Mid-level synoptic analysis of flood-generating systems in South-west of Iran (case study: Dalaki watershed river basin)

Abstract

Abstract. Flood is known as one of the most distractive natural disaster worldwide. Therefore, its prediction is of great importance from the socio-economical point of view. Despite the great improvement in computational techniques and numerical weather prediction approaches, so far, in Iran, an acceptable flood prediction method has not yet been introduced. The main aim of this study is to recognize and classify the patterns of synoptic systems leading to torrential rainfalls in a watershed basin located in south-west of Iran. In this research, 20 major floods characterized by high rainfall intensities and severe damage were selected. The pattern, extension, and the direction of movement of the selected synoptic maps from surface to 500 hPa pressure levels were identified. Furthermore, the position of cyclones, anti-cyclones and mid-level trough lines were carefully tracked and classified into different groups. The results show that the major severe floods occurring in Dalaki watershed river basin are mainly influenced by strengthening of the center of Sudan heat low (SHL) and the coincidence moisture feeding by the Indian Ocean and Mediterranean Sea. It was found that simultaneous merging of the SHL system and Mediterranean frontal system would intensify the flood intensities over the basin. The mean positions of high pressures, low pressures, the Red Sea trough lines and 1015 hPa isobars of the major floods are also discussed.

Extreme precipitation events in the Middle East: Dynamics of the Active Red Sea Trough

“…[48] Our study underscores that the intensified AA and associated moisture transport not only characterize the December 1993 event [Ziv et al, 2005] and the Jeddah 2009 event [Haggag and El-Badry, 2013], but are relevant for all analyzed Levant ARSTs (Figure 8). Apart from the ARST, the AA and associated moisture transport are also involved in precipitation and floods in Iran [Farajzadeh et al, 2007;Sabziparvar et al, 2010;Raziei et al, 2012]. The latter study found the AA to induce lower tropospheric moisture transport from tropical water bodies (Arabian Sea, Oman Sea, Persian Gulf, Red Sea, and northern Indian Ocean) into cyclonic systems near Iran.…”

Daily Precipitation Extremes in Iran: Decadal Anomalies and Possible Drivers

“…Iran, which is located in the mid-latitude belt of arid and semiarid regions of the Earth, is affected by extreme precipitation events. Due to specific topographic, land cover, and soil conditions in the country, heavy precipitation cannot penetrate into the ground, leading to sudden runoff flows and disastrous floods in vulnerable areas (Sabziparvar et al, 2010). For that reason, flash floods have increased during recent years in the country (Roughani et al, 2007;DOE, 2010).…”

Harmonic Analysis of the Spatiotemporal Pattern of Thunderstorms in Iran (1961–2010)

“…On the other hand, the patterns that do not form a cluster can be recognized too. Moran's I is calculated through equation (6) or equation (7). Z score is calculated by equation (8).…”

“…understorms may be the result of severe gradient between two systems [7,8]. A number of studies have indicated that height plays a significant role in the onset and evolution of storms [9].…”