Study on Abstraction-Induced Recharge as an Adaptation Response to
Climate Variation for Shallow Aquifer in Bangladesh
Abstract
The significance of groundwater is likely to grow in the coming years
because of the need to mitigate the negative consequences of climate
change. Adaptive capacity becomes important as more frequent and intense
rainfall variability would quickly increase the possibility of large
reduction in the amount of sustainable surface water supplies while
aquifers will be affected considerably more slowly by anticipated
climate change. On the other hand, the combined effects of population
growth, irrigation demand, and climate change will continue to put
pressure on the groundwater resource in the future. Against this
backdrop, the abstraction-induced recharge (AI-R) concept should be
regarded as a future adaptation option for some likely sites in
Bangladesh to solve unmet water concerns. The inherent concept of the
AI-R is that the sub-surface storage can rapidly be filled during the
wet season and consume during the following dry season. Variable
thickness in subsurface geology, aquifer system and inconsistent
response to monsoon rainfall as well as flooding made Bangladesh
incompatible for large basin wide AI-R concept. As a result, this
research thoroughly observed the reaction to rainfall events, aquifer
condition, historical water level and other factors in two case studies
that have the potential to be used in AI-R operations. High-resolution
(hourly) in-situ recordings of co-located groundwater level and rainfall
data are compared to low-frequency (daily rainfall and weekly
groundwater level) observations in this study. Historical groundwater
conditions, as well as rapid groundwater response to both diffuse and
concentrated recharge, were found to be favorable to AI-R at one place
(Bhuapur, Ishwarganj). Nearby ponds which store huge monsoon water and
have low aquitard thickness can play potential role in induced recharge
in this place. On the other place (Bochaganj, Dinajpur), groundwater
response to rainfall is complicated and groundwater level shows
decreasing trend in recent years which can get worsen if AI-R concept is
implemented here. So, this type of fine resolution field inquiry is at
the very least need to be observed on possible AI-R piloting locations.
Multi-isotope studies are also advised for assessing long-term effects.