Living with the undesirable consequences of urban flooding – soiled home furnishings, widespread traffic delays, economic disruption, and even casualties – is an everyday reality for Metro Manila’s nearly seventeen million residents. Urban floods annually affect more than three million Manileños, killing more than 600 and billing over $160 million in losses. For more than four million informal settlers situated along flood-prone waterways without legal tenure, public service access, or adequate protection from hazards, flooding often takes a backseat to more pressing needs until it’s too late. Four years after the particularly devastating Typhoon Ondoy hit the capital in 2009, the Metro Manila Development Authority and Department of Public Works and Highways released a comprehensive flood management master plan tied to twelve flood control infrastructure projects. This response, part of a series of internationally lauded transformative policies, tackled the region’s complex drivers of flooding in ways that also promoted the metropolitan area’s economic development. However, in pursuing largely technological solutions and the lowest hanging fruit, the master plan and related projects gloss over critical political and governance issues holding back genuine reform while failing to address the full extent of Metro Manila’s sources of flooding: (1) impervious surfaces, (2) inadequate drainage, (3) aquifer depletion, and (4) coastal exposure.* What the metro area needs to manage persistent and worsening floods faster, cheaper, and easier is comprehensive waste management, rainwater harvesting pilots, and more green space. Deeper governance reforms will take more time.

*This blog post does not fully discuss the effects of 1m of sea level rise and storm surge, but among the prime questions the government must answer is who and what is worth protecting and whether incremental onsite upgrades can effectively reduce flood risk without needing to relocate vast segments of the population to often equally risky locations.

Problem #1: The first major source of flooding stems from the dramatic decrease in pervious surfaces over the last five decades. Metro Manila receives 90% of its annual rainfall during its wet monsoon season from May to November, which has intensified in recent years. In three days alone during 2012, the monsoons dropped more than 3ft of rain. Since most of the built environment is concentrated in a low-lying coastal and riparian floodplain at the foot of a large central plateau, the region naturally funnels (flood)water into the sea. However, rapid urban expansion fueled largely by jobseekers from the rural provinces led to a doubling of impermeable surface areas since the 1980s. With only 13% of its original green space left, less of Metro Manila’s rain can infiltrate into the ground. The capital’s flood control infrastructure can’t even capture runoff properly since commercial and unsanctioned small-scale deforestation in the headwaters of the Sierra Madre Mountains eroded 50% of the watershed’s topsoil and then filled the city’s rivers and flood channels with silt.

Toolkit #1: Comprehensive flood management must involve increasing green space and permeable surfaces through developer requirements and incentives for site-specific low-impact development measures. In addition to privately funded initiatives for forest conservation, a promising strategy for addressing the root causes of deforestation involves negotiated transfers of land tenure to civil society organizations for affordably housing informal settlers in exchange for forest conservation activities.

Problem #2: The second source of flooding, inadequate flows and drainage, point to two main concerns – waste management and informal settlements. Since 1991, local governments assume the responsibility of providing solid waste services while the regional Metro Manila Development Authority provides interjurisdictional coordination. However, only two sanitary landfills and one open dump serves the entire national capital region’s population due to limited resources and availability of suitable land. River and harbor pollution from improperly disposed waste (mostly made up of plastics) clog already inadequately maintained drainage infrastructure, require frequent dredging, and make ambient floodwater even more of a public health hazard. Government agencies, development banks, and the urban elite are quick to blame informal settlements as sources of pollution and channel blockage when they remain situated along flood-prone waterways. While such settlements do influence the flow of water and carry risks to settlers themselves, these arguments tend to shift the blame from policies that incentivize extensive (impermeable) commercial development and leave few affordable, let alone livable housing options leftover.

Toolkit #2: Rather than pursuing mass resettlement programs for informal settlers along flood-prone waterways, national and local government institutions need to prioritize investments and dedicate more revenue not only for the purpose of siting solid waste facilities and performing routine collection with greater coverage, but also engage in community education campaigns as a flood management strategy. While innovative programs do exist at the local level, governments should be facilitating private and civil sector investment in community-based waste management programs as a strategy for the fastest, cheapest, and easiest gains in flood risk reduction. A prominent example with many possibilities for tailoring activities to local needs is launching small-scale community “waste banks” for exchanging recyclables in return for cash or other services.

Problem #3: One of the most overlooked challenges facing Metro Manila and other megacities in the Global South is aquifer depletion, which causes subsidence. Groundwater data and monitoring in the Philippines remains relatively new, but by the early 2000s, scientists identified consistent increases in localized sea level rise associated with nearby well-pumping. Even after the government sealed wells to prevent aquifer depletion, extraction rates of over 1,000 cubic meters per day north of Manila Harbor and in the Tullahan River Delta led to permanent compaction of clayey delta sediment and a subsidence rate of several centimeters per year. Most engineered infrastructure projects for flood control not only fail to recognize and address subsidence as a key driver of flooding in Metro Manila’s northwest, but they also do not ameliorate why many informal settlers resort to local sources of well water. After the metropolitan-level government privatized their water sector in the late 1990s, public service coverage increased but not affordably or in the majority of informal settlements. With private tankers charging the poor prices proportionally high relative to their income, few alternatives exist to tapping local aquifers for meeting immediate needs.

Toolkit #3: To provide affordable water access in informal communities, rooftop rainwater harvesting systems or collectively operated cisterns offer relatively cheap ways to cut into the practice of groundwater extraction, especially during the driest three months of the year. Existing small-scale projects for harvesting rainwater in the Philippines should be scaled up, where viable, through government incentives and subsidies paired with public education and outreach programs in interested communities. While these systems should not intend to supply all household water needs throughout the year or replace strategies such as affordable price vouchers on the part of concessionaires, rainwater harvesting tempers the root cause of irreversible subsidence.

While Metro Manila’s 2013 Flood Master Plan identifies various sources of flooding (impervious surfaces, inadequate drainage, aquifer depletion, and coastal exposure) and lays out engineered infrastructure projects over the next decade in attempt to address them, national and local institutions should prioritize comprehensive waste management, rainwater harvesting pilots, more green space, and alternatives to planned relocation. Planning and governance reforms, often ignored or not genuinely addressed, lie at the crux of bringing all of these strategies into one cohesive agenda. To integrate flood management concerns successfully across public service provision, disaster risk management, water resources, and other sectoral activities, a lead agency such as the Department of Interior and Local Government should review powers and resources across national and local agencies to avoid overlapping, conflicting, unfunded, or unspecified mandates. Second, to assist the most cash-strapped local governments in meeting their devolved authorities, asymmetric financing mechanisms should target those setting and meeting ambitious targets. Third, the national government needs to guide inter-local collaborations. Flood management across administrative boundaries often goes unsolved because of a lack of political will and cross-sector, cross-boundary alignment of interests and pooling of resources. Lastly, to root out the negative effects of patronage politics, national agencies need to appoint non-partisan monitoring and enforcement bodies to outlast short-term political administrations that tend to abandon the policies and projects of past regimes. Funding and implementing such reforms take leadership, but given years of public outcry and grassroots action following flood disaster after flood disaster, it is time for the national government to step up.