Rainwater harvesting potential in Bangladesh

Abstract

In Bangladesh, surface water was the principal source for drinking water ever upto recent past. However, during the recent decades, due to the intensive development programs, the ground water is utilized for drinking purpose in most rural areas. Unfortunately, recent investigations have demonstrated almost countrywide occurrence of high arsenic levels in the tubewell water. Today, Bangladesh seems to be one of the most arsenic affected countries in the world, Bangladesh is a tropical country and receives heavy rainfall during the rainy season. In the present context, rainwater harvesting is being seriously considered as an alternative option for water supply in Bangladesh. The objective of this research is to study the potential of the rainwater harvesting system in Bangladesh. Ninety seven percent of rural population has access to tubewell water and ground water is still good for all type of uses except drinking. Therefore, the main emphasis is given on the rainwater harvesting as a source of drinking water. The research includes a literature review on rainwater harvesting systems, costs and water quality. In performing the study, frequency analysis is undertaken on annual rainfall data from 25 stations of Bangladesh Meteorological Department (BMD). The most appropriate probability distribution for each location is determined and used to estimate the reliability of the system of that location. Based on this, design curves are developed to estimate the reliability of the system for any consumption rate at different areas in Bangladesh. Mass curve analysis is used to deterinine required storage volumes for every location. Based on statistical analysis of required storage volumes, design curves are developed for estimation of storage tank volumes covering the need for drinking water of different household sizes. These curves can be applied at field level by non professionals.