I have another specific example of this to offer: Active vs. passive flood control. One passive control mechanism is the retention basin. This is just a pond co

I have another specific example of this to offer: Active vs. passive flood control. One passive control mechanism is the retention basin. This is just a pond connected to a water system. When it rains and the water begins to rise, some water flows into the pond instead of flowing downstream, reducing the effect of the storm. You can improve the retention basin by adding a pump to actively manage the basin's capacity. When there is rain in the forecast, you pump water out of the basin, reducing its water level. When the rain arrives, you turn off the pump and let the basin refill. This increases the amount of water that the basin is able to divert during the storm. I worked with a company that designed such a system and we even installed a demonstration unit for a municipality. It worked as intended and the city engineer advocated for expanding the project to all suitable basins. However, when the municipality's lawyers looked at the project, they argued that if the system failed to activate prior to a storm, the city might be liable any flooding that occurred afterward. Of course, the scenario where the system failed to function was identical to one in which it had never been built in the first place*, but that was not a convincing argument and the project was killed. * I like escalators because an escalator can never break, it can only become stairs. - Mitch Hedberg