the effects of water stress. However, few studies estimating
changes in surface water account for climate and human drivers
synergistically. Therefore, we compared three sets of statistical models
using climate only, anthropogenic only, and the combination of climate
and anthropogenic explanatory variables to assess the influence of each
set of drivers on estimating surface water. We then used the most
accurate model, the combination of climate and anthropogenic drivers
(-0.17% average watershed mean percent error), with climate and land
use projection data to project surface water areas under different
climate and land use scenarios. For climate drivers, we used
precipitation and temperature data from ensembles of the
Inter-Comparison of Coupled Models-Phase 5 (CMIP5) Global Climate Models
under three Representative Concentration Pathways (RCPs)–RCP4.5,
RCP6.0, and RCP8.5. For anthropogenic drivers, we used three land
use/land cover change projections from the U.S. Geological Survey’s
FOR-SCE model corresponding to Intergovernmental Panel on Climate Change
(IPCC) Special Report on Emissions Scenarios (SRES) that have RCP
counterparts. Our models suggest an uneven distribution of projected
change in surface water area, where watersheds with more natural land
cover will experience less change (positive or negative) and watersheds
with less natural land cover will experience more change. We also expect
to find that, under the business-as-usual scenario, watersheds with
greater urbanization will see a reduction in surface water area by 2100.
These results highlight our ability to mitigate water stress with land
use management and also emphasize the need to account for both climate
and anthropogenic drivers when estimating and predicting surface water
area.