Rainwater Harvesting to Alleviate Water Scarcity in Drought-prone Barind Tract, NW,Bangladesh: A Case Study.

Abstract

This paper aims to evaluate the potentiality for rainwater harvesting (RWH)through dug well system in agro-based drought prone Barind Tract, NW Bangladesh - the granary. Meteorologically, the climatic condition leads to vulnerability of drought resulting hydrogeological as well as agricultural drought where annual average rainfall is about 1300mm(national average of 2550 mm), but due to the agricultural practices huge amount of groundwater is required for irrigation.The annual average temperature 25.930C with high average humidity values of 75.29 %.The geophysical survey shows that the top most clay layer of thickness (17m) of infiltration capacity is a great barrier for natural groundwater recharge and below top most clay layer sandy layer of 31m thickness is considered as a potential aquifer.Groundwater depletion for the period of 1991-2013 is nearly 10 m with an average rate of 0.40 m/per year but this rate has abruptly increased after 2004. The aquifer for large scale groundwater development exists at greater depth, but not fully recharged even during rainy season and the groundwater table (GWT) does not reach at original position after 2004. So groundwater resource is under stress and is becoming worse due to simultaneous increasing irrigation demand and extension of command areas.Moreover, temporal variability of precipitation along with the declining trend of GWT due to huge withdrawal of groundwater for irrigation is the main governing factor for burning need for effective utilization of the RWH systems as adaptation measure is expected to altered the future under the effects of climate change as sustainable water management measures in water scarce area like the Barind Tract.In the present study, a rainwater harvesting system is operated in the Kakonhat Pourashava, Godagari Upazila through construction of dug well structure where rainwater is harvested from the roofs of Pourashava Auditorium and the Administration building with a catchment area of 692 m2. Here the amount of water which consumed by each house hold purpose per day is 224 liters.The groundwater recharge with rainwater harvesting is operating through dug well of 1 m diameter with a depth of 23 m and the recharge box structure is filled with sands of different texture acts as rainwater filtering is constructed as 2.5 m width, 2.5m length and 3.5m depth.Considering the runoff coefficient of 0.85 and the annual rainfall of 1300 mm, this dug well RWH structure can harvest 765 m3of rainwater that can be stored in the aquifer for further use as adaptation measure. Otherwise if this amount of rainwater from buildings is not harvested though this way then this amount of rainwater would be lost as evaporation due to high temperature and low infiltration capacity of soil in the area, or flowing as runoff water into streams and ultimately to rivers.The research findings presented in this paper could be applied in areas with similar socio-economic status and climatic condition as a novel technique for adaptation measure in meteorological, hydrological and agricultural drought prone area in Bangladesh.

MD SUMAN MIAH

Environmental Specialist, Hydrogeologist, and Evaluation Practitioner

An Environmental Specialist with expertise in climate change impact and resilience, combining hydrogeology and data analytics to drive sustainable solutions in South Asia. Passionate about advancing environmental sustainability through research and community-centered projects.