Sciences marines : recherche et développement

Abstrait

Examination of Tectonic Activity Based on Knickpoint Distribution and Movement Potential of Faults in Khuzestan Province, South West Zagros, Iran

Rezvan Khavari

Although the distribution of fluvial knickzones, as an important geomorphic feature in bedrock river morphology, has been studied by many investigators, the role of them in examination of tectonic activity has not been well investigated [1], specially based on its comparision with movement potential faults over a broad area. This study examines the tectonic activity of Khuzestan province, South West Zagros, by considering two different parameters: distribution of the fluvial knickzones along Mountain Rivers and evaluation of faults activity in the study area. A segment of a river long-profile that is steeper than adjacent segments is commonly referred to as a knickzone or a knickpoint if it is visibly steeper than the trend of the longitudinal profile. Knickzones are often observed along bedrock rivers and the most visible form is a waterfall. Knickzones are supposed to be a response to base-level changes or to alternations of local lithology [2]. Upstream migration of knickzones has been argued to cause rapid river incision and result in the formation of terraces and instability of valley-side slopes. Knickpoint evolution on a river can provide evidence for uplift of plate margins [3]. Knickpoints can be used as geomorphic markers in steep, rapidly eroding landscapes that commonly lack datable river terraces [4]. In this paper we use the method that was proposed by Hayakawa and Oguchi [5] to extract knickzones in broad areas using DEMs (Digital Elevation Models) and GIS (Geographical Information System). DEM analysis of the longitudinal profiles of rivers permits quantitative, reproductible, and efficient identification of knickzones. The obtained inventory of knickzones will provide a basis for objective analyses of the distribution of knickzones.