Table 3. (concluded) 



Catastrophic 

 events 



Physical & chemical changes 

 in the envoronment 



Loss of habitat 

 Removal of vegetation 

 Removal of topsoil 

 Increase in surface runoff 

 Increase in soil erosion 

 Increase in slope grade 

 Lovk'ering of water table 

 Loss of groundwater 

 Alteration of drainage areas 

 Modification of seasonal 



flow patterns 

 Drastic fluctuations in 



water level Sc flow rates 

 Reduction in flow volume 

 Increase in dovvTistream 



flooding 

 Canal creation in wetlands 

 Increase in turbidity 

 Increase in sedimentation 

 Alteration of bottom topog. 

 Reduction in light penetration 

 Elevation of temperature 

 Modification of chemical 

 composition: 

 Soil 

 Water 

 Air 

 Increase in oxygen demand 

 Addition of nutrients 

 Addition of metals 

 Addition of chem. pollutants 

 Change in salinity 

 Disturbance (noise poll.) 



Explosions 



Floods 



Droughts 



X 

 X 



X 

 X 



X 

 X 



X 

 X 



X 



X 



X 



J 



X 

 X 



62 



