Design of Eco-Drainage System for Real Estate in Indonesia

Abstract

Land use change occurs in many cities in Indonesia. Population growth causes the expansion of residential area. Without proper planning and design, the development of residential area can increase the runoff volume. The objective of this study is to provide an eco-drainage system design for real estate in Indonesia to minimize the possible increased runoff.The study area in this paper is a bare area of 14,602.26 m2 in Mojokerto Regency, East Java, Indonesia which is planned to be developed into real estate. The design of eco-drainage system consists of installation of 4400 litre of rainwater storage tank and a 1200 m3 of retention pond. The analysis includes the estimation of peak discharge of the selected area using the Rational formula and estimation of evapotranspiration in the retention pond using Thornthwaite method. The result of the analysis shows that 50.2 m2 of roof surface can capture rainwater varies from 0.04 – 18.4 m3/month. The water is used to fulfil the household water needs in the real estate such as for sanitation & waste disposal, gardening, personal washing, cleaning home, and washing clothes along the year except in August and September. While overflow of the tank occurs in January, February, and March. The excess rainfall, which is not captured, flows to the retention pond. It is used for watering public garden using a sprinkling water system. The combination of chosen dimension of storage tank and retention pond can reduce the runoff volume minimum by 48.19% in February in the study area.The proposed design still cannot accommodate all excess rainfall due to the transformation of a bare land into real estate. Therefore, it is recommended to consider another utilization of water in the retention pond.