Tidal Wave

Because of a lack of flow in many streams due to water diversion or habitat change, three problems have risen: The lack of rapids lessens airration, the slower water speed raises water temperatures and also allows faster sediment buildup in possible breeding grounds for certain fish.

Most streams in hawaii, because of the above reasons do not flow regularly into the ocean like they normally would. A slower water flow means that sand banks always block the entrance of the river/ stream mouth to the ocean and the only time that they open is when a big rain comes. When this happens, sediment that would have normally been flushed out slowly comes out all at once, blanketing and killing nearby reefs.

Many native amphidromous fish species are not adapted to restricted water flows, higher temperatures and low oxygen levels, causing them to not complete their life cycle of returning from the ocean to streams and rivers.

In some local streams, large-diameter pipes have been installed to accomodate for the constant sand banks, but they themselves, if not cleared frequently, can be themselves clogged as fast as overnight.

My idea: Large-diameter pipes by themselves leave maintenance problems, but install a pressure or tidal activated valve and it will clean itself. Even with a tidal difference of only two feet, enough pressure can provide a rush of water flow that would serve different purposes:

The sudden rush of water in and out would: airrate the incoming water, clear the pipe of sand and debris, provide a more constant unsettling of sediment, allow for amphidromous fish life cycles.

It's a large pipe with a valve activated by tides or pressure that connects locked streams to the ocean. It is self-cleaning and improves stream conditions for native wildlife.

When enough pressure difference is detected or tides are determined, the valve opens and a small tidal wave is created. it's like a laxative for a constipated stream.