Output of bed load sediment from a small upland drainage basin in Hong Kong

Abstract

Sediment has been removed from a "natural" bed load trap in a small upland drainage basin in Hong Kong and from 1989 to 2003 annual yield has been determined. For the 15-year observation period the median yield was 607 kg with a highest yield of 3897 kg. Five years (1989, 1993, 1994, 1997 and 1999) recorded annual yields of over 2000 kg. Scattergraphs of annual bed load yield against annual maximum 24 and 48 h rainfall reveal a positive association with correlation coefficients of 0.69 and 0.67, respectively. Extreme rainfall events, as defined by high return periods, may be associated with annual bed load yields that are well above the median for the 15 years of observation.