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進入《TAIPEI TIMES》 CWA to recalibrate drought-related systems
A dried-up Banping Lake in Kaohsiung is pictured on April 17 last year. Photo: CNA
IMPROVED MONITORING: Armed with data from previous droughts, the CWA aims to provide water management and agricultural agencies with better drought warnings
/ Staff Writer, with CNA
The Central Weather Administration （CWA） said it is recalibrating its drought monitoring and early warning system to provide better early warnings to water management and agricultural agencies, after looking at data from three significant droughts Taiwan has experienced since 2000.
Taiwan’s regions are affected by drought differently, data from the National Science and Technology Center for Disaster Reduction’s Climate Change Disaster Risk Assessment Web site showed.
For example, when comparing the ratios of total precipitation between wet and dry seasons across the nation, the disparity is greater in southern Taiwan, so the risk of drought occurring in southern Taiwan is greater than in northern Taiwan.
There have been three severe droughts in Taiwan since 2000: one from 2002 to 2004, another from 2015 to 2016, and the last from 2020 to 2021, CWA climate forecasting division head Lo Tzu-ting （羅資婷） said.
Droughts are mainly caused by a lack of precipitation over an extended period, but there could be multiple causes, Lo said, adding that although the three severe droughts affected the whole nation, the severity varied depending on the region.
During the drought between 2020 and 2021, Taiwan had low rainfall due to strong North Pacific High pressure anomalies brought by La Nina. There were no typhoons during that period and the drought was more severe in central and southern Taiwan, Lo said.
Meanwhile, the severe drought from 2002 to 2004, which was not influenced by La Nina, was more serious in central and northern Taiwan, she said.
Rainfall across different regions was relatively low from October 2001 to June 2002, CWA data showed.
In addition to low total precipitation, the number of days with rainfall was also low, especially during the winter and spring seasons, with rainy days dropping to about one-third to one-half of the average number of rainy days for those seasons, the data showed.
In 2014, there was low precipitation during the wet seasons, causing a rare, major drought in Central Taiwan in 2015, which led to taxes being levied on heavy water users, the Water Resources Agency’s data showed.
There are several weather forecast models and drought indexes developed by different meteorological organizations and academics.
Taiwan uses the Standardized Precipitation Index （SPI） and Standardized Precipitation Evapotranspiration Index （SPEI） as meteorological drought indicators, Lo said.
The SPI characterizes droughts in different timescales, such as three months, six months or two years, while the SPEI measures drought severity according to its intensity and duration, and identify the onset and end of drought periods, she said.
Lo said the CWA is developing and recalibrating its drought monitoring and early warning system based on the SPI and the SPEI, which is expected to take about a year.
The improved drought warnings would first be provided to water management and agricultural agencies to help them prepare in advance, Lo added.
新聞來源：TAIPEI TIMES
