322 Big pictures
Figure 12.1Flood caused by extensive loss of natural vegetation. Without nature’s
absorptive capacity, water from a 30 cm (1 ft) rainstorm on relatively flat clayey soil
readily flowed to, and accumulated in, extensive low areas. Texas. Photo courtesy of
USDA-Soil Conservation Service.Hurricane (cyclone or typhoon)
This strong large-diameter rotating wind, commonly strengthening as
it moves over warm seawater, is especially dangerous to coastal cities, though
inland cities are also damaged. Devastating cyclones hit Hong Kong in 1937 and
Dhaka (Bangladesh) in 1942, 1961, 1963, 1965, 1970, and 1991. High winds of
course cause lots of property damage. If the hurricane is moving slowly, often
heavy rain precedes and follows the eye of the storm. Thus floods are common,
and saturated earth contributes to extensive tree blowdowns. A 1938 hurricane
in Central Massachusetts (USA) caused the most tree damage on the southeast
slopes and tops of hills, and on the northwest ends of large openings such as
ponds and meadows (Foster and Boose1992). These sites appear to have had the
highest wind velocities, probably just after the hurricane’s eye had passed. The
NewOrleans hurricane passed over an extensive area where wetland marshes
had been eliminated (Farber 1987). Yet one estimate suggests that the storm