Value of Flood Adaptation
Attributes
Medium: Water
Country: Philippines
Analytical Framework(s): Damage Valuation
Study Date: 2013
Publication Date: 2014
Major Result(s)
| Resource/Environmental Good | PHP (2013) |
PHP (2014)1 |
USD (2014)2 |
|---|---|---|---|
| direct damage cost for built-up land for neck-level floods3 | 410,000.00 | 428,294.20 | 9,576.04 |
| direct damage cost for built-up land for waist-level floods4 | 215,000.00 | 224,593.30 | 5,021.58 |
| direct damage cost for built-up land for knee-level floods5 | 85,000.00 | 88,792.70 | 1,985.28 |
| damage cost to farming (rice) land for a flood level of 2.5 feet and above6 | 29,600.00 | 30,920.75 | 691.34 |
| mean WTP for a technology-based early warning system7 | 140.00 | 146.25 | 3.27 |
About the Inflation Adjustment: Prices in Philippines (PHP) changed by 4.46% from 2013 to 2014 (aggregated from annual CPI data), so the study values were multiplied by 1.04 to express them in 2014 prices. The study values could be expressed in any desired year (for example, to 2026) by following the same inflation calculation and being sensitive to directional (forward/backward) aggregations using your own CPI/inflation data.
Study Note: This study covers the second phase of a three-year project that was conducted from January 2011 to December 2013. The first part of the project focused on vulnerability assessment. This second phase focused on the economic analysis of flood adaptation options. The study site covered three lakeshore municipalities belonging to the Sta. Cruz River Watershed: Pila, Victoria, and Sta. Cruz. Three sub-studies were also undertaken: (1) Direct Damage Cost Estimation for Floods; (2) Benefit-Cost Analysis of a Technology-Based Early Warning System, and (3) Cost-Effectiveness Analysis of Relocation vis-à-vis Evacuation and Building Modification.
Study Details
Summary: Working within a participatory framework and watershed approach, this study focused on the identification and economic analysis of flood adaptation options. A technology-based early warning system for the lakeshore municipalities of the study site, and relocation, evacuation and building modification adaptation options for lakeshore barangays exposed to long-term floods in the municipality of Sta. Cruz, Laguna were identified. The technology-based early warning system was subjected to benefit-cost analysis, while the three adaptation options for long-term floods were subjected to cost-effectiveness analysis. It was found that the respondents in the study site have a positive willingness-to-pay for a technology-based early warning system. The estimated mean willingness-to-pay was between PhP 127 and PhP 152 per household per month. The analysis also showed that the proposed project produced large social net benefits with a benefit cost ratio (BCR) reaching as much as 33. Hence, the implementation of this project in the study site was recommended. The direct flood damage costs corresponding to various flood depths and land use were also estimated and a simulation of flood inundation in the whole Sta. Cruz River watershed was conducted.
Site Characteristics: Sta. Cruz is the capital of the province of Laguna and has a land area of 3,860 ha, comprising of 29 barangays. The topography is level or nearly level with slopes ranging from 0 to 2.5%. In 2010, the estimated population was about 127,320, which is around 26,150 households. Although Sta. Cruz serves as the commercial and service hub of eastern Laguna, the municipality is still dependent on agriculture, with rice, coconuts and vegetables as the main crops. All of Sta. Cruz is considered urban. Flood water in the area comes from upland run-offs. However, the major flood contributor in the area is Laguna de Bay (Laguna Lake). Laguna de Bay is the largest lake in the Philippines with a surface area of 900 km2. More than 100 streams feed into the lake but it has only one outlet, the Pasig River, which drains out to Manila de Bay. It serves as the catch basin for the provinces of Laguna, Rizal, Batangas, Cavite, Quezon, and some parts of the National Capital Region. However, its water holding capacity has been declining over the years due to siltation. Its depth now only averages about 2.5 m, a substantial decline from its maximum observed depth of 10 m.
Comments: The authors discussed that three rounds of consultation were undertaken to identify flood adaptation options to be used for economic analysis. The first round of consultations were undertaken during a training-workshop that involved stakeholders. In the second round of consultations, the shortlisted options were presented to partner agencies. Then in order to validate the technical feasibility of the options, a last round of consultation was undertaken involving experts from academia. Using this rigorous process and taking into consideration the output of the vulnerability assessment done in the first phase of this project, the following options were considered for analysis: a technology-based early warning system for the whole of the Sta. Cruz River watershed; and relocation, evacuation and building modification illustrated via a case study undertaken in selected lakeshore barangays.