Climate change trends as measured by the Thornthwaite Moisture Index maps for Ghana

Civil Eng. Dept., KNUST, Kumasi, Ghana

^* Corresponding author: nakdzikunu-bansah@knust.edu.gh

Abstract

In geotechnical engineering, the Thornthwaite Moisture Index (TMI) has become an important climate parameter for investigating moisture conditions in unsaturated soils. It is used to quantify climatic influences on civil infrastructure in unsaturated soil profiles. TMI is based on the moisture balance at a specified location, considering precipitation, evaporation, water storage, water deficit, and runoff. Despite the critical effect of climate change on civil infrastructure, Ghana, like many other developing countries, does not have a reliable TMI map for modelling various future climate change scenarios. The purpose of this investigation is to develop reliable TMI maps of Ghana as a first step in understanding the effect of climate change on civil infrastructure in Ghana. This study utilised weather data from 53 stations in Ghana and applied the Witczak and co-workers’ [9] method to calculate TMI values. Bar charts and heat maps were plotted as average values for 1960 –1988, 1988–2016, and 2017–2050 for three different socio- economic shared path scenarios (SSPs) to capture snapshots of the changing trends over the past 56 years up to 2050. This historical TMI trend and the predicted trends based on climate models for three different scenarios to depict future TMI values are discussed.