Sediment imprint of the severe 2002 summer flood in the Lehnmühle reservoir, eastern Erzgebirge (Germany)

Aseriesof �18 �shortcor eshasb eenobtaine dfr omtheLehnmuhler eservoir �( operationsince �1932) �ine asternEr zgebirge �( Ger- many) �inordertoinv estigatetheeffe ctsofthese vereflo ode ventinA ugust �2002 �onse dimentationb ycombiningmicr ofacies � andhighr esolution �µ-X RFscanningte chniques. �Adistinctgrade ddetritallay er, �uniqueforthewholer ecord, �app earsinalmost � theentir er eservoirbasin, �ranginginthicknessfr om �33 �mmatpr oximalsitesclosetotheriv erinflo wto �5 �mmatdistalsites. � Thetotalse dimentinfluxduringthise ventwasestimate dtoappr oximately �2,400 �tons. �Ar oundtw o-thirdsofthese dimentwas � dep ositedinthesouther n-centralp artofthebasin �( approx. �32 �% �ofthebasinar ea) �duetobasinmor phometryandpr oximityto � theinflo w. �Anenhance dfluxoffinesiltandclay stoar easne arthedamwasobser vedandislik elydriv enb yaste adycur rent � to wardsthedam. �O ccurrenceofdetritalmaterialinalateralbayr evealsthatse dimentderiv ednotonlyfr omthemaininflo w � butalsofromsurfacerunoffthroughnon-permanentlywaterbearingstreamchannelsaroundthereservoir. � � Inadditiontothee xceptional �2002 �flo odlay er, �22 �micr oscopicallythindetritallay ersw eredete ctedinthese dimentcor es, �most � ofthematthede epestcor elo cationsclosetothemaindam. �Achr onologyofdetritallay erswasestablishe db y � 137 Csdatingof � thr eecor ese quencesandwastransfer redtoothercor esb ydetaile dcor relationbase donfourlithologicalmark ers. �Thecom - parisonwithinstr umentaldatar evealsthat �64 �% �ofthetotal �22 �flo ode ventso verthelastthr eede cadeswithadailydischar ge �> � 8 � m3s-1�ofthemaininflowingstreamresultedindepositionofalayerofdetritalmaterialinthereservoirbasin.�