Spatiotemporal Analysis of Extreme Rainfall and Meteorological Drought Events over the Angat Watershed, Philippines
Understanding the spatiotemporal distribution of extreme rainfall and meteorological drought on a watershed scale could be beneficial for local management of any water resources system that supports dam operation and river conservation. This study considered the watershed of Angat as a case, given i...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-12-01
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| Series: | Atmosphere |
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| Online Access: | https://www.mdpi.com/2073-4433/14/12/1790 |
| _version_ | 1827575716777033728 |
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| author | Allan T. Tejada Patricia Ann J. Sanchez Francis John F. Faderogao Catherine B. Gigantone Roger A. Luyun |
| author_facet | Allan T. Tejada Patricia Ann J. Sanchez Francis John F. Faderogao Catherine B. Gigantone Roger A. Luyun |
| author_sort | Allan T. Tejada |
| collection | DOAJ |
| description | Understanding the spatiotemporal distribution of extreme rainfall and meteorological drought on a watershed scale could be beneficial for local management of any water resources system that supports dam operation and river conservation. This study considered the watershed of Angat as a case, given its economic importance in the Philippines. A series of homogeneity tests were initially conducted on each rainfall dataset from monitoring stations in and near the watershed, followed by trend analysis to determine the rate and direction of change in the annual and seasonal rainfall extreme indices in terms of intensity, duration, and frequency. Three indices, using the rainfall deviation method (%DEV), percent of normal rainfall index (PNRI), and Standardized Precipitation Index (SPI), were also used to identify meteorological drought events. Generally, rainfall in the watershed has an increasing annual PCPTOT (4–32 mm/year), with increasing frequency and intensity in heavy rainfall and wet days. A significant increasing trend (α = 5%) in the seasonal PCPTOT (7–65 mm/year) and R10mm (1.7–10.0 days/decade) was particularly observed in all stations during the Amihan Monsoon Season (Dec–Feb). The observed increasing rainfall intensity and frequency, if it continues in the future, could have an implication both for the water resources operation to satisfy the multiple objectives of Angat Reservoir and for the flood operation that prevents damage in the downstream areas. The effect of each ENSO (El Niño- Southern Oscillation) phase on the rainfall is unique in magnitude, intensity, and duration. The seasonal reversal of the ENSO in the extreme rainfall and meteorological drought signals in Angat Watershed was also evident. The identified meteorological drought events in the watershed based on SPI-12 persisted up to 12–33 months, could reduce more than 60% (PNRI < 40%) of the normal rainfall. Insights from the study have implications for the hydrology of the watershed that should be considered for the water resources management of the Angat Reservoir. |
| first_indexed | 2024-03-08T21:00:58Z |
| format | Article |
| id | doaj.art-c1b4007bfee3483fbb67d116560379af |
| institution | Directory Open Access Journal |
| issn | 2073-4433 |
| language | English |
| last_indexed | 2024-03-08T21:00:58Z |
| publishDate | 2023-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Atmosphere |
| spelling | doaj.art-c1b4007bfee3483fbb67d116560379af2023-12-22T13:52:52ZengMDPI AGAtmosphere2073-44332023-12-011412179010.3390/atmos14121790Spatiotemporal Analysis of Extreme Rainfall and Meteorological Drought Events over the Angat Watershed, PhilippinesAllan T. Tejada0Patricia Ann J. Sanchez1Francis John F. Faderogao2Catherine B. Gigantone3Roger A. Luyun4Interdisciplinary Studies Center for Water, University of the Philippines Los Baños, Los Baños 4031, Laguna, PhilippinesInterdisciplinary Studies Center for Water, University of the Philippines Los Baños, Los Baños 4031, Laguna, PhilippinesInterdisciplinary Studies Center for Water, University of the Philippines Los Baños, Los Baños 4031, Laguna, PhilippinesInterdisciplinary Studies Center for Water, University of the Philippines Los Baños, Los Baños 4031, Laguna, PhilippinesInterdisciplinary Studies Center for Water, University of the Philippines Los Baños, Los Baños 4031, Laguna, PhilippinesUnderstanding the spatiotemporal distribution of extreme rainfall and meteorological drought on a watershed scale could be beneficial for local management of any water resources system that supports dam operation and river conservation. This study considered the watershed of Angat as a case, given its economic importance in the Philippines. A series of homogeneity tests were initially conducted on each rainfall dataset from monitoring stations in and near the watershed, followed by trend analysis to determine the rate and direction of change in the annual and seasonal rainfall extreme indices in terms of intensity, duration, and frequency. Three indices, using the rainfall deviation method (%DEV), percent of normal rainfall index (PNRI), and Standardized Precipitation Index (SPI), were also used to identify meteorological drought events. Generally, rainfall in the watershed has an increasing annual PCPTOT (4–32 mm/year), with increasing frequency and intensity in heavy rainfall and wet days. A significant increasing trend (α = 5%) in the seasonal PCPTOT (7–65 mm/year) and R10mm (1.7–10.0 days/decade) was particularly observed in all stations during the Amihan Monsoon Season (Dec–Feb). The observed increasing rainfall intensity and frequency, if it continues in the future, could have an implication both for the water resources operation to satisfy the multiple objectives of Angat Reservoir and for the flood operation that prevents damage in the downstream areas. The effect of each ENSO (El Niño- Southern Oscillation) phase on the rainfall is unique in magnitude, intensity, and duration. The seasonal reversal of the ENSO in the extreme rainfall and meteorological drought signals in Angat Watershed was also evident. The identified meteorological drought events in the watershed based on SPI-12 persisted up to 12–33 months, could reduce more than 60% (PNRI < 40%) of the normal rainfall. Insights from the study have implications for the hydrology of the watershed that should be considered for the water resources management of the Angat Reservoir.https://www.mdpi.com/2073-4433/14/12/1790rainfall extremesAngat DamEl Niñometeorological droughtSPI |
| spellingShingle | Allan T. Tejada Patricia Ann J. Sanchez Francis John F. Faderogao Catherine B. Gigantone Roger A. Luyun Spatiotemporal Analysis of Extreme Rainfall and Meteorological Drought Events over the Angat Watershed, Philippines Atmosphere rainfall extremes Angat Dam El Niño meteorological drought SPI |
| title | Spatiotemporal Analysis of Extreme Rainfall and Meteorological Drought Events over the Angat Watershed, Philippines |
| title_full | Spatiotemporal Analysis of Extreme Rainfall and Meteorological Drought Events over the Angat Watershed, Philippines |
| title_fullStr | Spatiotemporal Analysis of Extreme Rainfall and Meteorological Drought Events over the Angat Watershed, Philippines |
| title_full_unstemmed | Spatiotemporal Analysis of Extreme Rainfall and Meteorological Drought Events over the Angat Watershed, Philippines |
| title_short | Spatiotemporal Analysis of Extreme Rainfall and Meteorological Drought Events over the Angat Watershed, Philippines |
| title_sort | spatiotemporal analysis of extreme rainfall and meteorological drought events over the angat watershed philippines |
| topic | rainfall extremes Angat Dam El Niño meteorological drought SPI |
| url | https://www.mdpi.com/2073-4433/14/12/1790 |
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