Research: Mula Ilog Hanggang Look: Assessing the Five-Year Manila Bay Rehabilitation Program

Background of the Study

The Pasig River is a historic waterway traversing the center of Metro Manila and connecting two major bodies of water – the Laguna de Bay and Manila Bay. Due to its strategic location, it is a vital transport route integral to the economic functions of industries along the river system. Approximately 27 kilometers long, the river is a great recreational opportunity and water source for residents of Metro Manila. The Pasig River also serves as a flood catchment basin from several tributaries. It originates from its upstream source in Laguna de Bay, travels through the Napindan Channel, joins the Marikina River at the Pasig and Taguig boundary, connects with the San Juan River, and ultimately empties into Manila Bay (Gorme et. al., 2010).

Following the aftermath of World War II, population growth and rapid urbanization led to the neglect of the Pasig River water system (Gorme, et. al., 2010). Increased migration to Metro Manala also led to the development of informal settlements along the river, which exacerbated the pollution of its waters due to poor waste disposal.

In the 1990s, the river was officially declared biologically dead by the Danish International Development Agency (Suh et al., 2017).

Multiple governmental and non-governmental attempts have been undertaken since then to rehabilitate the Pasig River. The Pasig River Rehabilitation Commission (PRRC) was established in 1999 to manage and develop the Pasig River (Asia Development Bank, 2000). The PRRC was responsible for easement recovery, river cleanups, and relocation of informal settlements. In 2018, PRRC’s efforts were recognized when its rehabilitation endeavors were awarded the first Asia River prize (Quadra-Balibay, 2018). However, the commission was disestablished in 2019, but the Manila Bay Task Force (MBTF) was established in 2019 to consolidate rehabilitation efforts in the Manila Bay Region (Gita-Carlos, 2019).

The Manila Bay Rehabilitation Program

Along with the formation of the MBTF, a 5-Year Manila Bay Rehabilitation Program (MBRC) was launched.

This was per the Mandamus on Manila Bay issued by the Supreme Court in 2008 directing 13 government agencies to restore the bay’s water quality to the Class SB level, that is fit for swimming, skin diving, and other forms of contact recreation (DENR, n.d.).

The program was divided into three phases:

1. Water Quality Improvement, including river cleanup, solid waste management, and implementation of engineering interventions.

2. Rehabilitation and Resettlement, including the recovery of the three-meter easement along the river systems and the relocation of informal settlers along the riverbanks.

3. Protection and Sustainment, including waterway management incorporating phytoremediation measures, landscape development, and environmental education.

Pasig River is one of Manila Bay's major tributaries. Both the river and the bay suffer from similar polluted conditions that the government has long been trying to address. With the program concluding last February 2024, there is a need to assess the impact and effectiveness of the program and whether the transfer of mandate to the MBTF was beneficial for the rehabilitation of Pasig River.

Research Objectives

The goal of this research is to assess the impact of the 5-year Manila Bay Rehabilitation Program (MBRP) on the landscape composition of the Pasig River Floodplain, comparing data from 2004 (pre-program), 2019 (program inception), and 2024 (program conclusion). The study aims the following objectives:

1. To map the green and open space in the Pasig River Floodplain based on the categories: Amenity, Functional, Urban Forest, Riverside, Undeveloped, and Barren spaces.

2. To assess the landscape composition of the Pasig River Floodplain during 2004, 2019, and 2024 by calculating the class area (CA), number of patches (NP), mean patch size (MPS), and edge density (ED).

3. To analyze the landscape composition of patches directly along the Pasig River system.

Methodology

The research employs a mixed qualitative and quantitative method approach. The Pasig River and San Juan Floodplain in Lagmay’s (2020) map of Metro Manila sub catchments was used as the basis for the delineation of the site. However, only sub catchments traversed by the Pasig River system and its tributaries were included in the final study site.

Moreover, Quantum GIS (QGIS) was used as the main mapping software of the study. Satellite images from April 2004 and February 2019 were exported from Google Earth Pro and georeferenced into QGIS. Meanwhile, the default Google Satellite in the software was used for the 2024 data.

Green and open spaces were categorized based on Rakhshandehroo’s (2014) classification of urban green spaces– amenity, functional, semi-natural, and linear spaces. Amenity green spaces are composed of parks, playgrounds, plazas, and residential greenery. Functional spaces include greenery in institutional spaces like schools, churches, cemeteries, or civic offices. Semi-natural is replaced with urban forests while linear spaces are replaced as riverside spaces. Aside from these, undeveloped areas, vacant lands with vegetation, and barren areas, vacant lots with no vegetation, are added to the category. Using the satellite images per year, landscape patches from each category were visually identified and traced as vectors in QGIS.

The perimeter and area of each vector polygon from each green space category were obtained through the field calculator. The layers were then exported as a CSV file and copied into Google Sheets. From there, simple arithmetic was used to calculate the total class area (CA), number of patches (NP), mean patch size (MPS), and edge density (ED)

Aside from calculating the overall landscape metrics of the entire site, vector polygons directly adjacent to the river system were also isolated. The landscape metrics of these patches were also calculated to gain a better understanding of the landscape composition changes occurring near the Pasig River.

Results

In 2004, there were a total of 388 green and open space patches making up 5,756, 301 sqm of the Pasig River Floodplain. Amenity spaces covered 80 patches (1,944,292 sqm), Functional spaces covered 44 patches (701,543 sqm), Urban Forests covered only 6 patches (73,684 sqm), Riverside greenery covered 118 patches (235,899), Undeveloped spaces covered 85 patches (948,286), and Barren spaces covered 55 (2,800,883 sqm).

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Aside from riverside greenery, undeveloped land parcels have the second largest NP followed by amenity spaces. This is visually evident in the 2004 map (Figure 6)as evidenced by multiple patches of undeveloped and barren land as well as large patches of amenity green patches dominated by, Manila Golf and Country Club the Intramuros golf course, and Manila South Cemetery. Despite this, it can be noticed that barren spaces have the highest CA and MPS. However, the latter could be the result of an outlier value due to the large barren patch of the Bonifacio Global City (BGC).

In 2019, there was a total of 550 landscape patches comprising a total of 4,320,869 sqm of the Pasig River Floodplain. Amenity spaces covered 157 patches (2,147,851 sqm), Functional spaces covered 90 patches (1,126,604 sqm), Urban forests covered triple the number at 24 patches (73,684), Riverside covered 124 (215,870), Undeveloped land covered 82 (685,468 sqm), and Barren land covered 73 patches (646,212 sqm).

Riverside and Amenity spaces have the highest NP, but Amenity, followed by Functional spaces, have the highest CA and MPS. As shown in Figure 7, more amenity patches have already appeared in Makati and BGC areas in 2019. Functional patches remain relatively at the same locations but are still concentrated in the Manila University belt area as well as the Malacañang Palace.

In 2024, there was a total of 583 patches comprising 5,160, 890 sqm of the Pasig River Floodplain. Amenity patches covered 160 (2,232,137 sqm), Functional spaces covered 95 (1,170,411 sqm), Urban Forest covered 21 (159,606), Riverside spaces covered 143 (247,574), Undeveloped areas covered 82 patches (555,594), and Barren spaces covered 82 patches (795,568). Amenity green spaces have the highest number of NP, CA, and MPS, followed by Functional spaces.

Analysis

Pasig River Floodplain Landscape Composition and Changes

Table 1 illustrates the summary of results for the computed landscape metrics. Overall, NP increased while MPS decreased from 2004 to 2019 and from 2019 to 2024. From 2004 to 2019, the total CA in all classifications decreased but increased from 2019 to 2024. In contrast, ED increased from 2004 to 2019 but decreased from 2019 to 2024.

Considering all of these, green and open space patches from 2004 to 2019 increased in number but reduced in size. The increase in edge density also suggests that patches became more fragmented or more irregularly shaped. From 2019 to 2024, patches also increased in number, reduced in mean patch size, and increased in total area. This can be interpreted as the landscape patches being mildly fragmented due to the increase in their number. In both cases, barren patches served as the primary contributor to these landscape pattern changes.

Amenity Green Patches

Amenity patches are mostly composed of the Intramuros Golf Course, Manila Golf and Country Club, and the Manila South Cemetery. From 2004 to 2019, amenity patches increased in NP, CA, and ED, but reduced in MPS indicating that patches became numerous but reduced in size. This is evident on the map through the appearance of multiple small patches in the form of retail and condominium landscaping in Makati and BGC. From 2019 to 2024, amenity patches increased in all four-landscape metrics suggesting that patch shapes may have become more complex. This increase may be due to new landscape developments needing to be built around existing or proposed structures.

Functional Green Patches

Most of the functional patches are in the University Belt while a large portion of the patch comprises the Malacañang Complex. With an increase in NP, CA, and ED, but a decrease in MPS in both temporal intervals, Table 1 shows that over the years, functional patches increased in number but reduced in size. This result may be due to new structures being built within the institutional area, thereby decreasing the patch size and making the patch shapes more complex.

Riverside Green Patches

Riverside green patches are those narrow strips of greenery along the Pasig River network. This serves as an integral part of the study as most of the MBRP and other river rehabilitation efforts are focused directly on the waterway and esteros.

Findings show that from 2004 to 2019, NP and ED increased while CA and MPS decreased. This suggests that riverside patches increased in total area but became fragmented. From 2019 to 2024, riverside patches increased in NP and CA while ED and MPS decreased. This suggests that patches became numerous and reduced in fragmentation. Most of these changes can be observed in the estero network in Ermita and Paco.

Urban Forest Patches

In this study, urban forest is limitedly defined as the patches of land within the study site that are densely covered with trees. In 2004, Urban Forests could only be found in Rizal Park and Arroceros Park. By 2019 and 2024, these have already extended into other areas of the Pasig River Floodplain, albeit smaller in size. In 2024, urban forests in Rizal Park were removed from the category due to reduced tree cover brought about by ongoing redevelopments.

Qualitative computation of landscape metrics reflects these changes. From 2004 to 2019, urban forest patches increased in total CA, NP, and ED, but decreased in MPS indicating that the patches became smaller. In contrast, from 2019 to 2024, all four-landscape metrics decreased in number suggesting that some patches may have completely disappeared or may have been merged.

Undeveloped Open Patches

Undeveloped patches refer to vacant lands that contain vegetation (lawn, grass, or shrub massing), but have no major designated use or functional development. From 2004 to 2019, all landscape metrics decreased excluding the edge density indicating that undeveloped patches reduced in number and size. This is noticeable in Figures 4 and 5 with the increased patchiness in the western region of Mandaluyong as well as the disappearance of a group of undeveloped patches in Makati. Meanwhile, from 2019 to 2024, NP remained the same, ED increased, and CA and MPS decreased. This indicates that patches reduced in size and may have merged.

Barren Open Patches

Barren patches refer to vacant lands that do not have any vegetation. Large patches of barren land can be observed in the 2004 map in Figure 4. These are primarily located in Sta. Mesa, Mandaluyong, and especially in the whole BGC area. From 2004 to 2019, NP and ED increased while CA and MPS of barren patches decreased. This suggests that barren patches decreased in total area and became fragmented. This is evident in the disappearance of BGC under the barren classification as it was already developed by 2019. Patches in Makati, Sta. Mesa and a few in Mandaluyong also disappeared. On the other hand, a new barren land, the former Pandacan oil depot, appeared on the 2019 map in Figure 5. This is due to the order of the Supreme Court in November 2014 to relocate and transfer oil terminals in Pandacan for security and health concerns (Fonbuena, 2014).

From 2019 to 2024, barren patches increased in all landscape metrics excluding edge density which suggests that they increased in number and size and became less fragmented. Barren patches in the Mandaluyong area and Pandacan appeared once again—the latter noticeably concentrated along the river system

Pasig River Floodplain Riverside Landscape Composition and Changes

Aside from the analysis of the landscape composition and changes in the entirety of the Pasig River Floodplain, landscape compositions directly adjacent to the Pasig River system are also analyzed to gain a better understanding of the impacts of the rehabilitation program.

Table 2illustrates the summary of results for the computed landscape metrics of patches specifically along the Pasig River system. Overall, NP, CA, and ED increased while MPS decreased indicating that green and open patches increased in number but reduced in size. Class-level analyses of landscape metrics are further discussed below.

In 2004, patches along the river system were mostly barren patches (29) followed by undeveloped (23) and amenity (21) spaces. However, in terms of coverage, amenity spaces covered the largest area followed by undeveloped and barren patches. These landscape patches are concentrated in the City of Manila as it has an extensive network of estuaries (Figure 9).

In 2019, patches along the riverside consisted mostly of amenity (65) followed by undeveloped (62) and functional (42) spaces. In terms of coverage, amenity patches covered the largest area followed by functional and undeveloped patches. Compared to 2004, barren patches in Sta, Mesa, and Paco disappeared while new ones appeared in Pandacan and Mandaluyong. Additionally, a few amenity and undeveloped patches along Makati and Taguig appeared in 2019 (Figure 10).

In 2024, patches along the river system consisted mostly of undeveloped patches (68) followed by amenity (66) and barren (64). However, in terms of coverage, amenity covered the largest area followed by barren and functional. Visual analysis of the 2019 and 2024 maps shows an increase in undeveloped patches in the Mandaluyong and Pandacan areas. Additional amenity corridors can also be observed along Binondo, Ermita, and Intramuros due to the ongoing Pasig River Esplanade development (Figure 11).

Conclusion: Toward a Landscape of Hope Along the Pasig River

Waterways such as the Pasig River provide critical ecological services, offering flood protection while enriching the social and cultural life of urban communities through recreation, mobility, and identity. Despite decades of top-down rehabilitation efforts—including the most recent Battle for Manila Bay initiative led by the Manila Bay Task Force—long-term and evidence-based assessments are essential to understanding whether such programs are truly achieving their goals.

This study analyzed the landscape composition and spatial changes of the Pasig River Floodplain using landscape metrics—Number of Patches (NP), Class Area (CA), Mean Patch Size (MSP), and Edge Density (ED)—at three key timepoints: 2004 (pre-program), 2019 (program inception), and 2024 (program conclusion). Findings reveal that from 2004 to 2019, green and open patches increased in number but became smaller and more fragmented. Between 2019 and 2024, patch numbers continued to rise and became more spatially dispersed. Next to the river, patches also increased in number but decreased in size across both time intervals. The emergence of green spaces suggest signs of the ongoing rehabilitation efforts, though still modest and fragmented.

Far from being abstract, these landscape metrics offer concrete and quantitative evidence of how spatial patterns are evolving in this vital urban corridor. They help find opportunities for ecological connectivity and public space development that can benefit both biodiversity and local communities.

To build on these findings, the study proposes three key recommendations for future assessments: (1) ensure consistent time intervals in landscape mapping to allow for clearer trend analysis; (2) cross-validate identified green and open spaces with datasets such as Comprehensive Land Use Plans (CLUP), land cover maps, or NDVI imagery to improve accuracy; and (3) correlate landscape changes with specific intervention sites to assess the direct impact of rehabilitation actions.

The research reframes the Pasig River Floodplain not simply as a space of environmental decline, but as a landscape of hope—where ecological data not only guides strategic planning but also inspires a renewed vision for urban life.

The measurable emergence of green patches, though fragmented, signals the beginning of ecological recovery and the possibility of reconnecting people with nature in one of Metro Manila’s most degraded corridors. These spaces offer more than environmental value; they provide social, cultural, and psychological benefits—serving as potential habitats, recreational zones, and symbols of collective resilience. In showing that even small, data-driven improvements can shape more livable and inclusive cities, the study affirms that hope in landscape architecture is grounded in action, visibility, and long-term care. The floodplain thus emerges not just as a remnant of past neglect, but as a living corridor where restoration, community pride, and environmental justice can grow side by side.

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