The US Geological Survey Multi-Hazards Demonstration Project has placed a real-time webcam in Modjeska Canyon to monitor Santiago Creek. The gage provides continuous monitoring of river flow, stage, and precipitation.
The flow at the gage is slightly regulated by the Modjeska Reservoir, located about 1.5 miles upstream in Harding Canyon. The webcam provides valuable information to the National Weather Service, emergency managers, and local residents to evaluate real-time conditions in the creek channel during storms. This new monitoring station will be a very useful tool in watching for debris flows that could result from the Santiago wildfire (Oct 2007) that burned more than 28,000 acres and destroyed more than a dozen homes. According to the newly released assessment report of the burned basins, “A short period of even moderate rainfall on a burned watershed can lead to debris flows (Cannon and others, 2008). Rainfall that is normally absorbed into hill slope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation.”
Santiago Gage Station Webcam: http://ca.water.usgs.gov/webcams/modjeska/
National Water Information System Data: http://waterdata.usgs.gov/ca/nwis/dv/?site_no=11075800
Assessment Report: http://pubs.usgs.gov/of/2007/1419/pdf/OF20071419.pdf
Note: Please stay on all public roads and DO NOT go into any burn areas. Please be respectful of the residents, community, and this fragile environment. You will not need to leave the pavement at any time!
Logging Requirement: To log this cache, you will need to do a little homework, some preparation, as well as visit the Modjeska Canyon area. You must meet ALL 6 requirements or your log will be deleted. Email us the answers to all the questions, except post your picture for Question #6. General photos of the area or your homemade data collection tools are appreciated.
Research
Question 1
According to the assessment report, how many canyons/basins were identified as having the potential to produce debris flows with a volume between 10,001 and 100,000 cubic meters during a 10-year-recurrence, 3-hour-rainstorm?
Question 2
Straw wattles are one way of preventing major water runoff. Straw wattles, also known as straw worms, bio-logs, straw noodles, or straw tubes, are man made cylinders of compressed weed free straw (wheat or rice), 8 to 12 inches in diameter and 20 to 25 feet long. They are encased in jute, nylon, or other photo degradable materials, and have an average weight of 35 pounds. They are installed in a shallow trench forming a continuous barrier along the contour (across the slope) to intercept water running down a slope.
What other MAJOR AIR EFFORT has been done to the surrounding slopes to prevent debris flows? (Hint: This was especially evident in the Cleveland National Forest during December 2007, check the CNF website for hints.)
Data Collection
Question 3
Visit the USGS Webcam online to obtain the current data at the Santiago Gage Station. Email us the latest gage readings including the date, river flow/discharge, and stage/gage height.
Question 4
Go to the Modjeska Bridge at N33° 42.482 W117° 37.723 and record TWO of the following measurements of Modjeska Creek. You will need to do some preparation beforehand to determine how to take these measurements in the most eco-friendly way while remaining on the bridge/public road. (i.e. You will need to engineer a measuring method that will not impact the environment.)
A- Measure the DEPTH of the creek (in inches)
B- Measure the FLOW RATE of the creek at the surface(in feet per second)
C- Measure the TEMPERATURE of the creek (in degrees F)
This website http://ga.water.usgs.gov/edu/measureflow.html explains how geologists and hydrologists do this, your measurements will be much simpler.
Observation & Analysis
Question 5
Observe the area near the Santiago Gage Station by operating the Webcam. Also observe the area at the Modjeska Bridge (N33° 42.482 W117° 37.723). What are the differences geologically between the two locations? (Examples: Size of the rocks, erosional features, creekbed/canyon differences, differences in erosion prevention techniques, depth/flow rate differences, etc.)
Question 6
In your log online, post a copy of the webcam picture of the current conditions. (http://ca.water.usgs.gov/webcams/modjeska/)
Citations: Cannon, S.H., Gartner, J.E., Michael, J.A., Bauer, M.A., Stitt, S.C., Knifong, D.L., McNamara, B.J., and Roque, Y.M., 2007, Emergency assessment of debris-flow hazards from basins burned by the 2007 Santiago Fire, Orange County, southern California: U.S. Geological Survey Open-File Report 2007–1419, 1 sheet. http://pubs.usgs.gov/of/2007/1419/pdf/OF20071419.pdf