Feasibility Study for Development of Statewide Evapotranspiration Network
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Information was collected on existing mesonets, potential evapotranspiration networks, and stakeholder needs, in support of a comprehensive feasibility study for a Texas statewide evapotranspiration network. This report summarizes the data and information collected from interviews and online resources regarding the purpose, design, operation, and value of these mesonets. It analyzes existing network data within Texas and evaluates the costs and benefits associated with operating a more comprehensive or integrated network. Finally, it presents options for a sustainable Texas mesonet based on successes elsewhere and the specific needs and resources of Texas. A mesonet here refers to a set of weather stations designed to detect and monitor weather phenomena ranging in size from several miles to hundreds of miles (the "mesoscale"). Such disturbances include flooding and thunderstorms (i.e. convective precipitation), high winds, droughts, and heatwaves. Instruments may be located as high as 10 m above the ground, and stations are generally located to avoid influences from urban landscapes, irrigation, forests, and large bodies of water. This report restricts the term mesonet to networks that serve a variety of needs or stakeholders. ET (Evapotranspiration) networks differ in both their objectives and measurements. Their objective is to determine the atmospheric demand for water evaporation and transpiration from land covered by a well-watered reference crop either alfalfa or clipped grass. Such data is valuable for irrigation scheduling for agricultural production and for improving efficiencies in landscape watering for homes and businesses. ET networks use specific instruments often at 2 m heights sited well within a homogenous field of a well-maintained reference crop. Requirements of growers and stakeholders often drive the siting and spacing. An ET network has a particular specialized use while a mesonet is more of a multi-purpose network. Many existing mesonets in other states were originally established for agricultural purposes, while others were established in support of public safety. Most have been in operation for an average of twenty years and by now serve a broad range of sectors and constituencies. In Texas, there are three mesonets that serve a variety of purposes: the West Texas Mesonet, the Lower Colorado River Authority (LCRA) Hydromet Network, and the TexMesonet. There is one dedicated ET network, the TexasET Network, and there are numerous other single-purpose networks. All surveyed mesonets and ET networks measure air temperature, relative humidity, wind, and precipitation. Solar radiation is measured at all stations in the TexasET and TexMesonet networks, but only partially in the other two networks. In addition, many also measure soil temperature and soil moisture at a variety of subsurface levels as well as wind or temperature at multiple above-ground levels. Data transmission from individual stations is predominantly by cellular network. Users access the data via web sites, text alerts, apps, and through retransmission of data to larger aggregation networks such as the Meteorological Assimilation Data Ingest System, the National Mesonet Program, and MesoWest. Most mesonets quality control their data to either World Meteorological Organization or National Weather Service standards. Individual startup costs range from $6,200 to $25,000 per station, and network maintenance and operating costs range from $1,600 to $6,000 per station. Differences in cost largely reflect differences in instrumentation and maintenance needs. Maintenance costs for ET stations can be high due to irrigation infrastructure and land management required to maintain the reference grasses. Staffing needs depend on the mix of employees and outside contractors; labor-intensive tasks include station, instrumentation, and communication maintenance, calibration, product development, and administration. The benefits gained from fully functional ET networks are substantial. Analyses of benefits of existing ET networks find typical water savings of several inches per year on irrigated cropland, implying potential water savings exceeding one million acre-feet per year within the agriculture sector alone. Overall, the potential economic return on investment is substantial, with one study estimating it at 20:1. Mesonet business models range from comprehensive centralized networks with fully integrated operations to secondhand aggregators of data from existing networks. Most of the successful networks examined in this report operate on a partnership model with some centralized tasks and funding and some tasks and funding shouldered at the local level. Nearly all mesonets function through university or multi-university partnerships. In most cases, data is free of charge. In Texas, an appropriate model would be a consortium model, consisting of the Texas Water Development Board, universities such as Texas Tech University, Texas A&M University, and the University of Texas, and other statewide or regional stakeholders/operators such as the the Texas A&M Agrilife Extension Service, Lower Colorado River Authority and the Electricity Reliability Council of Texas. Additional stakeholder participation can be formalized through an advisory board. Successful mesonets elsewhere have avoided challenges which can potentially lead to failure of the network, including: 1. lacking an overall network vision; 2. failing to properly engage potential stakeholders; 3. misdiagnosing local needs; 4. lacking diversification in revenue streams; 5. not fully exploring potential government partners; 6. not properly budgeting for maintenance costs; understaffing; 7. lacking data and metadata standards; 8. insufficient communications infrastructure; and 9. not providing reliable web/automated dissemination of data.
