Projection of Snow droughts under climate change scenarios in the Urmia Lake basin

Abstract

Mountains are a crucial water source, especially for the mountainous catchments in arid and semiarid regions. Climate Change is a severe hazard to mountain regions as global temperatures rise and snowpack melt. Snowmelt more effectively infiltrates the subsurface than rainfall. So, more rain, less snow, and early snow melting could significantly impact the groundwater levels in mountainous systems. In arid and semiarid mountainous regions, surface water resources are generally limited, and groundwater is critical for water supply due to local accessibility and high reliability during drought.

Urmia lake as a mountainous catchment has recently faced extreme droughts, and since snow is a significant part of the precipitation in this region, understanding the impact of climate change on snow changes and spatiotemporal projection of the snow-covered surface and the impact of these changes is vital.

For this purpose, in our study, snow drought index of SMRI (Snow-Melt Runoff Index) over ULB were projected using the statistically downscaled runoff output of CMIP6 global climate models under the SSPs scenarios of SSP1-2.6, SSP2-4.5, SSP5-8.5. To remove model bias over the catchment, historical runoff retrieved from CMIP6 models have been compared with ERA5 runoff Output. Based on our results, more frequent, longer lasting, and stronger drought events are projected in the catchment. The findings of this study could be further used for future water management in the catchment.

Keywords: Urmia Lake, Mountainous catchments, CMIP6, SSP scenarios, Snow drought projection