Hydrologic Data Report Introduction This installment reports on the hydrologic conditions for the week of 4-16-2015, presenting hydrologic information about the American River Basin in California. The data used in this report is from a multitude of sources, one of which is a wireless sensor network (WSN) in the basin. This wireless sensor network offers unprecedented spatial and temporal resolution, and thus enhances the predictive capability of the forecasts below [1]. The time series plots below contain all of the available data from the WSN, and other sources, including the California Data Exchange Center (CDEC). For the time series plots shown below, the sites are shown in decreasing elevation, from top to bottom. The name of each site is abbreviated by a three letter acronym, which is expanded in the appendix. Sources labeled as Oper. data are operational data from CDEC. Snow Water Content (SWE) In the plot below, the SWE variations over time can be observed, from both the WSN, and the California Data Exchange Center (CDEC). 1
In this time series, one of the sites (ALP), contains data from two CDEC sources at the same location, marked as ALP, and FRN. As expected, the SWE is decreasing at the sites of lower elevation. Since the last report, the SWE continues to trail off towards zero. SWE at Mount Lincoln (MTL) is 10 inches and decreasing. Snow Depth In the plot below, the snow depth variations over time can be observed, from both the WSN, and the California Data Exchange Center (CDEC). For where it is present, the operational data reads a consistently larger snow depth than the data from the WSN. It is observable that the snow depth generally increases with elevation, as expected. There is particularly large variation in the snow depth at Mount Lincoln (MTL). Most recently, similar to the SWE trend, the snow depth continues to trend towards zero at all of the sites. The snow depth at Mount Lincoln is decreasing, and is currently at a value of 20 inches averaged from all of the sensor nodes. 2
Temperature In the plot below, the temperature variations over time can be observed, from both the WSN, and the California Data Exchange Center (CDEC). On average, the temperature still decreases with increasing elevation, as expected. The operational data seems to indicate a higher temperature than the WSN. Recently, the temperature seems to be leveling off. At the sites of higher elevation, it is leveling off at around 0 degrees Celsius, and at the sites of lower elevation, the temperature is leveling off at around 5 degrees Celsius. Recently, the temperature experienced a sharp increase from 5 degrees Celsius to about 11 degrees Celsius. Relative Humidity (RH) In the plot below, the RH variations over time can be observed, from both the WSN, and the California Data Exchange Center (CDEC). 3
The daily relative humidity data is only available from the WSN. The trends in relative humidity were similar from site to site, in magnitude, and direction. The largest change was at Mount Lincoln (MTL), which decreased from 90% to about 75% average relative humidity. Echo Peak decreased dramatically from 75% relative humidity to about 50%. 4
Soil Moisture In the plot below, the soil moisture variations over time can be observed, from the WSN. No data from CDEC is present for this time series, and two sites contain nodes with soil moisture sensors. At those two sites, there are five nodes with soil moisture sensors. The axes of this plot have been changed since the soil moisture plots of previous reports, in order to show a smaller scale of variability. Soil moisture remains fairly steady at ~ 300 mm, with a slight decrease recently to about 275 mm. Percent water in snow In the plot below, the percent water in snow variations over time can be observed. This plot was generated by combining the plots of snow water content, and snow depth. 5
Note that this plot of percent water in snow can also be interpreted as a specific density. The WSN currently does not measure percent water in snow, so this plot shows data from CDEC. The bottommost subplot shows the mean and standard deviation of all of the CDEC sites above it. The higher variability in the beginning of February can be attributed to a series of rainstorms. The percent water in snow has been very steady recently at all sites around 40%. Observations For this week, as expected for the change of season, the SWE, and snow depth are decreasing, as expected. The temperature increased suddenly, which is also expected, given the warmer climate. Relative humidity decreased at all of the sites. A more detailed picture of the soil moisture shows that it is steadily decreasing overall. Appendix The expanded abbreviations of the surveyed sites are as follows: Echo Pk. MTL Echo Pk. Mount Lincoln 6
CAP FNR DUN ONN RBB BTP ALP Caples Lake Forni Ridge Duncan Peak Onion Rob Saddle Bear Trap Alpha References 1. http://glaser.berkeley.edu/glaserdrupal/?q=high-performance-wireless-sensor-networks 7