Advanced Modeling in Civil Engineering
Projecting Meteorological and Hydrological Droughts Using LARS-WG and HEC-HMS in the West of Lake Urmia Watershed
Document Type : Original Article
Authors
1 PhD in Civil Engineering – Water Resources Engineering and Management, Islamic Azad University, Science and Research Branch, Tehran, Iran
2 Associate Professor, Department of Civil Engineering, Faculty of Engineering Technology, Maragheh University, Maragheh, Iran.
3 Associate Professor, Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran.
Abstract
Drought in semi-arid regions has widespread impacts on water resources, ecosystems, and communities. This study focuses on projecting meteorological and hydrological drought in the western part of the Lake Urmia basin (from Zolachay to Zab) using the LARS-WG and HEC-HMS models under the SSP5-8.5 scenario. The SPI and SPEI indices were calculated for meteorological drought, and the SSI and SDI indices for hydrological drought. Daily precipitation and discharge data from 20 stations were analyzed for the baseline period (1983–2022), the near future (2022–2061), and the far future (2061–2100). The results show an increase in the frequency and severity of hydrological droughts from the 2000s onward. The discrepancy between meteorological and hydrological indices highlights the role of anthropogenic factors, such as excessive water withdrawal. Climate projecting using LARS-WG indicates a temperature increase of 1.6 to 2.4 °C and a mean precipitation decrease of 2.9 to 3.3%. Results from the HEC-HMS model also show that surface runoff will decrease by 8.1% in the near future and by 11.2% in the far future compared to the baseline period. In future periods, the anomaly of drought severity for the hydrological indices (SSI and SDI) will be highest during the warm months (June to September), increasing by up to 1.6 units, while for the meteorological indices (SPI and SPEI), intensification is observed in autumn. Furthermore, drought duration in the far future will increase to 35 months. These findings emphasize the need for sustainable water resource policies and provide a basis for drought risk management in the basin.
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