In dry places with extreme downpours such as CA and the Southwest, slow the flow of water by upstream spreading and expandable bladders.
"Slow the Flow" is the idea that the best way to counteract the climate change effects of increasing heat and drought, combined with extreme downpours, such as we see in California and the American Southwest, is to reuse every drop of water multiple times. When water is diverted in small, frequent amounts from a stream bed it can percolate slowly through the soil, and when temporarily captured within the drainage, it can be used as needed when dryness returns. There can be many ways to "slow the flow." Most will be low tech, inexpensive, and locally driven. Making the most of local precipitation is a better idea than large scale water diversions or draining groundwater supplies, and efficiency alone is not enough.
Here are a couple examples of how the concept could be applied. In the upper elevations of watersheds, hikers & volunteers could simply put rocks & branches in small drainages to slow and spread the flow of water. This will help forests hold more water and thus better resist fire and disease. Small areas of natural, temporary, pre-positioned water could aid fire fighting. In other areas such as the coastal foothills of California, we should place temporary, moveable, inflatable water bladders to collect and temporarily store some of the water from extreme downpours. Since it's under pressure, this water could be used to help re-vegetate hillsides and reduce mudslide risk as well as wildfire risk. The bladders could be linked, like a string of pearls, and connected to groundwater recharge.
Category of the action
Mitigation/Adaptation, Changing public attitudes about climate change