Hydraulics: Erosion Control Testing

Erosion Expert
Blake Tullis | blake.tullis@usu.edu | 435-797-3194
Business Contact
Maria Gates | maria.gates@usu.edu | 435-797-3120

The UWRL provides erosion control testing services via an indoor drip irrigation rainfall-based erosion test facility. The UWRL rain simulation facility was the only one of its kind when it was built in 1974 with support from the Federal Highway Administration. Erosion control testing services began in the 1980s.

Erosion Control Laboratory Testing Services:

Rainfall Capacity:

  • 3.0 to 5.0 inches per hour for a 60-minute test represent typical test conditions.
  • Maximum rainfall capcity exceeds 20 inches/hour.

Test Results:

  • Product effectiveness (C-factor) reported for the two consecutive 30-minute test periods and the full 60 minutes relative to unprotected bare soil
  • Digital video and still photographic overview documenation
  • Turbidity data at 15-minute intervals

Test plots:

  • Three 4-ft wide by 20-ft long adjustable slope soil plots with a maximum slope of 1.5H:1V (56.3 degrees or 62.6% slope)
  • 12-inch deep soil plots feature sandy-loan soil compacted to ~70% standard proctor density.
  • Permeable bottom boundary allows excess water to drain, simulating an infinitely deep soil column. (Systems with impervious or uncontrolled [hard pan] bottom boundaries can create artificially high pore pressures and increas the likelihood of catastrophic landslides)

Quality Control Summary

Plot Preparation

  • Top 3 inches of soil is removed from each plot after each test to eliminate residual erosion control fibers and/or chemicals
  • Soil is spaded with a shove and mechanically tilled through the full depth to maintain uniform soil properties.
  • With the soil at the proper moisture content level, the plots are rolled with a weighted roller to a compaction of ~70% standard proctor density ±3%. For each test, soil densities are measured at three locations per plot using a nuclear density gauge.
soil density measurements

Product Application

  • Hydraulic erosion control products are prepared/applied using a lab-scale (70-gal) hydro-seeded. Based on the specified field application rate (e.g., 3,000 lb/acre), the corresponding amount of product is added to 50 gallons of the water in the hydro-seeder and mixed for approximately 5 minutes.
  • Following mixing, the hose is charged, and the appropriate volume of product is uniformly applied to a single test plot by tracking the change of product volume in the tank.
  • Following application, the tank is drained and the process repeated until product has been applied to all plots.
pretest soil conditions
Erosion test
rainfall erosion test close-up
rainfall erosion test


  • The Rainfall rate is calibrated prior to each test through a water capture/weighing process. Once the desired rainfall rate is reached, the plastic sheet covering the test plots is removed and the test initiated.
  • Turbidity samples are collected every 15 minutes.
  • In some cases, seeds and fertilizer are applied to the soil surface prior to applying the mulch or blanket material. Following the 60-minute test, the test plots are returned to a horizontal position, a light bank place over top and the seeds are allowed to germinate and grow for 7-10 days to quantify the plant establishment efficacy of the test product.
turbidity samples

Service and Outreach

Professional Assocation Affiliations:

American Society of Testing and Materials (ASTM), D18 Committee

National Trasportation Product Evaluation Program (NTPEP)

Water Engineering Education

Faculty within the Water Division have joint appointments with the Utah Water Research Laboratory and with the Department of Civil and Environmental Engineering at USU. The academic curriculum supporting research is one of the most comprehensive offered in the United States.

Elements of ongoing research projects are routinely and effectively incorporated into the courses offered. The program combines research, training, and experience to understand water issues and water resources management challenges in the State of Utah, the United States, and the world.