Reductions in urban outdoor water use as an adaptation to rising temperatures and declining water supplies in Southern California

Source

Authors

University of California, Irvine

Published

2012

Description

There is increasing evidence that climate change will exacerbate urban water shortages in southern California. A large proportion of household water use is applied outdoors for irrigation, so a potential response to decreasing water supplies is to promote changes in outdoor landscaping and irrigation regimes to reduce outdoor water use. Many urban landscapes are over-irrigated and there is a paucity of data on the average transpiration rates and water requirements of urban plants. This project involved making direct measurements of the transpiration rates of urban lawns, shrubs, and trees in the Los Angeles metropolitan area and evaluating the main factors determining spatial and temporal variability in plant water use. Results showed the transpiration rates of well-watered urban plants may vary by at least an order of magnitude depending on species and local conditions. Modeling was conducted on the transpiration and evapotranspiration at the plant, plot, neighborhood, and municipal scales using a variety of methods and computational models. The potential for water conservation was assessed through changes in outdoor landscaping such as changes in species composition, shading of lawns, decreases in irrigated vegetation density, and changes in irrigation technology. The results suggested that the methods most likely to contribute to significant outdoor water consumption reductions in southern California urban areas were: 1) removal of lawns or shading of lawns by large trees; 2) changes in irrigation technology, particularly soil moisture measurement-based irrigation systems; and 3) selection of low water use tree species, such as species adapted to non-riparian semi-arid or Mediterranean climates. A remote sensing-based modeling approach that can capture some of the high degree of spatial variability in water and energy balance that is characteristic of urban areas for large-scale analysis of evapotranspiration over the irrigated metropolitan area is also included in this report. This is a state-funded research study sponsored by the California Energy Commission.

Climate Impact Tags

Temperature

Adaptation Planning Guide Phases

Phase 3: Define Adaptation Framework and Strategies

Resource Type Tags

Scientific study

Topics

Extent: Los Angeles County, Orange County

423 Views

Last updated: April 25, 2024