Evaluating dairy waste management systems' influence on fecal coliform concentration in runoff

This report examines environmental factors influencing the die-off and transport of fecal coliform bacteria present in wastes applied to the land surface. These factors are examined specifically for dairy waste management systems and the net effect each system has on runoff water quality. A model is developed that considers the effects of precipitation, season, method of wastes storage and application, die-off of the bacteria in storage, die-off of the bacteria on the land surface, infiltration of bacteria into the soil profile, soil characteristics, overland transport of bacteria (runoff), and buffer zones. The model is then applied to the Tillamook Basin in northwestern Oregon to evaluate which waste management procedures significantly decrease bacterial pollution potential in agricultural runoff.Published November 1982. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo

First-order reliability method for estimating reliability, vulnerability, and resilience

Reliability, vulnerability, and resilience provide measures of the frequency, magnitude, and duration of the failure of water resources systems, respectively. Traditionally, these measures have been estimated using simulation. However, this can be computationally intensive, particularly when complex system-response models are used, when many estimates of the performance measures are required, and when persistence among the data needs to be taken into account. In this paper, an efficient method for estimating reliability, vulnerability, and resilience, which is based on the First-Order Reliability Method (FORM), is developed and demonstrated for the case study of managing water quality in the Willamette River, Oregon. Reliability, vulnerability, and resilience are determined for different dissolved oxygen (DO) standards. DO is simulated using a QUAL2EU water quality response model that has recently been developed for the Oregon Department of Environmental Quality (ODEQ) as part of the Willamette River Basin Water Quality Study (WRBWQS). The results obtained indicate that FORM can be used to efficiently estimate reliability, vulnerability, and resilience.Holger R. Maier, Barbara J. Lence, Bryan A. Tolson, and Ricardo O. Fosch