Effects of the Karkheh Dam construction on haze generation due to geomorphological changes in the Khuzestan Province, Southwest Iran

Arash Adib

doi:10.2166/ws.2021.376

Abstract

Abstract The construction of the Karkheh Dam is an important factor contributing to the occurrence of dust storms in the Khuzestan Province of Iran. It has reduced the annual mean flow discharge in the Karkheh River from 120 to 50 m3/s and dried land around the river. The area of dried land is 90.17 km2 around the river and 333.45 km2 in the Hawr-al-Azim wetland. The Rosgen method, Fluvial-12 software, and Shulits equation demonstrate the instability of the plan, cross sections and longitudinal slope of the river, respectively, around Pay-e-pol hydrometric station (upstream of the river). After dam construction, extreme erosion occurred in this part of the river. The type of sediment is clay and silt with D50 = 8 μm. The eroded sediment settles downstream (around Hamidiyeh hydrometric station) and the Hawr-al-Azim wetland. The wind can easily lift these particles especially from May to July. Because of the size of these particles, the haze concentration increased from 25% to 45% in dust storms. After construction of the dam, the dust storm days increased to 90 days in 2008. By increasing the stability of the river, the dust storms reduced from 2011. The annual volume of generated haze by geomorphological characteristic changes is almost 3107 m3.

Highlights

The environmental aspects of implemented projects are important for people who live in around of them
Since haze storms are very important problem for people who live in the Khuzestan province and developed changes in river geomorphology by construction of the Karkheh Dam have the fundamental role in this hazard, author of this paper evaluated relation between these changes and haze generation
Because of the relative stability of the geomorphological features of the river after 2013, this study considered the period 2004–2014 for evaluating dam construction effects on haze and dust storms

Summary

Introduction

The environmental aspects of implemented projects are important for people who live in around of them. In the Middle East, common projects between neighbor’s countries have serious effects on environment (because of competition between them). The area of the Hawr-al-Azim wetland reduced to one-third (from 307,000 hectares in the 1970s to 102,000 hectares ). Reducing the area of wetlands causes haze and dust storms. By variations of river geomorphological characteristics and reduction of river discharge, thickness of fine particles’ layer and area of dry lands increase in the Hawr-al-Azim wetland and downstream of river. The reduction of width and length of river increased area of dry lands. The topsoil layer of these lands is composed of fine- grained soils (clay and silt). These soils were suspended sediment that gradually settled in the river. Water content and shear strength of fine- grained soils reduced considerably and the wind could erode them (Adib et al 2018)

Methods

Results

Conclusion