As California enters a forth year of unrelenting drought, more students in Monterey County seem to be thinking about the importance of water in their future. This was evident at the Monterey County Science and Engineering Fair held last weekend on the campus of California State University – Monterey Bay. Of approximately 350 projects, 63 were water-related. A three-judge team considered 9 finalists before choosing the winner of this year’s “Water For Our Future” award.
Sponsored by CSUMB’s Watershed Institute and Stanford’s Hopkins Marine Station, this special award recognizes projects that seek ways to solve a water shortage at home, at school (work), or on the farm. This year’s winner was Megan Tang of York School. The title of her project was, “Effects of Windbreaks In Reducing Agricultural Water Usage.”
Megan is very interested in water conservation. During these last few years of drought, she realized conservation has become a top priority, especially in agriculture where irrigation demands in some parts of California have already exceed supply. She decided to focus her attention on ways to conserve agricultural water by managing water loss on farms. In her project’s Introduction she writes,
“In the world, 60% of available freshwater is used for irrigation, but this water is lost mostly through evaporation by wind, the sun, and soil properties.”
Megan understood how wind and rising temperatures could increase evaporation. She had read how windbreaks could help lower water loss in fields. Thus, she decided to design an experiment to quantify how effective windbreaks were at conserving soil moisture, which could help reduce the use of agricultural water.
First, she constructed two model farm fields – one with a windbreak (test plot), the other without (control). Soils for each model were equally moistened in a single tub then spread out across the two fields. Small shrubs were used to mimic “deciduous trees,” typical of windbreaks while household fans were used to generate winds. After preliminary runs to assess air flow and wind velocity in her experimental design, she was ready to put her question to the test: Would fields with windbreaks maintain higher soil moisture levels than those without? Fans blew across the “fields” at three different speeds (low, medium, high) for 10 hours. Temperatures and soil moistures were monitored and recorded. Experiments were then repeated. What the judges liked most about this project was the simple, yet eloquent use of logic in the experimenter’s design and execution, as well as the clear conclusions that followed. Megan showed how fields with windbreaks did indeed maintain higher soil moisture. Her study concluded that windbreaks reduced water loss by an average of 4%.
The study also revealed an interesting caveat. At faster wind speeds, airflow across fields with windbreaks displayed a non-linear pattern. That is, speed rose slightly about 2 meters behind the windbreak then abruptly dropped (see Graph, Figure 2). This suggests that when winds blow strongly across a field, water loss is best minimized at a certain distance away from the windbreak, not right next to it. Interesting! Windbreaks are nothing new. Farmers have used them for thousands of years to prevent soil erosion, optimize crop production, and even conserve water. But to see this simple, inexpensive technology on display at a science fair showing a 4% drop in water loss made me pause – I remembered a very similar result stated during a water forum last October. The forum, New Directions for U.S. Water Policy (for link, click here),” included some of our Nation’s top experts who spoke about looming water concerns. What I remembered was this:
“A 9% reduction in agricultural water consumption would double the amount of water currently available to residential, commercial, and industrial users.”
The speaker (Robert Glennon, University of Arizona) explained the importance of this fact in a paper he co-authored with others as follows: One acre-foot of water (about 326,000 gallons) used to grow alfalfa generates roughly $920. The same amount used to grow lettuce (in Arizona) generates $6000. But an acre-foot of water used by Intel to produce microprocessors for computers brings in $13 million. The arithmetic, he said, was intriguing. In other words, it is not just farmers who need water. We all do. But we also need farms to produce the food we eat. Hence, water solutions in the future must include innovative ways to irrigate farms while leaving enough water behind for the many other uses that benefit our State. Eighty percent of California’s water is used by agricultural. Better water management and conservation practices are needed for our future. Windbreaks can save farms water. Although trees (that consume water) are often used, I hope Megan’s project inspires creative ideas in landscaping that lower wind speeds, conserve soil moisture, and reduce the need of water for irrigation. Again, congratulations to Megan Tang and York School for winning this year’s Water For Our Future award!