Hydrological Response of the Pampanga River Basin in the Philippines to Intense Tropical Cyclone Rainfall

Abstract

The Philippines is frequently affected by tropical cyclones (TCs) and understanding the flood response of the PRB from TC-induced rain is needed in effective disaster risk management. As large uncertainties remain in TC rain forecasting, we propose a simple checklist method for flood forecasting of the PRB which depends on the general TC track, season, and accumulated rainfall. To this end, flood events were selected based on the alert, alarm, and critical river height levels established by the PhilippineAtmospheric, Geophysical and Astronomical ServicesAdministration (PAGASA). Results show that all flood events in the PRB were induced by TCs. All intense TCs that directly traversed the PRB resulted in critical level floods. These TCs also had the shortest flood onset of 7-27 hours from alert to critical level. Flooding from distant landfalling TCs, on the other hand, are dependent on season. TCs traversing north (south) of the PRB induced flooding only during the southwest (northeast) monsoon season. These TCs can raise water levels from alert to critical in 11 to 48 hours. Remote precipitation from non-landfalling TCs can also induce critical level flooding but with a longer onset time of 59 hours. These results indicate that a simple checklist method can serve as a useful tool for flood forecasting in regions with limited data and forecasting resources.

Spatial Prediction of Fluvial Flood in High-Frequency Tropical Cyclone Area Using TensorFlow 1D-Convolution Neural Networks and Geospatial Data

“…Floods continue to be a global concern [77,78], particularly in the western Pacific region, which is frequently impacted by tropical cyclones characterized by intense and prolonged rainfall [79,80]. While addressing flood challenges demands a multifaceted approach involving sustainable land use practices, improved infrastructure, community education, and comprehensive disaster preparedness and response strategies, accurate flood prediction continues to play a pivotal role.…”

Fecal Enterococci Levels in Selected Tributaries of the Pampanga River Basin, Philippines, and Their Relation to Land Use

“…With the Manila Bay as the endpoint, the Pampanga River has a total length of around 260 km, the Angat River at around 153 km, and the Santa Maria River at around 26 km (as per Google Maps estimate). In addition, according to the 2013-2018 monthly and yearly discharge data collected by Macalalad et al [24], the volume of water that drains from the rivers of the PRB to the Manila Bay, which generally increases from June to December, can exceed 500 m 3 per second when at least two (2) tropical cyclones occur. As previously stated, the survival of FIB could be extended when attached to nutrient-rich sediments that harbor feces, decaying organic matter, and other debris, which are commonly discharged into the water bodies near areas with poor or non-existent sanitation systems.…”

The Effect of the Cordillera Mountain Range on Tropical Cyclone Rainfall in the Northern Philippines

“…A summary of the options used is listed in Table 1. Choices of physical parameterisation schemes and model configuration were adapted from the operational forecasting configurations of the Philippine weather bureau, Philippine Atmospheric, Geophysical and Astronomical Services Administration [24], optimisation studies by Tolentino and Bagtasa (2021) [25], historical comparisons by Bagtasa (2021) [26], and sensitivity tests for TC simulations conducted by Delfino et al (2022) [27]. Additionally, we adapted the Planetary Boundary Layer scheme based on the study of Cruz and Narisma [28] due to its performance in simulating heavy precipitation over Luzon.…”

“…Additionally, two major river basins of the Philippines are located within the boundaries of the CMR, with the Cagayan River basin to the east and the Pampanga River basin to the south of the mountain range. Both river basins have experienced major flooding in recent years [17,18], and understanding how the CMR affects TC precipitation, especially for stronger TCs, may be helpful in regional flood forecasting efforts.…”