Is the BEHI Index (Part of the BANCS Model) Good for Prediction of Streambank Erosion?

Abstract

Sedimentation of waterways and reservoirs, decreasing quality of drinking water and costs necessary for maintenance of these objects directly related to streambank erosion. This study provides a tool for water management that can help with estimation parts of a streambank which are prone to erosion. The Bank erosion hazard index (BEHI) part of the BANCS (Bank Assessment for Non‑point source Consequences of Sediment) model is one of the several procedures for assessing streambank erosion condition and potential (Rosgen, 2001). On May 15th 2014 a high precipitation occurred in the watershed of Sestrč torrent, in the eastern part of Chočské vrchy (Sp = 27.64 km2). It reached 102.7 mm per 24 hours. The rainfall resulted in extreme streambank erosion. We started the research of annual stream bank erosion on Sestrč in the beginning of May 2014 and we established 19 experimental sections on the stream. Occurrence of heavy rainfall allowed us to erosion rates after flash flood. The aim of this paper was to verify, if BEHI index can really determine the most vulnerable parts of a banks to erosion. We measured erosion rates Eb (m3/m) using a bank pins and toe pin (Sass, 2011) on each experimental section and evaluated each section by BEHI index (Rosgen, 2001, 2008). The results were statistically verified and confirmed a strong relationship between BEHI and real damage of banks Eb (m3/m) (R: 0.88, R2: 0.78).