UCLA pools together data to help inform drought mitigation

By Tetra Balestri, Student Contributor

Over the years, Californians have seen a number of state-implemented policies and programs for conserving water. From mandatory watering restrictions to landscaping incentives, from trying tier-systems to withdrawing tier systems, from risqué advertising to not so risqué advertising, government officials are gambling on which policy will stick. Fortunately, research conducted at the Institute of the Environment and Sustainability (IoES) has revealed some numbers worth betting on.

UCLA doctoral student Caroline Mini took initiative to ask and answer fundamental questions as to why we are turning on and off our faucets. Funded by the National Science Foundation and under the supervision of Stephanie Pincetl, professor-in-residence at the IoES and director of the California Center for Sustainable Communities at UCLA, and Terri Hogue, a professor at the Colorado School of Mines, the researchers devised a simple approach toward understanding water usage: look at the data.

The team was able to collect data from the city of Los Angeles for single family homes over a ten year period (2001-10). They analyzed household water use of different socioeconomic levels and geographic locations. Coupling this data with the impacts of mandatory and voluntary water restrictions as well as water pricing, they were able to draw conclusions about what conservation practices worked best.

According to Pincetl, collecting and analyzing data in this way is a novel approach toward informing policy decisions.  “We were able to do a fine-grained analysis to understand the water use across geographical space and the ways in which water use changed over time depending on policy changes. That, to our knowledge, has never been done in that way.”

From this analysis emerged some important findings. First and foremost, income matters. Financial considerations were the most influential factor regarding water use, even more so than climate zones. One might think that residents in hotter, drier areas, such as the San Fernando Valley, would use more water than those on the coast. However, data reveals the wealthier coastal residents are consuming three times as much water than their less affluent counterparts. Much of this excessive water use can be explained by larger plot size, garden types, and the age of homes.

As it turns out, we all use too much water. The team was able to access satellite imagery over this ten year span to compare the green density of land plots. When mandatory regulations were in place, such as watering only at night, these images did not show a significant difference in green density before and after the restrictions. This inefficient use of water reflects that nearly 54 percent of single family water consumption is used in outdoor watering.

This data can influence policy decisions in a practical way. The numbers reveal that mandatory restrictions are more effective than voluntary restrictions. In 2009, mandatory restrictions were combined with a rise in water prices resulting in a water usage reduction of 23 percent- the highest reduction on record. In addition to mandatory restrictions, tier systems are an effective way of controlling water usage. Under the tier system, those who use more water pay more. When water prices increase, water consumption decreases. When this data was presented in a briefing to the city of Los Angeles, the researchers encouraged a multi-tiered block system that better reflects seasonal household usage.

In addition to informing policy making, this project presents an opportunity for state agencies to take advantage of university research.  “We really want to do public interest work that provides decision makers with a better understanding of the impacts of their policies and programs,” remarked Pincetl. As the drought looms over our heads, this kind of partnership will prove essential toward making effective decisions. “By pulling together good data in a smart way, you can really say a lot.” said Pincetl.