Assessment of mudflow risk in Uzbekistan using CMIP5 models

Abstract

Precipitation induced mudflows are a major and longstanding threat in Uzbekistan, impacting on many properties and livelihoods. In this paper, the role of large-scale atmospheric circulation in producing the conditions necessary to initiate mudflows in piedmont areas of Uzbekistan have been evaluated based on historical and scenario (Representative Concentration Pathways; RCP8.5) experiments along from 10 Coupled Model Intercomparison Project Phase 5 (CMIP5) models. Applying the well-established circulation weather type (CWT) technique, and CMIP5 models reveal that mudflow generating large-scale circulation flows will increase by up to 5% to the end of the century. Considering the historical simulations over 1979–2005 and following the projections of RCP8.5 emission scenario for the target period of 2071–2100, precipitation climatology has been evaluated using bias correction techniques. By this way, the synthetic rainfall series were linked to a central proxy – a mudflow generating weather types, such as cyclonic (C), westerly (W) and south-westerly (SW) in order to diagnose potential changes in mudflow occurrences given the changed CWT characteristics by running the statistical-empirical algorithm of antecedent daily rainfall model (ADRM) and statistical logistic regression (LRM). Results for the important weather types (C, W and SW) confirm that mudflow activity will increase in the selected region as precipitation values associated with the CWT C and W flows in CMIP5 projections are expected to increase in the warm season for the target period of 2071–2100.

The research focuses on piedmont areas of Uzbekistan as it has remained poorly understood due to limited climate research, particularly, in mountain areas. This is important in the face of climate change, which is likely to increase pressure upon high mountain areas that may need to investigate more frequent mudflow occurrences.