This project is based on the Rational Method for calculating watershed discharge.

Using the AREA module, the area of the watershed was calculated to be 21.3 square kilometres.

A rainfall intensity of 50mm/hr was used in all four scenarios.  This represents a realistic 5 or 10 year rainstorm event.

Calculating the weighted runoff coefficient for the watershed is where G.I.S. was extensively used.  As is evident from the tables of runoff coefficients, there are many possible unique combinations of the three factors (slope, landcover and soil).  Each combination results in a different coefficient of runoff.  With so many different unique combinations, covering very irregular areas, performing this analysis manually would be impossible.  This is a clear example of the power of G.I.S.  I used the CROSSTAB module to identify unique combinations of the three factors and then the AREA module to calculate the area of those regions.  The last couple steps were mostly mathematical and were calculated in Excel.  These steps are further detailed in the "Spatial Analyses" section.