Introduction

The interface between humans and hydrologic features across Earth's surface has helped shape human culture. From the earliest agricultural, complex societies established along some of the great rivers of the world to the bustling seaports of today, humans have gained from the myriad advantages of living in proximity to water. Fertile soil, ease of transportation, and availability of resources (both materials and energy) have allowed for the development of complex material and intellectual cultures. The relationship between water and humans also brings a great deal of risk. Flooding is one of these risks. The impact of floods on humans has been evident from Genesis to tonight's evening news. Early Mesopotamian maps may have been drawn to facilitate the reestablishment of property lines after flooding. While the impacts of flooding on humans have been positive in the case of fertile floodplains that support much of the world's agricultural productivity, there is the potential for a great deal of negative impact (Brown, 1984; Clark et al., 1985). Losses of life and property have focused the efforts of scientists, engineers, and government agencies on the prediction, control, and mitigation of floods and flood damage.

In spite of efforts to deal with flooding problems, monetary losses continue to rise at an alarming rate. In Venezuela in December 1999, two weeks of heavy rain resulted on December 15th in flash floods laden with soil, vegetation, and debris. Damages of US$3.2 billion, or 3.3% of the country's gross domestic product were reported. At least 20,000 people were killed. Generally, the number of lives lost due to flooding remains high. However, improvements in flood warnings particularly for major large-scale storms such as cyclones and typhoons have had dramatic effects. The severe 1991 cyclone in Bangladesh resulted in 140,000 dead and property losses

Handbook of Weather, Climate, and Water Atmospheric Chemistry, Hydrology, and Societal Impacts, Edited by Thomas D. Potter and Bradley R. Colman. ISBN 0-471-21489-2 © 2003 John Wiley & Sons, Inc.

of US$2.0 billion. A cyclone of similar intensity in 1993 resulted only in the loss of 126 lives. The early warnings and cyclone shelters accounted for the major improvement (www.ndndr.org). China has also witnessed a reduction in the number of lives lost to floods. While 3000 people died in 1998 floods, the 1998 floods were as great as those of 1931 and 1954 where the loss of lives was 145,000 and 33,000, respectively (www.ndndr.org). In October 1998 hurricane Mitch was the worst in the eastern Caribbean since 1780 when a hurricane killed 22,000 people. The death toll from Mitch is reported as 11,000. More than 3 million people were left homeless or were severely affected (www.ncdc.noaa.gov/ol/reports/mitch/mitch.html).

Floods take a variety of forms with the interplay of several factors leading to the inundation of normally dry land. Wohl (2000) identifies four primary challenges in reducing escalating flood damages. These are (1) estimating flood magnitude for a given recurrence interval, (2) accurately forecasting floods based on rapidly evolving weather conditions, (3) effectively operating flood-warning and evacuation procedures, and (4) establishing and enforcing land-zoning regulations. This chapter first discusses the contexts and causes of flooding, the first two points addressed by Wohl (2000). The second topic is the complex human responses to floods, points 3 and 4 of Wohl (2000). Many of these topics are illustrated with examples of floods.

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