DISTURBANCE, SUCCESSION AND ECOSYSTEM PROCESSES IN RIVERS AND ESTUARIES: EFFECTS OF EXTREME HYDROLOGIC EVENTS

摘要

Low frequency but high intensity events, such as severe floods or droughts, may have long-lasting effects on the structure and function of lotic ecosystems, as well as on man-made structures and human uses of rivers, floodplains, and estuaries. In the summer of 1993, major, global-scale atmospheric circulation anomalies caused unusual precipitation in the upper midwestern part of the US (return frequencies ranged from 75 to 300 years, dependent on location), creating extreme flooding (100-500-year) along the upper Mississippi River, the Illinois River, and the lower Missouri River, and many smaller tributaries (Dowgiallo, 1994; Southard, 1995; US Army Corps of Engineers, 1995).