ROOFTOP RAINWATER HARVESTING, CONSERVATION, AND MANAGEMENT STRATEGIES FOR WATER SOURCES IN SAJEK VALLEY, BANGLADESH
Presented by
Engr. Md. Shahadat Hossain
Environment, Climate & Water Specialist
BANGLADESH
MANAGING DIRECTOR & CEO
ONUSHANDHANI CREEDS LTD. (O.CREEDS)
B.Sc in Civil Engineering [BUET]-2009
M.Sc. in Water Resources Engineering [BUET]-2018
M.Sc. in Climate Change and Development [IUB]-2022
PGD on Disaster Management [University of Dhaka]
INTRODUCTION
Sajek Valley is an emerging tourist spot in Bangladesh situated among the hills of the Kasalong range of mountains in Sajek union, Baghaichhari Upazila in the Rangamati District. The valley is 1,476 feet (450 m) above sea level. Sajek valley is known as the Queen of Hills & Roof of Rangamati. Sajek is in the verdant hills of Kasalong range of mountains amidst the serene and exotic beauty of nature. Lofty mountains, dense forest, sprawling grasslands and miles of hilly tracks feature the valley. The simple and basic indigenous lifestyle of local people is just fabulous for visitors to spend a day.
METHODOLOGY
A total of 20 single-story residential dwellings with varying rooftop areas were surveyed for the projection of RWH potential. The relationship between the size and cost of a water tank and the rooftop areas of different houses is expressed using a general mathematical equation . Cost estimates for the proposed RWH system for all houses have been completed, and a cost model illustrating the relationship between rooftop or catchment area and associated cost of RWH system has been developed.
METHODOLOGY
In Sajek, Water for People is designing rainwater harvesting sites in the Sajek Valley, where the annual average rainfall is 1200 mm. We are designing for 17.5m3 of harvested rainwater for consumption .
After consumption needs are met, communities are also storing a portion of the rainwater in a masonry storage tank. Periodically, we apply the required coagulants to keep the water safe for the next season of water scarcity.
KEY FINDING
Average annual rainfall: 1056 mm per year
-Total demand: 715 liters per day or 21.75 cubic meters per mean month.
-Annual available rainwater (assuming all is collected) = 190x1.056x0.9 = 180.58m3.
-Daily available water = 180.58/365 =0.494.7 liters per day or 15.05 cubic meters per mean month.
It can be noted that the first month that the rainfall on the roof meets the demand is October. If we therefore assume that the tank is empty at the end of September we can form a graph of cumulative harvested water and cumulative demand and form this we can calculate the maximum storage requirement for the dispensary.
KEY FINDING
We organize capacity building activities focused on integrated water resources management (IWRM) and behavior change in Sajek valley to reduce extra useWe highlight the challenges associated with water scarcity according to the table below, especially limited access to water during the peak of summer. If we implement an appropriate integrated water resources management approach and all households adopt these techniques, then in one or two seasons, the rainwater could decrease due to the Climate Change considerably to 5 to 10%. This will not meet a good portion of unmet demand for Sajek. So we need to store water for dry season.
CONCLUDING RECOMMENDATIONS
The effects of population growth in the developing world and climate change have increased the stress on available water resources. The majority of Sajek, Bangladesh, is facilitated with land elevation. As Bangladesh is a country of monsoon climate, reserved rainwater can be contributed as an alternative to extracted groundwater. This study aims to develop a framework for rooftop rainwater harvesting (RRWH) for domestic purposes and estimate the appropriate size of the storage tanks and their costs required to fulfill the annual drinking and cooking water demands through RRWH in Sajek of Bangladesh. The novelty of this study is that it focused mainly on how significant RRWH can be to meet people’s daily required amount of water for household purpose and ascertain the cost reduction using the RWH method. This study also is unique as it assessed the volume of the storage tank that is sufficient to distribute the necessary amount of water for drinking and cooking purpose as a sustainable alternative source in the dry season.
Acknowledgements
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