Morphological Analysis and Assessment of a River Based on Morphological Characteristics, Artificial Structures and Channel Adjustment (Case Study: Talar River - Upstream of the Shirgah)

Alterations in river systems are inevitable and affect theenvironment. Rivers have played a very important role in creating and maintaining life on theearth since a long time ago. In other words, rivers are vital for sustaining life and ecosystems,providing essential freshwater for irrigation, drinking, and industry. However, humaninterventions including changes in land use patterns, construction near rivers, exploitation ofwater resources, and flood and storm management have significantly impacted on these crucialenvironmental systems. They can actually alter the spatial distribution and velocity ofgeomorphological processes such as sediment transport, erosion, and deposition, consequentlyleading to significant changes in river morphology. Therefore, assessing their morphologicalquality is important for their management and restoration. In this study, morphologicalassessment from the upstream to the midstream of the Talar River as a pilot has been conductedusing the Morphological Quality Index (MQI) to evaluate the morphological status.

First, Talar River was divided into two landscape units, three segmentsand 23 reaches based on the hierarchical approach and according to the physiographiccondition. Then, geomorphological functionality, artificial structure and Indicators of channeladjustment have been assessed by MQI which includes 28 parameters.

The results obtained from 28 MQI parameters in 23 reaches showedthat about 15% of the reaches have a "good" condition; almost 35% have a "moderate"condition, and more than 50% have "poor" and "very poor" conditions. Based on the assessmentalong the Talar river, the areas that are in the urban area due to the large amount of agriculture,urban development and road crossing have poor and very poor morphological quality class, andthe areas that are in the forest area are natural and have good morphological quality. Also, theresults of the assessment indicate that the average quality class of the investigated reaches is in"moderate" conditions.

The results show that most reaches of Talar River requires urgent measures for itsrestoration. In addition, although the MQI method can be appropriate and effective tool indiagnosing hydromorphological challenges. However, it is not still enough for an integratedmanagement and restoration, and it should be integrated with other indices regarding humanpressures i.e. water quality, hydrological and biological pressures.