Floods - Applied Geography: Principles and Practice - page 93

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Floods

Edmund Penning-Rowsell

impact of humans on flood regimes (Hollis 1988),
through evaluating spatial flood patterns (Newson
1989) or understanding the geomorphology of
floodplain processes (Anderson et al . 1996).
From other disciplines has come the sociology
of human group interaction in floods and other
extreme events (Torry 1979), the psychology of
behaviour under risk circumstances and of risk
communication (Handmer and Penning-Rowsell
1990), and the configuration of institutions to
tackle such hazard phenomena (Hood and Jones
1996). Many of the key debates centre on whether
flood and other risk is socially determined rather
than physically based, and whether risk is socially
divisive (Beck 1992).

INTRODUCTION

Of all the 'natural' hazards to which humans are
exposed, floods are probably the most widespread
and account for most damage and loss of life
(Alexander 1993). Floods also appear to have a special
impact on their victims, instilling a fear of the
consequences that often exceeds their actual impacts
(Green and Penning-Rowsell 1989). They also can
have serious secondary impacts on the economy of
the regions affected, and they can markedly influence
agriculture in disaster-affected areas for some time
after the event has passed, by affecting cropping
patterns and yields, as dramatically is the case in
Bangladesh (Alexander 1993).
Geographers have studied the complexity of
such flood hazards for many years and have
made significant contributions to their
understanding, not least by tackling the
interface between physical geography and
human geography that is highlighted in the
flood situation by the complex relationships
between human behaviour and extreme
geophysical events.
The foundation of such research was in the
'Chicago' school of hazard geography pioneered by
White and others (Burton et al . 1978; 1993). This has
been followed by the work of Hewitt (1997) and
Mitchell (e.g. Mitchell et al . 1989) and elsewhere in
the world in Australia (Smith 1999), New Zealand
(Eriksen 1986), the UK (Penning-Rowsell et al . 1986;
Arnell et al . 1984) and elsewhere (Chan and Parker
1996; Kanti Paul 1997, Pelling 1998).
In addition, geographers have contributed to
the hydrology of floods, mainly by evaluating the

THE NATURE OF FLOODING AND
FLOOD HAZARDS

Flood types and mechanisms
Floods can be classified into fluvial, coastal and
those that result from deficiencies in urban
drainage. Fluvial floods occur when river
discharge exceeds its bankfull capacity. The return
period of out-of-bank flood flow is generally 2.3
years (Newson 1989), and the magnitude of floods
and their probability of occurrence are strongly
connected, although these relationships are
regionally specific and depend on climatic
conditions and river catchment character (ibid.).
Coastal flooding occurs where tide levels
exceed land levels, exacerbated by extreme wave
conditions and by sea level surges caused by low-