Model construction, evaluation, and prediction of flood under climate change scenarios using the HEC-HMS mathematical model (A case study: Nazlochai basin, Urmia)

Articles in Press

Document Type : Research Paper

Authors

1 MS in Water Resources Engineering of Water Engineering Department, Urmia University

2 Water Engineering Department and Urmia Lake Research Institute, PhD in Hydrology, Urmia University,

3 Phd in water science and engineering - water resources, West Azarbaijan Regional Water Joint Stock Company

10.22059/jwim.2024.378868.1172

Abstract

In integrated watershed management, calculating peak flow for full identification of flood effects and reducing damage is essential. Activities related to estimating runoff volume and flood peak can be easily simplified by adopting a modeling concept and understanding rainfall configuration and the main factors creating runoff. Building a basin model requires the model to respond to low flows and high flows (high return period), which for both, the model must meet the needs. In this study, due to the lack of a data logger or short term recording rainfall gauge(tipping rain gauge) in the study basin; based on six corresponding rainfall events related to nearest UrmiaCamp station for simulation and validation of flood data were used. Thus, four rainfall events for simulation and calibration and two rainfall events for validation were used. Also, calibration was performed for curve number, lag time, and initial losses parameters. After calibrating the model, to ensure the accuracy of the simulated model and calibrated values, the model was validated with new data. The results showed that the simulated hydrograph has an acceptable match with the observed hydrograph. The evaluation indices R2 and RSME in this case are 0.90 and 0.67 at Abajalu station and 0.86 and 0.34 at Tepik station, respectively. To build a model for large floods, rainfall with different return periods of the basin entered the model and the peak flow of each return period at the final station of lower Abajalu in Nazlu Chay river was simulated. The results of comparing the estimated flood, observed river flood values (Q1) and calculated with the HEC-HMS model (Q2) in the 25-year return period were 196.1 and 198.9 cubic meters per second, respectively, and in the 50-year return period were 235.2 and 255.1 cubic meters per second, respectively, and the error in the lower return periods up to 10,000 years was between 3 to 7 percent, which indicates a high agreement of the simulated values with the observed ones.According to the results obtained from the comparison of historical river floods with future floods under climate change scenarios with different return periods with the help of the LARS-WG model, it indicates a large increase in the amount of these floods in the coming years.

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Main Subjects

Water and Irrigation Management

Articles in Press, Accepted Manuscript
Available Online from 03 November 2024

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