Defining a Disturbance Gradient in a Middle-Eastern River Basin

Area of Science:

• River ecology
• Environmental science
• Water resource management

Background:

• Evaluating river ecological quality is crucial for effective restoration.
• Disturbance gradients impact riverine ecosystems significantly.
• Integrated assessment requires physical, chemical, and biological data.

Purpose of the Study:

• To develop and validate an approach for identifying a disturbance gradient in the Karun River Basin.
• To classify river sites based on their level of disturbance.
• To provide tools for characterizing riverine environmental quality.

Main Methods:

• Collected physical structure and physico-chemical data seasonally from 54 sites (October 2018 - September 2019).
• Utilized Principal Components Analysis (PCA) on 17 variables to identify key influential factors.
• Classified sites into least, moderate, and most disturbed categories.
• Validated the classification using the Ephemeroptera, Plecoptera, and Trichoptera (EPT) taxa metric.

Main Results:

• Five key variables (conductivity, total habitat score, stream morphology, clay & silt, sand) were influential across seasons.
• 54 sites were classified into 14 least disturbed, 26 moderate, and 14 most disturbed.
• Least disturbed sites showed significant ecological differences from moderate and most disturbed sites (p < 0.01).

Conclusions:

• The proposed criteria and methods are appropriate tools for characterizing disturbance gradients in river basins.
• The validation confirmed the a priori reference site selection process.
• This integrated approach supports ecological quality assessment and restoration planning for the Karun River Basin.