The Journal of Environmental Science and Management (JESAM) (ISSN 0119-1144) is Web of Science-indexed journal that is produced semi-annually by the University of the Philippines Los Baños (UPLB).

It features research articles, theoretical/conceptual papers, discussion papers, book reviews, and theses abstracts on a wide range of environmental topics and issues.

Special Issue 1 - 2023

Development of Synthetic Unit Hydrographs Using Spatial Proximity Regionalization for the Makiling Forest Reserve, Philippines

Alex D. Follosco, Jr., Roger A. Luyun, Jr., Rubenito M. Lampayan, Jeffrey A. Gonzales

Abstract: There is a dearth of streamflow data in the Philippines to generate hydrographs needed for flood forecasting and water resources assessment. A method of generating and calibrating synthetic hydrographs using model simulations and spatial proximity regionalization is presented. Synthetic unit hydrographs of four storm events in the gauged watershed of Makiling Forest Reserve were generated using Soil Conservation Service Unit Hydrograph, Clark Unit Hydrograph, and Snyder’s Unit Hydrograph methods. The generated synthetic hydrographs for each runoff modeling technique were calibrated with the actual hydrographs of the watershed. Snyder’s Unit Hydrograph model results were the most acceptable based on the Nash-Sutcliffe Efficiency, Index of Volumetric Fit, and Relative Error of Peak Flow. The weighted values of the calibrated watershed parameters computed using spatial proximity regionalization technique and the hyetographs derived from the Rainfall Intensity Duration Frequency Curve of the University of the Philippines Los Baños-National Agrometeorological Station were used to generate the synthetic unit hydrographs for three neighboring ungauged watersheds at 2-, 5-, 10-, 15-, 20-, 25-, 50, 100-year return periods. Total runoff volume, the magnitude of peak flows, and time to peak derived from the generated hydrographs can be used in watershed planning, water resources management, flood forecasting and the design of various water control structures.

Arsenic in Philippine Groundwaters: Exploring Governance Limitations for Drinking Water Safety

Chrislyn Joanna P. Faulmino, Agnes C. Rola

Abstract: Arsenic in drinking water is an emerging environmental health threat in the Philippines. Local studies investigate the occurrence and health effects of the hazard, but governance dimensions remain understudied. This study explores why some consumers remain vulnerable to arsenic poisoning despite the existence of a water institution framework for groundwater management and drinking water safety. The framework for arsenic risk management for safe drinking water in the Philippines was mapped from “source-to-sip”. Textual analysis of pertinent legal documents and official reports; and transcripts of a roundtable discussion and minutes of meetings with national agency representatives were undertaken with regard to the principles of integrated groundwater management and the human right to safe drinking water. Findings suggest that existing programs and policy instruments for groundwater quality monitoring provide insufficient information for early arsenic detection. Furthermore, while the country’s legal framework supports functions for arsenic risk mitigation for formal water supplies, the current regulatory approach fails to protect self-provisioning households as they access water from informal systems uncovered by water quality surveillance. Enhancing groundwater quality monitoring in suspected arsenic hotspots to alert self-provisioning households will promote a self-protection policy so they can shift to safer sources of drinking water.

Water Footprints of Philippine Agricultural Products

Marlon C. Pareja

Abstract: Compared to the usual measuring of national water usage using water withdrawals from the different sectors, the use of water footprint as a tool for calculating water usage provide more insights on the efficiency of the use of freshwater resources. Various water footprints of Philippine agricultural products were calculated together with the corresponding energy water productivity. The findings in this paper also showed that the Philippine per capita water requirement for food (CWRF) is significantly higher compared to other developing countries since it needs more water to produce a food item and affects the total water usage as shown in total water requirement (TWRF). In terms of TWRF, the computed data indicates that it will continuously increase in the next four decades and will become a big factor in determining water sustainability. This paper recommends that water scarcity should be identified and be recognized as a major threat to sustainable development besides population growth and externalities of uncontrolled economic growth. Accurate identification of the “blue” “green,” and “gray” water” components of food production will help in the formulation of appropriate strategies in water productivity and its efficient use.

Rainfall and Land Cover Changes Impact on the Hydrologic Responses of Santa Cruz Watershed, Laguna, Philippines

Angelica T. Magpantay, Patricia Ann J. Sanchez, Marisa J. Sobremisana, Cristino L. Tiburan, Jr.

Abstract: Watershed provides a wide range of ecosystem services. Part of its provisioning services is the quantity, distribution, and timing of water supply. The state of water resources is affected, among others, by rainfall and land use and land cover (LULC) changes. With the Philippines consistently ranking very high in the World Risk Index reports in terms of disaster risks and land use intensification due to continuous growth in population and economic activities; it is crucial and timely to conduct research in relation to its hydrological impacts. This study aimed to detect and project the separate and combined impacts of these changes on the surface runoff responses of Santa Cruz Watershed during a typhoon event using the Hydrologic Engineering Center’s Hydrologic Modeling System (HEC-HMS) model. The study was able to identify, and bias-corrected five General Circulation Models (GCM) under Representative Concentration Pathways (RCP) 4.5 and 8.5 storylines to account for the future impact of change in rainfall. Meanwhile, LULC modeling was executed using the Markov chain method to project its 2040 state. Combined impacts revealed a certainty that peak discharge and total volume will increase, and the time of peak will be earlier than the baseline model for both RCP 4.5 and 8.5 scenarios. The output of the study can serve as a vital input in crafting evidence-based policy and decision-making in relation to watershed planning and management.

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Removal of Pesticide Residues in Aqueous Solution by Adsorption Using Pineapple Peel Activated Carbon

Eric Jhon D. Cruz, John Julius P. Manuben, Maria Lorena R. Cruz

Abstract: The use of synthetic pesticides in crop protection generates dilute pesticide solution resulting from the cleaning of pesticide application equipment, also known as pesticide rinsate. If not disposed or treated properly, this may result to the contamination of surface water or groundwater. One of the possible management practices for pesticide rinsate is the use of activated carbon as an adsorbent. Activated carbon was prepared from pineapple peel using phosphoric acid through chemical activation. Characterization of the surface morphology through Scanning Electron Microscopy (SEM) confirmed the successful activation of the carbon. The resulting Pineapple Peel Activated Carbon (PPAC) was utilized as adsorbent in the removal of the carbamate methomyl in the pesticide rinsate. Analysis of the cleaned rinsate using a High-Performance Liquid Chromatograph confirmed the removal of 96.0-98.4% of methomyl residues in a 7.5 mg L-1 methomyl pesticide rinsate using a 0.5-1.0% w/v PPAC:rinsate ratio. This study showed that activated carbon could be successfully prepared from pineapple peel and used as an effective adsorbent for the remediation of pesticide rinsate to prevent the pollution of surface water or groundwater.

Performance Evaluation of the Water Advisory for Irrigation Scheduling System (WAISS) Capacitance Soil Moisture Sensor

Roger A. Luyun, Jr., Ronaldo B. Saludes, Toni-An Mae C. Salcedo, Bryan M. Baltazar, Christian Martin Casedo, Jay Ann Q. Lomod, Ginalyn Robel M. Brazil, Jan Albert M. Atienza

Abstract: The agriculture sector accounts for 80% of the total freshwater resource use in the Philippines. With increasing competition for the scarce water supply, it is necessary to utilize water resources efficiently. The application of smart irrigation technology can help achieve higher water use efficiency, increase farm water productivity, and maximize crop yield. To minimize excess or insufficient irrigation water application to crops, and provide more effective and efficient water management, an integrated water monitoring system called Water Advisory for Irrigation Scheduling System (WAISS) was developed. The performance of WAISS was initially evaluated by comparing the soil moisture measurements of its capacitance soil moisture sensor with a commercially developed sensor and the standard gravimetric method. Statistical analysis shows that the low-cost WAISS soil moisture sensors are comparable with the commercially developed sensors with a Percent Error of 5.5% compared to METER ECH2O EC-5’s 16.1%. This highlights WAISS’ potential as a cost-effective yet reliable alternative for soil moisture monitoring.

Water Footprint of Bioethanol Production in Negros Occidental, Philippines

Bernadette Tongko-Magadia, Rex B. Demafelis, Antonio J. Alcantara, Rex Victor O. Cruz, Rico C. Ancog

Abstract: This study investigates the water scarcity implications of bioethanol production in Negros Occidental, Philippines. The water footprint (WF) of three bioethanol production scenarios was assessed, revealing respective values of 3,574 L L-1, 3,935 L L-1, and 4,293 L L-1 for Case 2 (molasses bioethanol), Case 3 (50% sugarcane and 50% molasses bioethanol), and Case 1 (sugarcane bioethanol). Predominantly, 99% of the total WF comes from sugarcane plantation activities, with the blue WF (freshwater use) accounting for a mere 1.3%, owing to predominantly rainfed sugarcane farms. Region VI, encompassing Negros Occidental, faces severe blue water scarcity at 41%, with projections indicating exacerbation unless water footprint mitigation strategies are implemented. Notably, the contribution of the bioethanol industry to the total WF of the region is only about 0.1%. Sensitivity analysis for varying sugarcane yield done revealed that increasing yield from 65 t ha-1 to 115 t ha-1 can significantly reduce WF to about 43%. This research underscores the need for water-efficient practices to address potential water scarcity of the region, while emphasizing the limited water scarcity impact of bioethanol industry.

Farmers’ Adaptation of Floods, Droughts and Disaster Risk Preparedness: The Case of Angat, Bulacan, Philippines

Vanessa Camille A. Agbay, Patricia Ann J. Sanchez, Donny Rey D. Camus, Jessa O. Aquino-Cando, Eduardo Miguel N. Barroga, Ashemir B. Velasco

Abstract: Variability of rainfall caused by climate change has brought great impacts in the country, especially the agriculture sector. This study aimed to assess the effects and impacts of climate change, particularly flood and drought events, in the agriculture sector of Angat, Bulacan, Philippines. A household survey was conducted with 393 farmers surveyed using multi-criteria questionnaires. Sixty-two percent of farmers has been affected by drought, and 33.84% of them had their crop production decreased for more than 50% of their usual harvest. Absence of rain has affected majority of farmers (29.50%) whose farmlands are rainfed. Lack of irrigation facilities also affected the level of crop production in the locality. Majority of the respondents (46.56%) have experienced the effects of floods, especially those who reside near Angat River where overland flow occurs. Aside from damaged infrastructures and properties, the respondents also experienced water-borne diseases like diarrhea and skin infections. Farmers were able to adapt with the effects of climate change such as creating their own wells and planting crops that are suitable for the season. This study could aid in the improvement of adaptation measures of local farmers in Angat.