Extraction of Intensity-Duration-Frequency (IDF) Curves under Climate Change, Case study: Isfahan Synoptic Station

Many hydraulic structures are designed by using the design precipitation with return periods duration time based on concentration time. Therefore, in any region, Intensity-Duration-Frequency (IDF) curves play a significant role in the design of dimensions and components of these systems especially in regions without adequate rain gauge stations. However, following climate change due to the increasing human activities precipitation patterns has changed in various regions of the world. Therefore, the historical IDF curves are not applicable. In this study, according to the Isfahan meteorological synoptic station IDF curves were developed. Eextraction of precipitation intensity with continued short of 24-hour precipitation has been done by using fractal theory. In the present study, extractions of the IDF curves were divided into three periods: the historical period (1967-1993), the present period (1994-2016), and the future period (2017-2035). It was perceived that precipitation intensity with short-term duration increased because of changes in the climatology, and IDF curves are shifted upwards. In this study, to predict the daily precipitation weighted output 15 AOGCM models under the A2 emission scenario related to the Fourth Assessment Report (AR4) IPCC, as the most reliable tool were used. The results show that the predicted IDF for future (2017-2035) will increase about 52 percent related to past IDF (1967-1993) in this region.