Evaluating technological resilience of small drinking water systems under the projected changes of climate Mohammad Adnan Rajib, Md. Mujibur Rahman and Edward A. McBean ABSTRACT With prevailing changes in climate and increasing population, small drinking water systems in the climate-vulnerable parts of the world have already exhibited and left traces of prominent unpredictability of water availability, in terms of both water quantity and water quality. Dimensions of climate change, such as large variability in precipitation pattern, rise in temperature and associated increase in evaporation rates, as well as their consequences, are surely going to affect the unsophisticated, small drinking water systems which are serving mass populations in South Asia and many other parts of the world. This research paper aims to analyze the possible extents of vulnerability of some selected small drinking water systems currently being operated in the coastal areas of Bangladesh as a result of the predicted changes in climatic parameters such as temperature, precipitation and evaporation along with sea level rise and extreme events such as cyclones. However, to examine possible future climate change scenarios, four Global Climate Models have been applied in developing projections of different climatic parameters for Bangladesh. Based on the projections of climate models and associated key vulnerabilities being assessed, this paper features the evaluation of potential technological resilience of specific small drinking water systems from the Bangladesh perspective. Mohammad Adnan Rajib (corresponding author) Md. Mujibur Rahman Department of Civil Engineering, Bangladesh University of Engineering and Technology (BUET), Dhaka-1000, Bangladesh E-mail: adnanrajib@ce.buet.ac.bd Edward A. McBean University of Guelph, Ontario, Canada Key words | Bangladesh, climate, precipitation, temperature, water INTRODUCTION According to the assessment reports of the Intergovern- mental Panel on Climate Change (IPCC), South Asia is one of the most vulnerable regions of the world to climate change impacts (McCarthy et al. ). The international community also recognizes that Bangladesh, in the South- Asian domain, ranks high on the list of the most climate-vulnerable countries on Earth. Bangladesh’s high susceptibility to climate change is due to a number of hydro-geological and socio-economic factors that include: (i) its geographical location in South Asia; (ii) its flat del- taic topography with very low elevation; (iii) extreme climate variability that is governed by monsoon, resulting in uneven water distribution over space and time; (iv) its high population density and poverty incidence; and (v) the dependence of the majority of the population on crop agriculture which is highly influenced by climate variability and change. Concomitantly, enormous chal- lenges associated with water supply in Bangladesh are already present. Bangladesh possesses: (i) high levels of arsenic in the ground water over a significant part of the country; (ii) significant salinity in ground water of the coastal region; (iii) high microbial contamination levels in the surface water and so on. Future challenges will be even more severe as a result of high population growth. Equally important as the challenges identified above, is the widespread acceptance of ongoing climate change. Hence, Bangladesh is a country of extensive climate vari- ation and vulnerability. It is therefore of utmost importance to assess its potential for adaptation to climate change, particularly focusing on drinking water resources. The dimensions of climate change for Bangladesh include more intensive precipitation events, increase in dry 110 © IWA Publishing 2012 Journal of Water and Climate Change | 03.2 | 2012 doi: 10.2166/wcc.2012.019