Eva- Optimizing Evaporation Prevention Strategies

Eva's first time in water- February 2016
Eva collecting data in Pondicherry, India- March 2016
Eva after a long day of trials, with Professor Shanti Ramanathan our guide and close friend
Variation of the Penman equation used to calculate a value of evaporation from the data collected by Eva
Testing sensors with Artik 10 - Drawing table
The part where science stops behaving - Tracking Eva downstrean
Testing the water
Documenting, documenting
Makers against drought - Artistic progress goes boink

Eva- Optimizing Evaporation Prevention Strategies

As the drought in California continues into its fifth year, drastic efforts have to be made in all areas concerning water in order to solve the crisis. Everyone – from homeowners to agriculturists to landscapers- has been hit by the emergency. Everyday Californians are rationing water and cutting usage, but it stills seems that they are fighting a losing battle. Fortunately, solutions exist. And with the internet of things on our side - we can find them.

Over the past few decades, humanity has tapped into a powerful tool called interconnectedness: a phenomenon that makes vast amounts of raw, unsegregated data easy to gather and quick to analyze. Using this information we can find solutions to seemingly intractable problems. The technologies used to gather such information have become smaller and cheaper which gives us more power to gather information from the world around us in a less intrusive manner. Using the IoT, many parts and pieces can come together to render form and cohesiveness to a complex puzzle, like California's drought.

Water usage in California is divided between three major sectors: 50% constitutes of environmental replenishing, 40% goes towards the agricultural sector, and 10% is used in urban areas. Environmental water aside, vast quantities of water for agriculture and urban use are transported from the northern part of the state towards the more arid south. The transport happens along the ‘The California State Water Project’ and the ‘Central Valley Project’, a network of canals, reservoirs, aqueducts, power plants and pumping plants. The network extends for more than 700 miles, nearly the whole length of California.

The problem is, most of the canal is uncovered and open to air. As a result evaporation contributes to a major loss of water along the system. In 2015, a research group at UC Davis studying a section of the canal found that if they extrapolated the volume of evaporation found in the section of study along the entire 700 miles of the State Water Project (SWP), the volumetric evaporative totals 9300 acre-feet per day.(1) That amounts to 3 billion gallons lost per day, which is a little more than the a daily water usage of 31 million Californians, or 80% of the state’s population. That is a massive amount of water and it's important to think of ways to save it. Turning the power of the internet of things on this issue has positive environmental and economic benefits.

Since much of the SWP is made up of open aqueducts, it would seem that covering the whole canal could solve the problem of evaporation. Further covering the canal with solar panels bridges could render the project cost-effective. In fact, researchers hold that “… it is economically favorable to implement solar panels over the canals to prevent losses and produce power.”. (2) Although, this seems like the perfect solution in theory, it holds three crucial flaws. First, the aqueduct is essentially a man-made river that connects to natural rivers and deltas. As a result, it boasts its own ecosystem with a flourishing number of fish and other aquatic species that require oxygenation and sunlight. Covering all of the canal would have negative effects on the environment the species depend on. Second, in some areas along the river, tree coverage is thick enough to act as a natural wind barrier and shade protection. Building supportive structures for solar panels would require uprooting these trees, which would accelerate erosion. Third, the economic cost of such an extensive project is high, and effectively balancing the yield to cost would include many efficiency factors - such as solar panel positioning and orientation - that may not be ideal along every stretch of aqueduct. There is a clearly demonstrable need to address these flaws, and find a way to efficiently, cost effectively reduce evaporation along The California State Water Project and the Central Valley Project.

Our solution aims to identify the stretches along the entire system that are the most vulnerable to evaporation and, simultaneously, to indicate the areas that are most favorable for the implementation of solar panels. We will measure real-time data of the various parameters that cause evaporation using a fleet of small devices floating on the canal to collect precise, localized data. After collecting and mapping this information, to create a model, we will be able to pinpoint the areas along the canal that are most vulnerable to evaporation. We can then strategically “bandage” those areas with solar panel bridges or wind barriers, as appropriate. To do this, we use Eva.

In essence, Eva is a small solar-powered floating hydrology and meteorology lab. She is equipped to measure water temperature, dry bulb and wet bulb air temperature, pressure, relative humidity, irradiance, wind speed, wind direction and the certain chemical attributes of the water. These factors are used to calculate precise, instantaneous and localized values of evaporation. Eva also measures other environmental information - such as rainfall - to feed into the grid. She is talkative and uses a combination of Artik’s communication protocols to stay in touch with the rest of her fleet as well as with the internet data base, sharing and analyzing data. Artik is compatible with many IoT data hosting websites, for our purpose we use Temboo as a base to upload data and share our statistical analysis. Eva’s code is written in C++ and uses many of the sensors' specialized libraries. In our code, we implemented a slight variation of the Penman equation to translate the continual hydrometeorological data into values to describe evaporation rates at any given point. Our preliminary tests indicate that different stretches of a given canal are more susceptible to evaporation than others. Furthermore, bridging these specific areas with solar panel bridges would reduce evaporation and be economically viable.

The economic and environmental benefits of bridging canals with solar panels have already been seen in other parts of the world. In India a 1MW pilot project started in 2012 over a section of the Narmada canal in Gujarat generates 1.6 million kWh annually, and saves 2.4 million gallons of water per year. Though the cost of installation was higher than that of a traditional land installation, building costs were recovered because the space over the canal was free - there was no need for land acquisition. Research on The California State Water Project and the Central Valley Project has indicated that something similar to the Narmada project would work well in California. Adding together the cost of energy that could be produced by solar panels and the cost of water saved from evaporation, researchers found that the benefits considerably outweighed the costs.

It is clear that finding a way to prevent evaporation through the strategic use of solar panels is a workable and effective means to fight and resolve California's drought. However to do so efficiently localized data is of paramount importance because it gives us the resources to build an extremely accurate model of the evaporation dynamics of the system. We believe that once precise data is collected and the models are made, there can be a smarter distribution of resources to create change, and spur incentives and initiatives to make change.

Though Eva’s conception was inspired by the drought in California, her applications are global. Every passing day, water becomes a more precious and scarce resource to the whole of the global community. Eva’s fleet can be deployed in water systems all around the world - either for scientific research, project planning, or to simply add data to the IoT resource - providing solutions and contributing to the future of a smarter planet.

(1),(2) Evaporation, An analysis of the California State Water Project’s efficiency, Kory Burt, Erin Good, Micah Shachar, Justin Pascual, 2015