Laserfiche WebLink
RGDSS Memorandum <br />Final <br />To: Ray Bennett, Ray Alvarado, Andy Moore <br />From: LRCWE, Ross Bethel and Erin Wilson <br />Subject: Rio Grande Historic Crop Consumptive Use -Ditch System Efficiencies <br />Date: June 1, 2004 <br />Introduction <br />This memorandum describes the approach and results obtained under Task 3.8 -Estimate <br />Ditch System Efficiencies. This task includes an estimation of both ditch system and <br />application (on-farm) efficiencies likely to be experienced in the Rio Grande Basin, plus <br />a recommendation on efficiencies to use for the historic consumptive use analyses. It has <br />been updated from the June 2002 version to reflect refinements to maximum flood <br />irrigation efficiency, based on recommendation from peer review. <br />Factors that affect conveyance efficiencies include: <br />• Frequency and duration of diversions (i.e. beginning of diversion season <br />versus late summer) <br />• Underlying soil characteristics <br />• Canal cross-section <br />• Canal length <br />• Location of water table relative to the canal <br />• Canal flow <br />Factors that affect application efficiencies include: <br />• Irrigation practice (i.e. sprinkler, flood) <br />• Crop types <br />The StateCU model uses estimated conveyance efficiencies to determine the amount of <br />water delivered to the farm for application on the crops. The maximum application <br />efficiency is used to estimate the maximum water available to meet crop consumptive use <br />demands. StateCU calculates the actual application efficiency by dividing the water <br />delivered to the farm by the crop consumptive use demand. <br />Approach <br />The following approach was taken to determine the likely range of efficiencies <br />experienced in the Rio Grande Basin. Conveyance system efficiencies and maximum <br />application efficiencies were investigated separately as described below. <br />appendB_cropcu_6-2004.doc B-1 of B-19 June 2004 <br />