Archive for November, 2012

Hydrologic landscapes

Tuesday, November 27th, 2012

Early View article:Oregon Hydrologic Landscapes: A Classification Framework,” by Parker J. Wigington Jr., Scott G. Leibowitz, Randy L. Comeleo, and Joseph L. Ebersole.

Hydrologic landscape units

The authors developed a hydrologic landscape (HL) classification approach that describes factors of climate-watershed systems that control the hydrologic characteristics of watersheds. Their assessment units are incremental watersheds (i.e., headwater watersheds or areas draining directly into stream reaches). Major components of the classification include indices of annual climate, climate seasonality, aquifer permeability, terrain, and soil permeability.

The objective of their Oregon HL approach is to classify the intrinsic climate-watershed attributes of assessment units across the entire state in a manner that provides a basic description of the macro hydrologic characteristics of the units. In this article, they present the development of the Oregon HL classification system and evaluate the ability of HLs to explain variability in hydrologic behavior of a series of gauged river basins. The Oregon HL approach has potential to be a useful framework for comparing hydrologic attributes of streams and rivers in the Pacific Northwest.

Thanksgiving

Thursday, November 22nd, 2012

Today is Thanksgiving Day, a national holiday in the United States. It is celebrated by parades and feasting to give thanks for all our blessings. Not the least of these is freedom of the press. A good day to all!

The Arkansas Valley “Super Ditch”

Monday, November 19th, 2012

Early View article:The Arkansas Valley ‘Super Ditch’— An Analysis of Potential Economic Impacts,” by Tyler G. McMahon and Mark Griffin Smith.

Although selling water rights may benefit some farmers, the reduced agricultural activity can be felt among the entire community supplying the farming business. This article describes an innovative approach to sustain agricultural communities.

Arkansas Valley map

(Abstract) In Colorado’s Arkansas River basin, urban growth and harsh farming conditions have resulted in water transfers from agricultural to urban uses. Several studies have shown that these transfers have significant secondary economic impacts associated with the removal of irrigated land from production. In response, new methods of sharing water are being developed to allow water transfers that benefit both farm and urban economies, compared with previous permanent transfers that negatively impacted surrounding farm communities. One such project currently under development is the Arkansas Valley “Super Ditch,” which is a rotational crop fallowing plan based on long-term water leasing designed to provide an annual supply of 25,000 acre-feet of water (31.6 Mm3). This article analyzes the net benefits of implementing the “Super Ditch” for both the farmers and the surrounding community.

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

Riparian grazing

Saturday, November 17th, 2012

Early View article: “Riparian Grazing Impacts on Streambank Erosion and Phosphorus Loss Via Surface Runoff,” by Mustafa Tufekcioglu, Richard C. Schultz, George N. Zaimes, Thomas M. Isenhart, and Aydin Tufekcioglu

We often assume a stream can be protected from grazing effects by specifying some buffer distance. This article shows the impacts are far more heterogeneous than we thought. It’s what the cows are doing that counts!

Rainfall simulations were conducted on nine grazed pasture sites with different stocking rates in three different regions of Iowa to determine the impacts of cattle grazing on the amounts of sediment and phosphorus in surface runoff within a 15-m wide strip on both sides of the stream from different source areas (SAs). These riparian SAs included stream-side loafing areas, cattle streambank access paths to the stream, and the other vegetated areas adjacent to the streambanks. Sediment and phosphorus losses from access paths and loafing areas within the 15-m wide strips accounted for up to 72 and 55% of the total losses, respectively, even though they accounted for only 2.7% of the total area within the 15-m wide strips. This suggests that access paths and loafing areas require special attention to mitigate the impacts of cattle on stream water pollution.

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

Boggess Award to Boggess Award

Wednesday, November 14th, 2012

AWRA President Bill Battaglin (center) congratulates WillIam R. Boggess Award winners Richard D. Horan (L) and James S. Shortle (R) for their paper entitled “Economic and Ecological Rules for Water Quality Trading” published in the February 2011 issue of JAWRA. Bill himself won the award in 1999. Congratulations to all!

Morphodynamic Models for the Lower Yellow River

Tuesday, November 13th, 2012

Early View article:Comparison of Morphodynamic Models for the Lower Yellow River,” by Junqiang Xia, Zhengbing Wang, Yanping Wang, and Xin Yu

Sketch of the Yellow River

China’s Yellow River carries a great deal of sediment, which makes modeling this important river immensely complex. Here’s a paper discussing some aspects of modeling in this difficult situation. The abstract is below:

Significant channel adjustments often occur during flood seasons in the Lower Yellow River (LYR), and it is a challenging work to accurately simulate the morphodynamic processes in the LYR using numerical models. A comparison of two morphodynamic models (Delft3D and 2DLLCDM) for the LYR is presented herein to identify critical improvements for these models. The concepts of these models are first compared with each other. The models were then used to simulate the processes of flood routing, sediment transport, and morphological changes occurring in a braided reach of the LYR. The differences were investigated between the simulated results from these models and corresponding field measurements, and the results indicate that: (1) the hydrodynamic processes calculated by both models agree closely with the measurements if an appropriate Manning’s roughness coefficient is used; (2) the concentrations of suspended load at the downstream boundary calculated by the models agree reasonably with the observed data; and (3) the predicted cross-sectional profiles obtained from these models do not correspond well with the measurements. Based on these findings, the weak aspects of the models are clarified, and three critical improvements are recommended, including: (1) the development of roughness predictor; (2) the refinement of graded sediment transport capacity formulation; and (3) the consideration of bank erosion module. These improvements need to be implemented in the future.

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

Customer response to drought

Saturday, November 10th, 2012

Early View article:Analysis and Predictive Models of Single-Family Customer Response to Water Curtailments During Drought,” by Austin S. Polebitski, and Richard N. Palmer

Per-capita water reductions

This research investigates customer response to demand management strategies during two drought periods in the City of Seattle. The authors found, larger values of income, lot size, and living space enhanced water reductions whereas larger family size tended to reduce the effectiveness of curtailments.

Then, they carried the analysis a step further. Projections of changes in Seattle’s built environment and demographics between 2000 and 2030 were obtained from an urban simulation model and were processed through the regression models to investigate changes in future curtailment effectiveness. This research found that increasing household size hardened demands (decreased curtailment effectiveness) whereas decreasing household size increased per-capita curtailment effectiveness. These results suggest that changes in the number of residents within a home is likely to be the most important factor in determining future curtailment effectiveness.

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

Subway Repairs

Friday, November 9th, 2012

The New York Times has a great article today on the intense effort to get the New York City subways running after Superstorm Sandy. Good reading about restoring infrastructure in a crisis. And remember, every one of those heros is a government employee, and nearly all union. When the chips are down, there is no substitute for dedicated employees with institutional knowledge.

Chinese Briefing

Tuesday, November 6th, 2012

Dick Engberg and I went downtown today to brief a delegation of 23 water managers from the Peoples Republic of China. Dr. Wang Hanmin, Deputy Director General, Minister of Water Resources, headed the delegation. Dick talked about AWRA’s mission and goals, and I described some of the “hot” topics in JAWRA. I stressed the importance for practicing engineers, scientists, and managers to keep up with journals. I noted they could learn from the US’s mistakes on water development because we’ve made so many!

We allowed time for questions, and that’s where things became really interesting. The group has a lot of questions about how water is managed in the US. We had to explain our federalist system, where the states have primary authority over their waters subject to some national standards. Ever try to explain, through an interpreter, how we fund our water projects? :-) I hope they are not thoroughly confused! In response to one question about governmental influence on JAWRA, I recall using the term, “fiercely independent.”

Storm flow dynamics in the coastal plain

Monday, November 5th, 2012

Early View article:Characterization of Storm Flow Dynamics of Headwater Streams in the South Carolina Lower Coastal Plain,” by Thomas H. Epps, Daniel R. Hitchcock, Anand D. Jayakaran, Drake R. Loflin, Thomas M. Williams, and Devendra M. Amatya

The authors monitored two first-order lower coastal plain watersheds in South Carolina, United States, a region with increasing growth and land use change. Storm events over a three-year period were analyzed for direct runoff coefficients (ROC) and the total storm response (TSR) as percent rainfall. ROC calculations utilized an empirical hydrograph separation method that partitioned total streamflow into sustained base flow and direct runoff components.

Variability in event runoff generation was attributed to seasonal trends in water table elevation fluctuation as regulated by evapotranspiration. Groundwater elevation breakpoints for each watershed were identified based on antecedent water table elevation, streamflow, ROCs, and TSRs. These thresholds represent the groundwater elevation above which event runoff generation increased sharply in response to rainfall. For effective coastal land use decision making, baseline watershed hydrology must be understood to serve as a benchmark for management goals, based on both seasonal and event-based surface and groundwater interactions.

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