تأثير برداشت شن و ماسه بر خصوصيات ريخت سنجي رسوبات بستر رودخانه

Effects of sand and gravel mining on bed sediment morphometric characteristics

Exploitation of materials from river beds changes hydraulic and geometric characteristics of rivers which increases the flow turbidity and flow energy. It consequently accelerates erosion, causes environmental hazards and also affects the bed sediment morphometyric characteristics. The present research was conducted in Vaz River located in Mazandaran Province, Iran, to study the effects of exploitation of two sand and gravel mines on morphometric characteristics of bed sediment. To 6 achieve the study purpose, four cross sections were selected in the study river before and after each mine. The bed sediment were then sampled using combining technique and the important bed sediment characteristics viz. mean, standard deviation, skewness, kurtosis, mode, d10,d50, d90, gravel, sand, mud, large, medium and small diameters, shape factor, nominal diameter, sphericity, roundness, width ratio and sediment texture were then determined. The results of the study, despite of general similarities in hydraulic characteristics of cross sections before and after mines, revealed that the sand and gravel mining activities have had significant effects on all of the studied morphometric characteristics except sphericity and sediment texture.