The results show that the effect that full forestation has on reducing drainage basin peak flow discharge is quite dramatic.  With a shift of only 27.1% of the forested watershed to cultivation, the peak flow discharge increases by 13.8%.  The increase from the current conditions of landuse (Scenario 3) to the proposed future conditions of relatively substantial growth (Scenario 4) resulted in an increase of 6.2%.  The hypothetical future situation was the result of dramatic development in the area - more than half of the forest regions were cleared; commercial and industrial districts more than doubled in area; and proliferation of large-lot residential developments exceeded 150% (refer back to Future vs. Current Landuse table).  However, it can still be expected that further growth, or at least transition, would occur in the region.  Peak flow runoff produced by rainstorm events would continue to increase as the predominant landuse shifts, in very general terms, from a natural landscape to a rural then suburban and then urban landscape.

The increase in discharge may not seen significant but it will slowly increase the amount of damage the stream causes and flood events will slowly increase in frequency.  What was originally a 10-year flood, will gradually increase in frequency - perhaps to the point where that level of flooding usually occurs once every 5 years.  This means that the costs (damage and/or mitigation efforts) that typically fluctuated on a 10 year basis would then occur twice as often.  From direct property damage to decreased agricultural productivity to programs that are cut back due to the need for an increase in government funded flood programs, the direct and indirect effects can be far-reaching.  It is important to note that in this situation there has been no change in rainfall.  This potential increase in flooding is strictly related to an increase in the amount of runoff (less rain infiltrating the surface) and not to an increase in the amount of rain.  Climate change may compound this effect in some regions while countering it in others.
 
 
 
 

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