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Map of California showing the implementation plan for a soil science monitoring network. Open purple circles denote RAWS sites where DWR and SIO plan to deploy soil sensors. The open red circles denote CalFire Stations, where PSD plans to deploy soil sensors. Sites enclosed by the two blue ovals have already been installed.
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Example of a PSD soil science station. This particular installation is in the Sierra foothills at O'Neals, California.
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May 20, 2011
Joint Project to Measure Soil Properties Across California
When California experiences its first storms of the wet season, the vast
unirrigated regions of the state are replenished with life sustaining
water. The uptake of water by the soil also can determine whether a storm
produces flooding. If the soils are dry enough, these early season storms
do not induce widespread flooding. However, when the soils are wetter,
like later in the winter, more of the liquid precipitation runs along the
land surfaces, increasing runoff and the potential for floods. Some soils
may essentially soak up the first few inches or more of precipitation
before heavy runoff can begin. Thus, soil moisture is an important
hydrometeorological parameter to monitor and research related to soil
moisture is part of a major activity area for hydrologic applications in
HMT.
Under a five-year agreement between the NOAA Earth System Research
Laboratory's Physical Sciences Division (NOAA/PSD) and the California Department of
Water Resources (DWR), 43 soil science stations are being deployed across the state using modern,
unattended soil measurement techniques that only have been available over
the last decade or so. So far a dozen of these stations have been
installed in the flood-prone Russian River Valley north of San Francisco
and along the foothills and upper elevations of the central Sierra (see
Fig. 1). Because research conducted under HMT has shown that soil
properties vary with elevation in the Sierra, DWR and the Scripps
Institution of Oceanography (SIO) will partner to put soil stations at
higher elevations across the state, while NOAA/PSD will concentrate on
lower elevation installations. DWR and SIO are taking advantage of existing
monitoring and communications infrastructure at interagency Remote
Automated Weather Stations (RAWS). NOAA/PSD is partnering with the
California Department of Forestry and Fire Protection (CalFire) to locate
sensors near CalFire Stations. An example of one of NOAA/PSD's
installations is shown in Fig. 2. In addition to measuring soil
temperature and volumetric moisture content at two levels (10 and 15 cm
below the surface), these sites also measure air temperature, relative
humidity, and rainfall. The observed data are transmitted back to DWR and
NOAA/PSD through satellite communications, telephone lines, or wireless
internet. Numerical data and time series images are available to everyone
on NOAA/PSD's website,
and rainfall data are transmitted to the National Weather Service (NWS) Western Region
Headquarters in the preferred NWS format. Soon, soil temperature, soil
moisture, and surface meteorology parameters will be added to this special
NWS data feed. The soil science stations are part of an unprecedented
observing network being developed for California that will provide critical
information on the forcings of extreme precipitation and flooding, as well
as long-term climate observations to help decision makers adapt to a
changing climate.