RESERVOIR SEDIMENTATION ASSESSMENT GUIDELINE - Aneel

Reservoir Sedimentation Assessment GuidelineGLOSSARY OF TERMS, SYMBOLS AND UNITSThe following definitions are provided in order to assist in the understanding ofthe terms used in this Guide. They were mainly obtained from the InternationalCommittee on Large Dams Guide (ICOLD, 1989) and publications from USGS.• AGGRADATION –Geologic process wherein streambeds, floodplains, sandbars,and the bottom of water bodies are raised in elevation by the deposition of sediment;the opposite of degradation.• ALLUVIAL – Pertaining to deposits of alluvia by either a water stream or runoff.• ALLUVIAL RIVER or ALLUVIAL STREAM – a stream in which the bed channelis made up by significant amounts of sediments transported by the runoff, and inwhich changes on the bed shape due to changes on the runoff usually occur.• ARGYLE – particles of sediments smaller than 0,004mm, according to AGUclassification. According to ABNT, argyle is particles with granulometry lower than0,005mm.• AVERAGE DIAMETER– the sediment size where half material is composed byparticles greater than the average diameter, and the other half is made up by smallerparticles.• BED or BOTTOM – the bed or bottom of a stream, reservoir or lake.• BED FRONT LAYERS DEPOSIT – a layer of sediment deposit on the top of adelta surface.• BED LOAD –Sediment that moves by jumping, rolling or sliding along or nearbythe streambed• BED-LOAD SEDIMENT DISCHARGE SAMPLER – equipment for directlymeasuring bed-load sediment discharge, for part or all the stream width.• BED MATERIAL- material composing the riverbed, usually made of fragmentedrocks.• BED MATERIAL DISCHARGE– the quantity of sediment passing through a crosssectioncorresponding to bed material particles in movement, both suspended and atthe bed.• BED MATERIAL SAMPLER – equipment for collecting a sampling of thesediment that composes the bed.• BED SEDIMENT DISCHARGE (usually called as entrainment sediment discharge)– the quantity of bed sediment passing through a cross-section in a time unit.• BED UPPER LAYERS DEPOSIT – sloped layers of sandy material settled along ahigher slope. That layer progressively covers an overbank and, on its turn, iscovered by a front layer.• CHANNEL – generic term for any natural or artificial water runoff having freesurface.• COHESIVE SEDIMENTS – sediments in which the initial resistance to movementor erosion is greatly affected by cohesion chain among particles.ANEEL – Brazilian Electricity Regulatory Agency / SIH – Hydrologic Studies and Information Department96