DOWNSTREAM CONTROL OF MULTIREACH CANAL SYSTEMS

A downstream control algorithm was developed for the control of multireach canal systems. The objective of the control is to maintain a target water level at the downstream end of each pool by adjusting the control gate at the upstream end of the pool. If the measured water level differs from its target value, the gate is adjusted, aiming to eliminate the deviation as soon as possible. The method is based on an explicit solution procedure of the St. Venant equations. Adjustments of each control gate are calculated according to water levels and flow rates at the information nodes downstream of the gate and the water level immediately upstream of it. Unless the pool is extremely long, an effective control can be obtained with only two information nodes in each pool (at the most upstream and downstream ends of the pool). If flow rates at information nodes are estimated using the slope stage method, four water levels are measured in each pool.