Disaggregation of future GCMs to generate IDF curves for the assessment of urban floods


Taysi H., Özger M.

JOURNAL OF WATER AND CLIMATE CHANGE, vol.13, 2022 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 13
  • Publication Date: 2022
  • Doi Number: 10.2166/wcc.2021.241
  • Journal Name: JOURNAL OF WATER AND CLIMATE CHANGE
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Aqualine, Aquatic Science & Fisheries Abstracts (ASFA), CAB Abstracts, Compendex, Geobase, Veterinary Science Database, Directory of Open Access Journals
  • Keywords: climate change, disaggregation, GCM, IDF curves, RCP, urban floods, CLIMATE-CHANGE, RAINFALL, REGIONS, MODEL
  • Istanbul Technical University Affiliated: Yes

Abstract

Urbanization and industrialization cause an increase in greenhouse gas emissions, which in turn causes changes in the atmosphere. Climate change is causing extreme rainfalls and these rainfalls are getting stronger day after day. Floods are threatening urban areas, and short-duration rainfall and outdated drainages are responsible for urban floods. Intensity-Duration-Frequency (IDF) curves are crucial for both drainage system design and assessment of flood risk. Once IDF curves are determined from historical data, they are assumed to be stationary. However, IDF curves must be non-stationary and time varying based on preparation for extreme events. This study generates future IDF curves with short-duration rainfalls under climate change. To represent future rainfall, an ensemble of four Global Climate Models generated under Representative Concentration Pathways (RCP) 4.5 and 8.5 were used in this study. A new approach to the HYETOS disaggregation model was applied to disaggregate daily future rainfall into sub-hourly using disaggregation parameters of hourly measured rainfalls. Hence, sub-hourly future rainfalls will be obtained capturing historical rainfall patterns instead of random rainfall characteristics. Finally, historical and future IDF curves were compared. The study concludes that increases in short-duration rainfalls will be highly intensified in both the near and distant futures with a high probability.