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FUTUREFLOOOS would be much less severe than the Standard Project Flood. Compar- ison of Intermediate Regional Flood depths at various locations in Wray can be made by referring to the stream profile on plate 6. This section of the report discusses the lnterp~diate Regional Flood and the Standard Project Flood for the North Fork Republican River at Wray and the hazardS of great floods. Floods the size of the Standard Project Flood represent reasonable upper limits of e~pected flooding. Those of the size of the Intermediate Regional FloOd represent floods that may reasonably be e~pected to occur more frequently although they will not be as hign as the Standard Project Flood. Standard Project Flood. Severe as the ma~illlUlI known flood may have been on any given stream, only in rare instances will It have reached what hydrologists regard as the ma~lmum flood poten- tial of the basin. The threat of flooding in e~cess of any past event must be recognized. The Corps of Engineers. In cooperation with the Weather Bureau, has made broad and comprehensive studies based on the voluminous records of past storms and floods and ~s evolved generali~ed procedures for estimating the flood potential of streams. These procedures have been used in determining the Stand- lIrdProjectFloodforWray. Th1s flood is defined as the largest flood that can be e~pected from the most severe combination of mete- orological and hydrological conditions that are considered reason. ably characteristic of the geographical region involved. Unfortunately, when data for the Intermediate Regional Flood or the Standard Project Flood are presented, many people tend to ignore them in the mistaken belief that they could not occur during their lifetime. Actually, the chance of a flood the si~e of, or greater than the Intermediate Regional Flood occurring in the ne~t 25 years is better than 1 to 4. Intermediate Regional Flood. The Intermediate Regional Flood IS defined as a flood having an average freQuency of occur- rence in the order of once in 100 years at a oesignated location although the flood can occur in any year. Probability estimates of this kind are normally based on statistical analyses of streamflow records available for the watershed understudy. The estimate for the North Fork Republican River was determined in this way. Since there are no available official records of severe flooding in the basin above Wray. adjustments were made to the basic analysis to refl~ct the potential for severe flooding frc~ cloudburst storms occurring in the area. Standard Project storm rainfall used for the North Fork Republican River amounts to 5.4 inches in 3 hours. 10.0 inches in 24 hours. and a total of 12.1 inches in 96 hours. Tne 24-hour rain- fall amount for the Standard Project Flood is over 3 inches more than the greatest rainfall recorded at Wray. The peak discharge calculated from these rainfall amounts would be 11,100 cubic feet per second at Wray. The flood profile for the Standard Project Flood is also shown on plate 6. !t is not practical to assig~ a frequency to the Stand~ arc Project Flood because the occurrence of such a flood would be a rare event although it could occur in any year. Results of these studies indicate that the Intermediate Regional Flood would have a peak discharge of 4.200 cubic feet DeT second at Wray. A flood of this magnitude could be disastrous but 17 "