Variability of the steering factors for extreme hydrometeorological events in Central Asia and its relation to the formation of mudflows in the piedmont areas of Uzbekistan

Mamadjanova, Gavkhar ORCID: 0000-0002-0678-5473 (2019). Variability of the steering factors for extreme hydrometeorological events in Central Asia and its relation to the formation of mudflows in the piedmont areas of Uzbekistan. University of Birmingham. Ph.D.

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Abstract

Mudflows are formed almost every year in Uzbekistan and neighbouring countries which present a major threat to human life and settlements and can significantly damage infrastructure. The central goal of this thesis is to understand mudflow risks that could potentially arise due to the hydrometeorological factors, such as precipitation patterns and precipitation driving mechanisms in synoptic and large scale over Uzbekistan. Empirically developed local synoptic classification (SWT, synoptic weather type) results show that the advection of westerly airflow initiates mudflows more frequently compared to other SWTs. Objective approach (CWT, circulation weather type) outputs show that cyclonic (C), westerly (W) and south-westerly (SW) are the main mudflow generating weather types in Uzbekistan. Statistical modelling of rainfall threshold triggering mudflows also proves that rainfall associated with the C, W and SW weather types group has sufficient magnitude to induce mudflow occurrences.

Risks of mudflows are discussed to increase in the future due to an increase in global population and enhanced anthropogenic activities in previously sparsely populated regions prone to hazardous mudflow events, specifically in mountainous areas. In addition to this, any future potential effect of anthropogenic climate change e.g. increased precipitation intensity and/or changes associated with atmospheric circulation characteristics will increase the potential of disastrous mudflows by impacting on respective triggering mechanisms. Applying well established weather typing and state-of-the-art reveal that mudflow generating large-scale circulation flows will increase by up to 5% to the end of the century. Applying the statistical-empirical transfer function for the important weather types (C, W and SW) inducing mudflows show that mudflow activity will increase in the selected region as precipitation values associated with the CWT C, W and SW flows in Coupled Model Inter-Comparison Project Phase 5 (CMIP5) projection are expected to increase for the target period of 2071-2100.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):