Exploring optimal tank size for rainwater harvesting systems in Asian tropical climates

Abstract

This paper explores optimal tank size for domestic rainwater harvesting systems in Asian tropical climates. A total of 128 locations in Vietnam covering three regional climate patterns were selected for the study. The system behavior was simulated on a daily basis using between 27 and 32 years of rainfall data. Annual water cost was investigated to determine optimal tank size. The relationship among optimal size, climate and system conditions was also analyzed. Results of the study emphasize the economic benefit of rainwater harvesting for the whole study area. The optimal tank size for a non-potable rainwater harvesting system has a range of 1.2-2.6 m 3 , exhibiting 19-65% supply efficiency and a payback period of 7-17 years. Extended system scenarios reveal a contrast in the influences of demand and roof area on optimal size in relation to rainfall amount. The roof area is critical in determining optimal size in the low rainfall area while the demand is important in the high rainfall area. Although there is a certain degree of variability in optimal tank size, it does not considerably undermine the economic benefit of a rainwater harvesting system.

Decision support system for community managed rainwater harvesting: A case study in the salinity-prone coastal region of Bangladesh

“…However, the performance of RWH systems is likely to change over time, especially considering changes in precipitation patterns due to climate change [ 18 , 19 , 56 , 112 ]. The water quality and availability of other sources like groundwater and surface water greatly influence the community's willingness to adopt large-scale RWH intervention.…”

“…Thirteen criteria were selected and the relative importance of each criterion was assigned in the pairwise comparison matrix following a literature review of prior studies [ 18 , 19 , 21 , 26 , 28 , 31 , 32 , 36 , 56 , [110] , [111] , [112] , [113] , [114] , [115] ], interviews with thirty-seven beneficiaries, and eight engineers on site, as well as consultation with four DPHE officials and eight experts from Bangladesh University of Engineering and Technology (BUET) and Khulna University of Engineering and Technology (KUET). Additionally, comparable scales must be identified for the different criteria, as units and scales of the criteria are different.…”

“…RWH systems have already been implemented in various countries to address water scarcity issues [ 17 ]. Rainwater harvesting offers a viable alternative water source due to its technical, economic, and environmental feasibility in different climate zones [ [18] , [19] , [20] ] of Bangladesh [ 16 , [21] , [22] , [23] , [24] , [25] ] and all over the world [ 19 , [26] , [27] , [28] , [29] , [30] , [31] , [32] , [33] , [34] ]. For example, The net benefit is estimated to be US$1.3 million per year if 10 % of households in an average rainfed district in Nepal adopt RWH systems [ 35 ].…”