Excess land in the right-of-way as well as adjacent vacant and publicly owned lots offer opportunities for resource generation and community services. However, the river as a resource must be balanced by acknowledging the river as a risk. Currently some portions of the river channel do not provide 1% flood capacity, and large swaths of land and critical infrastructure and facilities along the river remain susceptible to flooding.1Los Angeles District U.S. Army Corps of Engineers, “Los Angeles River Ecosystem Restoration Integrated Feasibility Report”, Volume 1, Appendix E, Table 17, September 2015.
The LA region is categorized as a Mediterranean climate, with ample sunshine and hot and dry summers and relatively cool and wet winters. The same elements responsible for this temperate mean climate also contribute to large annual fluctuations in extreme precipitation, prolonged drought, and extreme heat.2Daniel L. Swain, Baird Langenbrunner, J. David Neelin, and Alex Hall, A. Increasing precipitation volatility in twenty-first century California. Nature Climate Change 8, pages 427–433 (2018).
CalEnviroScreen 3.0 for LA County
Social Vulnerability to Climate Change
The channelization of the LA River has been largely successful in managing the risk of extreme flooding events; however, climate change projections indicate a “threefold increase in sub-seasonal (extreme precipitation) events comparable to California’s Great Flood of 1862” by 2100.3Daniel L. Swain, Baird Langenbrunner, J. David Neelin, and Alex Hall, A. Increasing precipitation volatility in twenty-first century California. Nature Climate Change 8, pages 427–433 (2018).
Additionally, increases in extreme heat due to climate change combined with the rising impacts of the urban heat island effect could mean that many portions of the LA River will see substantial increases in the number of days with temperatures above 95°F.4UCLA Dept. of Atmospheric and Oceanic Sciences, The Climate Change in the Los Angeles Region Project, accessed on July 30, 2018. Studies have indicated there are an estimated 19-25 deaths a year and over 2000 emergency room visits in LA County linked to extreme heat. Providing ample shade structures, sites for cooling and potable water, and connecting communities to the river beneath an increased urban tree canopy will all help in making a more sustainable and resilient public open space along the river.
Maximum, Minimum, and Differential Air Temperature
As potential public open space, the LA River channel and right-of-way consist of over 2,396 acres.5Calculated from aerial analysis by Geosyntec While much of this is within the banks of the channel, barren and underutilized lands outside the channel in the right-of-way can be part of a network of parks, stormwater wetlands, and habitat areas, but also intermixed with sites for power generation, urban agriculture, and new community facilities.
Recently, sustainability and resilience planning in the county has been addressed through the Los Angeles Countywide Sustainability Plan, “Our County” (adopted 2019), Los Angeles County Community Climate Action Plan (2015, currently being updated), Los Angeles County Office of Emergency Management, and the All Hazard Mitigation Plan (2014). These county efforts are joined by resiliency planning, climate action plans, and sustainability plans at the municipal level.
Collectively, these resilience and sustainability planning efforts help collect and implement policies and projects that will ensure the long-term vitality of the region, and therefore should be integrated with planning efforts along the LA River where appropriate.
The resources in and around the LA River should be sustained to guarantee welfare and promote equity for current and future generations. In a region that is both arid and increasingly short on available land, an underutilized 51-mile river corridor presents an incredible opportunity to create new multi-benefit uses that enhance resiliency and quality of life of river adjacent-communities and the region as a whole.