Search

Search Results

• 1. [Article] TMDLS: Statistical Correlations or Mechanistic Modeling?

  In developing TMDL waste-load allocations for the Snake River-Reservoir system in Western Idaho and Eastern Oregon, determinations of the assimilative capacity of the system and the impact of pollutant ...

  Citation × Citation Citation Abstract Copy Title: TMDLS: Statistical Correlations or Mechanistic Modeling? Author: Wells, Scott A., Cole, Thomas M. Year: 2002 In developing TMDL waste-load allocations for the Snake River-Reservoir system in Western Idaho and Eastern Oregon, determinations of the assimilative capacity of the system and the impact of pollutant reduction strategies has been performed using both a statistical-correlation approach and a mechanistic modeling approach. The system included the Lower Snake River, Brownlee Reservoir, Oxbow Reservoir, and Hells Canyon Reservoir with the focus was on Brownlee Reservoir. The statistical approach used on Brownlee Reservoir divided the system into riverine and lacustrine zones. Field data were then averaged over season and location to provide statistical correlations, such as between total phosphorus (TP) and chlorophyll a (chl a), between an anoxic factor (AF) and TP, and between a hypoxic factor (HP) and TP. The anoxic factor is defined as the number of days when dissolved oxygen was less than 2 mg/l and the hypoxic factor was defined as the number of days when dissolved oxygen was less than 6.5 mg/l. The mechanistic approach used a two-dimensional, unsteady, hydrodynamic and water quality model called CE-QUAL-W2. The model was calibrated to field data over a three year period for 1992 (a low flow year), 1995 (an average flow year), and 1997 (a high flow year). Some of the important questions that the TMDL process was to answer included the following. What level of TP is necessary in the river coming into Brownlee Reservoir to reduce the number of days of hypoxia in the reservoir? What are the causes of low-dissolved oxygen in Brownlee Reservoir and what management strategies can be implemented to improve water quality? This paper examines the strengths and weaknesses of answering management questions using these two approaches. Recommendations are suggested for answering assimilative capacity questions that arise in TMDL studies. Title: TMDLS: Statistical Correlations or Mechanistic Modeling? Author: Wells, Scott A., Cole, Thomas M. Year: 2002 In developing TMDL waste-load allocations for the Snake River-Reservoir system in Western Idaho and Eastern Oregon, determinations of the assimilative capacity of the system and the impact of pollutant reduction strategies has been performed using both a statistical-correlation approach and a mechanistic modeling approach. The system included the Lower Snake River, Brownlee Reservoir, Oxbow Reservoir, and Hells Canyon Reservoir with the focus was on Brownlee Reservoir. The statistical approach used on Brownlee Reservoir divided the system into riverine and lacustrine zones. Field data were then averaged over season and location to provide statistical correlations, such as between total phosphorus (TP) and chlorophyll a (chl a), between an anoxic factor (AF) and TP, and between a hypoxic factor (HP) and TP. The anoxic factor is defined as the number of days when dissolved oxygen was less than 2 mg/l and the hypoxic factor was defined as the number of days when dissolved oxygen was less than 6.5 mg/l. The mechanistic approach used a two-dimensional, unsteady, hydrodynamic and water quality model called CE-QUAL-W2. The model was calibrated to field data over a three year period for 1992 (a low flow year), 1995 (an average flow year), and 1997 (a high flow year). Some of the important questions that the TMDL process was to answer included the following. What level of TP is necessary in the river coming into Brownlee Reservoir to reduce the number of days of hypoxia in the reservoir? What are the causes of low-dissolved oxygen in Brownlee Reservoir and what management strategies can be implemented to improve water quality? This paper examines the strengths and weaknesses of answering management questions using these two approaches. Recommendations are suggested for answering assimilative capacity questions that arise in TMDL studies. Close

• 2. [Article] Laurance Lake Temperature Model

  Laurance Lake is a reservoir located in Hood River County, Oregon (Figure 1). It is located at the base on Mt. Hood in Oregon (see Figure 2 and Figure 3), discharges into the Middle Fork of the Hood River. ...

  Citation × Citation Citation Abstract Copy Title: Laurance Lake Temperature Model Author: Berger, Chris, Wells, Scott A., Annear, Robert Leslie Year: 2005 Laurance Lake is a reservoir located in Hood River County, Oregon (Figure 1). It is located at the base on Mt. Hood in Oregon (see Figure 2 and Figure 3), discharges into the Middle Fork of the Hood River. The reservoir was constructed in 1968 for irrigation storage and has a capacity 3564 acre- feet at full pool. Since the river vio lates temperature standards, this study has been designed to construct a hydrodynamic and temperature model of Laurance reservoir in order to assess strategies for improving temperatures in the Middle Fork River. The objectives of the study are then to Develop a hydrodynamic and temperature model of Laurance Lake Calibrate the model to field data collected from November 2002 through Spring 2004 Use the model to evaluate strategies for temperature improvement through operational or structural changes to Lake Laurance The model chosen for development was CE-QUAL-W2 Version 3.2 (Cole and Wells, 2004). This is a two-dimensional unsteady hydrodynamic, temperature and water quality model that includes typical eutrophication parameters (algae, nutrients, temperature, organic matter, dissolved oxygen, pH). PSU, under the support of the Corps of Engineers Waterways Experiment Station, is a center for development of this modeling tool. Title: Laurance Lake Temperature Model Author: Berger, Chris, Wells, Scott A., Annear, Robert Leslie Year: 2005 Laurance Lake is a reservoir located in Hood River County, Oregon (Figure 1). It is located at the base on Mt. Hood in Oregon (see Figure 2 and Figure 3), discharges into the Middle Fork of the Hood River. The reservoir was constructed in 1968 for irrigation storage and has a capacity 3564 acre- feet at full pool. Since the river vio lates temperature standards, this study has been designed to construct a hydrodynamic and temperature model of Laurance reservoir in order to assess strategies for improving temperatures in the Middle Fork River. The objectives of the study are then to Develop a hydrodynamic and temperature model of Laurance Lake Calibrate the model to field data collected from November 2002 through Spring 2004 Use the model to evaluate strategies for temperature improvement through operational or structural changes to Lake Laurance The model chosen for development was CE-QUAL-W2 Version 3.2 (Cole and Wells, 2004). This is a two-dimensional unsteady hydrodynamic, temperature and water quality model that includes typical eutrophication parameters (algae, nutrients, temperature, organic matter, dissolved oxygen, pH). PSU, under the support of the Corps of Engineers Waterways Experiment Station, is a center for development of this modeling tool. Close