Small-Scale Flooding and Muddy Floods as a Geomorphologic Hazard in Central Belgium: Some Financial Consequences

Abstract

Over the last decades off-site problems of soil erosion have increased in many parts of north-western Europe (Boardman et al. 1994). In central Belgium these problems are a widespread phenomenon as small-scale flooding events, often with a muddy character, are frequently occurring after moderate to intense rainfall events. It was recorded that no less than 43% of the municipalities (n = 123) in central Belgium suffer from muddy floods generated by direct runoff from arable land and 36% with flooding of permanent streams (Verstraeten and Poesen 1998). Because these hazards are not only causing financial costs but also much emotional damage to private households, different government levels take control measures, like retention ponds, to reduce or even avoid these problems for the future. During the last two decades around 100 retention ponds have been constructed with 50 to be built in the near future (Verstraeten and Poesen 1998). Frequent dredging of these ponds due to severe sedimentation in these ponds is an unexpected source of financial costs. In this paper a short overview will be given of both the nature and the financial consequences of these problems. More detailed information is presented by Verstraeten and Poesen (1999).