Study on feasibility of rainwater harvesting using MAR model in drought-prone Barind Tract, Bangladesh

Bangladesh heavily relies on groundwater resource for all major uses and ranks sixth in the global league of large groundwater extracting countries. Its northwest part—the drought-prone Barind Tract faces challenges in rainfall scarcity and drought; constrain for runoff water conservation due to improper management; low infiltration capacity of thick top surface clay soil layer (Barind clay) to recharge aquifer insufficiently; loss of major portion of runoff water runs toward canals (Kharies), surrounding rivers, etc., immediately after rainfall; less potentiality of groundwater resource development results its depletion due to over-exploitation for domestic and agriculture sectors and eventually discharged into surrounding canals, rivers, etc., in both the dry and monsoon seasons. At the same time, unsustainable water management practice consequences are a rapid declination of groundwater level since the last few decades, the system leads to unbalance condition. Unfortunately, no such study for sustainable water source management has yet been conducted for the area. In this context, rainwater harvesting through artificial recharge of groundwater using managed aquifer recharge (MAR) has been considered as a viable solution to revert the ongoing depletion of this resource and to restore the water balance scenario as a terrific and challenging task. Here, the potentiality of MAR has been considered as an integrated approach of remote sensing and geographical information system using multi-criteria decision-making technique as time-consuming and cost-effective efforts. The potentiality of MAR application covers an area of 448 km2 (20%) as ‘highly suitable’; that of 1456 km2 (66%) as ‘moderately suitable’; and that of 312 km2 (14%) as ‘unsuitable.’ Here, 35% of rainfall is lost as runoff and the remaining 14% as soil moisture. Again, groundwater resource used for irrigation equals 24% of the annual rainfall, whereas that of only 8.5% infiltrates to recharge aquifer naturally, and the rest 68% of runoff water has a scope to injection artificially to revert balanced condition. Using MAR, the cost of recharge per cubic meter of water is about US$ 0.18. Although this is little bit expensive, it can be a valuable gift for economically marginalized and unprivileged Barind communities facing hardship for drinking and agricultural water. Finally, the present study provides a guideline to water resource managers and decision makers to ascertain availability of water resource as lauded in the Bangladesh Water Act (BWA) (2013).