Stormwater planning in the US is typically concerned with improving drainage in small urban areas, via low-impact development. However, in Yolo County, California, where most of the landscape is farm fields and native oak savannah, SEI played a different, complementary role by evaluating large landscape opportunities for controlling and re-deploying winter runoff.
Through field visits, literature review, interviews and several modeling tools, SEI sought to find the most promising solutions that both reduced the impacts of frequent low-intensity flooding in western Yolo County and increased groundwater recharge from excess winter runoff from those flood events.
Flooding in Yolo County in January 2019. Photo: Photo: Leo Refsland / Madison Service District.
In the process, SEI evaluated the opportunities and constraints to recharging groundwater from unlined canals in the winter; the flow contributions of old intermittent stream channels (called sloughs) further upstream; and ways to mitigate runoff from farm fields that frequently cause road flooding. SEI also helped collect a community-driven catalog of flooding in the small town of Madison. A list of recommendations was shared with the Yolo County Flood Control and Water Conservation District (YCFCWCD), and other agencies involved in flood management in the county.
