Climate Change and It's Impact on Ground Water Resources in Northwest Bangladesh

Abstract

Northwest region of Bangladesh is one of the most water stressed region of the country. All the rivers and cannels of the area dry up during the dry season and make the people completely dependent on groundwater. Cultivation of dry season rice which is the lifeline of the livelihood in the most part of the region completely relies of groundwater supply. Scarcity of groundwater for irrigation during the recent years has hampered the agricultural production in the area. Prolonged absence of groundwater within the operating range of shallow tube-wells during the dry season is a growing concern in the area. It is anticipated that climate change will aggravate the situation in near future. A study has been carried out in the present research to identify the causes of groundwater scarcity, estimate the groundwater demand, project the future climate, and to assess the impacts of climate change on groundwater scarcity in the northwest districts of Bangladesh. Long-term groundwater hydrographs are analyzed and correlated with standardized precipitation index to identify the probable causes of groundwater scarcity in the region. Climate models are run with IPCC B2 SRES scenario to project the future change of climate in the region. The projected climatic parameters are then used to estimate the change in irrigation demand in the context of climate change. Finally, the impacts of changing irrigation demand on groundwater level are assessed. The study revealed that recurrent droughts, rapid expansion of groundwater based irrigation and cross-boundary anthropogenic interventions are the main causes of groundwater scarcity in the area. The climate models project an average increase of temperature and rainfall in the region. This will cause an increase of water requirement for land preparation, evapotranspiration and effective precipitation during irrigation period. However, there will be no appreciable change in overall irrigation water requirement as the irrigation period will be substantially shortened by the increased temperature. The study revealed that the climate change will cause an increase in daily use of water for irrigation in the end of this century. As groundwater is the main source of irrigation, higher abstraction rate of groundwater for irrigation will cause a negative impact on groundwater level which in turn will negatively affect the prevailing situation of groundwater scarcity in the area during the dry season.