Road Construction and Geomorphic Instability in Deserts

Vest parts of the central and eastern of Iran are covered by mountain basin-rangedeserts. These deserts have developed during the quaternary alternating between dryand wet climatologically conditions, and now that earth is going through aninterglacial age, they are passing through a dry period. In such conditions, when thedesert landforms seem to be stabilized for short periods; rapid changes take place indesert geomorphic systems due to human-induced changes in the environment.Road construction has a great impact in deserts than the other human activities. Thisarticle, using air photos and satellite images and, particularly, field data, discusses theeffect of road construction on geomorphic instability of alluvial fan surfaces, playa anddesert pavements. The results show that:1. Road construction operations carried out on the surface of dry alluvial fans changethe equilibrium profile of main and secondary channels, resulting in intense verticalerosion;2. Road construction carried out in playa environments disrupt the balance of waterand sediments of surface streams and the terminal basin, bringing about changes inlandform boundaries.3. Road construction operations carried out on desert pavements in the resumption ofdeserts, causing wind deflation.