Riverbank Stabilization Using Vegetation Cover in the Ferizi River, Khorasan Razavi Province

The use of vegetation cover for the sustainable riverbank stabilization is not only economical in most cases, but also ameliorates the landscape. The purpose of this research was to evaluate vegetatative stabilization of the Ferizi River, s erodible banks. Considering that each vegetative form offers a unique type of protection, 8 grass species, short shrub and a tree species were selected for this research. Salix eleganos Scop.,Salix alba L. Elaeagnos angustifolia L. were planted at suitable spacing on the banks. A plot without vegetative protection was established as the control steel pins with specific lengths were driven in to the banks at two rows and three cross sections. The depth of erosion was measured monthly for 4 years by an increase in the length of the pins outside of the river side on transects. The flow data were collected at the hydrometry station. The results indicated that shrub and tree cover performed satisfactorily in stabilizing the riverbank. The erosion depth for the shrub and tree cover was <1% of the control; this was 50% for the grass cover; therefore it was not as effective in erosion control as we had expected. The reason for this poor performance is due to the growth season of these grass species which is not synchronized with flooding season of the Ferizi River. It is interesting to note that the study duration coincided with the 5-year flow regime of the river.