Establishment of sustainable water supply system in small islands through rainwater harvesting (RWH): case study of Guja-do

Many islands in Korea have problems related to water source security and supply. In particular, the water supply condition is worse in small islands which are remote from the mainland. A couple of alternatives are developed and suggested to supply water to islands including water hauling, groundwater extraction, and desalination. However, these alternatives require much energy, cost, and concern in installation and operation. Rainwater harvesting is a sustainable option that supplies water with low energy and cost. However, lack of practical or comprehensive studies on rainwater harvesting systems in these regions hinders the promotion of the system. Therefore, this research examines defects of current RWH systems on an existing island, Guja-do, and provides technical suggestions in quantitative and qualitative aspects. A simple system design modification and expansion of system capacity using empty space such as a wharf structure can satisfy both the qualitative and the quantitative water demand of the island. Since rainwater harvesting is estimated to be a feasible water supply option under the Korean climate, which is an unfavorable condition for rainwater harvesting, implies a high potential applicability of rainwater harvesting technology to other regions over the world suffering from water shortage.