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OJJ2J3 SECTION V TRANS I T LOSS ES When discussing transit losses in a stream, it is necessary to define terminology. The main problem in communications regarding transit losses during a reservoir run is whether or not one Is speaking of the total stream loss, most of which would exist whether or not "new water" was being trans- ported down the river, or whether One is speaking of the incremental loss imposed on the river as a result of the transportation of the new water. In canal studies, for Instance, most work is aimed towards total canal losses, and when a new user on a canal wishes to transport his project water through the canal, he is generally charged the same percentage as those al- ready in the ditch. This is an administrative and policy matter decided by the ditch officials. However, It is well-known that in many ditches the more water carried in the ditch, the more water there is for storage and application and there is less transit loss as a percent of water carried. Obviously, this is not always the case because new water carried in the ditch might result in some new permeable areas being wetted. In regard to this Arkansas River study, it is the writer's op,nlon that One should deal primarily with incremental losses rather than with the total losses for the stream. The final determination of this, however, might very well be the subject of high level administrative decisions and/or litigation. There most certainly are arguments for both cases. Obviously, if incremental losses are charged to those transporting water in the river, the losses would be substantially less than if they were charged with a percentage reflecting the total loss in the stream. If the percentage of loss representing the full river flow were to be applied to the foreign water being transported, the per- centage would always be larger than if the incremental losses were charged. Some of the numerous factors affecting, to some degree, transit losses of reservoir runs in a natural channel are: Length of reach used for transporting water Natural flow in river Size of reservoir release Ratio of release flow to "native" flow Rising or fall ing river at time of release Rai n Unaccountable fluctuations in stream flow Diurnal Variation Slope of river channel Roughness of channel Hydraulic radius of channel Elevation and slope of water table in relation to river Fluvial geomorphology (geology, degree of sinuosity, etc) Degree of sealing of river channel Temperature of air and water Humidity and vapor pressure Wind velocity Radiation and exposure to radiation Unauthorized diversion Increased legal diversions 32