February 2013, Vol. 25, No.2

Research Notes

Professionals share knowledge to prepare for extreme weather and climate events

As extreme weather and climate events become more common, the ability of water resource managers and water service providers to respond is challenged, and the potential increases that these events will disrupt stormwater control and wastewater conveyance and treatment. 

To protect against this, water-sector professionals are sharing their experiences. An effort that will culminate this year in a research report began in August 2010 with a 2-day workshop. More than 80 drinking-water-sector professionals met to discuss their weather-related information needs for making key decisions on investments. 

Workshop participants were concerned about risks, vulnerabilities, preparation, and adaptation strategies associated with an increase in the number and intensity of extreme weather events,” said Lauren Fillmore, Water Environment Research Foundation (WERF; Alexandria, Va.) senior program manager. Many noted that they knew colleagues who had faced such events recently and recognized the need to exchange knowledge gained to better prepare, she added. 

As a result of the workshop, the U.S. National Oceanic and Atmospheric Administration and the U.S. Environmental Protection Agency agreed to collaborate with water research organizations, including WERF and the Water Research Foundation (Denver), to document experiences and synthesize collective knowledge. As the project moved forward, other research organizations, such as Concurrent Technologies Corp. (Stafford, Va.) and Noblis (Falls Church, Va.), joined the effort.

The collaborative research project examines how water utilities, resource managers, and county and regional planners make decisions before and during extreme weather, and how they have adapted and expect in the future to adapt planning efforts to better prepare. When complete, the project will identify how scientific data were used, what information gaps exist, and what information is needed to improve water utilities’ ability to adapt and respond to recurring events. 

Participating organizations currently are hosting six workshops across the United States. The workshops are organized by type of extreme event — drought, heavy rain and flooding, sea-level rise and storm surges, and extreme temperatures — and will be complete by late spring, Fillmore said. 

The research team is compiling case studies documenting the workshop findings, including lessons learned and information needed by water service providers so that both utilities and communities are able to make better decisions in the future, Fillmore said. These case studies will address 

  • challenges experienced while responding to extreme event conditions; 
  • partnerships, technologies, tools, information, services, and other approaches that were helpful; 
  • communication conducted before and during these events; 
  • procedures that were in place and used when responding to events; 
  • decisions made, who made them, under what conditions, and how successful they were at coping with the events; 
  • social, economic, and ecological effects; 
  • effects on water resources; and 
  • changes in planning, implementation, approaches, capital improvements, collaboration, communication, and decision-making that resulted. 

For more information, read the WERF report The Future of Research on Climate Change Impacts on Water at http://goo.gl/Wu8xr. 


Determining how to optimize the Phosphorus Index

The Phosphorus Index was designed in 1992 to help farmers identify appropriate management practice for phosphorus application, depending on different soil and environmental conditions, according to an American Society of Agronomy ( Madison, Wis. ) news release. It was meant to be easily computed from readily available data, but because many factors influence phosphorus loss, different regions and states were left to develop their own versions. Today, there are 48 different versions, according to Nathan Nelson, an American Society of Agronomy member and co-author of a paper in the Journal of Environmental Quality that introduces a special section on the Phosphorus Index. 

“The challenge now is to develop consistency in phosphorus indices across state boundaries and quantify the accuracy of phosphorus index risk assessments,” Nelson said in the news release. 

The Phosphorus Index was developed to assess the risk of phosphorus leaving a site, create a method to identify parameters influencing phosphorus loss, and select management practices to decrease vulnerability to phosphorus loss, the news release says. Factors include how much phosphorus is in the soil, rates of phosphorus fertilization, methods or timing of phosphorus addition, and phosphorus transportation factors, such as erosion, runoff, and distance to streams. 

The special section (“Evaluation of Phosphorus Indices after Twenty Years of Science and Development”) published in the Journal of Environmental Quality includes a collection of papers assessing the effectiveness of the Phosphorus Index. “The section acknowledges the problems that have been encountered with P[ hosphorus] Index development and implementation … and also suggests ways in which the indices can be tested against data or models to improve risk assessment and shape future indices,” the news release says. 

The seven papers in the collection “conclude that [ phosphorus] indices can provide accurate assessments of [ phosphorus] loss, but must be evaluated appropriately,” according to the section’s introductory paper. Evaluation requires compiling regional data sets on small-watershed scales.  

The papers also conclude that simulation models can generate phosphorus loss estimates if they are calibrated and validated to ensure accuracy, the paper says. “Further development of [ phosphorus] indices will require coordinated regional efforts to identify common P[hosphorus] Index frameworks and standardized interpretations,” the paper says. 

Find the special section at https://www.soils.org/publications/jeq/tocs/41/6.



DARIES model predicts efficiency of anaerobic technology




Predicting the potential for anaerobic technology to recover resources and reduce costs can be an important tool for U.S. dairy farms interested in using manure waste as a nutrient and energy resource. Researchers from the Clarkson University Institute for a Sustainable Environment presented the Dynamic Anaerobic Reactor and Integrated Energy System (DARIES) model as a prediction tool in the December 2012 issue of Water Environment Research (WER). 

Anaerobic technology has the potential to recover biogas, reduce odors and pathogens, and manage nutrients, but often has high capital and operating costs, the WER article says. Modeling the potential for this technology to benefit farm operations would prove a useful tool. 

DARIES is a dynamic system that uses hourly weather data to calculate heat losses and digester temperature, which affects biokinetic transformations and biogas production. The model can be used in a completely mixed or plug-flow reactor configuration and predicts biogas production and composition as well as electricity production, the article says. 

The researchers looked at the DARIES model’s ability to predict biogas and electricity production and to identify operational and design parameters that have the greatest effect on model output. They compared the model’s predictions to recorded data for 18 full-scale dairy digesters in the northeastern United States as well as results from the U.S. AgSTAR model FarmWare 3.4, the article says. 

Researchers concluded that DARIES was an accurate model for biogas, methane, and electricity production predictions. The model predicted biogas accurately, underpredicted methane by 12% on average, and predicted electricity production within an expected range of variation, the article says. The researchers concluded that the model is more accurate than the “overly optimistic” FarmWare model that over-predicted both biogas and methane by 20% to more than 50%, the article says. 

Researchers also determined that DARIES output was most sensitive to influent flow rate, chemical oxygen demand, and biodegradability, and somewhat sensitive to hydraulic retention time and digester temperature, the article says. 

The article, “The Dynamic Anaerobic Reactor & Integrated Energy System (DARIES) Model: Model Development, Validation, and Sensitivity Analysis,” appears in the December 2012 issue of Water Environment Research and can be downloaded free at http://goo.gl/ZQzmD. 

Water Environment Research allows open access to one article per issue on a range of important technical issues such as nutrient removal, stormwater, and biosolids recycling.