Abstract:
Water crisis is prevailing as a result of the ever increasing population across the globe with
advances in society and economy which significantly affects the ecosystems, environment and
economy. Water resources are limited and needs to be efficiently managed by estimating
streamflow. The Soil and Water Assessment Tool (SWAT) model is a physically based,
continuous, computationally efficient, and distributed model considering similar slope,
landuse and soil conditions as its smallest unit in the basin. It has been effectively applied at a
wide range of watershed scales under different circumstances around the globe to estimate
streamflow. Therefore, a process-based distributed model has to be defined and evaluated to
estimate the streamflow in order to meet water demands for efficient watershed
management.The objective is to evaluate the potential of process based distributed SWAT
model for the estimation of streamflow in Attanagalu Oya Basin for sustainable water resource
management.
In this study, the SWAT model has been applied over Dunamale watershed in Attanagalu Oya
basin for a period of 10 years from 2008 to 2018 on a daily time scale basis. SWAT-CUP was
used as calibration and validation tool with SUFI-2 as the optimization algorithm. The model
was semi auto calibrated from 2008 to 2012 and validated from 2013 to 2018. Nine parameters
were selected from literature review for calibration and validation. The calibrated and
validated results are plotted in flow duration curve. A total of 34 iterations were carried out
with each iteration having a total simulation of 200 numbers.
The process based distributed SWAT model can be developed for Attanagalu Oya Basin in
Dunamale watershed to estimate streamflow with R2 value of 0.77 during calibration and 0.58
during validation with hydrograph matching pattern. The model gives a better matching for
medium flow when compared to high flow and low flow and hence it can be used for
sustainable water resource management. Daily model results when accumulated into monthly
time frame has higher accuracy in the outcome when compared to daily and can be used in
efficient decision making for water planning and management. SWAT model has more
parameters and is complex when applied but the results are generated in a detailed manner
with HRU as its basic unit and can be used for a better understanding of the watershed.