| Title: | Comparative analyses of hydrological responses of two adjacent watersheds to climate variability and change using the SWAT model |
| Authors: | Lee, S., I-Y. Yeo, A.M. Sadeghi, G.W. McCarty, W.D. Hively, M.W. Lang and A. Sharifi |
| Year: | 2018 |
| Journal: | Hydrology and Earth System Sciences |
| Volume (Issue): | 22 |
| Pages: | 698-708 |
| Article ID: | |
| DOI: | 10.5194/hess-22-689-2018 |
| URL (non-DOI journals): | |
| Model: | SWAT |
| Broad Application Category: | hydrologic and pollutant |
| Primary Application Category: | climate change |
| Secondary Application Category: | nitrogen cycling/loss and transport |
| Watershed Description: | 220.7 km^2 Tuckahoe Creek and 290.1 km^2 Greensboro River, tributaries of the Choptank River that drain portions of eastern Maryland and/or western Delaware, U.S. |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | Water quality problems in the Chesapeake Bay
Watershed (CBW) are expected to be exacerbated by climate
variability and change. However, climate impacts on agricultural
lands and resultant nutrient loads into surface water
resources are largely unknown. This study evaluated the
impacts of climate variability and change on two adjacent
watersheds in the Coastal Plain of the CBW, using the Soil
andWater Assessment Tool (SWAT) model.We prepared six
climate sensitivity scenarios to assess the individual impacts
of variations in CO2 concentration (590 and 850 ppm), precipitation
increase (11 and 21 %), and temperature increase
(2.9 and 5.0 C), based on regional general circulation model
(GCM) projections. Further, we considered the ensemble of
five GCM projections (2085–2098) under the Representative
Concentration Pathway (RCP) 8.5 scenario to evaluate simultaneous
changes in CO2, precipitation, and temperature. Using
SWAT model simulations from 2001 to 2014 as a baseline
scenario, predicted hydrologic outputs (water and nitrate
budgets) and crop growth were analyzed. Compared to the
baseline scenario, a precipitation increase of 21% and elevated
CO2 concentration of 850 ppm significantly increased
streamflow and nitrate loads by 50 and 52 %, respectively,
while a temperature increase of 5.0 C reduced streamflow
and nitrate loads by 12 and 13 %, respectively. Crop biomass
increased with elevated CO2 concentrations due to enhanced
radiation- and water-use efficiency, while it decreased with
precipitation and temperature increases. Over the GCM ensemble
mean, annual streamflow and nitrate loads showed an
increase of ~70%relative to the baseline scenario, due to elevated
CO2 concentrations and precipitation increase. Different
hydrological responses to climate change were observed
from the two watersheds, due to contrasting land use and soil
characteristics. The watershed with a larger percent of croplands
demonstrated a greater increased rate of 5.2 kgNha-1
in nitrate yield relative to the watershed with a lower percent
of croplands as a result of increased export of nitrate
derived from fertilizer. The watershed dominated by poorly
drained soils showed increased nitrate removal due do enhanced
denitrification compared to the watershed dominated
by well-drained soils. Our findings suggest that increased implementation
of conservation practices would be necessary
for this region to mitigate increased nitrate loads associated
with predicted changes in future climate. |
| Language: | English |
| Keywords: | |