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How low will they go? The response of headwater streams in the Oregon Cascades to the 2015 drought

From a distance, Anne has been watching an incredibly unusual summer play out in the Pacific Northwest, following a winter with far less snow (but more rain) than usual. Folks on the ground in Oregon have been collecting data on the response of the Oregon Cascades streams to “no snow, low flow” conditions. Anne is making minor contributions to the following poster, to be presented in Session No. 291, Geomorphology and Quaternary Geology (Posters) at Booth# 101 on Wednesday, 4 November 2015: 9:00 AM-6:30 PM.


LEWIS, Sarah L.1, GRANT, Gordon E.2, NOLIN, Anne W.1, HEMPEL, Laura A.1, JEFFERSON, Anne J.3 and SELKER, John S.4, (1)College of Earth Ocean and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, (2)Pacific Northwest Research Station, USDA Forest Service, 3200 SW Jefferson Way, Corvallis, OR 97331-8550, (3)Department of Geology, Kent State University, Kent, OH 44242, (4)Biological & Ecological Engineering, Oregon State University, Corvallis, OR 97331,

Larger rivers draining the Oregon Cascades are sourced from headwater systems with two distinct runoff regimes: surface-flow dominated watersheds with flashy hydrographs, rapid baseflow recession, and very low summer flows; and spring-fed systems, with slow-responding hydrographs, long baseflow recession, and summer flow sustained by deep groundwater fed coldwater springs. Our previous research has explored these differences on both the wet west-side and dry east-side of the Cascade crest, as expressed in contrasting discharge and temperature regimes, drainage efficiency, low and peak flow dynamics, and sensitivity to snowpack and climate change scenarios. In 2015, record low winter snowpack combined with an anomalously dry spring resulted in historically low flows across our research sites and throughout Oregon. These extreme meteorological conditions, equivalent to a 4°C warming scenario, offer an exceptional opportunity to witness how these contrasting stream networks might respond to anticipated changes in amount and timing of recharge.
Conceptually, channel network response to decreasing discharge may involve both lateral and longitudinal contraction. Lateral contraction, the decrease of wetted channel width and depth, occurs in both surface-flow and spring-fed streams as flows diminish. Longitudinal contraction may be expressed as (a) a gradual drying of the stream channel and downstream retreat of the channel head, (b) a “jump” of the channel head downstream to the next spring when an upper spring goes dry, or (c) no change in channel head despite diminishing flows. We hypothesize that while individual stream channels may display a combination of these dynamics, surface-flow and spring-fed watersheds will have distinctive and different behaviors. We field test our hypothesis by monitoring channel head locations in 6 watersheds during the low flow recession of 2015, and repeatedly measuring discharge, water quality and hydraulic geometry at a longitudinal array of sites along each surface-flow or spring-fed channel. The resulting data set can be used to explore the fundamental processes by which drainage networks accommodate decreasing flows.

Post-doc Opportunity in Watershed Modeling at Kent State University

This position has been filled. Thanks for your interest.

Post-doctoral Associate in Watershed Modeling

A post-doctoral position focusing on hydrologic modeling of urban watersheds is available in the Department of Geology, Kent State University, in the lab of Anne Jefferson ( The successful candidate will have experience using RHESSys or another distributed watershed model and interest in applying their skills to questions about the effects of green infrastructure and climate change in urban areas. The post-doc will be expected to contribute to research design and undertaking, publication, and pursuit of external funding. There will also be the potential to develop additional projects building on the strengths, interests, and expertise of the successful candidate. The post-doc will have access to a wealth of data sets, field sites and instrumentation; an interdisciplinary, collaborative group of researchers and external partners focused on urban ecosystems; and a campus mentoring program for postdocs.

Kent State University (, the second largest university in Ohio, is a state-supported, doctoral degree granting institution ranked as ‘high research’ by the Carnegie Foundation. The Department of Geology ( has a strong graduate program (both MS and Ph.D. degrees) in both applied and basic areas of geologic research. The city of Kent combines the eclectic atmosphere of a small midwest college town with easy access to major metropolitan centers, including Cleveland, Akron, Columbus, and Pittsburgh.

Salary will be commensurate with experience and includes a competitive benefits package. Funding is initially available to support 1.5 years of work and opportunities will be sought to extend the support. If you are interested in learning more about the position, e mail Anne Jefferson (ajeffer9 at kent edu) with your CV, a description of your interests and experiences, and contact information for three people willing to serve as references. Review of applications will begin March 1st and continue until the position is filled. Kent State University is an Affirmative Action/Equal Opportunity Employer and encourages interest from candidates who would enhance the diversity of the University’s faculty.

CUAHSI Cyberseminar on Watershed Sensitivity to Climate and Land Use Change

From an email to CUAHSI members today:

A quick reminder that we invite you to join us for a special CUAHSI Cyberseminar this Thursday at a special time hosted by Roy Haggerty,  Tom Meixner, and Patrick Belmont, members of the Water, Sustainability and Climate  (WSC) community.

Thursday, January 23rd, 2 -3 PM ET

Dr. Thomas Johnson

EPA Office of Research and Development

Watershed Modeling to Assess  the Sensitivity of Streamflow, Nutrient, and Sediment Loads to  Potential Climate Change and Urban Development in 20 U.S. Watersheds

Join the seminar at:

Dr. Johnson will discuss the release of the final report released by EPA this fall. From the release:

“There is growing concern about the potential effects of climate change on water resources. To develop this report, watershed modeling was conducted in 20 large U.S. watersheds to characterize the sensitivity of streamflow, nutrient (nitrogen and phosphorus), and sediment loading to a range of plausible mid-21st century climate change and urban development scenarios. The report also provides an improved understanding of methodological challenges associated with integrating existing tools (e.g., climate models, downscaling approaches, and watershed models) and data sets to address these scientific questions. To view the study and related links, visit:”

Please join us on January 23rd. Dr. Johnson will present on the results of the report, and there will be a Q&A following the presentation.

Our regular Cyberseminar series will have a spring theme of “Snow Hydrology,” and is being hosted/organized by Dr. Jessica Lundquist (Washington). The spring series begins February 7th. See for more info.

New paper: Seasonal versus transient snow and the elevation dependence of climate sensitivity in maritime mountainous regions

Snowline near Skykomish, Washington (photo on Flickr by RoguePoet, used under Creative Commons)

Snowline near Skykomish, Washington (photo on Flickr by RoguePoet, used under Creative Commons)

Jefferson, A. 2011. Seasonal versus transient snow and the elevation dependence of climate sensitivity in maritime mountainous regions, Geophysical Research Letters, 38, L16402, doi:10.1029/2011GL048346.


In maritime mountainous regions, the phase of winter precipitation is elevation dependent, and in watersheds receiving both rain and snow, hydrologic impacts of climate change are less straightforward than in snowmelt-dominated systems. Here, 29 Pacific Northwest watersheds illustrate how distribution of seasonal snow, transient snow, and winter rain mediates sensitivity to 20th century warming. Watersheds with >50% of their area in the seasonal snow zone had significant (? ? 0.1) trends towards greater winter and lower summer discharge, while lower elevations had no consistent trends. In seasonal snow-dominated watersheds, runoff occurs 22–27 days earlier and minimum flows are 5–9% lower than in 1962, based on Sen’s slope over the period. Trends in peak streamflow depend on whether watershed area susceptible to rain-on-snow events is increasing or decreasing. Delineation of elevation-dependent snow zones identifies climate sensitivity of maritime mountainous watersheds and enables planning for water and ecosystem impacts of climate change.

Anne in the news

Flooding along the Mississippi River
Last week, I wrote a post for the Scientific American Guest Blog on “Levees and the Illusion of Flood Control,” about the ways that while levees around individual communities may be good, the systematic leveeing of entire waterways is a bad long-term strategy. On Friday, that post was also featured on the front page of on their Science Agenda. (I’ll add a screenshot if I can dig it back up.)

Linkages between climate change and severe weather
This morning my name may be in your local newspaper, as I’m quoted in an article about how this spring’s severe weather (including flooding along the Mississippi) fits with scientific expectations about climate change. The article was written by the McClatchey syndicate and versions of it may appear in multiple newspapers. For example, here’s the Charlotte Observer’s version of the story.

Pakistan floods: Predicted or Predictable, but a disaster nonetheless

Cross-posted at Highly Allochthonous

Unusually heavy monsoon rains in July and August 2010 left large swaths of Pakistan underwater. At least 18 million people were affected by the flood, and it is estimated that, more than six months later, several hundred thousand remain without even temporary shelter. As a result of lost crops and livelihoods from the flood and inadequate relief supplies, malnutrition continues to kill people. Like most floods, the Pakistani poor have suffered far more than those with resources to avoid the flood, or at least its aftermath.

Remains of a school destroyed by flooding, near Jacobabad by DFID - UK Department for International Development, on Flickr

Remains of a school destroyed by flooding, near Jacobabad by UK Department for International Development, on Flickr. Used under a Creative Commons license.

A paper in press in Geophysical Research Letters shows that the 2010 floods were extraordinary. Monsoonal rains tend to occur in pulses, with multi-day wet periods followed by multi-day dry periods, and while the total rainfall over Pakistan during the 2010 monsoon season was not unprecedented, the number and intensity of extremely heavy rains over northern Pakistan was very unusual. The authors are working with very limited historical and satellite data, but they estimate that the number of intense rain bursts that occurred in 2010 had a probability of less than 3% in any given year.

Using data from the European Centre for Medium Range Weather Forecasts collection of meteorological models, the authors of the new paper show that the timing and intensity of northern Pakistan’s monsoon rain bursts are predictable up to 6 to 8 days in advance – including the rains that caused the flooding in 2010.

Lead author, Peter Webster, and his coauthors from the Georgia Institute of Technology, draw the following conclusion from their analysis:

We conclude that if these extended quantitative precipitation forecasts had been available in Pakistan, the high risk of flooding could have been foreseen. If these rainfall forecasts had been coupled to a hydrological model then the high risk of extensive and prolonged flooding could have anticipated and actions taken to mitigate their impact.

The floods really kicked off with a burst of rain on 28-29 July 2010, and according to Webster’s reanalysis, that rainfall was predictable with good skill 7 days in advance (21 July). Webster and colleagues argue that if that forecast was available in Pakistan, lives would have been saved and the immensity of the disaster reduced. But, C. Christine Fair, writing on the Foreign Policy magazine website suggests that the flood was forecast in Pakistan.

In the middle of July, the PMD began tracking a storm brewing in the Bay of Bengal. This eastern weather system developed interactively with a western weather system to produce the massive rains and the subsequent super flood of 2010. On July 24, the PMD issued a flood warning to the provincial government of Khyber-Pakhtunkhwa (KPK). Despite these increasingly severe warnings, KPK’s citizenry did not believe them. … The PMD kept issuing warnings to KPK as the rains began to fall. However, as fate would have it, on July 28, … a passenger jet coming to Islamabad from Karachi crashed …With the media beset upon this tragic spectacle, the PMD’s warnings went unheeded as the rain began to fall.

So the Pakistani government did forecast the flood – at least four days out – in plenty of time to get people in northern Pakistan’s valleys out of the way. The problem was not with the meteorological and hydrologic science either internationally or in Pakistan. Instead, disaster was ensured when flood warnings were not taken sufficiently seriously by regional authorities, media, and residents.

Why wouldn’t flood warnings be heeded? Perhaps more could have been done to communicate to Pakistanis through channels whose authority they respected. Webster cites an example of flood warnings in Bangladesh being disseminated by imams at local mosques. The Foreign Policy article quoted above places some blame on media distractedness.

But there was also a more insidious reason the forecasted flood was ignored. It was a rare event, but it was also part of a new climatic pattern for Pakistan. As the Foreign Policy article describes it:

in recent years there has been a slow but steady change in the location where Pakistan’s major rainfalls concentrate. In the past, monsoon rains fell most intensely over the Punjab. Slowly and steadily, the concentration of rainfall has moved north and west to KPK. This redistribution of concentrated rainfall away from the Punjab and towards KPK explains why no one in KPK had any reason to believe the predicted weather.

Flooding frequency and intensity have increased in Pakistan in the last 30-40 years compared to earlier in the 20th century. Webster and coauthors state, “This recent increase is consistent with the increase in intensity of the global monsoon accompanying the last three decades of general global warming.” The flood warnings were ignored, in part, because the statistics of monsoon rain patterns are changing. Human memory and historical records are not good guidance if the weather system is changing. In situations like this one, the past is not the key to the present.

There are lots of things that should have been improved to lessen the magnitude of the Pakistani flood disaster – reservoir management should have been altered; emergency relief supplies should have been distributed more equitably, broadly, and consistently; international assistance should have been much more generous – but the two big lessons for hazard mitigation coming out of the Pakistan floods seem to be: “find a system for making sure that warnings are issued and that they actually make it to people in harm’s way” and “don’t assume the climate of living memory is a very good indicator of the weather of the present and future.”

Webster, P. J., Toma, V.E., & Kim, H.-M. (2011). Were the 2010 Pakistan floods predictable? Geophysical Research Letters : 10.1029/2010GL046346

Tenure-track faculty position for a Regional Climate Modeler in our department

Assistant Professor, Dept. of Geography and Earth Sciences, Univ. of North Carolina at Charlotte
The University of North Carolina at Charlotte, Department of Geography and Earth Sciences is recruiting a tenure-track, assistant professor specializing in regional atmospheric climate modeling for appointment in July 2011. Required qualifications include: 1) a doctoral degree in atmospheric science, meteorology, climatology, geography, or a related field at the time of appointment; 2) the ability to develop and maintain an externally funded research program; 3) the ability to teach atmospheric science courses at the graduate and undergraduate level; and 4) the ability to contribute to the department’s interdisciplinary teaching and research mission.

The successful candidate will play a major role in expanding the atmospheric component of our graduate and undergraduate programs while contributing to the department’s interdisciplinary teaching and research missions in geographic, earth and environmental sciences. Successful candidates are expected to maintain an active, scholarly research agenda while advising students in the department’s graduate programs, including the Ph.D. in Geography and the Ph.D. in Infrastructure and Environmental Systems. Candidates with research interests in climate dynamics, regional climate change, multi-scale numerical modeling, and human-environment interactions are especially encouraged to apply. Preference will be given to candidates who strengthen bridges across the atmospheric, earth, and geographical sciences curricula and research collaborations. The successful candidate is expected to develop new courses in their area of expertise and teach a core undergraduate course in dynamic, synoptic, or physical meteorology.

The Department is an interdisciplinary community of physical and social scientists with over 30 faculty members representing meteorology, climatology, hydrology, geology, geography, GIS, community planning, and the environmental sciences. UNC Charlotte is a rapidly growing doctoral-intensive urban university located in the state’s largest metropolitan area. Over 25,000 students are currently enrolled at the university. The Department, the College of Liberal Arts and Sciences, and the University are strongly committed to creating and maintaining a diverse community in which all students, staff and faculty can work, learn and live in an environment of respect and support. We welcome applications from candidates who will foster these goals. We encourage applications from women, minorities, and individuals from underrepresented groups.

Review of applications will begin December 1, 2010 and continue until the position is filled. Applications must be made electronically at and must include: 1) letter of application describing research interests, teaching interests, and teaching philosophy, 2) a full curriculum vita, and 3) the names of three referees.
We encourage prospective candidates to review our departmental web site ( prior to applying. For additional information, contact Dr. Matthew Eastin at 704-687-5914 or mdeastin at uncc dot edu.