Managementul apei în vestul SUA: OpenET – o soluție inovatoare

BY: stiridinromania.ro In Magazin

În decembrie 2022, 65% din vestul Statelor Unite se confrunta cu o secetă severă, rezultatul unei mega-secete care a durat două decenii în Bazinul Fluviului Colorado și care a captat atenția presei din întreaga lume. Cu toate acestea, nu seceta a fost cea care a făcut titlurile de știri când am început cercetarea pentru această poveste despre OpenET, o nouă platformă online revoluționară destinată să ajute fermierii și managerii de apă să monitorizeze și să reducă consumul de apă în bazinele hidrografice unde rezervele nu țineau pasul cu cererea.

Începutul anului 2023 a adus inundații în multe comitate din California, lăsând 68% din stat brusc fără sau cu foarte puțină secetă. Aceste inundații l-au determinat pe Forrest Melton, omul de știință de proiect NASA pentru OpenET și manager de program asociat pentru agricultură și resurse de apă în cadrul programului NASA Earth Action, să întrerupă interviul video după ce un copac a căzut în afara casei sale din Bay Area, într-o zi ploioasă din martie 2023.

Melton nu părea prea optimist în privința condițiilor umede, menționând că California tinde să oscileze între cele două extreme, secetă și inundații. Acesta a făcut referire la iarna 2016/17, care a avut precipitații foarte ridicate, urmată de condiții uscate în anii următori, înainte de ploile abundente și inundațiile din începutul lui 2023.

Conform Sistemului Național Integrat de Informare despre Secetă al NOAA, va fi nevoie de mai mult de un iarnă umedă pentru a reînnoi nivelurile de apă subterană în multe părți din vestul Statelor Unite. Nivelurile apelor subterane din Valea Centrală a Californiei și multe părți ale Acviferului Ogallala continuă să scadă. Necesitatea unei gestionări mai bune a apei rămâne esențială, dar datele necesare pentru a susține abordări noi nu au fost disponibile pe scară largă.

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Proiectul OpenET a intrat în scenă, fiind un efort colaborativ multidisciplinar pentru a pune la dispoziție date de evapotranspirație (ET) bazate pe satelit publicului larg. Melton descrie proiectul ca oferind date valoroase și științific robuste la toate nivelurile, “care pot fi folosite pentru a susține luările de decizii de zi cu zi și planificarea pe termen lung pentru a încerca să rezolve unele probleme de gestionare a apei cu adevărat importante în Vest”.

Evapotranspirația este procesul combinat de evaporare și transpirație, ambele transferă apă de la suprafața pământului către atmosferă sub formă de vapori de apă. Deși este un proces care se întâmplă în jurul nostru aproape tot timpul, măsurarea acestuia pe teren este foarte dificilă deoarece vaporii de apă sunt invizibili cu ochiul liber.

Pentru a înțelege efectul evapotranspirației asupra unui ciclu local al apei, putem lua exemplul unei fântâni decorative. De obicei, aceste fântâni reciclează aceeași apă în mod repetat. Pe măsură ce o fântână funcționează, apa este pompată din capetele fântânii, cade înapoi în bazinul fântânii și apoi curge înapoi prin sistemul de conducte înainte de a începe din nou. Putem considera apa rămasă în cadrul sistemului local al fântânii ca fiind o utilizare nefolositoare a apei. Totuși, o parte din apă va fi pierdută din sistemul local al fântânii prin evaporare de la suprafața bazinului sau prin ceață de la pulverizarea fântânii. Imaginați-vă că fântâna are și frunze de nuferi care cresc în bazinul său. Frunzele de nuferi vor folosi apa fântânii pentru a supraviețui și a crește, pierzând o parte din acea apă prin transpirație. Apa totală pierdută este evapotranspirația și este considerată o utilizare consumatoare, deoarece nu poate fi reutilizată de fântână.

Urmărirea evapotranspirației ne poate spune câtă apă este îndepărtată sau “epuizată” dintr-un sistem local al apei și câtă apă trebuie adăugată înapoi pentru a susține creșterea plantelor și a menține un echilibru sănătos între oferta de apă și consumul de apă. Dacă prea multă apă părăsește fântâna, va înceta să funcționeze. Dacă se adaugă prea multă apă, va deborda.

Aceste concepte pot fi aplicate mai larg la ciclul hidrologic în ansamblu, iar datele de evapotranspirație pot juca un rol important în proiectarea și implementarea practicilor durabile de gestionare a apei pentru a combate probleme mai mari precum seceta, precum și reduceri pe termen scurt și lung în disponibilitatea apei.

În mod tradițional, datele despre ET au fost obținute din instrumente și metode pe teren, cum ar fi lisimetrele de cântărire, care cântăresc solul și plantele pentru a urmări volumul de apă pierdut prin evaporare sau transpirație. O altă metodă obișnuită se numește covarianța eddy, care calculează cantitatea de vapori de apă transportată de la suprafața pământului de vârtejele de vânt pe măsură ce se deplasează pe suprafața pământului. Dar ambele sunt costisitoare și dificil de instalat și întreținut, iar măsurătorile sunt reprezentative doar pentru o mică parte a unui câmp agricol individual. Este prohibitiv din punct de vedere al costurilor să se colecteze aceste măsurători pe suprafețe mai mari.

Echipa OpenET a observat nișa importantă lăsată deschisă de metodele tradiționale de măsurare a evapotranspirației și a umplut-o. Aceștia s-au bazat pe decenii de cercetare finanțată de NASA, USDA și USGS și au dezvoltat o nouă platformă care poate lua date deja accesibile și disponibile din programele satelitare, cum ar fi Landsat, și le poate combina cu date meteorologice pentru a calcula ET pentru fiecare sfert de acri de pământ. Sateliții pot înregistra informații precum temperatura suprafeței Pământului și cât din lumina care intră de la soare este reflectată înapoi în spațiu. OpenET poate utiliza modele matematice bazate pe fizică pentru a combina datele satelitare și meteorologice și a furniza date precise despre ratele și volumele de evapotranspirație.

Aceste informații sunt apoi făcute ușor accesibile prin intermediul Explorer-ului de date OpenET, o unealtă gratuită bazată pe web care permite oricui cu o conexiune la internet să acceseze datele furnizate de OpenET. Utilizatorii încep prin selectarea unei zone de interes de pe o hartă a vestului Statelor Unite care oferă date la rezoluția satelitară a unui sfert de acri, dar și împărțite în zone de interes cunoscute și câmpuri agricole individuale, fiecare codificate cu culori cu un harta termică a evapotranspirației. Culorile reci indică rate mai mari de evapotranspirație, în timp ce culorile calde indică rate mai mici. Utilizatorii pot face zoom pe anumite zone de pe hartă și, cu doar un clic, apare un grafic care arată tendințele evapotranspirației pentru o anumită zonă, pentru anul curent și ultimii cinci ani.

Acest lucru poate arăta tendințele lunare ale ET, utile pentru înțelegerea fluctuațiilor sezoniere, dar și tendințele cumulative, utile pentru înțelegerea schimbărilor anuale în evapotranspirație. “Echipa OpenET a abordat proiectul din perspectiva utilizatorului încă de la început, și fiecare element al Explorer-ului de date și serviciilor de date deschise se află acolo pentru că un manager de apă sau un fermier a cerut-o,” a explicat Melton. Pe măsură ce ne jucam cu harta, a devenit evident cât de mult s-a muncit pentru dezvoltarea acestui proiect. Oamenii de știință au trebuit să îmbunătățească modelele și să evalueze acuratețea datelor, programatorii au trebuit să dezvolte interfața utilizatorului și serviciile de date, designerii au trebuit să facă interfața intuitivă suficient de impactantă, grupurile de agricultură și mediu au trebuit să ajute la validarea acurateței modelului, iar utilizatorii de toate tipurile au trebuit să ofere cerințe și apoi să testeze produsul pentru a se asigura că nevoile lor sunt îndeplinite.

Consorțiul OpenET include NASA, USGS, USDA Agricultural Research Service (ARS), Environmental Defense Fund (EDF), Google Earth Engine, California State University Monterey Bay (CSUMB), Desert Research Institute (DRI), Habitat Seven, Chapman University, Cornell University, University of Nebraska-Lincoln și aproape o duzină de alte universități și experți din SUA. Centrul de Cercetare Ames al NASA și CSUMB au jucat roluri cheie în conducerea științifică și tehnică a efortului de la început, lucrând îndeaproape cu DRI, EDF și cu non-profitul recent format OpenET, Inc. În plus, peste 100 de parteneri din comunitatea de gestionare a apei, agricultură și conservare au furnizat cerințe de utilizare și au asistat la proiectarea și testarea platformei și instrumentelor OpenET. “OpenET nu ar fi posibil fără contribuțiile fiecărui partener,” a spus Melton. “Atât din partea implementării, cât și a celor care traduc datele de la OpenET în soluții la probleme de lungă durată.”

Modelele ca cele încorporate în OpenET pot fi instrumente extrem de utile pentru înțelegerea modelelor din…

At the end of 2022, 65 percent of the Western United States was in severe drought, the result of a two decades long mega drought in the Colorado River Basin that had captured headlines around the world. 

However, it was flooding, not drought, that was making headlines when we began our research for this story about OpenET, a revolutionary new online platform geared towards helping farmers and water managers monitor and reduce water use in watersheds where supplies were not keeping up with demand.  

The start of 2023 brought flooding to many counties in California, leaving 68 percent of the state with suddenly little to no drought. And caused Forrest Melton, the NASA Project Scientist for OpenET and Associate Program Manager for agriculture and water resources with the NASA Earth Action program, to pause our video interview after a tree fell down outside his Bay Area home on a rainy day in March, 2023. 

Coming online again after calling the fire department, Melton didn’t seem all too optimistic that the wet conditions would last. “California tends to swing between the two extremes of drought and flood,” Melton said. He referenced the 2016/17 winter which had particularly high precipitation but was followed by dry conditions during the following years, before the relief brought by the heavy rains, and flooding, in early 2023. 

According to NOAA’s National Integrated Drought Information System it will take more than one wet winter to replenish groundwater in many parts of the western United States. Groundwater levels across the California Central Valley and many parts of the Ogallala Aquifer continue to decline. The need for better water management remains essential, and yet the data necessary to support new approaches has not been broadly available. 

Enter the OpenET project, a multi-disciplinary, collaborative effort to make satellite-based evapotranspiration (ET) data available to the public. Melton describes the project as providing invaluable and scientifically robust data at all scales, “that can be used to support day to day decision making and long range planning to try to solve some really long standing and important water management challenges in the West.”

Evapotranspiration is the combined process of evaporation and transpiration, both of which transfer water from the land surface to the atmosphere as water vapor. Evaporation transforms water from the surface of the ground or bodies of water into water vapor, while transpiration is water vapor that is evaporated from plant tissues and escapes through the stomata, the tiny pores in plant leaves and stems. It is a process that is happening all around us almost all the time, but because water vapor is invisible to the human eye, it is very hard to measure on the ground.  

To understand the effect evapotranspiration has on a local water cycle, picture a large decorative fountain. Typically, these fountains recycle the same water over and over. As a fountain runs, water is pumped out of the fountain heads, falls back into the fountain’s basin, and then flows back through the pipe system before starting the process all over again. We can think of the water remaining within this fountain’s local water system as non-consumptive water use. Some water, however, will be lost from the fountain’s local water system by evaporating from the pool’s surface or mist from the fountain’s spray.

Imagine the fountain also has lily pads growing in its basin. The lily pads will use the fountain’s water to survive and grow, losing some of that water to transpiration. The total water lost is evapotranspiration, and is considered consumptive water use, because it cannot be reused by the fountain. Tracking evapotranspiration can tell you how much water is removed or “depleted” from a local water system, and how much water needs to be added back in to support plant growth and maintain a healthy balance between water supply and water use. If too much water leaves the fountain, it will stop running. If too much water is added, it will overflow.  

These concepts can be applied more broadly to the hydrologic cycle as a whole, and evapotranspiration data can play an important part in designing and implementing sustainable water management practices to combat larger issues like drought, as well as both short and long-term reductions in water availability. Historically, ET data have been obtained from ground-based instruments and methods, such as weighing lysimeters, which weigh soil and plants to track the water volume lost by evaporation or transpiration. Another common method is called eddy covariance, which calculates the amount of water vapor transported away from the land surface by wind eddies as they move across the land surface. But both are expensive and difficult to install and maintain, and measurements are only representative of a small portion of an individual agricultural field. It is cost prohibitive to collect these measurements over larger areas. 

The OpenET team saw the important niche left open by traditional evapotranspiration measurement methods and filled it. They built upon decades of research funded by NASA, USDA and USGS and developed a new platform that can take easily accessible and already available data from satellite programs, like Landsat, and combine it with weather data to calculate the ET for every quarter acre of land. Satellites can record information like the Earth’s surface temperature and how much of the incoming light from the sun is being reflected back out to space. OpenET is able to use physically-based mathematical models to combine the satellite and weather data and output accurate data on evapotranspiration rates and volumes. 

This information is then made easily accessible through OpenET’s Data Explorer, a free web-based tool that allows anyone with an internet connection to access the data OpenET provides. Users begin by selecting an area of interest from a map of the western United States that provides data at the satellite resolution of a quarter-acre, and also broken down into known areas of interest and individual agricultural fields, each color coded with a heat map of evapotranspiration. Cooler colors indicate higher rates of evapotranspiration while warmer colors indicate lower rates. Users can zoom into specific areas on the map, and with just a click, a chart pops up showing the evapotranspiration trends for a given area, for the current year and the past five years. 

The chart can show monthly ET trends, useful for understanding seasonal fluctuations, and also cumulative trends, useful for understanding year-to-year changes in evapotranspiration. “The OpenET team took a user-driven design approach from the beginning, and each element of the Data Explorer and the open data services is there because a water manager or farmer asked for it,” Melton explained. As we played around with the map, it became apparent how much work was put into developing this project. Scientists needed to improve models and assess the accuracy of data, programmers had to develop the user interface and data services, designers needed to make the interface intuitive enough to be impactful, agriculture and environmental groups needed to help validate the model’s accuracy, and users of all types needed to provide requirements and then test the product to make sure their needs were actually met. 

The OpenET consortium includes NASA, USGS, USDA Agricultural Research Service (ARS), Environmental Defense Fund (EDF), Google Earth Engine, California State University Monterey Bay (CSUMB), Desert Research Institute (DRI), Habitat Seven, Chapman University, Cornell University, University of Nebraska-Lincoln and close to a dozen other universities and experts across the U.S. NASA Ames Research Center and CSUMB have played key roles in the scientific and technical leadership of the effort from the outset, working closely with DRI, EDF and the recently formed non-profit OpenET, Inc. In addition, over 100 partners from the water management, agriculture and conservation community provided user requirements and assisted with the design and testing of the OpenET platform and tools.

“OpenET would not be possible without the contributions of each one of those partners,” Melton said. “Both on the implementation side and those who are translating the data from OpenET into solutions to long standing challenges.” 

Models like those built into OpenET can be extremely useful tools for understanding patterns in ET and water use, but are only helpful if their accuracy is known. The OpenET science team recently completed the largest accuracy assessment to date for field-scale satellite-based ET data, comparing the satellite data to ground-based measurements at more than 150 sites across the U.S. Led by John Volk of the Desert Research Institute, the study was published in Nature Water earlier this year. A key finding was that across all sites, an ensemble value computed from six different ET models performed the best overall, leveraging the strengths of each individual satellite-driven model. 

However, the study also found that some models performed best for particular crop types or regions, which is important information for water managers and farmers who need the most accurate data possible. Publishing the results as an open access study with all data and analysis made publicly available was also important to build trust in the data. While the study highlighted some limitations of the models and priorities for future research, the rigorous and reproducible accuracy assessment helps to build user confidence that they can use the data, while being aware of the expected accuracy for different applications of the data.  

OpenET has already contributed to one significant win for farmers that affects how water use will be monitored and reported in the Sacramento-San Joaquin Delta. 

This inland river delta covers 750,000 acres and is an important water resource in California, but one where accelerated demand combined with habitat loss and water quality issues has led to major concerns. In the Delta, large portions of the agricultural land are below sea level. Levees protect the fields and contain the river channels that supply water for irrigation. In 2023, the state began requiring farmers to maintain a water meter or measuring device on each diversion, where water is diverted from a river for irrigation. However, this measurement proved challenging and costly as there are thousands of diversions in the Delta, and the measuring equipment was inaccurate and difficult to maintain in this environment. In addition, water users also had to pay for meters at the locations where water that drained from the fields was pumped back over the levees and into the river channels.

“Mostly, what the state was interested in was the consumptive use: how much (water) was actually removed from the supply in that region,” Melton said. “So, it’s the perfect place for using OpenET because evapotranspiration really is the majority of the consumptive use in the Delta, if not all of it.”

After the launch of OpenET, farmers in the Delta worked with the Delta Watermaster, the California State Water Resources Control Board, the OpenET team and the Delta Measurement Consortium to develop an alternative compliance plan that used OpenET data to help streamline the water use required reporting for this complex region. Once the alternative compliance plan was approved, Forrest Melton and Will Carrara of NASA worked with the state Water Resources Control Board, the Delta Watermaster and water management agencies, and Jordan Harding of HabitatSeven to implement this solution. The Delta Alternative Compliance Plan, also known as the Delta ACP, allows farmers to use OpenET data to estimate their water usage; enabling farmers to complete their use reports in a matter of minutes. 

“It’s the first time that satellite-based evapotranspiration data has been automatically integrated with a state-managed water reporting system,” Melton said. 

Last year, more than 70% of farmers in the Bay-Delta region chose to use OpenET and to report their water use through the Delta ACP website, and they expect this percentage to continue to increase over time. 

“The best part is that it is saving farmers hundreds of hours on preparing and submitting reports, avoiding millions of dollars in costs for farmers to deploy and maintain meters, and giving the state consistent and reproducible data on water use that has been reviewed and approved by the water user,” Melton said. 

According to Delta Watermaster, Jay Ziegler, this approach has a clear benefit in the unique water flow setting of the Delta. “In reality, OpenET – and the use of publicly accessible data measuring ET is the only way to really discern consumptive use of water in the Delta on a reliable basis,” Ziegler said. “Candidly, we don’t really have a viable “plan B” in the absence of applying Open ET for water use reporting.”

Jay ziegler

Sacramento-San Joaquin Delta Watermaster

As water scarcity is increasingly becoming an urgent issue all around the world, it’s easy to imagine how many countries could benefit from OpenET data. 

OpenET’s first international partnership is led by Anderson Ruhoff, a professor in Hydrology and Remote Sensing at the Federal University of Rio Grande do Sul, Brazil, where his team developed an evapotranspiration model called geeSEBAL for Brazil’s Water Agency.

Ruhoff learned about OpenET while he was in the US on a visiting professorship in Nebraska. He was intrigued and reached out to Melton who encouraged him to attend an upcoming conference in Reno, Nevada, where OpenET would be featured. The conference was due to start in just a few days time.

“So I had to find a last minute ticket to Reno and I’m glad I bought it, because when I arrived there they invited me to join Open ET. It was quite a coincidence,” Ruhoff said, smiling as he remembered the spontaneous decision. “We adapted our model for the US and started to participate in their work.”

In March, 2024, Ruhoff and OpenET launched an extension of the tool, called OpenET Brazil, with financial support from the Agência Nacional de Águas e Saneamento Básico (ANA), the Brazilian national water agency. The tool, called OpenET Brazil, will have similar goals as OpenET in the U.S., and the data collected will help improve Open ET’s accuracy overall.

Melton feels this will be a “great test case” for both working with new environmental conditions (in Brazil there frequently is more cloud cover than in the US during key parts of the growing season) and also developing new collaborations.

“The partnership will help us figure out how we can work with international partners to make the ET data useful,” Melton said. “The key aspect of our approach to geographic expansion is that leading scientists in each country and region, like Dr. Ruhoff, will lead the implementation, accuracy assessment, and the development of applications and partnerships for their country.”

Brazil has one of the world’s largest sources of freshwater, the Amazon River, and yet it can still be affected by drought. This is partly due to the fact that deforestation in the Amazon Rainforest has an impact on the entire region’s water cycle. Trees draw water up from the soil and during photosynthesis they release vapor into the atmosphere. This water vapor will accumulate and form precipitation. Trees are “basically a huge water pump,” Ruhoff said, and the Amazon Rainforest is large enough that it helps to produce the rainy season. But when deforestation is allowed to happen over large areas, that mechanism is interrupted. As a result of this disruption, the dry season is predicted to intensify, becoming longer and dryer, which in turn can affect crop production in Brazil as well as the rainfall that is critical for sustaining water supplies in Brazil and other areas of South America.

“Water doesn’t see borders. It doesn’t follow our rules,” Ruhoff said. “Deforestation in one place can affect people thousands of kilometers away.”

Anderson Ruhoff

Professor of Hydrology and Remote Sensing, Federal University of Rio Grande do Sul, Brazil

Studying evapotranspiration can reveal the impacts of deforestation with even more clarity. And importantly, it’s also public information. “So not only the farmers and water managers but every citizen can check how much water is being used in their area, especially during drought. It’s democratic information in that way,” Ruhoff said. “I think it’s important to have this information openly available and to try and reach as many people as possible.”

Melton feels there’s the potential to expand the project, if more people like Ruhoff are there to lead the way.

“There’s huge potential, but there do need to be stakeholders that come to the table and say that this is something that they’re interested in,” Melton said. “Water is so important and at times so contentious that it’s really important the data is seen as trusted. When there is a local leader, that substantially increases the likelihood that it will be trusted, and most importantly, used to bring people together to develop solutions.”

Even when you live in a water-scarce region like California it’s easy to take water for granted. What platforms like OpenET can do for us, however, is make water, even in its most diffuse form, more visible to everyone.

Written by Jane Berg and Rachel Sender, co-published with the Bay Area Environmental Research Institute

To learn more about OpenET, visit https://etdata.org/

Program Contact:
Forrest Melton
NASA Ames Research Center
forrest.s.melton@nasa.gov



Acest titlu a fost scris de inteligență artificială Chat GPT, unele date pot fi incorecte. Pentru stirea originala, verificati sursa: Link catre sursa

Sursa si foto: NASA

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