Abstract
Check dam is the most costly watershed management practice. This research was an attempt to evaluate the effectiveness of individual check dams in different watersheds of Chaharmahal-va-Bakhtiari. 11 criteria impacting upon check dams’ individual efficiency were considered: check dam location, check dam stability, longitudinal profile fixing, check dam's coefficient of sediment storage, check dam's crest to be perpendicular to channel's axis, spillway dimensions, check dam strength, anchorage, check dams built according to channels' cross section, consistency of spillway center with stream alignment and apron length. The importance of each criterion for each check dam’s efficiency was measured using analytical hierarchy processes. 41 cement- masonry and gabion check dams constructed previously in different parts of the province were selected and were scored based on these criteria. Then by multiplying the weight of each criterion by the score each check dam received on that criterion, the distance of performance of each check dam from expected efficiency was computed. Results show that check dam's crest perpendicular to stream axis and consistency of spillway center with stream alignment averagely gained the highest score but longitudinal stream fixing and correct spillway dimensions gained the lowest score. And the location of check dams with the weight of 0.214 and apron length with the weight of 0.035 gained the highest and lowest weights, respectively. Economic assessment of check dams were done by comparing their final score in efficiency and the size of material used for that. It was revealed that small check dams constructed by consideration of designing principles showed more efficient and cost effective than huge check dams.
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