The big storms hitting our region this winter have been unusually powerful. And one of them was just plain unusual.
The Dec. 15 storm which caused some minor flooding around the Valley was stronger here than at the coast, and it dumped more rain in unexpected places. It was a bigger storm, relatively speaking, for the Nathanson Creek watershed that surrounds the City of Sonoma than for Sonoma Creek’s watershed, and bigger for Sonoma Creek than for the Russian River.
(Such things are easier to measure now thanks to a new stream-flow gauge on Nathanson Creek, which will inform planning for building, roads, water supply and habitat protection. Thanks to Sonoma County Water Agency and USGS for funding that! Another permanent stream-flow gauge on Sonoma Creek at Agua Caliente Road has recorded water levels there for years.)
The fact is we’re more vulnerable to flooding today than we were 20 or 30 years ago, for two reasons: 1) there are more roads, buildings and other development in flood-prone areas, and 2) the changing climate is bringing larger and less predictable storms.
From an ecological perspective, floods are not a bad thing. Every so often during heavy rains water will overtop a stream channel – a natural, beneficial and unstoppable phenomenon. If allowed to spread out over open land – typically an open space alongside streams which biologists call a “floodplain” – the ensuing floodwaters grow lush riparian forests full of birds and bobcats, reduce erosion to the streams, and recharge our aquifers.
But when we build over those floodplains, the floodwaters enter our streets and homes instead, as happened recently along the Russian River. And when that happens no one benefits: property is damaged, nature loses out, and none of that water is stored. The water we curse in winter is the same water we thirst for in summer.
The answer, then, is to work together on ways to capture more water when it’s abundant. This requires better planning, including more space set aside for floodplains – talk to city and county leaders about how to implement such practices. Or talk to Sonoma Ecology Center about joining or forming one of our Neighborhood Water Teams (NeWTs) so that you and your neighbors can better tackle these problems as a group. And streamside landowners can learn more about how climate change is affecting their properties with a Climate Smart fact sheet we co-wrote with our partners at North Bay Climate Adaptation Initiative.
The forces of nature are powerful. But working with them, rather than against them, can result in less flood damage in wet winter months and more groundwater in dry summer months. It only takes a lot of planning – and that’s something we can all make happen.