| dc.description.abstract | Climate and land use/cover (LULC) change affects groundwater recharge through alteration of
the hydrological cycles especially in major agricultural and rapid population growth areas.
However, studies on the combined effect of climate and LULC changes on groundwater recharge
are scanty. Therefore, this study applied SWAT–MODFLOW to assess the combined impact of
changing climate and LULC on groundwater recharge in Sezibwa sub-catchment, Uganda. The
model was calibrated using River Sezibwa records and average static groundwater levels. Climate
projections for the MIROC5 global circulation model (GCM) under RCP 4.5 and RCP 8.5 were
downscaled for the period 2020–2070 and used to model impacts of future climate changes in the
catchment. The Cellular Automata-Markov model was used to project LULC changes for the
periods 2020-2040 and 2040-2070. Relative to the baseline scenario (1999 – 2019), The results
showed that in the study period (2020 – 2070), minimum (18.3 °C) and maximum (30.29 °C)
temperatures are projected to increase between 0.54 °C - 1.02°C and 0.56°C-1.7°C for RCP4.5.
While for RCP 8.5 temperatures increased between 0.47°C- 1.07°C and 0.55°C-1.75°C for both
minimum and maximum temperatures. The average daily precipitation relatively remains
unchanged for the 2020 – 2039 under both RCP 4.5 and RCP 8.5 scenarios, however, it decreases
by –1.22% for the time period 2040 – 2070 in comparison with baseline average daily
precipitation of 3.5 mm/day. The dominant LULC was small scale farming in 2019 (1446.5 km2).
LULC projections from 2019 to 2070 showed that built-up areas are expected to increase by
48.7%. Woodlands on the other hand will reduce by 63.3%. The calibrated SWAT-MODFLOW
model showed that under the baseline scenario, the average groundwater recharge was 198
mm/year. Considering only climate changes, the average annual ground water recharge is
expected to reduce between 9.53- 11.5% for RCP 4.5 while for RCP 8.5 the decrease will be
between 6-9.68% relative to baseline scenario of the study period 2020-2070. However, if land
use/cover change is considered only, the recharge decrease for study period will vary between
0.05 – 1.06%. When the integrated climate and LULC changes are considered, average annual
ground water recharge is expected to decrease recharge between 4.05%- 18.17% under RCP 4.5,
while for RCP 8.5, recharge is expected to reduce between 2.16% - 17.70% for the study period.
Climate and LULC changes individually impacts ground water recharge. However, the effects
are more pronounced when both drivers are combined. Therefore, authorities responsible for
water resource management should consider combined effects of climate and LULC changes in
planning and management of groundwater systems. | en_US |
