Environmental-economic water accounts for the Pagsanjan-Lumban watershed (PLW), Philippines

Date

6-2025

Abstract

Natural capital, particularly water, underpins economic production but is often undervalued and overused. This study developed a scalable environmental-economic water accounting model, applying the UN SEEA-Water framework to the Pagsanjan-Lumban Watershed (PLW) an ungauged yet economically vital sub-basin of the Laguna de Bay River Basin. It produced physical Water Asset Accounts (WAA) and Physical Supply and Use Tables (PSUTs), providing a foundation for integrating natural capital into watershed governance and economic planning. PLW's total renewable water volume was estimated at 3,904.71 MCM, with 24% sourced externally. Despite high gross water use (2,554.49 MCM), actual consumption remains low due to significant return flows. Green water plays a crucial role in crop production, though some bioproduction systems show minimal or even negative net green water contributions. Conversely, blue water use through irrigation often enhances net economic benefits. Economic valuation reveals that diversified systems (e.g., rice-vegetable, coconut-fruit) outperform monocultures in water productivity and profitability. Scenario modeling indicates that climate and land-use changes will intensify water stress, especially for water-sensitive crops. The study recommends investing in monitoring infrastructure, promoting high-value diversified crops, reforming water pricing, and enhancing local storage and recycling. As the first basin-level SEEA-Water application in the Philippines, this study offers a replicable model for sustainable water governance and climate-resilient agriculture.

Document Type

Dissertation

Degree

Doctor of Philosophy in Forestry

College

Graduate School (GS)

Adviser/Committee Chair

Margaret M. Calderon

Co-adviser

Canesio D. Predo

Committee Member

Asa Jose U. Sajise, Cristino L. Tiburan Jr., Juan M. Pulhin

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

En – AGROVOC descriptors

WATER ACCOUNTING; TRUE COST ACCOUNTING; INTEGRATED WATERSHED MANAGEMENT; WATER PRODUCTIVITY; WATER MANAGEMENT IN UPLAND

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