En studie av sedimenttransport, död ved och kantzoner längs två vattendrag i Kilsbergen : från skog till slätt

Abstract: Headwater streams are affected by anthropogenic impacts at multiple scales. One aspect of human impact is sediment transport associated to the abundance of stream structures as large woody debris and the composition of the riparian zone from forest to agricultural landscapes. Riparian buffer zones and stream structures like dead wood are considered as generally important structures for protection against an increasing amount of sediment particles in the water. Hence, in this study these structures were quantified in thirty different stream segments on land and in the water. To measure the transport of sediment Whitlock-Vibert boxes were used in three different types of landscapes; forest, transition and fields. The boxes were left in the stream segments for three months, the taken up and dried and weighed. The results showed that the transition-land in Frösvidalsån had the highest sediment transport. The second highest transport of sediment was in Blackstaån at the fields. A factor in common for both these stream sections was that their naturally meandering shape had been straightened. That indicates that straightened water streams attain a higher degree of sediment transport. One contributory cause to the higher sediment transport is the increasing velocity of the water stream. To see if large woody debris could have a connection to the sediment transport a correlations test was made. The test showed that the connection was weak. In a second test the basal area of the riparian zones and the sediment transport was compared to each other in the correlations test, the results showed that the connection was week. In a third correlation test the basal area of the riparian zones was compared to dead wood, also that test showed a weak connection. In the last test the basal area of riparian zones and large woody debris was compared and the test showed a weak connection.