Abstract: A canal is the major facility for water transfer and distribution, and the indicator of its controllability is a prerequisite for reliable and efficient control of its flow system via the Internet of water. In this paper, an indicator of canal controllability is established based on the general controllability principle of the first-order systems with time delay using the parameters of an integrator-delay model. We also work out a quantitative relationship of this indicator versus the selection of a control algorithm for the second canal of Changma South Irrigation District in the Shule River basin, and verify it via numerical simulations. The results show that for this case canal, its indicator of controllability is 0.2 - 0.3 and a proportional-integral algorithm is ineffective in controlling its flow. And a linear quadratic control produces an actual operation greatly affected by disturbance amplitudes, while a model predictive control achieves satisfactory effects. All this is consistent with the judgment by using the indicator of canal controllability, further demonstrating the dependency of the canal control effect on the synthesis of canal controllability and control algorithm capability.

Key words: internet of water, canal automation, integrator-delay model, first-order system with time delay, canal controllability, indicator, control algorithm