Stability Analysis of Masonry Check Dams in the Kelestan Watershed

Assessing performance of watershed management activities will provide valuable information to managers and decisionmakers for long-term planning. Stability of 70 masonry check dams was evaluated that have been constructed on the Kelestan Watershed, Shiraz, in 2006. Relevant information of these structures, namely position, number, type competence of materials, current performance, degradation status (intensity and location), type and culprits of damage were recorded during field visits, and the distribution map of the structures was prepared. Stabilitiesagainst subsidence, overturning and sliding were also investigated. The designed discharge of the check dams was to be correlated with the different return periods during the elapsed time. The results showed that as the designed discharge of the check dams for a 25-years return period had not occurred yet up to the evaluation date (2014), their stability cannot be evaluated based on the lower discharges. As to subsidence, no measurable settlement was discovered. Furthermore, 98.6 percent of the check dams showed stability against overturning and sliding and only1 (1.4 percent) of the check dams was collapsed completely. Signs of damage are observed in the check dams despite showing stability against subsidence, overturning and sliding. Poor quality building materials, unsuitable placement and piping are the main causes of damage on this watershed. To prevent the piping phenomenon, the soil under the structure must be removed and compacted in different layers.