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<br />. <br /> <br />b) Hydrologic Methods <br /> <br />. <br /> <br />Hydrology deals with the water balance in a water- <br />shed and results in a determination of flood flows <br />and volumes (see Figure _). Many times hydrology <br />has been referred to as an art rather than a sci- <br />ence. Today, it is felt that science has developed <br />reasonably consistent methods and procedures for <br />determining representative discharge values, A <br />flood hydrologic investigation will first determine <br />the potential cause of flooding and then determine <br />volumes or rates of flow that would be expected when <br />a given set of probabilities are calculated. In a <br />detailed hydrologic analysis these calculations will <br />be performed for the 10-, 50-, 100-, and SOO-year <br />frequency flood discharges. The analysis will be <br />based on existing drainage basin conditions except <br />where future development within the basin may be <br />significant. The selected flood discharges may be <br />computed by either an analysis of available stream <br />flow records or by a synthetic rainfall - runoff <br />method (see Glossary) (a mathematical representation <br />of ~xpected precipitation and the resultant runoff). <br /> <br />. <br /> <br />Most of the damaging floods in Colorado have been <br />rainfall floods for elevations below 8000 feet and <br />snowmelt floods for elevations above 8000 feet MSL <br /> <br />-19- <br />