Abstract:
Land use land cover change (LULC) is a very significant issue in terms of global dynamics and
their responses to hydrological features and soil and water management of a watershed because it
has a great effect on stream flow. This study aims to evaluate the land use land cover change
effect on stream flow using the QSWAT model. The land use land cover data are obtained from
USGS earth explore and developed land use land cover maps of 2000, 2010, and 2021 by using
Semi-automatic classification plugin software through the maximum likelihood of supervised
classification techniques. Prediction of future land use land covers LULC map of 2035 and 2050
was prepared using the Cellular-Markov model. To validate the accuracy of the simulated map
with the actual map Kappa index agreement was used. The physical-based semi-distributed
hydrological QSWAT model was used to simulate LULC effects on the hydrological response of
Dirma watershed. The performance of the SWAT model was evaluated through sensitivity
analysis, calibration and validation by using SWAT-CUP software. The calibration result shows
good agreement between monthly observed and monthly simulated streamflow having values of
coefficient of determination ( ) of 0.86, 0.9, 0.85, 0.88, and 0.88, Nash-Sutcliffe coefficient
(NSE) 0.83, 0.84, 0.89, 0.79, and 0.77 for 2000, 2010, 2021, 2035, and 2050 LULC maps for
calibration respectively and having values of coefficient of determination ( ) of 0.87, 0.88,
0.91, 0.89, and 0.88, Nash-Sutcliffe coefficient (NSE) of 0.81, 0.79, 0.83, 0.81, and 0.78 for
2000, 2010, 2021, 2035, and 2050 LULC maps for validation respectively. The result of this
study indicates that the mean seasonal stream flow increased from 44.9 ⁄ to 63.3 ⁄
and 42.3 ⁄ to 63 ⁄ for the wet season and decreased from 2.6 ⁄ to 0.9
⁄ and 1.7 ⁄ to 1 ⁄ in dry season stream flow for both calibration and
validation periods respectively. The mean annual surface runoff increase from 93.55mm to
133.25mm while mean annual groundwater flow decrease from 68.79mm to 39.42mm
throughout the whole periods. From the overall results of the study, it is concluded that due to
the expansion of built up area, bare lands, and dominant coverage of agricultural land have an
effect on increasing stream flow in the wet season and surface runoff whereas decreasing stream
flow in the dry season and groundwater flow within the watershed during the study period.
Key Words: QSWAT, Cellular-Markov, Land use land cover, Semi-Automatic Classification
plugin, streamflow