ET, Lysimeters, Bowen ratio and Eddy correlation

Dr. Howell, I did not intend to "imply" but to ask. The knowledge and experience that has been evident here is exponentially greater than mine.

I would like to stir the pot a little though, now.

Why did I even ask the question in the first place?

Many of you, that are familiar with California and California Department of Water Resources, know of DWR Bulletin 113-3, Vegetative Water Use in California and Bulletin 113-4, Crop Water Use in California. The Department is about to embark on an update of these publications. Some of you probably know the history of these publications better than I do. I know that lysimeters were used for development of 113-3 and I think neutron probes were as well. I do know that neutron probes were use in other studies done by the Department in the 1970's and 1980's. The numbers, contained in these publications, were developed for planning and irrigation scheduling purposes and I think do a pretty good job in that respect.

Today, however, water marketing is becoming commonplace in California and other western states. Most water transfers are from agriculture to urban. I won't grow this crop and I will sell you the water I save. Since the State or federal government releases the water from a dam and the city takes that amount of water at its diversion, we need to be able to determine the "real water" saved. If the seller is credited for saving 3 feet of water, that is the amount paid, the buyer gets 3 feet. If in fact the grower would have only used 2 feet the people of the State of Ca. have donated 1 foot.

Now that dollars are being attached to the numbers it is necessary to develop as accurate numbers as we can within our time and budget constraints. Yes, Science meets the "real world." Of course none of you have these problems, Right?

Since I doubt we will get the time or money to do the long term studies required to develop numbers of our own we will probably have to review the work of people like you as well as water districts, farm advisors, etc. In order to do that type of review we need to understand the limitations of the methods used, and I have gained a lot from this discussion. We will also need to find the work that has been done on Crops grown in California that we can then fit to our climatic conditions.

Any suggestions or comments you have are appreciated,and please continue on.