ASSESSING THE HYDROLOGIC EFFECTS OF URBANIZATION THROUGH NUMERICAL MODELING USING SWAT: A CASE STUDY OF LAGUNA DE BAY BASIN

Laguna de Bay, having a surface area of about 900 km2 is the largest freshwater lake in the Philippines, and is the most important water body in Metro Manila with its variety of uses ranging from aquaculture, irrigation, water supply and flood control. Due to its available resources and strategic location, over extraction, land conversion, and urbanization, have resulted in massive changes in the lake's watershed. The objective of this study is to simulate the impact of land cover change, particularly urbanization, on the hydrology of Laguna de Bay watershed. By hypothetically converting brushland to urban areas and using ArcSWAT to simulate the effects of urbanization, discharges and water balances were assessed. The long-term hydrologic simulations showed an annual increase of 20.6 m3/s (68%) in surface runoff and a 12.8 m3/s (26%) decrease in groundwater recharge for the entire watershed as urban areas increase. The mean seasonal flows were 75. m3/s during the dry season and 149.4 m3/s during the wet season for the original land cover, and 70.2 m3/s and 154.1 m3/s for the urbanized land cover, during the dry and wet seasons, respectively. Water percolating into the aquifers beneath the ground were also lessened by 13.6 m3/s (23%). The calibration of Marikina subbasin resulted to a satisfactory percent bias (PBIAS), Nash-Sutcliffe (NSE), and the ratio of the root-mean-square error to the standard deviation of measured data (RSR). Other subbasins resulted in a relatively lower performance rating due to limited available monitoring stations within the basin.

Investigating Fish Contamination Scenario and Community Willingness to Adopt Consumption Advice Proposing an Advisory Model

Consumption advice to ensure the health and safety of fish consumers remains urgent to handle the ever-increasing panic over heavy metal toxicity. Moreover, studies of fish consumption rarely focus on the perceptions and awareness of consumers. Considering this, the present study examines the knowledge and perceptions of the risks and benefits of fish consumption among consumers of Laguna de Bay to explore their willingness to follow fish consumption advice. The seasonal variation in selected types of heavy metal contamination in two commercially important fish species, tilapia and mudfish, was analysed and a vulnerability map based on the risk‒benefit ratio was produced for Laguna de Bay. Furthermore, this study formulates fish consumption advice for consumers of fish in the area. Primary data on consumers’ perceptions were collected through a questionnaire, whereas heavy metal contamination data were compiled from the best available literature. We concluded that people’s willingness to adopt consumption advice is mostly dependent on their existing level of fish consumption. Moreover, consumption advice is formulated to indicate restrictions on consumption for the areas identified as vulnerable due to contamination. This empirical study can serve as a model for the future development of fish consumption advice in the region.

IoT-based Estimation System for Microcystis aeruginosa Cyanobacteria in Laguna de Bay using an Arduino-controlled Spectrophotometric Device

Laguna de Bay, the largest freshwater lake in the Philippines, provides livelihood to the fishermen and serves as a source of potable water to the locals. However, freshwater quality has degraded, whereas one of the main contributors are Cyanobacteria that produce cyanotoxins. Existing studies that uses a similar device are either too expensive or too bulky. The purpose of this study is to estimate the cyanobacteria concentration by using a low-cost 16-channel spectrophotometric device to determine the level of severity efficiently. Using Linear Regression, the dataset is modelled by the algorithm to estimate the number of cyanobacteria present on the water sample, while Support Vector Machine (SVM) algorithm for severity level classifier. This study achieved high accuracy in estimating the cyanobacteria using linear regression and classifying the level of severity by support vector machine.

CRUSTACEAN WASTE SHELLS AS ADSORPTION MATERIALS FOR HEAVY METALS IN AN AQUEOUS SOLUTION

Laguna de Bay is one of the country’s major lakes, providing a third of the fish consumed by Metro Manila’s 16 million residents. It also provides support for agriculture, industry, and hydropower generation, as well as providing a welcome respite for many Filipinos. However, because of the lake’s importance, it is threatened by a variety of issues, including pollution. Heavy metals such as mercury and lead are present in high concentrations in the lake. And these heavy metals may persist in fish, water, air and the human body. As a result, an adsorption technique for heavy metal removal in an aqueous solution was investigated. As an adsorbent, the produced chitosan from crustacean waste shells was employed. The study’s parameters were contact time, adsorbent quantity, and pH. Results showed that 0.5 g of chitosan has a higher absorption rate of 99% in 500 mg/L solutions compared to 1.0 g of chitosan with an adsorption rate of 98%. In terms of contact time, 60 minutes showed almost 100% adsorption rate while 120 minutes was 98%. With increasing pH, the amount of metal adsorption rises. This developed chitosan from crustacean waste shells indicates high capacity as adsorbent materials for heavy metals. As a result, it appears to be a viable material for water treatment.

CRUSTACEAN WASTE SHELLS AS ADSORPTION MATERIALS FOR HEAVY METALS IN AN AQUEOUS SOLUTION

Laguna de Bay is one of the country's major lakes, providing a third of the fish consumed by Metro Manila's 16 million residents. It also provides support for agriculture, industry, and hydropower generation, as well as providing a welcome respite for many Filipinos. However, because of the lake's importance, it is threatened by a variety of issues, including pollution. Heavy metals such as mercury and lead are present in high concentrations in the lake. And these heavy metals may persist in fish, water, air and the human body. As a result, an adsorption technique for heavy metal removal in an aqueous solution was investigated. As an adsorbent, the produced chitosan from crustacean waste shells was employed. The study's parameters were contact time, adsorbent quantity, and pH. Results showed that 0.5 g of chitosan has a higher absorption rate of 99% in 500 mg/L solutions compared to 1.0 g of chitosan with an adsorption rate of 98%. In terms of contact time, 60 minutes showed almost 100% adsorption rate while 120 minutes was 98%. With increasing pH, the amount of metal adsorption rises. This developed chitosan from crustacean waste shells indicates high capacity as adsorbent materials for heavy metals. As a result, it appears to be a viable material for water treatment.

Economic Impact Evaluation and Household Adaptation to Extreme Weather Events in the Municipality of Bay, Laguna, Philippines

Bay is one of the municipalities in the province of Laguna that is situated along the coast of Laguna de Bay, and is particularly vulnerable to natural disasters including typhoons and flash floods. Among these, Barangay Dila, San Isidro, and Tagumpay located in low-lying elevation of the Municipality of Bay were not spared by the impacts caused by the disaster. Hence, the study site was conducted in these flood-prone areas of the Municipality. In this study, it highlights the impacts and adaptation of the household to extreme weather events. Specifically, the study aims to identify, quantify, and monetized (whenever possible) the household's impacts of extreme floods and typhoons; described the adaptation actions undertaken by the households; and to evaluate the factors that significantly affect the choice of adaptation activities. The data used in this study was collected through a survey of 90 households. In selecting the household, random sampling was employed using the data that was acquired from the municipality. The selected household heads were interviewed using the structured sample questionnaire. Probit regression was employed to test the significant factors of the choices of adaptation activities of the household. The study revealed that the impacts of extreme weather events on the households of Bay, Laguna could be considered to be ranging from moderate to severe cases depending on the geographical location of the households. Also, households of Bay, Laguna considers the height of flood and distance from bodies of water as significant factors for undertaking adaptation actions.

Vorticella and Colacium as epibionts of copepods in Pasig river, Philippines

The chitinous exoskeleton of copepods serves as a scaffold for microepibionts such as protozoa. Although copepods are highly cosmopolitan, their associated epibionts in the tropics are poorly known. This study presents the first account in the Philippines of the ciliate Vorticella on calanoid copepod Arctodiaptomus dorsalis and both Vorticella and the euglenoid Colacium on the cyclopoid copepods Thermocyclops crassus and Mesocyclops microlasius in the Pasig River. Infestation, however, was low at 0.83% (108 out of 13,039) observed copepods from four collection sites in January-May and July-December 2018. Interestingly, Vorticella and Colacium were frequently observed in cyclopoid than on calanoid copepods, predominantly on the urosome, thorax, cephalosome of copepodites and adult stages of copepods. Colacium was also found attached on the antennules, swimming legs, caudal rami and setae. Prevalence of epibionts was site-related; Vorticella being more abundant in waters near Manila Bay (Site 1) where high salinity, conductivity and total dissolved solids were recorded while Colacium was found more near Laguna de Bay (Site 4). Both were abundantly present in September and absent in May, due to increased inflow of seawater from Manila Bay. Nevertheless, overall low infestation resulted in neither significant spatial nor temporal variation of epibiosis in Pasig River, probably due to heavy loadings of wastewater from nearby tributaries, noticeable algal blooms, detachment of epibionts by predations and changes in water chemistry.