FLOOD06086 - Laserfiche WebLink

Home Browse Search

also regulate flow in the basin. The Rio Grande is affected by the Beaver Creek, Santa Maria, Rio Grande and Continental reservoirs. 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 grea ter percentage of runoff is permitted by the sparse vegeta ti on 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 snowmelt. This type of flooding has a long duration runoff which results in a continuous rise in water level thus producing a high runoff volume. Flood potential al so exists from long and short duration rain storms. Short duration floods are characterized by high peaks and small volumes. The potential for the most severe flooding is created by the combination of rapid snowmelt with long duration rainfall . Detailed information on floods before the turn of the century is very limited. Information on past flooding is based on newspaper accounts and interviews with longtime residents of the area. Large floods occurred at Del Norte in 1905, 1911, 1927, 1949, and 1973. These floods have caused major damage, disrupting highway and rail road traffic and conmunication services, drowned 1 ivestock, destroyed agricultural lands, roads, bridges and buildings. The flood of October, 1911, is consi dered the most severe flood known in Del Norte. The Rio Grande inundated the railroad tracks just outside of the depot. Water was also 1 1/2-2 feet deep at the intersection of 4th and Pine. The flood was triggered by intense rains in the mountains over an extended period of time. Diversion ditches, canal s and arroyos, from the Rio Grande carried almost twice as much water as compared with other years. Roads turned into ditches and low lying areas became lakes (Reference 2). The USGS has estimated the flow to be 18,000 cfs (Reference 3). This represents a recurrence interval of approximately 500 years. Flooding problems within the Town of Del Norte are aggravated by the restriction of drainage channel s due to vegetation growth and accumulated debris. 2.4 Flood Protection Measures The Town of Del Norte ha s no exi sti ng regul ati ons or ordi nances concerning flood management or protection measures. There is very little flood protection for the Town of Del Norte. The main protection from the Rio Grande during floods is sand bags along the south edge of the river. This protects the Town from more frequent floods. 5