Getting to the root of the water cycle
In a remarkable outdoor laboratory in the Sierra, UC Merced and UC Berkeley researchers use sensors to gather a mother lode of data to greatly improve ecological measurement and hydrologic forecasting.
What winter brings to the Sierra Nevada determines, more than anything, how much water can be tapped in summer by California’s communities and businesses, including the state’s $35 billion agricultural industry. About 60 percent of the water used in California comes from melting Sierra snow.
Water managers have always faced a difficult task trying to allocate the state’s most precious resource. They need to know how much water to store in reservoirs and how much to send downstream, and when.
But estimates of the amount of Sierra water the reservoirs will receive sometimes are off by as much as 20 percent to 30 percent. At rates of $100 to $600 per acre-foot delivered to metropolitan areas, a 20 percent error could translate into a more than $150 million shortage or excess of water needed downstream.
The solution lies in matching broad-coverage satellite data with more detailed measurements from an extensive wireless monitoring grid on the ground. Specially designed wireless sensors developed at UC Berkeley now are being deployed and tested in an ambitious pilot project directed by researchers at the UC Merced Sierra Nevada Research Institute.
The Berkeley–Merced collaboration uses matchbook-sized sensors with wireless communicating microprocessors, known as motes, to measure soil moisture, snow depth and other features critical to predicting spring and summer water availability. The system is designed to transmit the real-time measurements to researchers and water managers.
The prototype grid is being established on a 2.5-square kilometer site in the Sierra Nevada, which itself is a portion of an even more ambitious ecological research project called the Southern Sierra Critical Zone Observatory, or CZO, an National Science Foundation-supported mountain research site located about an hour east of Fresno.