Progress 10/01/19 to 09/30/20
Outputs
Target Audience:Other scientists both nationally and internationally. Federal and state water agencies. Changes/Problems:No fundamental changes in original objectives have been required. However, some activities have been compromised and delayed by the pandemic. What opportunities for training and professional development has the project provided?This was limited by cancellation of meetings and workshops due to the pandemic. How have the results been disseminated to communities of interest?Some key results were delivered directly to funding sources. In the case of the vineyard research, results were also shred with the private corporation (Gallo Inc.) that is a research partner in the NASA funded grant. What do you plan to do during the next reporting period to accomplish the goals?The NASA project of water use by irrigated vineyards will continue. The main emphasis will be directed at data analyses, rather than more data collection. First, the simultaneous measurements of temperature and humidity inside the canopy (microclimate) and their connections with the properties of the air above will be analyzed. These involve various advanced time series analyses to document the scales of space and time that govern the exchanges of air in and out of the canopy, and the changes in microclimate that result. The data will also be used to run an advanced model for canopy-atmosphere exchanges, called ACASA, developed at UC-Davis. This model can simulate the microclimate, and our measurements can be used to validate the model, and later to improve it. The scientists at UC-Davis have already agreed to cooperate in this and run the model. The four towers funded by Bureau of Reclamation (BOR) will continue to be operated. The considerable maintenance at each site and the massive amount of data analyses will continue, largely through the efforts of the research technician. We added a large number of additional soil moisture measurements at different depths at the site in Utah. This will allow us to estimate weekly ET from soil water storage changes, and compare with the eddy covariance. The amount that soil heat flow is out of phase with other energy balance measurements will be examined with the data. However, to address this issue more fundamentally, utilization of a mechanistic soil transport model would be advisable. We are talking with the soil physics group at USU to arrange for running the HYDRUS model to address this issue. A new graduate student is to start in 2021. She will work with both Dr. Hipps and Dr. Alfonso Torres at USU on urban water use by ET. The funded project looking at ET of irrigated turfgrass will be used to provide part of the data for the research. The new project related to demand management irrigation in Colorado, resulted in a large data set for much of the growing season of 2020. The data are to be analyzed by us to quantify the hourly, daily and seasonal values of ET. These are critical to assessing the water balance of the reduced irrigation study. These will also be compared to some remote sensing model estimates made by other investigators.
Impacts
What was accomplished under these goals?
The research conducted in this project integrates several externally funded studies on quantifying the water use by irrigated crops including: NASA study of evapotranspiration (ET), microclimate and use of remote sensing-based models in vineyards; and Bureau of Reclamation (BOR) project to determine the ET of irrigated lands at four sites in the Upper Colorado River Basin; and a Colorado-based study on the effects of irrigation reductions on crop production and saving of water resources, sometimes called demand management. For the NASA study, earlier published work here at USU showed that light wind conditions common for irrigated agriculture in arid regions, result in very unsteady and episodic transport of energy and water from vineyards. Recent findings this year indicate that even the most mechanistic remote sensing based models for ET, do not perform as well under these conditions. Physical reasons for this were also proposed. The NASA project also includes unique microclimate measurements inside the vineyards. These were started last year and expanded this year to a much longer period of several months. These involve fast response temperature and humidity fluctuations in the air inside the vineyard crowns, as well as above the canopy. All the measurements are made simultaneously, allowing the time average and short term changes in the microclimate and its connections to the air above to be assessed. The initial results show the temperatures and humidity inside the vineyard crow (where the majority of leaves and fruit exist) are very different than the air even just above the canopy. It is also observed that the connections between the microclimate and air above are intermittent. Periods of low turbulence allows the air in the canopy to become more moist and cool. Occasional turbulence events are strong enough to create significant exchanges and partially mix out the canopy air. The typical time average of temperature and humidity in the canopy, will not mean what we normally think it does under these conditions. More results will be analyzed from the larger data set collected in the summer of 2020, to quantify the true temporal nature of microclimate in these vineyards, and how it connects with the ET process. A new set of measurements was conducted during the summer to examine the role of the transport of hot and dry air from upwind surroundings in altering the ET or water use of the irrigated vineyards. A new set of eddy covariance and energy balance measurements was installed in a large and dry section of land (over 10 square km) directly upwind of the vineyard study site. In addition, a transect of station between the sites measured air temperature changes and horizontal wind. These results will be analyzed to attempt to quantify how much the water use of the vineyard is enhanced by the presence of the large arid zone upwind of the site. The BOR funded study of the ET of irrigated crops at four locations in the Upper Colorado River Basin (one in each of the states of Utah, Colorado, Wyoming and New Mexico) continued. The crops include: alfalfa, orchard grass, mixed grass and a peach orchard. The daily and seasonal ET values at each site, we supplied to other researchers to test multiple modes of ET. Results show significant differences among the models in their ability to simulate the ET. The soil sensors at one of the sites were augmented to allow a better set of analyses of the portion of available energy used by heat flowing in/out of the soil surface. Initial analyses shows that the flow of heat into the soil is not in phase with the other energy terms., which is implicitly assumed. Results suggest this causes an error when comparing the ET to the energy available, to check that total energy is conserved. More analyses is being conducted. We started cooperating with a new project funded by several entities in the State of Colorado and Trout Unlimited. The study is to document voluntary reductions of irrigation in locations in Colorado on the production and water resources. USU designed the ET and energy balance system, installed and maintained it, and is doing all the data analyses and interpretations of the ET. Another related project is funded by PacifiCorp to use eddy covariance estimates of ET in three agricultural fields for scheduling irrigation with saline waste-water from a power plant. These results are integrated with soil moisture and precipitation to determine irrigation applications to ensure that saline water does not reach the groundwater.
Publications
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Progress 07/02/19 to 09/30/19
Outputs
Target Audience:
Nothing Reported
Changes/Problems:No substantial changes have been required at present. What opportunities for training and professional development has the project provided?Hosted workshop for other scientists at USU, where I went over some new mathematical approaches to analyze and interpret the types of data we often collect and analyze to estimate crop water use. How have the results been disseminated to communities of interest?Some key data and results delivered directly to funding sources. In the case of vineyard researh, some results are also shred with the private corporation that is a research partner in the NASA funded grant. What do you plan to do during the next reporting period to accomplish the goals?The research activities for the NASA project of water use by irrigated vineyards will continue this year. Several intensive field studies of 4 - 7 days each, will be conducted again this year. A major goal of the PI this year, is to intensify measurements of the microclimate inside the vineyards, and study the processes which determine how much it differs from the weather conditions above the vegetation. This will involve interactions with scientists at UC-Davis, who have a very advanced model for interactions of plant communities with the atmosphere. This model can simulate the microclimate, and our measurements can be used to validate the model, and later to improve it. Other field measurements and analyses will be used to evaluate of a key part of the USDA-ARS remote sensing two-source model, which is fundamental to the NASA project. The study of ET of irrigated turfgrass will continue, with more advanced analyses being conducted on the data set already collected by the graduate student who has just completed his thesis. Given the preliminary findings of daily and seasonal water use by the turfgrass and the ability to estimate this by remote sensing models estimates, new research will be to test an ET model that uses weather data and a model for stomatal conductance to predict daily ET. If this model validates, it can be used to estimate the changes in ET that might result from warmer summer temperatures in the region. The measurement of ET and water balance at fields irrigated with saline water by two power plants, will continue for another season. This contract provides the power plants the ability to manage irrigation scheduling so as to protect the groundwater, as equipped by law. The four towers funded by Bureau of Reclamation (BOR) will continue to be operated. We have added a significant number of additional soil moisture measurements at one site to test for the importance of estimating a complete water balance for an irrigated site. This will require additional analyses. We are also investigating how calculations of heat flowing into and out of the soil, may be not represent the time period being considered. In other words, the delay in moving heat into the soil, means the values estimated may actually represent some period before the measurements would suggest. All four sites are monitored and maintained by a technician funded and reporting to the PI. As the sites are in four separated states, a good deal of travel is often necessary. All data will be processed and analyzed to provide actual daily and seasonal water use for the irrigated fields. This involves huge data sets and many layers of analyses, done by a technician supervised by the PI. The final data sets are delivered to the BOR. We also Interact with them on a monthly basis to discuss progress, and help them evaluate their models for water use.
Impacts
What was accomplished under these goals?
This project connects and integrates with several externally funded and multidisciplinary research projects on water use by irrigated crops including: NASA study of evapotranspiration (ET), microclimate and use of remote sensing-based models in vineyards; and Bureau of Reclamation (BOR) project to determine the ET of irrigated lands at four sites in the Upper Colorado River Basin. Recent published work here at USU showed very intermittent turbulence transport of water can be observed from the irrigated vineyards, which affects how research measurements of ET are properly analyzed and integrated with models. Analyses shows that the models do not perform as well under intermittent conditions. A unique set of microclimate measurements were conducted this year in the vineyards, including simultaneous fast response temperature and humidity inside the vineyard crowns, in the inter-row of the canopy and above the canopy. Preliminary analyses show that large differences in temperature and humidity exist between parts of the canopy as well as the air above. But the results also show that there are very distinct and coherent changes over time between "moist" and "drier" periods. The time average, which is the traditional way to look at microclimate, does not tell the correct story in this case. More results are being analyzed to quantify the true temporal nature of microclimate in these vineyards and how it connects with the ET process. The BOR study conducts ET and energy balance analyses at four research sites (one in each of the states of Utah, Colorado, Wyoming and New Mexico). The daily and seasonal ET values are calculated for each site, and are being used by the Bureau to test some models of ET. USU is also using the data to look at how ET in the Upper Colorado River Basin responds to annual variations in climatic conditions, especially temperature and humidity. In addition, some technical analyses are being conducted with the data to test the hypothesis that the accepted procedure to determine the flow of heat into the soil is not in phase with the other energy terms, and can produce subsequent error is correcting ET estimates. Related to this project is a funded study to measure and model the water use of irrigated turfgrass in Utah, using data from an eddy covariance system at a golf course in northern Utah. A published remote sensing model called the "Triangle Method", was used to estimate water use during satellite overpasses. The model results are compared with the measured ET, and resulted in reasonable predictions. However, more analyses is being conducted as part of graduate student thesis. Another related project is funded by PacifiCorp to use eddy covariance estimates of ET in three agricultural fields for scheduling irrigation with saline waste water from a power plant. These results are integrated with soil moisture and precipitation to determine irrigation applications to ensure that saline water does not reach the groundwater.
Publications
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