In the last 50 years, Bangladesh has experienced about 20 droughts, which affected nearly 56.9% of the cultivated area (Shahid & Behrawan 2008, MOE 2013, Banglapedia 2012; Alauddina and Sarker 2014). Drought affects about 47% of the total area of Bangladesh and 53% of the population (WARPO, 2005). In recent decades, Bangladesh has shown an increased drought frequency and intensity due to land use pattern changes (National Drought Mitigation Center 2008). In Bangladesh nearly 2.7 million hectares of land are vulnerable to annual drought events with a 10% probability that 41%–50% of the country facing drought conditions in a year and those results are forecast to increase in both geographic location and drought event intensity (IPCC, 2013). Besides, climate change is likely to shift the patterns of drought and possibly increase the frequency and intensity of drought events in the foreseeable future (IPCC, 2007). It is predicted that northwestern region of the country will be at higher risk of drought, as a result of a potential temperature increase of 2°C and nearly 10% decrease in rainfall by 2050 (Sarker et al. 2012). This will limit irrigation water availability and decrease the country’s food security (FAO …show more content…
2015), the effects of climate change on rice production (Mahmood, 1998; Mahmood et al. 2003; Basak et al. 2010). Earlier studies on the effects of climate change on rice yield primarily concentrated on the effects of higher temperature and higher carbon dioxide. They did not consider the combined effects of major climatic variables on rice production under climate change. However, the estimation of future irrigation water demand, previous studies ignored irrigation efficiency for the paddy rice in Bangladesh. The research on projected design water requirement for paddy rice under climate change, which is vital to the optimal design and operation of agricultural water resources, has not been undertaken in Bangladesh. Furthermore, the researches of climate change impacts on the design water requirement for the paddy rice in Bangladesh, which accounts for a maximum agricultural water usage, need to be introduced as a matter of concern. Nevertheless, a comprehensive overview of drought hazard under climate change conditions has not been conducted in Bangladesh. Crop simulation modeling (ORYZA2000) study is very limited in Bangladesh, which can simulate significantly rice yield under future climate change conditions. Taking into consideration the combined effects of irrigation water demand, drought hazard and climate change in an