12/11/2008 5:01:00 PM River study helping irrigation companies
VVN/Steve Ayers
Rob Ross of the Arizona Water Institute at Northern Arizona University has installed pressure transducers at strategic locations on some of the ditches in the Camp Verde area in order to accurately measure the amount of water flowing through them.
Ross’s work is part of a study being conducted by Yavapai County to help understand the surface water flows of the Verde River.
One of the keys to understanding the Verde Valley's water resources is understanding the Verde River itself.
The Verde is a dynamic desert stream with irregular flows and a meandering pathway, fed by multiple tributaries, and depleted by streamside vegetation, underground seepage and several manmade diversions.
From a hydrologic standpoint, it is a complex system.
A year and a half ago, the county hired the Arizona Water Institute at Northern Arizona University to begin unraveling the river's complicated web of flow paths by conducting something called a geospatial database study.
Geospatial is a scientific term that basically refers to gathering information on a particular place.
Having an understanding of the river and how it flows has been deemed by the county's Water Advisory Committee (WAC) to be one of the first and most important steps in developing an overall water management plan.
The study covers a stretch of the river from upstream of the Yavapai-Apache Reservation to Beasley Flats, including the perennial tributaries and all major diversions.
Information collected in the study will be used to develop a computerized model that will help future water managers better understand how the river will flow when impacted by specific hydrologic events.
"I think it is a great project that will hopefully lead to some predictive capabilities and management tools for the Verde Valley, as well as some basic understanding of how that system works," WAC coordinator John Rasmussen said.
But there are others, outside of the county, who are benefitting from the study.
"It will definitely have more uses than what it was designed to have," said one of the study's lead investigators, Robb Ross. "It will be interesting to see what those uses are."
One of the major benefactors so far has been the ditch companies participating in the study, including the four major ditches in Camp Verde that take their water from the Verde River -- the Verde (Woods), Eureka, OK and Diamond S ditches.
Not only are they receiving what may very well be the first accurate maps of their ditches and laterals, but they are also gaining some insights on how many acres of land they are currently irrigating and how much water they are using.
The first phase of the study involved extensive mapping of the ditches, using GPS coordinates, and adding that information to the county's existing global information system database.
In addition, Ross has installed pressure transducers on the intakes and outlets of the ditches, allowing the ditches for the first time to accurately measure their flows.
"Pressure transducers are similar to the fish finders used on bass boats," Ross said. "They measure the pressure of a column of water and give us a good approximation of what the ditch flows are."
Ross said there has never been an accurate study of the ditches.
"The most recent study, done in 1997, relied heavily on anecdotal information and lacked any real measurement. The ditches play an important role in calibrating the numerical model, so understanding how they work will gives us a more accurate picture of how the surface flows of the river work," Ross said.
