New Mexico Water eNews

NM Tech Students Developing Calibration Procedures for Large Aperture Scintillometers
by Catherine Ortega Klett, Program Manager

In a generally arid state like New Mexico, it's important to have some way to keep track of evapotranspiration, the evaporative flux of moisture to the air from the ground and plants. This is governed mainly by the ventilation of the Earth's surface by turbulent winds. Fortunately, there is an instrument which can, in effect, directly "read" the state of a turbulent atmosphere. This is the scintillometer, which typically consists of an optical transmitter and receiver at opposite ends of an atmospheric propagation path. It tracks light intensity fluctuations due to temperature and humidity fluctuations in the air, which cause light beams to randomly wander and spread. We can see the result of such effects directly with our own eyes when viewing twinkling starlight in the night sky.

The brightness fluctuations measured by a scintillometer, when combined with meteorological data, make it possible to estimate the flux of sensible heat from the land surface. The word "sensible" refers to the normal heat that you can feel or sense, in contrast to the "latent" heat flux due to evapotranspiration, which measures the heat energy required to bring about the phase change from liquid water to vapor during evaporation. Using the principle of energy conservation, it's possible to infer the magnitude of the latent heat flux of evapotranspiration from the sensible heat flux data provided by the scintillometer readings. In this way the scintillometer does in fact provide a very useful technique for tracking evapotranspiration.

In a 2015 NM WRRI Student Water Research Grant project report, New Mexico Tech graduate student Reid Brown presented evidence that second generation large aperture scintillometers have improved tremendously, and can therefore be used for reliable daily sensible heat flux measurements; however, the first generation scintillometers are not as consistent or accurate. In order to assure high quality measurements of the sensible heat flux from the first generation scintillometers, an interdisciplinary project between the mathematics and earth science departments at NM Tech was formed, consisting of members John Chilleri, masters student in mathematics as well as recipient of the 2016 NM WRRI Student Water Research Grant, Dr. Brian Borchers, John’s advisor and professor in the Mathematics Department, along with Sebastian Hendrickx, undergraduate student in the Physics Department, and Dr. Jan Hendrickx, professor in the Earth and Environmental Sciences Department.

The goal of this research group is to develop a calibration procedure whereby the first generation scintillometers can effectively be tuned to a second generation reference instrument, thus enabling continuing use of the expensive first generation equipment to acquire reliable data in field applications. To determine the calibration function, side-by-side first and second generation scintillometer data has been acquired over a period of several days. To get the most accurate calibration, the data must first be filtered to retain correct values while excluding unrealistic outlier values that occur from time to time. Once this filtering has been done, a regression analysis to fit the data begins. Preliminary data suggests the calibration function between first and second generation scintillometers may follow a simple power law form. They also show that the calibration is sensitive to variations in atmospheric conditions (turbulent versus non-turbulent conditions and temperature). Separate calibrations are being developed for these different environmental conditions.

The first generation Kipp & Zonen Large Aperture Scintillometer (LAS) is an analog instrument with an analog readout. Here, the signal strength is about 57% and the path length has to be set by turning the black knob just above the signal strength pointer. This instrument has limited capability to filter and manipulate its output signal. This LAS needs a Campbell scientific datalogger; it was not calibrated before shipping and its sensible heat flux can vary by 5 to 25% of its true value. Calibration of the nine first generation LAS instruments at NM Tech to obtain sensible heat fluxes within a few percent of their true value is the overall goal of this student project.

The second generation Kipp & Zonen Large Aperture Scintillometer (LAS) is a digital instrument with a digital readout. Here, the signal strength is exactly 90.2% and the path length can be inserted with meter precision by using one of the many menu options accessed through the four silver buttons just below the digital readout. This instrument has ample capability to filter and manipulate its output signal by changing coefficients in its software using the four silver buttons. The GPS antenna above the LAS keeps its clock accurate with sub-second precision. This LAS has its own build-in data logger; it is calibrated before shipping and its sensible heat flux is within a few percent of its true value.

John Chilleri was one of 14 students statewide to receive a 2015 NM WRRI Student Water Research Grant. Projects will end on June 30, 2016 and all projects will have completion reports posted on the NM WRRI website. Click here to review.

Collaboration Under an NSF Grant Sends Faculty and Staff to Chile, South America
by Jesslyn Ratliff, Program Specialist

In March, faculty and staff from NM WRRI, NMSU, NM Tech, and Oregon State University traveled to Chile. The trip was made possible by the National Science Foundation funded project entitled “CNH: Acequia Water Systems Linking Culture and Nature: Integrated Analysis of Community Resilience to Climate and Land-Use Changes.”

The “CNH” project includes collaboration with a Chilean sister research site as the project participants have integrated closely with an ongoing investigation in Chile for interchange of project ideas, knowledge, and international testing of project techniques and models. Chile was chosen as a sister research site because of its hydrologic and cultural settings and advanced efforts to characterize irrigation communities. Jose Luis Arumi, the Chilean collaborator, professor, and dean of the College of Agricultural Engineering at the University of Concepción, kindly coordinated tours and meetings with students and representatives of the local canal association.

While in Chile, project participants attended the 18^th Biennial Seminar on Water Resources and Environmental Management at the University of Concepción; toured the Chillán and Bío Bío rivers; visited the Dam of Bocatoma Asociacion de Canalistas del Laja; and toured a watershed starting at the head waters in the Andes Mountains.

The “Acequia CNH” project is in its sixth year and will come to a close in September 2016. A final project report will be available online early 2017. For more project information, use this link http://aces.nmsu.edu/cnhacequia/index.html

NMSU Graduate Student Studies Water Dynamics of Laguna de Bustillos in Chihuahua, Mexico
by Catherine Ortega Klett, Program Manager

Cuauhtemoc Basin in the state of Chihuahua in Mexico is a region that is characterized by the production of agricultural crops such as corn and apple. Agricultural activity occupies almost a third of the surface of the basin, which has no water outlet, and for which the only water input is by precipitation. Because of this, farmers extract groundwater to irrigate their fields, causing the aquifer level to fall dramatically in recent years. Since there is no water infrastructure in the streams, water drains into the only body of water in the region, Laguna de Bustillos. Laguna de Bustillos is a shallow lagoon that has an average depth of 1.2 meters, and all precipitation within the basin that does not infiltrate into the soil or evaporate drains to the Laguna. It is therefore necessary to calculate the water balance in the watershed to understand the dynamics of this water body.

Doctoral student Hugo Luis Rojas Villalobos, an NMSU student in the Water Science & Management program is working under the supervision of geography Professor Chris Brown to explore a low-cost and effective way to calculate the volume of water in Bustillos Lake. Rojas Villalobos was awarded a 2016 NM WRRI Student Water Research Grant for this project.

Rojas Villalobos explained that bathymetry is the technique used to measure the depth of a water body. One of the methodologies for measuring depth is to use a graduated line tied to a plumb bob, which is thrown into the water from a boat. Another technique used is a sonar transducer. This equipment uses sound to measure distances: the sound wave is sent, it strikes the surface of an object, and its echo is recorded. Sound travels at a constant speed in the water, and the sensor measures the time until the echo is detected and thus calculates the depth. This way of measuring depths is clearly faster, and also more accurate since the required length of chord in the plumb bob approach is influenced by its unwanted but unavoidable drift in the water flow. Another problem with the plumb bob method is that it requires a ship of nearly impossibly shallow draft, since the water in this case is extremely shallow (30 to 40 cms). For these reasons, Rojas Villalobos and Dr. Brown are developing an Autonomous Surface Vehicle (ASV) prototype that will be lighter, autonomous, and will be powered by solar energy.

The boat is a catamaran in which one transducer is installed. The sensor sends a sound signal directed toward the bottom of the lagoon; the transducer detects the echo carrying depth information, and that signal is transmitted to an electronic circuit (Arduino Mega). At the same time, a GPS sends the position signal to the Arduino, which then stores both the geographical location and depth information on an SD memory card. The guidance system is an ArduPilot circuit in which the geographic points are stored for the catamaran to automatically follow. ArduPilot sends signals to the two motors that control the speed and direction of the boat; if the GPS detects a path and it is not in the right direction to the predetermined point, ArduPilot corrects the course by accelerating one of the engines to turn like a tank. Since it is estimated that surveys will last approximately 4 to 6 hours each, the electronic and propulsion systems are powered by both lithium polymer batteries and a solar cell.

In this way the ASV can produce three-dimensional geographic locations (latitude, longitude, and depth); these are then deployed in ArcMap, which is a geographic information system (GIS). The set of points describes the underwater topography of the lake, but at this stage the continuous surface is not shown. The points are interpolated using a specialized tool called Topography to Raster, which generates a surface with continuous variation between points. The generated surface is a grid (raster), wherein each cell has a value for image depth of the lagoon. This grid is then turned into a network of irregular triangles (TIN), which defines more precisely the underwater topography. To calculate the volume of the lagoon, the current height of the water level is determined relative to the corresponding underwater level curve, and then the amount of water that is between that topography and the water level is calculated.

This research addresses the very real challenge of how to obtain water depth and volume information that meets suitable standards of quality and precision. The development of these technologies will allow researchers of limited financial resources to acquire the necessary components and to build their own ASV at relatively low cost. This may prove to be a very beneficial technological advancement for Mexico, Latin America, and developing countries worldwide.

Rojas Villalobo’s final report on the project will be posted on the NM WRRI website in early July.

New Water Sources Grants Announced by NM WRRI
by Catherine Ortega Klett, Program Manager

NM WRRI announced three faculty grant awards associated with the recently signed Cooperative Agreement between the Bureau of Reclamation and New Mexico State University, Research for the Development and Use of Alternative Water Supplies. This collaborative project will help increase scientific knowledge and research expertise in the area of characterization, treatment, and use of alternative waters for water supply sustainability in New Mexico and the western U.S.

NMSU researchers receiving awards included Dr. Catherine Brewer, Department of Chemical & Materials Engineering, who received funding for a one-year project entitled, Biochar for Desalination Concentrate Management. Another faculty member from the same department, Dr. Reza Foudazi, received funding for a two-year project entitled, In-situ Synthesis of Antibacterial Ultrafiltration and Microfiltration Membranes with Controllable Pore Size. Also receiving funding through the agreement is Dr. Pei Xu of the Department of Civil Engineering. Dr. Xu’s two-year project is entitled, Reducing Treatment Costs of Alternative Waters with Antifouling Ion-exchange Membranes. Congratulations to these NMSU researchers.

• NM WRRI hosts conference on Environmental Conditions of the Animas and San Juan Watersheds with Emphasis on Gold King Mine and Other Mine Waste Issues, Farmington, NM May 17-18, 2016 http://animas.wrri.nmsu.edu/
• UCOWR/NIWR Annual Conference, Pensacola Beach, Florida,
  June 21-23, 2016
  http://www.ucowr.org/conferences/2016-ucowr-conference
• Toward Sustainable Groundwater in Agriculture - An International Conference Linking Science and Policy 2016, Sponsored by University of CA, San Francisco, CA , June 28-30, 2016
  http://ag-groundwater.org/
• 31^st Annual WateReuse Symposium, Increasing Safe and Reliable Supplies, September 11-14, 2016, Tampa, FL https://watereuse.org/news-events/conferences/annual-watereuse-symposium/
• NM WRRI 61^st Annual New Mexico Water Conference, Where Does All the Water Go? History, Hydrology and Management of New Mexico’s Scarce Waters, October 5-7, 2016, Silver City, NM http://nmwaterconference.wrri.nmsu.edu/
• AWRA Annual Water Resources Conference in Orlando, FL, Nov 13-17, 2016 http://www.awra.org/meetings/Orlando2016/

NM WRRI Welcomes New GIS Research Assistant

Joshua Randall recently joined the NM WRRI as a GIS research assistant. His educational background includes two BS degrees from Arizona State University in sustainability and in geography. In 2014, Josh completed an MS in geography from Rutgers University. His master’s thesis was “Understanding Water Use in Phoenix, AZ: A Spatial Statistics Approach.”

Josh will be helping Program Specialist Ken Peterson, on the development of the New Mexico Dynamic Statewide Water Budget (NMDSWB). He will be working within Powersim to help improve the NMDSWB model architecture and interface, which will improve the model's readability and user friendliness. Additionally, Josh will be helping with data analysis in EXCEL and ArcGIS to get new and updated hydrologic data into the NMDSWB model framework.

NM WRRI Staff Participate in Retreat

On Friday, April 15, NM WRRI hosted a retreat for its staff to review its mission and to work on goals for the coming year. The retreat began with a team-building activity aimed at having the 17-member group get to know each other better. It was followed by a review of key program outcomes, which highlighted successes and challenges. An interactive discussion ensued with participants suggesting ideas for group approaches to moving forward effectively on goals. Key items were identified that the group was enthusiastic about pursuing, and these will form the basis for focused strategic action item planning.