New England WSC Seminar series Granato 20170105

Science Center Objects

Example analyses for total nitrogen, total phosphorus, suspended sediment, and total zinc in highway-runoff were done by the U.S. Geological Survey in cooperation with the Federal Highway Administration to simulate long-term annual loads for Total Maximum Daily Loads (TMDL) analyses with the Stochastic Empirical Loading and Dilution Model (SELDM).

Date/Time: Thursday, January 05, 2017, 12:00 pm

Title: Estimating long-term annual highway-runoff loads for total maximum daily load analyses with the Stochastic Empirical Loading and Dilution Model (SELDM)

Presented by: Greg Granato, Hydrologist, USGS New England WSC

Location: USGS, Massachusetts Office, Northborough, MA

Abstract: 

The Massachusetts Department of Transportation (DOT) and the Rhode Island DOT are working to assess and address roadway contributions to Total Maximum Daily Loads (TMDLs). Example analyses for total nitrogen, total phosphorus, suspended sediment, and total zinc in highway-runoff were done by the U.S. Geological Survey in cooperation with the Federal Highway Administration to simulate long-term annual loads for TMDL analyses with the Stochastic Empirical Loading and Dilution Model (SELDM). Concentration statistics from 19 highway-runoff monitoring sites in Massachusetts were used with precipitation statistics from 11 long-term monitoring sites to simulate long-term pavement yields (loads per unit area). Highway sites were stratified by traffic volume and/or surrounding land use to calculate concentration statistics for rural roads, low-volume highways, high-volume highways, and ultra-urban highways. The median of the event-mean concentration statistics in each traffic-volume category was used to simulate annual yields from pavement over a 29–30 year period. Long-term average yields for total-nitrogen, -phosphorus, and -zinc from rural roads are lower than yields from the other categories, but yields of sediment are higher than for the low-volume highways. The average yields of the selected water-quality constituents from high-volume highways are 1.35 to 2.52 times the associated yields from low-volume highways. The average yields of the selected constituents from ultra-urban highways are 1.52 to 3.46 times the associated yields from high-volume highways. Example simulations indicate that both concentration reduction and flow reduction by structural best management practices are crucial for reducing runoff yields.