World leaders and other decision makers who tackled issues related to water supply now could access a dataset of the water volume of their country's natural and artificial lakes. Researchers believe that the data they gathered could help the decision-makers understand the role of bodies of water in Earth system and weather forecasting.
First Global Lake Evaporation Volume Dataset Revealed
The Texas A&M researchers have announced the first global lake evaporation volume (GLEV) dataset that monitors evaporative water loss information of 1.42 million lakes around the world every month. The dataset covers information from 1985 to 2018. It measures the evaporation volume of natural and artificial lakes referred to as reservoirs.
In the past, the dataset presented by existing global studies focused only on evaporation rate changes. In addition, accurate data of open water area and evaporation rate were not possible because of several challenges such as lake ice duration modeling, lake heat storage quantification, and cloud contamination of satellite images.
The new dataset has solved the problems and provided and improved an accurate evaporation rate estimation. For example, the heat storage changes for lakes per quantified now improve the evaporation rate estimation accuracy. Delete open water areas were calculated now as the product of lake surface and the fraction of open water duration. In the new dataset, we construct the monthly lake surface areas using a Landsat-based global surface water dataset. It also used air temperatures and 3/4 leg information in modeling the monthly fractions of duration.
The monthly results from the data were aggregated on an annual basis to help in the assessment of the long-term trend of each variable.
Lake Evaporation Volume Dataset Results
Using GLEV as a point of reference, it showed that the annual volume of evaporation of global lakes hit 1,500 plus or minus 150 cubic kilometers per year. Compared to the previous estimates, it is 15.14 % larger.
Gang Zhao, a postdoctoral fellow in the Department of Global Ecology at the Carnegie Institute for Science, said that lake evaporation plays a larger role in the hydrological cycle than previously thought.
GLEV estimates that 6,715 reservoirs only make up 5% of the total water storage capacity and 10% of the surface area of all lakes. However, 16% of the evaporation volume comes from reservoirs. The amount of evaporative reservoir loss is equal to 20% of the global annual water usage. Evaporative water loss from reservoirs has risen by 5.4% annually over the past 33 years, surpassing the global trend of 2.1% for all lakes.
In the U.S., it was reported that the country's largest reservoir in Lake Mead is draining rapidly because of the above-normal temperature and below-average rainfall that the country experiences.
"With regard to evaporation loss, this study will be an invaluable venue to serve water resources researchers and decision-makers. Our findings have significant environmental, societal, and economic implications as the global evaporative loss will be accelerated and further exacerbated in the future under global warming," said Huilin Gao, associate professor in the Zachry Department of Civil and Environmental Engineering at Texas A&M University.
He added that the results help the science community to better understand the role of the bodies of water in the Earth's system, including flood and drought modeling, Earth system modeling, and global weather forecasting.
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Future Project Related to Evaporation Volume Monitoring
Recently, researchers from Texas A&M University, the Desert Research Institute, and the U.S. Bureau of Reclamation collaborated to develop daily reservoir evaporation monitoring, which is satellite assisted. It is a nearly $1 million NASA Applied Science project.
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