Genesis of the Sinkholes at Al-Najaf Governorate, South Iraq

Varoujan K Sissakian,Mohammad K Mohammad,Hayder Al-Rammahi

doi:10.46717/igj.55.1a.6ms-2022-01-25

Varoujan K Sissakian, Mohammad K Mohammad + Show 1 more

Open Access

https://doi.org/10.46717/igj.55.1a.6ms-2022-01-25

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Abstract

Al-Najaf Governorate covers a large part of the western side of the Southern Desert of Iraq and extends to the Iraqi-Saudi Arabian borders. The western and southern western parts have almost a desert environment with flat terrain, which is dissected by tens of valleys; all trend in SW- NE direction and drain to the Euphrates River. The area under consideration is covered by Umm Er Radhuma, Dammam, Euphrates, Ghar, Nfayil, Injana, and Zahra formations ranging in age from Paleocene to Pleistocene age, with different types of Quaternary sediments. The main rock types are limestone and dolostone, with subordinate amounts of marl, sandstone, claystone, and breccia. One of the main characteristics of this wide and flat plain is the karstification, which is expressed by development of sinkholes. Seven large sinkholes were studied with detailed characteristics of each sinkhole to indicate the genesis of their development and relation between them. From the seven studied sinkholes, six are still active, and one of them called Soga’a sinkhole was developed in 1944.

Highlights

The area of Al-Najaf Governorate; as all other areas of the Iraqi Southern Desert is well known karstified areas (Ma’ala, 2009)
Because it is an active sinkhole; the existing small aperture will be widened by time; due to continuous dissolution of the limestone beds by ground and surface water, and the aperture will be widened by continuous collapsing of the roof
The following can be concluded: Seven sinkholes are developed in Al-Najaf Governorate, which forms part of the Iraqi Southern Desert

Summary

Introduction

The area of Al-Najaf Governorate; as all other areas of the Iraqi Southern Desert is well known karstified areas (Ma’ala, 2009). The majority of the exposed rocks are carbonates; this is one of the main reasons for the intense karstification, which is still active Some rocks such as limestone, dolomite, and gypsum have high ability of dissolving by water; voids and caverns will be developed which is known as karstic area. Such areas are well known to include drainage systems on surface and subsurface with different karst forms (Jackson, 1997). The area under consideration is a desert; the average annual rain fall is 95.5 mm, annual relative humidity is 46.756%, mean annual temperature is 24.19○ C, and wind speed ranges from 1.8-4 m/ sec.

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