Monitoring the hydrologic cycle in the Sierra Nevada mountains

What is the hydrologic cycle? The hydrologic or water cycle is the movement of water on, above, below, and through the earth’s surface.

Why do scientists measure the hydrologic cycle?  Weather forecasting  Water use forecasting  Understand climate trends  Flood preparation  Hydrologic modeling Why is it important for scientists to measure the hydrologic cycle in CA?

A rain gauge measures liquid and solid precipitation Precipitation measurements Precipitation is the general name given for any form of condensed water that falls to the earth’s surface. Snow depth sensors use sound to record snow depth Snow pillow records weight of snow

Measuring Streamflow Flumes make the stream fit into a known shape.  Runoff is the movement of water over the land surface.  Stream flow is the flow of surface water runoff contained in a stream channel. Water depth sensors measure the height of water.

Measuring soil moisture Water that does not flow to the stream channel moves through the soil and/or rock through a process called infiltration. This water is known as groundwater. Soil moisture sensors buried at different depths underground. A series of soil moisture sensors buried underground to understand water uptake by tree roots. c

Measuring evapotranspiration  The movement of water from the liquid phase to the gas phase occurs by evaporation and/or transpiration.  Evaporation is the change of water from a liquid to a gas by heating.  Transpiration is water released from plants.  Combined, this process is called evapotranspiration. Sap flow Flux tower instruments

Measuring evapotranspiration The eddy-covariance flux tower measures water vapor from the surrounding forest. The tower measures: - wind speed and direction - CO 2 and H 2 O content - air temperature - relative humidity - solar radiation An evapotranspiration dome measures evaporation and transpiration coming off of soil and plant matter.

Weather stations This weather station is used to measure: - air temperature - wind speed - relative humidity - solar radiation - precipitation - snow depth Peak snow depth last winter

Collecting and retrieving data  An immense amount of data are collected each year.  Instruments are located in remote areas, making it hard to collect data on foot during the winter Data stored on a datalogger and can be downloaded with a laptop

Collecting and retrieving data The wireless embedded sensor network (WSN) was developed to make it easier to collect data remotely. Data sent to satellites can be retrieved remotely. Small radios send data from one node to the next, and end at the base station at the flux tower.

Powering instruments A series of solar panels and batteries power all the instruments within the basin.

Measuring the hydrologic cycle in the Sierra Nevada  Many different electronic instruments are available to measure the water cycle.  People use data from these instruments to understand many aspects of environmental science.  Scientists in California need to measure the water cycle in order to determine how much fresh water is stored in the mountains.