Archive for August, 2011

Stream networks for SPARROW

Wednesday, August 31st, 2011

October 2011 article (early view): “Digital Hydrologic Networks Supporting Applications Related to Spatially Referenced Regression Modeling,” by J.W. Brakebill, D.M. Wolock, and S.E. Terziotti. Part of Featured Collection on SPARROW.

Continuing along on Huge Dataset Week, this paper looks at the kind of stream network representation you need to model the conterminous United States.

Stream network representations

Anyone familiar with the field knows there have been many representations of the U.S. stream network at various scales and levels of quality. The original “River Reach File” (RF1) schema was developed by Bob Horn of EPA way back in the 1970′s; with subsequent modifications, mergers, and updates, it forms the backbone of stream reach identification and attributes today in the form of the National Hydrography Dataset (NHD). It’s worth reading this paper for the historical background alone.

A key to successful stream modeling is to have a network with just the right amount of detail, and this paper shows how the authors achieved this for the SPARROW collection. Digital hydrologic networks modified from the RF1 and NHD geospatial datasets provided frameworks for SPARROW in six regions of the conterminous United States. In addition, characteristics of the modified RF1 were used to update estimates of mean annual streamflow. This produced more current flow estimates for use in SPARROW.

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

National nutrient loading dataset

Tuesday, August 30th, 2011

October 2011 article (early view):A Multi-Agency Nutrient Dataset Used to Estimate Loads, Improve Monitoring Design, and Calibrate Regional Nutrient SPARROW Models,” by David A. Saad, Gregory E. Schwarz, Dale M. Robertson, and Nathaniel L. Booth.  Part of Featured Collection on SPARROW.

Some of you know how much I like working with huge national or worldwide datasets. This effort almost makes me wish I were back at USGS!(!): “A rigorous evaluation procedure was applied to reduce nearly 125,000 sites with available water quality to a select set of 2,739 sites for which water-quality and flow data were of sufficient quality and conformity to be suitable for long-term load estimation and inclusion in the calibration of regional Major River Basin SPARROW models.”

Huge datasets collected over many years from numerous sources for many purposes have some unique characteristics. First of all, only a relatively small part may be of interest for any particular study. Secondly, even with good quality assurance, the data will inevitably contain errors: huge, honking blunders ready to make a mockery of calculations and graphs. Moreover, dataset size makes it impractical to manually inspect each data point: you have to screen with algorithms.

In this case, the authors had to look for sites with a suitable record of nitrogen and phosphorus sampling, plus a means of associating flow data, to calculate loading. Units and species form (e.g., N, NO3, TKN) had to be standardized, estimating where necessary. Everything had to be indexed to the stream network. Here are some examples of the criteria:

  1. An overlap between water-quality and flow data of ‡2 years.
  2. The ratio of drainage areas between the water-quality site and the flow site of 0.5-2.
  3. If the drainage area of the water-quality site was ‡260 km2 (100 mi2), then the flow gage must be on same stream.
  4. If the drainage area of the water-quality site drainage area was <260 km2, then the gage could be on a nearby stream.
  5. The gage must be within a reasonable distance of the water-quality site so as to represent similar environmental conditions.

This qualified set of water-quality and flow data represents a significant by-product of USGS Major River Basin analyses; one that could provide considerable utility in other national, regional, or local water-quality assessments. A huge amount of supporting information is available online.

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

SPARROW featured collection

Monday, August 29th, 2011

October 2011 article (early view): “Sparrow Modeling to Understand Water-Quality Conditions in Major Regions of the United States: A Featured Collection Introduction,” by Stephen D. Preston, Richard B. Alexander, and David M. Wolock.

The entire October issue is dedicated to an ambitious modeling effort put together by Guest Associate Editors Stephen D. Preston and David M. Wolock, along with Associate Editor Richard B. Alexander. SPARROW — SPAtially Referenced Regressions On Watershed attributes — is a hybrid empirical / process-based mass-balance model that can be used to estimate the major sources and environmental factors that affect the long-term supply, transport, and fate of contaminants in streams. Other major models such as SWAT and MODFLOW have adapted successfully to the GIS age, but SPARROW is perhaps the first to be developed originally using GIS technology and geospatial data. The spatially explicit model structure is defined by a river reach network coupled with contributing catchments.

The regional models described in this collection were developed as part of the USGS National Water Quality Assessment (NAWQA) program efforts to assess the water quality of the nation’s streams. NAWQA adopted SPARROW as a modeling framework that could be used to define the spatial distribution of water-quality conditions and identify the primary environmental factors that affect water quality regionally. Papers describing SPARROW models for seven “major river basins” which cover most of the conterminous United States — an eighth, covering California, eventually will complete the set — are presented here. An overview article provides post analysis of the regional SPARROW models to assess their consistency as to the major sources and environmental factors that explain spatial patterns in mean annual nutrient loads across regions of the conterminous U.S.

Compiling these huge models represented a tour de force in developing and managing geospatial data. Three additional papers describe:

  • National digital stream networks with attributes, which form the infrastructure for SPARROW;
  • Stream monitoring data and estimates of long-term mean annual nutrient loads, for calibration; and
  • Nationally consistent estimates of municipal and industrial wastewater discharges of nitrogen and phosphorus.

The collection concludes with a new technique for estimating regional variability in the coefficients of a national SPARROW model, in which the authors demonstrate that the simultaneous modeling of water-quality conditions across regions can provide more precise estimates of regional coefficients and model predictions than can be obtained through independently estimated regional models.

Part of the collection is online now in Early View, and the remainder will be added shortly.

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

Missing online articles

Thursday, August 25th, 2011

When we partnered with Wiley-Blackwell in 2007, one of the first things we did was ship W-B a full set — 42 volumes — of woodware JAWRA issues for digitizing. Voila! Our whole back catalogue was online. Or so we thought… This week we found a second paper which inadvertently had been omitted. An earlier one had been noticed about 2 years ago. Though percentagewise we’re doing great, the system clearly is not perfect.

The first was found because an author checked his own papers. The second was found by an alert reader following a citation from elsewhere. The online table of contents for each issue includes page numbers. The telltale sign of a missing paper is a gap in the numbers. If I have some time on my hands, I will check each TOC. It’s not a priority, however. Meanwhile, if you happen to come across a missing paper, please let us know.

Since 2007, the version of record has been the online one. As the uploading process is completely different for post-2007 papers, we are quite confident all are online.

Climate, geology, elevation, and climate.

Thursday, August 25th, 2011

August 2011 article: “Streamflow Response to Climate as Influenced by Geology and Elevation,” by Timothy D. Mayer and Seth W. Naman

This study examines the regional streamflow response in 25 predominately unregulated basins to warmer winter temperatures and snowpack reductions over the last half century in the Klamath Basin of California and Oregon, and found streamflow characteristics and response to climate vary with stream type.

Geology and elevation are both very important in determining streamflow response to climate in this region. Elevation influences temperature and the form and timing of the winter recharge signal whereas geology mediates the transition of the winter recharge signal to streamflow. The groundwater-dominated basins have much less seasonal and annual variation and much greater summer and fall flows compared to rain and snowmelt surface-dominated basins.

Not all streams respond uniformly to the same climate signal. Because stream type may vary spatially at a finer scale than climate parameters like temperature and snowpack, this may necessitate studies at a smaller geographic extent than is common for most climate studies.

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

Whole lotta shakin’

Tuesday, August 23rd, 2011

JAWRA World Editorial Headquarters in Reston is ok following the devastating (or not really) East Coast earthquake.  Chandeliers rocked, file drawers opened by themselves, and Casey the official JAWRA cat took cover in the closet. Our building probably will have a residents’ meeting downstairs this evening; it likely will involve liquor.

The 5.9 earthquake was centered about 80 miles south of us.

Indices for water quality buffers

Tuesday, August 23rd, 2011

August 2011 article: “Comparison of Indexes for Prioritizing Placement of Water Quality Buffers in Agricultural Watersheds,” by Michael G. Dosskey and Zeyuan Qiu.

Buffer

As there is substantial cost associated with installing vegetative buffers in watersheds, cost-effectiveness would be improved by targeting buffers to those locations where they would produce greater impact and to avoid locations where the impact would be low.

Five physically based, spatially distributed, empirical indexes were compared for the degree to which they identified the same or different locations in watersheds where vegetative buffers would function bet- ter for reducing agricultural nonpoint source pollution. The results, not unsurprisingly, did not find any single index superior in all situations. Rather, there seemed to be advantages in incorporating aspects of various indices.

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

Hydropower Relicensing

Tuesday, August 23rd, 2011

August 2011 article: “Hydropower Relicensing and Climate Change,” by Joshua H. Viers.

The author takes issue with the United States Federal Energy Regulatory Commission, arguing that licensing decisions should take climate change into account. “Given the rapidity of climate warming, and its anticipated impacts to natural and human communities, future long-term fixed licenses of hydropower operation will be ill prepared to adapt if science-based approaches to incorporating reasonable and foreseeable hydrologic changes into study plans are not included. The licensing of hydroelectricity generation can no longer be issued in isolation due to downstream contingencies such as domestic water use, irrigated agricultural production, ecosystem maintenance, and general socioeconomic well-being.”

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

Susan on Vacation

Thursday, August 18th, 2011

JAWRA Adminstrator Susan Scalia will be on a well-deserved vacation the week of August 22-26. Even if she manages to find an internet connection, I am encouraging her to relax and not reply to her email. I’m sure a refreshed Susan will catch up when she returns to work.

If any authors have a terribly urgent, can’t-possibly-wait issue during this period, I encourage them to contact me directly.

Schedules

Thursday, August 11th, 2011

It’s summer, and travel is wreaking havoc with our manuscript review schedules.

One nice thing about having Associate Editors with so many international connections and interests is their experiences bring a broader perspective to their work. Unfortunately, travel presents its limitations to communications. Lugging a laptop onto an airplane seems to get harder and harder, and foreign connections can be pricey, if available at all. So, we’ve experienced a few delays in our usually quick review process.

It hasn’t helped that more than a couple of reviewers have defaulted on their obligations. I won’t rant again, you can look up earlier posts. I’ll just note our system has a long memory. Keeping track of errant reviewers can be particularly difficult when an Associate Editor is overseas, with other interests at hand and with a tenuous internet connection.

In any event, I think most of the lagging manuscripts are getting back on track. Authors can always log in to ScholarOne and see how their manuscripts are progressing. And, my apologies for any delays.