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

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 Floods are threatening urban areas, and short-duration rainfall and outdated drainages are responsible for urban floods.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.

Disaggregation of Global Climate Model Data to Create Idf Curves Under RCP8.5 Scenario

“…In the study of Tayşi and Özger (2021), according to the HadGEM-ES model, precipitation will increase for Istanbul, and in the study of Gürkan et al (2016), there will be a general decrease in precipitation in Turkey in the 2023-2098 period according to the GFDL-ESM2M model. Similar results were observed between the results obtained in this study and some studies in the literature.…”

“…Studies have been conducted on the effects of global climate change on the environment (Davis et al, 2010;Angelique and Culley 2010), its effects on glaciers (Thompson 2010;Dinar and Mendelssohn 2009), and its regional effects (Brunettia et al, 2003;Abreu and Schönfelda 2003). Some of the studies have been done on climate models and scenarios (Tayşi and Özger, 2021;Giannakopoulos et al, 2009). In this study, it is aimed to predict IDF curves over climate models and scenarios.…”