FLOOD10655 (2) - Laserfiche WebLink

Home Browse Search

ground cover. Increased precipitation supports dense pine and aspen forests above this elevation to timberline. Rock outcrops and tundra grasses predominate on the high mountain peaks where climatic candi ti ons are too severe for forest growth. A number of irrigation ditches; such as the North Fork Ditch, Cameron Ditch, and the Missouri Park Ditch, convey water across natural drainage boundaries into adjacent basins. The Larkspur Ditch conveys wa ter fran the headwa ters of T 001 i chi Creek ; n the Co, ora do River Basin across the Continental Divide at Marshall Pass and into the Poncha Creek Basin. 2.3 Principal Flood Problems While slopes are steeper in the upper drainage basins, the dense vegetation in these areas serves to reduce rainfall runoff. A greater percentage of runoff is permitted by the sparse vegetation of the foothills and pasture land at the lower elevations. Conse- quently, the majority of the flood problems in the study area are caused by rapid snowmel t. Thi s type of fl oodi ng has along duration runoff which results in a continuous rise in water level thus producing a high runoff volume. Flood potential also exists from long and short duration rain storms. These types of floods are characterized by high peaks, small volumes and short duration. The potential for the most severe flooding is created by the combination of rapid snowmelt with long duration ra i n fa 11 . Detailed infonnation on floods before the turn of the century ;s very limited. Information on past flooding is based on newspaper accounts and interviews with longtime residents of the area. Large floods occurred at Salida in 1901, 1923, 1924, 1947, 1948, 1957 and 1973. These floods have caused major damage, disrupting highway and railroad traffic and communication services, drowned livestock) destroyed agricultural lands, roads, bridges and buildings. The flood of June, 1957, is considered the most severe flood known in Sal ida. The South Arkansas River reached a record high of 8.1 feet (Reference 3). The flood was triggered by high temperatures over an extended period of time and melted the heavy snowpack of the previous winter. Diversion ditches fran the South Arkansas River carried almost twice as much water as compared with other years. A farm bri dge on the Hutchi nson Ranch was lost and County Road 125 bri dge was threatened. Other low-level private bridges and foot bridges were al so lost. Peak di scharges have been estimated by carrel ati on to other gagi ng stations since the gaging station on the South Arkansas River near Sal ida was not in use from 1940 to 1971. The peak discharge was estima ted at 1841 cfs (Reference 1). Thi s di scharge represents a recurrence interval of approximately 50 years. 5