TOPANGA : Weather Buffs Assist Canyon Rainfall Study

A small army of volunteer weather buffs, using back yard rain gauges, are key to a new study of erratic rainfall patterns in Topanga Canyon.

The study, which is being pieced together from readings taken by weather enthusiasts scattered across the canyon, will help a citizens committee draft regulations for managing development in the delicate Topanga Canyon area, home of one of the last natural stream beds feeding Malibu Bay, said Rosi Dagit, a consultant for the Topanga-Las Virgenes Resource Conservation District.

Dagit said she started recruiting volunteers for the project because Los Angeles County did not have the money to do its own study, and was instead using rough projections of rainfall to identify areas of high flood risk.

“They were making assumptions based on no data,” said Dagit, a biologist. “So, I thought because a lot of people do weather monitoring as a hobby, that we could maybe tap into that.”

Dagit began seeking amateur weather enthusiasts who could provide a cheap alternative to a full-blown scientific study of the region.

So far, she has located about 30 canyon residents to do the job. They include clinical psychologist Gerry Haigh, who has been assiduously keeping rainfall data for fun for about a dozen years.

Dagit said Haigh’s computer records of readings taken not on a monthly, but a daily basis, have been a surprise windfall for the study.

Haigh said he uses a simple plastic rain gauge, really just a calibrated cup, to measure water after every storm.

When asked why he does it, he pauses, perplexed.

“I’m not sure why,” he said. “I guess the variation between flood and drought here intrigued me . . . You get up in the morning and it’s been raining and you just want to know how much. Everyone’s always curious.”

The volunteers are nearing the end of their first winter of data-taking. Haigh said the year has been an especially dry one; his gauge has registered about 12 inches of rainfall compared to 40 inches by this same time the previous year.

The information collected by data takers will be plugged into computer models to project flood patterns in the 20-square-mile Topanga Canyon Watershed.

The Topanga Canyon Floodplain Management Citizens Advisory Committee will use the projections to map areas of high flood risk in the canyon, and to draft regulations to protect the safety of residents and preserve the wildlife of the creek bed.

Chandler said the information gleaned from back yard rain gauges is especially important because changes in the weather are often highly localized across the steep and varied terrain of the Santa Monica Mountains.

“The difference in rainfall between Old Topanga and Fernwood Canyons in a single storm can be two to four inches,” said Dagit.

The committee has about two more years to complete its work. Dagit said she is still trying to recruit as many citizen researchers as she can to find out more about where and when it rains in Topanga Canyon.

To volunteer to help with the study, contact the Resource Conservation District at (310) 455-1030.