The ability of the root suckers in the estimation of gully erosion by dendrogeomorphological analysis in Nilkooh catchment(Galikesh), Golestan province.

Accurate understanding of geomorphological processes plays an impoortant role in the management of soil erosion. Soil erosion caused by the development of gully is one of the serious environmental problems that disturbs the balance of natural systems through the loss of water and soil. Dendrogeomorphology is one of the new techniques to determine the erosion based on the appreciation of the morphology and structure of the tree roots and stems and it is a suitable substitute to traditional methods. This method is appiable for parts of roots that have been exposed by erosion processes and are datable.After tree root exposure due to the gully erosion, suckers can develop. In this study, the estimation of gully erosion rate in Nilcooh (Galikesh) catchment was carried out based on dendrogeomorphological analysis of annual growth ring of suckers formed on roots. In this regard, a total of 23 samples from the roots of broadleaf trees, including Evangelical and wild persimmons, that  have been exposed after erosion, were dated. The minimum and maximum ages of roots were 3 and 18 years respectively. In this study, roots that their ages were from 2001 to 2016 were sampled during 2013-2016. During sampling, the information such as dimension of gully and geographical coordinates were also recorded. then Samples were dried in natural conditions and have been sanded for better clarity. Results of this study reveal that the rate of gully bed erosion increases as elevation and gradient of earth surface increases while the rate of lateral gully erosion decreases as elevation and gradient of earth surface increases. The average of annual volume erosion of gully is 0.043 m3 and the rate of the average of lateral and bed gully erosion are 0.153 and 0.036 meter respectively.