Introduction:

Surabaya City has a population of around 2.9 million people, which increases to 9.5 million if we count residents living in the extended metropolitan area outside the city. The population mainly comprises Javanese, and the main religion observed is Islam. Surabaya is a rapidly growing city, both economically and population size due to urbanization and industrial expansion.

Geography and Hydrology:

Surabaya is the capital city of the East Java Province in Indonesia. It is the second largest city in Indonesia. Surabaya is located in the Brantas River Basin. The Brantas River is the longest river in East Java. Surabaya is bordered by the Madura Strait in the North and East, Sidoarjo Regency in the south, and Gresik Regency in the west.

Rainfall is seasonal and not consistent throughout the year. It tends to fall mostly from November to December and January to April. Peak rainfall in 2019 was in January with an average of 337.9mm, while the lowest rainfall was in September with 0.1mm (19). The average yearly rainfall is 167.9mm. The wet season can cause high volumes of water flow and flooding (18).

Two main current climate issues are:

Rainfall flooding: Due to intense rainfall events such as from La Nina, Surabaya can experience intense flooding due to high precipitation rates in the region. This is exacerbated by the highly built-up areas in the cities, where an estimated 148 areas in Surabaya are prone to flooding. It is further estimated that homes in these areas experience flooding of an average of 16 times a year, while the average street flooding was 30 times a year with an average duration of 12 hours and average depth of 24cm.

River Flooding (Brantas River): Brantas River, was divided into two rivers; Surabaya River, the main river in Surabaya City, and Porong River, a man-made diversion channel that was built to protect Surabaya from flooding. However, the ongoing mud flood disaster arising from the volcano since 2006 in Sidoarjo, a nearby municipality from Surabaya, reduces the capacity of Porong River. As a result, a larger proportion of Brantas River discharge enters Surabaya City, causing flood problems in Surabaya and affecting the water quality in the rivers.

Water Supply and Management

Current Infrastructure:  Water from the rivers flow along several cities before reaching Surabaya, thus upstream water management is vital for Surabaya’s water quality and quantity and illustrates the area’s high inter-regional water dependency. There are many dams along with the main Surabaya (Brantas) River most of which are upstream except for 2 main dams – the Gunungsari and Jagir Dams – which can be found in south Surabaya. The Surabaya water system comprises piped and non-piped sources (wells, bottled water) from both public and private vendors. It has nearly 5.5 million meters of water piping with a capacity of 192 000 cubic meters.

Pollution: Surabaya River is polluted by untreated industrial and domestic wastewater. The daily pollution load due to non-industrial waste discharged into the Surabaya River was estimated to be over 65,000 kg of biological oxygen demand and 170,000 kg of chemical oxygen demand, with the increasing number of malls and factories discharging insufficiently treated wastewater being reported as a contributing factor (12). There is also a high degree of domestic pollution due to untreated discharges from cities and settlements along the waterway (12; 15). Surabaya’s citizens also discharge a great quantity of untreated domestic wastewater into the Surabaya River because the city does not have an extensive and uniform wastewater infrastructure. PDAM Surabaya reported in 2014 that only 60% of Surabaya’s households use latrines with septic tanks (13). The rest of the city, including small businesses like restaurants, laundry services, and carwash shops, discharges its wastewater into an open sewer system, which empties directly into the Surabaya River. Moreover, many people dispose of their solid waste into the open sewer channels, either because their area is not covered by the city’s waste management service or to avoid paying garbage pick-up service fees.

Current Service Providers

Water Treatment: The government owns and operates the water utility in Surabaya through the local water supply company, Perusahaan Daerah Air Minum (PDAM). PDAM covers 79% of the total water supply in Surabaya (17), and are located in each municipality in Indonesia. The federal government gives municipalities stipulations on water tariffs but otherwise allows them to independently function and operate according to their local municipal standards.

Wastewater Treatment: Surabaya treats blackwater and greywater separately. Blackwater from households is usually channeled to septic tanks or nearby water bodies while the greywater goes untreated to drainage channels or nearby water bodies. Most of the wastewater from nearby slums are discharged directly into the Surabaya River. Surabaya has around 21 composting centers, 200 temporary disposal sites known as waste banks, 1 medium sorting station in Super Depo Sutorejo, and 1 sanitary landfill in Benewo. The community-run waste banks are particularly effective and pay for segregated recyclables, providing opportunities for greater engagement with the informal sectors.

3 Challenges Facing Water Provision

The three main challenges of water provision and management in Surabaya are: the physical dimension that leads to infrastructural inefficiencies; the political dimension that results in chronic misgovernance; and the hydrological dimension that is exacerbated by climate change.

Infrastructure:

Infrastructural inefficiencies affect both water quantity and quality in Surabaya.  Rapid urbanization and population increase have placed heavy stress on existing water infrastructure, often drawing more water than initially planned and significantly reducing their utility lifespan. The existing water distribution structures, such as pipelines and laterals, are highly fragmented and sparse, leading to inequitable access to water. While there are several private companies that treat wastewater for large buildings or campuses, only a small percentage of households are connected to a wastewater treatment system (14). This causes improper disposal of household wastewater which contaminates nearby surface water such as smaller streams and rivers. Furthermore, most of the water distribution pipelines are considered to be outdated and in need of urgent repairs or overhaul (1) The degradation and corrosion of water pipes have polluted the treated water it carries. Frequent leakages from material breakdown in pipes have reduced water quantity up to 27% and generated significant financial losses for the water utility companies (14). 

Governance:

The misgovernance of water resources is plagued by problems that prevent any fruitful resolution to the water issues facing Surabaya. First, any present governance structures set up to tackle water problems are severely hampered by the fragmentation and conflicting responsibilities of various stakeholders. This is apparent in ensuring effective coordination in the fields of water supply capacity management and river pollution management. On a macro-level, neighboring cities that use common water resources often run into conflict because each city has its autonomy in water provision thus are guided by city-level self-interests at the expense of others. At the micro-level, local agencies run into operational and management problems. For instance, Perum Jasa Tirta 1 (PJT1) is responsible for securing water resources for consumers along the river, while the responsibilities of issuing water permits are left to BBWS Brantas. However, BBWS Brantas often issues these permits without consulting PJT1, putting them in a difficult situation as they are already struggling to serve current needs amidst the limited water supply in the Brantas River (14). Second, the commercialization of Surabaya’s water utility causes a trade-off between cost-efficiency and modernization. PDAM Surabaya was established as a business entity and is profit driven. The focus on profits limits any investments to mainly generate profits, often at the expense of any potentially innovative developments that may solve water issues. For instance, while several projects have been proposed to harvest the large amounts of rainwater that Indonesia has been naturally endowed with, PDAM Surabaya actively dismisses and blocks most ideas since it would reduce the demand of the company’s customers and thereby cut its revenues (14). This affects the accessibility and availability of water resources to residents. With a monopoly on high water prices, citizens who cannot afford to pay are excluded.

Climate Change:

Surabaya is a coastal city prone to pluvial, fluvial and coastal flooding. These flood risks will continue to increase in duration and intensity due to climate change. Pluvial flooding is mainly caused by high precipitation rates in the region and highly built-up areas in the cities, where an estimated 148 areas in Surabaya are prone to flooding (16). It is estimated that homes in these areas experience flooding of an average of 16 times a year. The average street flooding was 30 times a year with an average duration of 12 hours and average depth of 24cm. With climate change estimated to change precipitation patterns by prolonging the duration and intensity of monsoon seasons, pluvial flooding is expected to become a recurring sight. Next, fluvial flooding in Surabaya is caused by the ongoing mud flood disaster from a 2006 volcanic eruption in the neighboring municipality, Sidorajo. The mud from the volcano has piled into a man-made river diversion channel designed to prevent flooding, reducing the flow capacity of the Porong River and increased river discharge of the Brantas River into Surabaya City (16). With increased precipitation and the possible reoccurrence of mudflows in the near future, climate change could increase the risk of fluvial flooding. Last, coastal flooding is caused by Surabaya’s low-lying ground of 0-3m above sea level and gradual land subsidence from overdrawing of groundwater where an estimated 50% of the city is sinking at a rate of 20mm per year (14). As climate change continues to drive sea level rise (SLR) and more land subsidence occurs, most of Surabaya’s population which mainly comprises the coastlines and low-lying areas will experience flooding at higher frequencies and intensities.

Proposed Solution: Rainwater Harvesting

Why rainwater harvesting? Rainwater harvesting takes advantage of the seasonal heavy rainfalls in Surabaya and the greater Brantas River Basin. As climate change impacts continue, the precipitation patterns will change, causing heavier rainfalls and droughts. 

We propose building rainwater storage reservoirs in areas in Surabaya that have been designated to capture flooding inundation, as the flooding is caused by heavy rainfall. Areas around the reservoir can be made into outdoor spaces and parks. Dense areas can have residential stormwater catchment on rooftops as a small means of supplementing domestic water needs. 

Rainwater harvesting is a solution that incorporates the need for increased water quality and quantity.  In terms of quality, by adding it to the current water portfolio, Surabaya will have another source of water that is less polluted. Rainwater is less polluted as agricultural and industrial runoff contaminants are not contained in it. Additionally, rainwater harvesting will decrease stormwater runoff and allow for less downstream flooding. In terms of quantity, if rain can be caught and stored and used for domestic needs it will expand the water supply. 

Rainwater harvesting solutions are aligned with Indonesian national goals of resilience to climate change, particularly extreme flooding, and access to sanitation for all. Additionally, having parks around reservoirs in Surabaya aligns with their goal of having more open spaces for physical activity and leisure.

Authority: We plan to commission a federal-level government body that is independent of any partisan politics. This agency will be allowed to work independently of any ministries and has sufficient authority over the municipal and city agencies involved in water management. It is important to develop an agency outside the current governance structure as currently there are too many government bodies monitoring water which creates a deadlock in advancements. The Brantas River Basin has many agencies that have implemented Integrated Water Management, however, there has been little success and it is focused on halting the loss of biodiversity in the region. 

Financing: Collecting water from rainfall could be one of the least costly solutions since the harvested water could be reused for daily domestic water needs and irrigation/agricultural needs. Our solution would appeal to the World Bank and other sources of foreign aid to obtain funds. 

Reservoirs would be cost-effective as there is land zoned for flooding overflow, and local rainwater collection infrastructure could be tacked on to other World Bank projects, such as their Kampong Improvement project that worked on drainage and sanitation in Kampongs in Surabaya. The World Bank has a large presence in Indonesia, another current project is a railway from Jakarta to Surabaya, connecting two commercial hubs.

Pricing and Metering: Progressive pricing will be adopted. Residents connected to the supply mains of stormwater will be charged a meter fee with high subsidy rates of 80%. This subsidy will decrease over a period of 5 -10 years to allow sufficient time for residents to adjust to taking over the costs of water management without significantly affecting affordability. Any low-income families that are unable to afford this pricing will be referred to other social agencies or relevant ministries to work out a financially sustainable plan which may include areas in loan financing or job searching.

Examples of Rainwater Harvesting in Singapore and Chennai

Rainwater reservoirs and drainage has been done effectively in Singapore and Chennai, India. Using these case studies provide evidence for success in Surabaya. Both places have similar climates to Surabaya, tropical with monsoons, and therefore best practices in rainwater storage can be applied- for example, how to keep the water from attracting mosquitoes which would increase the risk of mosquito-borne illnesses. While Singapore’s governance and infrastructure are stronger than Surabaya, their climate risks are similar. In Chennai, the economic and infrastructure capacity is similar. Chennai has implemented large rainwater storage schemes at the community level where rainwater is collected and stored from rooftops or on temple grounds.

Implementation Timeline: We plan to use the first round of financing to build the necessary infrastructure, namely stormwater reservoirs and drains. This should be done within 2-3 years of the date of implementation. Subsequently, we will begin developing community-level infrastructure and linking the main pipes to water treatment plants before linking them to homes through distribution channels. Smart water meters will also be installed alongside the other infrastructural upgrades. We will then expand the same set of community infrastructure to different provinces or villages. The speed of expansion will depend on available revenues, and a fraction of additional stormwater will be returned back into underground aquifers for longer-term sustainability.

Solution Pyramid in 4 Phases: Rainwater harvesting is the first step to expanding the water supply in Surabaya. Once the water supply has been addressed then infrastructure can be improved and expanded, more homes in the city can be connected to water pipes, and ideally, the increased water supply could be used to recharge depleted aquifers that are causing subsidence and saltwater intrusion.

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