Causes and consequences of recent floods in the Golestan catchments and Caspian Sea regions of Iran

Abstract

In August 2001, the worst flash flooding event of the Caspian Sea regions in over two centuries claimed over 300 lives after a weekend of heavy rainfall and brought about a devastating disaster in the Mother-Soo catchment, province of Golestan, Iran. As a result of this event, a series of site investigation were carried out to identify the pertinent factors that led to a flood of this magnitude. This paper identifies the fundamental causes of the frequent floods and debris flow occurrence in the area prone to flooding and analyzes the main runoff mechanism of these events. The maximum observed 24-h rainfall depths and maximum peak discharges at the existing gauges were compared with the depths of rainfall and the peak values corresponding to the August 2001 flood respectively. For the majority of the rain gauges, the rainfall depth exceeded those of historical recorded events. In Golestan dam, an increase of 7.5 times the maximum value observed in the past 20 years was noted. The flood height was 10-15 m while passing through the middle subcatchment area of Golestan National Park. The preliminary evaluation indicates the existence of bare soil in the catchment, movable material, steep slopes, high rainfall intensity, deterioration of pasture and forest land, and inappropriate agriculture and development practices as well as climate change were the main factors for the occurrence and the extent of the August 2001 disaster. Finally, due to the likelihood of flooding and debris flow events in future, some countermeasures are proposed.

Application of Harmony Search Algorithm to Reservoir Operation Optimization

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“…Over the past 10 years, extreme precipitation events have contributed to an increase in the frequency of flash floods in this area. During the first half of the 2000-2010 decade, Golestan experienced the most deadly flash floods in its recorded history (Sharifi et al, 2011). On August 10, 2001 an extreme storm and flood occurred in the eastern part of the province, as a result of a nearly 10-hour rainfall with 170 mm depth.…”

Assessment of climate change downscaling and non-stationarity on the spatial pattern of a mangrove ecosystem in an arid coastal region of southern Iran

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