Archive for April, 2013

Air-water temperature relationships

Tuesday, April 30th, 2013

Early View article:Air-Water Temperature Relationships in the Trout Streams of Southeastern Minnesota’s Carbonate-Sandstone Landscape,” by Lori A. Krider, Joseph A. Magner, Jim Perry, Bruce Vondracek, and Leonard C. Ferrington Jr.

(Abstract:) Carbonate-sandstone geology in southeastern Minnesota creates a heterogeneous landscape of springs, seeps, and sinkholes that supply groundwater into streams. Air temperatures are effective predictors of water temperature in surface-water dominated streams. However, no published work investigates the relationship between air and water temperatures in groundwater-fed streams (GWFS) across watersheds. We used simple linear regressions to examine weekly air-water temperature relationships for 40 GWFS in southeastern Minnesota. A 40-stream, composite linear regression model has a slope of 0.38, an intercept of 6.63, and R2 of 0.83. The regression models for GWFS have lower slopes and higher intercepts in comparison to surface-water dominated streams. Regression models for streams with high R2 values offer promise for use as predictive tools for future climate conditions. Climate change is expected to alter the thermal regime of groundwater-fed systems, but will do so at a slower rate than surface-water dominated systems. A regression model of intercept vs. slope can be used to identify streams for which water temperatures are more meteorologically than groundwater controlled, and thus more vulnerable to climate change. Such relationships can be used to guide restoration vs. management strategies to protect trout streams.

Documenting BMPs

Monday, April 29th, 2013

Early View article: Locating Existing Best Management Practices Within a Watershed: The Value of Multiple Methods,” by Caitlin A. Grady, Adam P. Reimer, Jane Frankenberger, and Linda Stalker Prokopy.

There is an increasing need to document the impacts of conservation-related best management practices (BMPs) on water quality within a watershed. However, this impact analysis depends upon accurate geospatial locations of existing practices, which are difficult to obtain. This study demonstrates and evaluates three different methods for obtaining geospatial information for BMPs. This study was focused on the Eagle Creek Watershed, a mixed use watershed in central Indiana. We obtained geospatial information for BMPs through government records, producer interviews, and remote-sensing aerial photo interpretation. Aerial photos were also used to validate the government records and producer interviews. This study shows the variation in results obtained from the three sources of information as well as the benefits and drawbacks of each method. Using only one method for obtaining BMP information can be incomplete, and this study demonstrates how multiple methods can be used for the most accurate picture.

[Please note: I have quoted and paraphrased freely from the article, but the interpretation is my own.]

Wildfire-affected watersheds

Friday, April 26th, 2013

Early View article:Examining Modeling Approaches for the Rainfall-Runoff Process in Wildfire-Affected Watersheds: Using San Dimas Experimental Forest,” by Li Chen, Markus Berli, and Karletta Chief

Wildfire can significantly change watershed hydrological processes resulting in increased risks for flooding, erosion, and debris flow. The goal of this study was to evaluate the predictive capability of hydrological models in estimating post-fire runoff using data from the San Dimas Experimental Forest (SDEF), San Dimas, California. Four methods were chosen representing different types of post-fire runoff prediction methods, including a Rule of Thumb, Modified Rational Method (MODRAT), HEC-HMS Curve Number, and KINematic Runoff and EROSion Model 2 (KINEROS2). Results showed that simple, empirical peak flow models performed acceptably if calibrated correctly. However, these models do not reflect hydrological mechanisms and may not be applicable for predictions outside the area where they were calibrated. For pre-fire conditions, the Curve Number approach implemented in HEC-HMS provided more accurate results than KINEROS2, whereas for post-fire conditions, the opposite was observed. Such a trend may imply fundamental changes from pre- to post-fire hydrology. Analysis suggests that the runoff generation mechanism in the watershed may have temporarily changed due to fire effects from saturation-excess runoff or subsurface storm dominated complex mechanisms to an infiltration-excess dominated mechanism. Infiltration modeling using the Hydrus-1D model supports this inference. Results of this study indicate that physically-based approaches may better reflect this trend and have the potential to provide consistent and satisfactory prediction.

[Please note: I have quoted and paraphrased freely from the article, but the interpretation is my own.]

TMDL’s for bacteria

Tuesday, April 23rd, 2013

Early View article: “TMDL Balance: A Model for Coastal Water Pollutant Loadings,” by Stephanie L. Johnson, David R. Maidment, and Mary J. Kirisits.

Bacterial contamination accounts for more than 60% of the impairments included on the 2008 Texas 303(d) List. Many of these bacterial impairments are along the Texas Gulf Coast because coastal waters often are regulated for oyster harvesting, which have strict water quality standards. Under the Clean Water Act, each one of these impaired waterbodies requires a total maximum daily load (TMDL) study to be performed. A recent, statewide study recommended the development and application of simple modeling approaches to address the majority of Texas’s bacteria TMDLs, including “… simple load duration curve, GIS [geographic information systems], and/or mass balance models.” The authors developed the TMDL Balance model in response to this recommendation. TMDL Balance is a steady state, mass balance, GIS-based model for simulating pollutant loads and concentrations in coastal systems. The model uses plug-flow reactor and continuously-stirred tank reactor equations to route spatially distributed point and nonpoint source loads through a watershed via overland flow, non-tidal flow, and tidal flow, decaying the loads via first-order kinetics. This paper explains the development of the watershed loading portion of the TMDL Balance model, demonstrating the methodology through a case study: computing bacterial loads in the Copano Bay watershed of southeast Texas. The application highlights an example of distributing bacterial sources spatially based on land use data.

[Please note: I have quoted and paraphrased freely from the article, but the interpretation is my own.]

Associate Editor, Water Quality Monitoring

Monday, April 22nd, 2013
JAWRA is looking for an Associate Editor for Water Quality Monitoring. This particular position would focus on evaluating articles about chemical and biological sampling efforts, looking at the temporal and spatial coverage and the statistical treatment of data. We would consider two positions in this area, depending on how the candidates match, and if needed to cover the anticipated workload.
JAWRA Associate Editors (AEs) serve as primary advisors to the JAWRA Editor. Responsibilities fall into two areas: reviews and subject development. The AE for Water Quality Monitoring handles about 20 papers per year, which would be divided between the two incumbents. All manuscripts are processed through our ScholarOne Manuscripts™system, with the AE selecting reviewers and, when reviews return, making a recommendation to the Editor. AE’s are encouraged to seek out qualified authors in their subject areas and encourage them to submit papers to JAWRA. These could be individual submittals or as featured collections of related papers organized around an introduction.
Associate editorship is a volunteer position earning our heartfelt thanks and an invitation to our annual AE luncheon. It also offers the opportunity to make a difference on the cutting edge of multidisciplinary water resources. Many AE’s have found the experience of making decisions on manuscripts helpful in sharpening their own professional writing skills. The term of an AE is three years, but may be extended by mutual agreement.
Interested individuals should email their CV to the Editor at editor@awra.org. We are happy to answer any questions. We will hold this position open at a minimum until May 3, 2013.

New AE, Atmospheric Science and Hydrometeorology

Monday, April 22nd, 2013

I am pleased to announce the selection of Dr. Edwin P. Maurer of Santa Clara University as JAWRA Associate Editor for Atmospheric Science and Hydrometeorology. Ed brings to the position a wealth of experience in downscaling global climate models to evaluate local impacts. He will be immensely helpful in selecting original and creative solutions in this area. Please join me in welcoming Ed to the JAWRA Editorial Team!

AE Ken Reckhow is resigning

Monday, April 22nd, 2013

I regret to announce Ken Reckhow, JAWRA Associate Editor for Water Quality Monitoring is resigning due to time conflicts with his current consulting position. Ken will complete his current assignments and move on. I thank Ken for his work with us and wish him the best in his retirement activities.

An announcement for Ken’s successor will appear soon in this blog. We will defer a decision on selecting a second AE in this field.

E. coli diurnal variations

Sunday, April 21st, 2013

Early View article:Escherichia coli Concentrations in Urban Watersheds Exhibit Diurnal Sag: Implications for Water-Quality Monitoring and Assessment,” by Anuradha M. Desai and Hanadi S. Rifai

The variability of indicator bacteria over a fine resolution time scale on the order of minutes has yet to be fully understood. The authors collected more than 700 Escherichia coli samples at a 10- and 30-min resolution in an urban watershed in Houston. A Bacteria Diurnal Sag (BDS) marked with daytime exponential decay followed by an exponential nighttime regeneration was observed. This pattern was observed during all sampled events but varied depending on other variables. The concentrations during a 24-h period varied 1 to 5 orders of magnitude and the fecal load was at least 10 times lower than what would be obtained using a single morning E. coli measurement, the typical sampling scheme in most monitoring programs. Decay rates, ranging from 3.67 to 24.7/day, decreased E. coli concentrations to below the water-quality standards from 14:00 to 18:00 h and were strongly influenced by water temperatures and solar radiation intensities. Rapid regeneration occurred on the order of 9.41 to 64.1/day allowing E. coli concentrations to return to their pre-decay levels. The data indicated that four to six samples taken between 06:00 and 18:00 h may be sufficient to define the BDS depending on stream conditions, and that a threshold concentration of approximately 100 MPN/dl (most probable number in a deciliter) existed for the studied urban watershed. These findings have significant implications for water-quality monitoring, regulation, and compliance.

[Please note: I have quoted and paraphrased freely from the article, but the interpretation is my own.]

Learning which sources to trust

Tuesday, April 16th, 2013

Among all the bad news in this morning’s Washington Post was an encouraging story on a subject I’ve long believed needed attention. “Schools demanding news literacy lessons to teach students how to find fact amid fiction,” tells of a growing effort in high schools, in which students learn to identify credible information and good journalism. Creating skeptics? I hope so! There’s a lot of untrustworthy information out there, as I’ve often pointed out in this blog.

Learning how to read with critical judgment is something which comes naturally in the editor business. However, we are bombarded with untrustworthy and even deliberately false information in our daily lives. As I like to say, “There’s a lot of information on the internet; some of it’s even true.” The skills these students are learning will be essential to good citizenship. Too bad most of them can’t vote yet. I just can’t wait for this fall’s Virginia gubernatorial election!

Nutrient export

Monday, April 15th, 2013

Early View article:Modeling Nutrient Export from Coastal California Watersheds,” by Timothy H. Robinson and John M. Melack.

Nitrate and phosphate export coefficient models were developed for coastal watersheds along the Santa Barbara Channel in central California. One approach was based on measurements of nutrient fluxes in streams from specific land use classes and included a watershed response function that scaled export up or down depending on antecedent moisture conditions. The second approach for nutrient export coefficient modeling used anthropogenic nutrient loading for land use classes and atmospheric nutrient deposition to model export. In an application of the first approach to one watershed, the nitrate and phosphate models were within 20% of measured values for most storms. When applied to another year, both nitrate and phosphate models generally performed adequately with annual, storm-flow, and base-flow values within 20% of measured nutrient loadings. Less satisfactory results were found when applied to neighboring watersheds with difference percentages of land use and hydrologic conditions. Application of the second approach was less successful than the first approach.

[Please note: I have quoted and paraphrased freely from the article, but the interpretation is my own.]