FLOOD10335 - Laserfiche WebLink

Home Browse Search

. ( ". ~ . ... '~ ." l ~ ( . - 33 - The Grand Valley Irrigation Company provides irrigation 'A'ater to about 37,380 acres of crop and pasture land. The Ditch Superintendent states that if the Grand Valley Canal were broken at Indian Wash, the entire system would have to be shut down because all of the head ditches require'a'full canal'to take out Water. , . Based on long-term projected prices for crops and factors of production, average crop yields, local production practices, and a composite average growing season of 153 days, the average daily gross return on the 37,380 acres in the Grand Valley Irrigation Canpany system is $20,656 per day. From the above information damages were estimated for the project design storm of 7,300 c. f. s. peak fl,ow and the intermediate storm producing 3,700 c.f.s. peak flow at the Grand Valley Canal flume over Indian Wash channel. A discherge damage curve for a delay in water delivery was then constructed using these damages and with 3,500 c.f.s. di scharge as the point of beginning damages. Average annual damages were then computed by relating damages to discharge and frequency of occurrence. Floodwater and sediment damages to residential and commercial properties in and near the City of Grand Junction, Colorado, were obtained by field investigations and appraisals. Each city block in the overflow area subject to da~age was considered as an evaluation reach in the damage appraisal. This evaluation was aided by the use of an aerial photograph showing the boundaries of the 1958 flood which was provided by the City of Grand Junction. A work map and tabulations were prepared for the overflow area subject to damage showi-nq the approximate location of all properties, type of construction, ~nth or without basements, the estimated value of buildings and contents, and an appraisal of the damages which would result fram the project design storm and two other selected storm frequencies. Field appraisals and flood d~~age estL~ates of probable d&nages to floodplain roads and bridges were made with the assistance of the Grand Junction Director of Public Works and correlated with the damage estimates made by the U. S. Corps of Ar.rny Engineers during the preliminary investigations. In the absence of recorded damages to railroad property in the watershed, field appraisals and estimates were made of the probable flood damages to the Denver and Rio Grande Western Railroad mainline track and classification yard.