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OOlGG4 31.2--2 WATER INFORMATION MANAGEMENT SYSTEM HANDBOOK ( 3. In energy limited systems, a change in any variable in the relationship Qsd - QwS results in a compensatory change in one or more of the remaining variables. Channel responses can be anticipated in kind and magnitude whenever there is a change in one or more of these variables. Some such change occurs naturally due to the normal variance in a heterogeneous environment. However, such change is generally limited in magnitude, random in occurrence, of a temporary nature, and has produced a channel form capable of accomodation. Artificial changes in these variables, especially discharge, tend to be long term, systematic, and of substantial consequence. 4. The quantity of sediment delivered to the point of quantification will not change appreciably. The procedure calculates the water discharge needed to maintain the dynamic equilibrium between sediment discharge, particle size and stream slope. A change in the quantity of sediment which must be transported would necessitate a change in the required flow if equilibrium is to be maintained. 5. There is an effective discharge that forms the active channel in erodible bed/bank.channels. 6. The effective discharge is approximately equivalent to the discharge which occurs at bankfull stage. 7. Bankfull discharge is frequently occurring and can be characterized by the flow with a recurrence interval of 1 to 5 years and reasonably estimated using the flow associated with a 1.5 years recurrence interval (log-Pearson Type III analysis of annual peak series). This procedure is designed to maintain the capacity of the active channel only. Therefore, the use of an effective discharge (also called the formative or. dominant discharge) will achieve the desired capacity maintenance objective. This assumption is necessary to allow for the application of the procedure to numerous diverse drainages for which little or no field data are available. This particular return interval (1.5 years) is the one most frequently encountered in the literature and, thus, the one least likely to be in error in most cases. However, the procedure does not preclude the use of a different return interval if there are reasonable and substantial grounds for its selection. 8. Baseflow dfscharge plays a role in the maintenance of channel equilibrium. IC No. 1 9/10/85