UC Irvine

Despite major advances in water efficiency, urban water resources are increasingly strained due to population growth and severe droughts. In arid regions, water managers often promote water conservation rebate programs: the most common is known as a “turf rebate” program – offering participants a fixed rebate amount per unit area (e.g., $2 per square foot) in exchange for replacing turf grass with drought-tolerant landscaping. In southern California where outdoor watering can comprise more than half of residential water use, hundreds of millions of dollars worth of turf rebates were distributed during the 2011-2016 drought.

In my thesis, I focus on single-family residence (SFR) participation in a turf rebate program in the Irvine Ranch Water District (IRWD) in southern California. Spatial analyses at the village (i.e. neighborhood) level and at the parcel level reveal that drivers of participation are tied heavily to aspects of the built environment, whether it’s home age (at the village level) or outdoor area (at the parcel level). From these results we propose a probabilistic framework for estimating, and potentially optimizing, the water savings achieved by cash-for-grass programs, taking into account constraints of outdoor area imposed by the built environment, climate, demographic drivers of conservation behavior, and financial incentives.

I also explore temporal patterns of participation and find that a universal temporal pattern captures the majority of the monthly participation probability across all villages (i.e. neighborhoods) in the IRWD service area. This temporal pattern is highly correlated with Google search rates for the phrase “turf rebate”, which serves as a proxy for mass media coverage on the California drought and the turf rebate programs that became more heavily advertised as a result. In conjunction with California Governor Jerry Brown’s 2014 emergency drought proclamations, IRWD conducted water conservation and education programs. These local and state actions led to very high SFR participation in the IRWD turf rebate program.

Together, these built environment, demographic, and mass media coverage variables help explain water savings potential and spatiotemporal patterns of participation in IRWD’s turf rebate program.