Jim Goodridge
Jim Goodridge

James D. Goodridge


Special Recognition Award

The following is the text found on the Special Recognition Award presented to James D. Goodridge, California State Climatologist (Retired), California Department of Water Resources, Sacramento, California at the 2005 California Extreme Precipitation Symposium held at the California State University, Sacramento on April 22, 2005.



James D. Goodridge

This award is in recognition of a lifetime of service to the water community by collecting, analyzing, developing, and presenting rainfall statistics for design of storm drainage and water control facilities. The initial DWR Bulletin 195, "Rainfall Analysis for Drainage Design", published in 1976, was a classic for water engineers. During your tenure as State Climatologist, you diligently and enthusiastically collected all the weather data you could get your hands on, cataloged and analyzed data from hundreds of rain gages, and made available systematic information on extreme precipitation. You have continued these activities in retirement like the dedicated scientist and engineer you are. The fact that stormwater, drainage, and flood control projects in California have done such a good job of protecting lives and property is a tribute to your vision and diligence. Your colleagues are most pleased to present you with this token of our appreciation and gratitude.

April 22, 2005

2005 California Extreme Precipitation Symposium

Professional Background

My interest in the rainfall started on the day I reported for work for the US Weather Bureau in Sacramento. The day was November 18, 1950. It was a day when the road into Yosemite Valley was washed out. This was an exciting event for the first day on the job for a newly recruited weather observer. We were deeply involved in weather and flood stage forecasting at the time. Those forecasts were largely based on the messages arriving by phone from a broad ranging corps of volunteer weather and stream-flow observers. The sprit of volunteering and of public service in weather observation is still quite touching.

It was to my amazement that there were 100 years of historic monthly rain records in the weather office. Volunteer observers (Drs. Logan and Hatch) compiled the early records starting in 1849 for the Smithsonian Institution. The Army Signal Corps took over on July I, 1877. After two years of opening the office at 4 AM, I switched to the Army Engineers with a gentler starting time. At the Corps I worked with people who showed how to check rain record homogeneity by double-mass plotting and with Leo Beard who illustrated how useful statistic could be in hydrology. Leo Beard was a very inspiring teacher and the founder of the Corp's Hydrologic Engineering Center. Later he became Professor of Hydraulic Engineering at the University Texas.

In 1953 I found myself at the Division of Water Resources where I realized that all water agencies were dipping into the same pool of historic weather records. It was apparent that those wonderful data sets were defining the boundary conditions of nearly all civil engineering enterprises. All engineers did not cherish these rain records in proportion to their great importance, at least not by my reasoning. I felt like a savior arriving to correct an oversight.

At DWR I learned about similitude in engineering design from John Teerink, who was working on the design of the Edmonson Pumping Plant, the worlds largest, at the time. Cliff Courtright, Chief of the Dam Safety Office, requested a better procedure for calculating design values for a 1000-year storm. They needed a procedure where all workers would come up with the similar rainfall analysis for use in spillway safety studies. I understood in a flash, that similitude might be applied to the study of rainfall statistics, how to average dimensionless rainfall statistics in regions of similar climate. At that time the reliance on sample statistic was producing chaotically wide-ranging sizes of design storms, as they were mainly based on short rain records. I was challenged to define similar climate regions, but later we compromised and decided that the various 13 hydrologic regions of the State were adequate to use as regions of climatic homogeneity.

There were many papers in the hydrology literature in phrase of various frequency distributions. The clarity that was offered in Ven Te Chow's 1964, Handbook of Applied Hydrology was much appreciated. Phil Warren a statistician at DWR suggested using Karl Pearson's concept of a skew-kurtosis map to select a frequency distribution. The Pearson Type III distribution was chosen by this method.

A sensitivity analysis would show that choice of frequency distribution was a very minor factor compared to using the averaging of the dimensionless parameters like the coefficient of variation (CV). Averaging the CV, and skew seemed like a radical concept. But it did introduce the much-needed stability into the calculations of return periods for 1000-year rainfalls based the short records available near the construction sites.

We now have an archive of over 5000 data sets of annual series extreme values of precipitation. These were developed for drainage studies. They are available for regional mapping of the dimensionless coefficients of variation, skew, kurtosis and slope of the IDF curves for GIS applications. These all fit comfortably on a compact disk for easy file sharing. The maintenance of these files has been a personal obsession for fifty years.