Thursday, November 20, 2014

The Santa Fe River Basin Observatory: Exploring linkages between geology, hydrology, ecosystems and humans in a karst terrain



Presentation by Dr. Wendy Graham, Director of the University of Florida Water Institute
UF Student Chapter AWRA Meeting, November 12, 2014

We were delighted to host the Director of the University of Florida Water Institute, Dr. Wendy Graham, at our third monthly meeting of the fall semester. Earlier this semester, we hosted author and journalist Cynthia Barnett and water resource manager Kevin Morris of the Peace River Manasota Regional Water Supply for our September and October meetings, respectively. Dr. Graham joined us for our November meeting to tell us about her work on water modeling in the nearby Santa Fe River Basin and share her extensive knowledge of local hydrology and current springs research.
The Santa Fe River basin is an “interesting and vulnerable place to study” according to Graham. The upper basin is confined while the lower basin is unconfined, so they are governed by different hydrologic processes. This allows researchers to compare how water and nutrient transport processes differ in the two regions. 
Study area in the Santa Fe River Basin. The upper basin is confined (green area) while the lower basin is unconfined (orange). For a more in-depth description of confined vs unconfined, see this USGS site.
Graham’s research, as well as that of the UF Water Institute, focuses on incorporating humans into the equation. “We can draw springsheds on a map, but they’re dynamic systems,” she said, and adding humans to the complex array of causes and solutions to Florida’s water issues is tricky. For example, the proposed minimum flows and levels (MFLs) are being challenged by environmentalists on one side and utilities on the other. Water managers are walking a fine line as fingers are pointed in many different directions, from placing blame for water woes on agriculture and climate to watering lawns in Jacksonville and users in southern Georgia.
Numeric nutrient criteria for springs is 0.35 mg/L, and according to Graham, few springs currently meet this requirement. She and her team are trying to better understand the hydrologic, ecologic, and economic tradeoffs required to meet these numeric nitrate requirements. Their specific goals are to “improve predictive understanding of hydrologic flow paths and travel times; nutrient sources, transport and transformation; and karst evolution within an eogenic karst basin.” Basically, they’re trying to better understand how water and nutrients move within our watersheds.
The source of nitrate in the Santa Fe Springs and river is predominantly from groundwater, and isotope signatures indicate that most of this nitrate is from synthetic fertilizers. Nitrate concentrations in the Santa Fe River depend on several factors, one of which is flow. In the unconfined portion of the basin, the lower the flow rate, the higher the nitrate concentration. In this unconfined region, there is also a high correlation between nitrate and specific conductivity (which depends on the amount of dissolved solids in the water). She said this is helpful because nitrate sensors are over $20,000, whereas measuring specific conductivity is much cheaper and can be done with a less expensive instrument. Researchers use specific conductivity measurements taken in the river to separate contributions of groundwater and surface water and to test model predictions.
The hydrologic model they are working on uses climate data, along with information regarding land cover, soils, and geology to predict evapotranspiration (ET), stream flow, groundwater elevation, temporal dynamics of surface/groundwater interactions, and surface/groundwater travel time distributions in the Santa Fe River. It can predict these variables on different timescales, i.e. for a specific event (i.e. hurricane or rain event), for an entire season, or over decades.
The researchers are trying to use the model to evaluate their current understanding of how the system works and gain a more comprehensive understanding of the impacts of future water, land use, and climate scenarios.
The current model does a good job predicting stream flow characteristics in the confined region, but the model has some problems in the unconfined region, which she and other researchers are working to address. While the predictions of the timing of stream flow are good, the rate of recession of streamflow after storm events is too fast in the unconfined region. Using specific conductivity data, they determined that the “missing” flow is from groundwater, especially after wet periods.
To understand where the streamflow originates, they use “particle tracking.” This means that they release 100,000 particles into the river (via the model) and run the model backwards, which basically tracks the particles until they leave the system.
Researchers use this “particle tracking” to estimate the age of the water (i.e. how long it takes individual particles of water to exit the system into the atmosphere when the model is run backwards) and figure out which areas to target in order to most efficiently reduce loading of nitrates into the aquifer. According to Graham, areas near conduit regions have been identified by the model as high priority areas.
The model predicts that the age of water in the unconfined part of the Santa Fe River ranges from less than one month to more than 500 years, with a median age of 17 years. This median age matches well with spring flow age measurements made by Dr. Brian Katz (Florida Department of Environmental Protection).
But what does this mean in terms of management? “People have to understand how long it may take to reduce nitrate concentrations in springs,” Graham said, “it could be decades.” Seeing and making these changes will require “patience and believing in the restoration program until we can see the benefits,” according to Graham. And meeting the nitrate limits is not going to be easy: “it will require large-scale changes in how we use land and water,” she said.
After Graham’s presentation, curious students followed up with many questions. From the discussion after her talk, it became clear that a more comprehensive understanding of springs ecology, as well as other factors, will also play large roles in solving Florida’s springs and water issues - it’s going to require a truly interdisciplinary effort to come up with solutions for our springs. The next question is whether or not we’re up for it.

By Jenny Adler (jennifermadler@ufl.edu), UF Water Institute Communications

Thursday, November 13, 2014

Live tweet of last night's meeting featuring Dr. Wendy Graham

A huge thank you to Dr. Wendy Graham, Director of the University of Florida Water Institute, for coming to speak at our monthly student chapter meeting last night!
"UF Water Institute Interdisciplinary Springs Research: Nutrient sources, transport and transformation in the Santa Fe River" by Dr. Wendy Graham.
Photo by UF/IFAS IrriGator (@IrriGatorUF)
I'm currently working on a more comprehensive article about her presentation, but for those of you who were not able to attend and are interested in a few details about Dr. Graham's presentation, I live tweeted the meeting. If you don't have twitter, here are the tweets (read from the bottom up!!)...

https://twitter.com/aMermaidLife
 






https://twitter.com/aMermaidLife

Check back soon for a full recap of her presentation! ~Jenny (@amermaidlife)

Sunday, November 9, 2014

Meeting on Wednesday this week (& other news!)

We hope you can join us this coming Wednesday at 6pm for our monthly chapter meeting. All are welcome - grads, undergrads, professors, etc... if you have an interest in water, stop by for a great talk and some free pizza and drinks!


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Other News:

The AWRA - floridan section will take place in St Augustine the Friday November 21st: Hot Topics in Water Resources with a North Florida Focus.

As always it is a great opportunity to remain well aware of the water-related issues and answers brought by the community (see program athttp://www.awraflorida.org/event-891668), but is also a great opportunity for networking and fun time. The day ends with a walking history trivia / scavenger hunt around St Augustine.

Registration fees for students are $10, including lunch, but will raise to $50 the November 14th, so go ahead and register now: http://www.awraflorida.org/event-891668.

We will organize a carpool... let us know if you are interested in joining us!