Comparative Performance of the Drainage Area Ratio method and the HEC-HMS model in modeling of ungauged catchments. A Case study of River Nyamwamba.
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Date
2023-07-14Author
Nakayiwa, Jovia
Muhinda, Peter Collins
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Show full item recordAbstract
Globally, surface water sources play a crucial role in providing drinking water, making it
essential to understand their availability and ensure their long-term sustainability. However,
studies investigating surface water resources in data-poor regions are limited, leading to
challenges in their effective management and protection. This research study focuses on the
comparative performance of two hydrological modeling methods, the Drainage Area Ratio
(DAR) method and the Hydrologic Engineering Center's Hydrologic Modeling System
(HEC-HMS), in modeling ungauged catchments. Given the scarcity of data in Kasese, this
study addresses the critical need for assessing the suitability and accuracy of hydrological
modeling techniques for ungauged catchments like the Nyamwamba River. Data from
various sources, including the Department of Water Resources Management (DWRM) and
Uganda National Meteorological Authority (UNMA) were collected to facilitate the analysis.
The methodology involved applying the DAR method to estimate discharges in the
Nyamwamba River by transposing available data from the gauged Mubuku River catchment.
In parallel, an HEC-HMS model was developed for the Mubuku River, calibrated, and
validated using the available data. The calibrated model parameters, such as curve numbers
and Muskingum X and K values, were then transferred to a newly created basin model for the
Nyamwamba River. Historical data for Nyamwamba spanning 20 years (2000-2020) were
used to simulate peak discharges in the newly created basin. An HEC-HMS model was also
constructed for the Nyamwamba River using a configuration comprising six sub-basins for
comparative analysis. Calibration, validation, and simulation were performed using the
available data. The performance of the DAR method and the HEC-HMS (Nyamwamba, 3
sub-basins) was evaluated using statistical metrics, including Nash-Sutcliffe Efficiency
(NSE) and Root Mean Square Error (RMSE). The results showed that the DAR method
yielded an NSE of -0.346 and an RMSE of 4.39, while the HEC-HMS (Nyamwamba, 3 sub-basins) achieved an NSE of 0.563 and an RMSE of 0.7. Furthermore, when compared to the
HEC-HMS model with six sub-basins (NSE = 0.579, RMSE = 0.6), the HEC-HMS
(Nyamwamba, 3 sub-basins) demonstrated comparable performance. This research study
provides valuable insights into the application and accuracy of hydrological modeling
techniques within ungauged catchments, specifically in the context of the Nyamwamba River
in Kasese District, Western Uganda. The findings contribute to addressing the knowledge gap in data-poor regions, facilitating informed decision-making, and sustainable water resource
management practices.