## 1 Introduction  
The Philippines is located within the pacific ring of fire, where earthquakes, volcanic eruptions, and typhoons occur frequently. Agence France-Presse [1] listed ten of the deadliest natural disasters in the country, and 5 of them were typhoon and flooded-related. According to Tropical Cyclone Information, the country is struck by an average of 20 typhoons annually, 70% of which occur from July to October [2]. The Philippine Statistics Authority [3] released a more comprehensive record of all the major disasters in the country from 2010 to 2019, and the results showed flooding as the most frequently experienced disaster at 387 occurrences that induced tremendous economic losses. Data and records proved how flood-prone the country is, and this trend is expected to worsen in the future considering the effects of climate change [4]. Marinduque is one of the most beautiful islands in the country, located in Region IV-B of Luzon. The province's total land area is 952.58 square kilometers and has a total population of 239,207 as of 2020 [5]. The island is also often visited by typhoons, as presented in Figure 1a. Figure 1b shows that many typhoons passed the province, particularly in May, September, and December, suggesting that these are the months when typhoon-induced flooding events are most likely to occur in the area. Last 2014, Marinduque experienced one of the strongest typhoons to hit the island, which caused the three major rivers on the island, the Sta Cruz, Boac, and Mogpog rivers, to overflow. The maximum flood height in Boac was 2.52 m during typhoon Glenda last July 2014 [6]. Another typhoon event was experienced in 2020, swelling the same rivers [7] due to intense rainfall. With these frequent and disastrous flooding events in the area, a government project entitled Phil-Lidar 1 created hazard maps to identify flood-prone areas and predict how extensive flooding would be regarding different rainfall return periods. The Boac and Mogpog rivers have a watershed area of 214 km\({}^{2}\) and 58 km\({}^{2}\), respectively. About 36.1% of the municipality of Boac, and 18.4% Mogpog, are prone to flooding [6]. Another dilemma of the people in the area is the contamination of surface water and soils by hazardous heavy metals from the abandoned open mine pits and tailings storage facilities (TSFs) located upstream of the two rivers. Marinduque province is home to the porphyry copper-gold-molybdenum deposit, a 372-million-ton orebody containing 0.55% copper, 0.004% molybdenum, 0.11 g/t gold, and 0.7 g/t silver [8]. Major mining activities commenced in 1969 and ran smoothly until 1997. The mining operation stopped after two mining incidents that occurred in 1993 and 1996. In December 1993, the company's Maguilaguila TSF embankment collapsed and flooded the town of Mogpog [9]. Because of this incident, twenty-one barangays in Mogpog were buried in tailings and toxic floodwater. The second disaster, one of the worst mining and environmental disasters in the Philippines,  
Figure 1: Typhoon Occurrences in Marinduque Province (**a**) Typhoon Tracks and (**b**) Number of typhoons that visited the island per month from 1948 to 2017.  
occurred on 24 March 1996 when the concrete drainage tunnel \"plug\" of the Tapian pit gave way, releasing more than 1.6 million cubic meters of toxic mine tailings into the Boac River [10]. The Tapian pit is a decommissioned open pit, which was repurposed by the company as an in-pit TSF from 1989 for their San Antonio mine site. These two mining disasters contaminated the two rivers and their surrounding environments with heavy metals via two pathways: (1) release and dispersion of sulfide minerals like pyrite (FeS\({}_{2}\)), chalcopyrite (CuFeS\({}_{2}\)), galena (PbS), and sphalerite (ZnS) found in the tailings; and (2) formation mine drainage contaminated with heavy metals in the abandoned mine sites.