WSP04162 - Laserfiche WebLink

Home Browse Search

. (\ ,', ') n()~,UO" . period, except during April 1976 through November 1977. Precipitation records for the nearby Mesa Verde National Park were used to replace the missing Cortez data. The Mesa Verde weather station is located only 12 miles from Cortez, and the average precipitation at the two locations is similar. A summary of monthly Cortez precipitation is presented in Table 3. . . Runoff from summer thunderstorms is very sporadic, and in some years it is negligible. Short-term runoff from thunderstorms is characterized by a high-rate discharge that quickly peaks and then recedes within a period of about one week. Spring snowmelt runoff in McElmo Creek occurs only to a limited extent hecause McElmo Creek does not include areas with high mountain snow- pack. . . The USGS gage records for McElmo Creek near the Colorado-Utah state line were analyzed on a daily basis to determine the amount of incremental flow associated with short-term runoff events. Table 4 provides a summary of this analysis. Column entries in Table 4 are described as follows: 1. Precipitation Beginning Data - The first day of a rainy period at Cortez, resulting in a sharp rise in McElmo Creek. . 2. Cortez Precipitation - Total measured precipitation during 'each rainy period for which a sharp rise was recorded at the state line gage. . 3. Total Flow at State Line - Total historic flow of McElmo Creek at the gaging station near the Colorado-Utah state line during the period when a sharp rise in the flow was recorded. The period of time ranges from the beginning of the runoff event until the flow recedes to its approximate initial level. . 4. Base Flow at State Line - The total base flow during the period is consid- ered to be the average flow at the gage for the conditions immediately before and after the rise occWTed. . -16- .