"The potential availability of water in Indonesia reaches 690 billion cubic meters per year. It is estimated that only about a quarter of this has been utilized. Damage in the upstream areas, whether due to deforestation or forest land conversion, pollution, distribution systems, and wasteful surface water disposal, has rendered water usage inefficient." - Djoko Kirmanto, former Minister of Public Works (2012)
Did you know that issues related to water in Indonesia, especially regarding its management, continue to be ongoing problems? The statement from one of the former Ministers of Public Works above adequately illustrates how water availability in Indonesia is still not maximally and efficiently utilized. What are the issues occurring in Indonesia?
- Some regions in Indonesia experience extreme water abundance during the rainy season and water scarcity during the dry season due to seasonal variations and spatial imbalances in water availability.
- The distribution of available water is uneven.
- Water usage is rapidly increasing, leading to a decline in water quality and narrowing down alternative water sources for the community.
On the island of Java, which covers 7% of Indonesia's land area, is home to 57.5% of the population, and holds 4.2% of Indonesia's water potential, there is even a threat of becoming a net importer of water. Moreover, inhabitants of small islands in Indonesia struggle to access clean water and have to rely on rainwater collection. Isn't rainwater supposed to be safe?
In the hydrological cycle, if water is not captured or absorbed, it will become surface runoff that carries various pollutants towards bodies of water, making groundwater difficult to find and lowering the ground level. Conversely, if water continues to accumulate in water bodies, it will cause flooding. Therefore, Stormwater Management can be one of the solutions.
What is Stormwater Management?
Stormwater management is an effort to reduce the runoff of rainwater or melting snow to streets, lawns, and other locations for the improvement of water quality.
Stormwater management is divided into two types:
- Hard engineering or gray infrastructure, relying on pipes and drains to channel rainwater to treatment facilities, but it is risky for carrying pollutants, toxins, and microscopic organisms.
- Soft engineering or green infrastructure contains elements that assist nature in working, allowing water to be absorbed into the soil, filtering pollutants, and retaining water as nature does.
But, which one is better from the perspective of urban design?
One solution is Low Impact Development or LID.
Low Impact Development changes the perspective that stormwater should be moved as quickly and as much as possible; instead, it should be detained and infiltrated into the soil for reuse. This can be achieved by utilizing micro-scale rainwater management practices integrated between local drainage systems, small-scale, and regional water resource control.
Some examples of LID techniques include:
- Bioretention
- Green roofs
- Permeable pavement
- Rain barrels and cisterns
- Soil amendment
- Tree box filter
What if LID is implemented in Indonesia?
According to a case study by the University of Indonesia on a catchment area in 2019 by Luluk Azkarini, et al., the effectiveness of peak flood flow can be obtained by using non-surface sand filters or surface sand filters. With the addition of the LID concept, a reduction in peak flow occurs in the second year because LID is a rain management concept on a light to moderate spectrum.
The LID concept is suitable for application in urban areas with limited open space by effectively utilizing surrounding land so that low-range rainwater can be retained above the ground and then absorbed into the soil.
So, how can we help?
- The concept of rainwater management must continue to be developed and evaluated. Rainwater should be detained as far as possible from where it falls, evaporated, used, and/or infiltrated through the active soil zone.
- The transition from conventional water management systems to sustainable systems is not easy, but it can be achieved if stakeholders, communities, and infrastructure developers work together.
- Increasing awareness of the importance of implementing environmentally friendly urban design techniques and strategies.
- Urban designers must be able to design and promote new trends. "People-oriented" design trends can be reconsidered to create a balance between social, economic, and environmental aspects.
Indonesia can be said to be experiencing a clean water availability crisis due to uneven water distribution and declining water quality. Therefore, Stormwater Management can be one solution to improve water quality with Low Impact Development practices. Its utilization, which manages micro-scale rainwater and can be applied in urban areas with limited open space, is also considered suitable for implementation in Indonesia.