Using Lake Observations from Citizen Scientists and Satellites to Understand Regional Variations in Lake Water Storage

Abstract:

Worldwide, there are millions of small lakes that remain entirely unmonitored. Most of the world’s limited lake monitoring capacity is focused on large lakes, along with a few smaller lakes located largely in economically developed countries. This data deficiency means that we have a limited understanding of the processes controlling these lakes at local and regional scales. On the one hand, the characteristics of individual lakes, including their underlying geology and (dis)connectivity with stream networks, may lead to lake-to-lake differences in water storage variation. On the other hand, regional climate patterns may lead to similar variations among nearby lakes. To assess the relative importance of local and regional factors, we have worked with citizen scientists to collect lake level data in more than seventy lakes across four countries (Bangladesh, India, France, and the United States) as part of the Lake Observations from Citizen Scientists and Satellites (LOCSS) project (http://locss.org). We pair these lake levels with lake areas measured using satellite data to assess changes in water storage over time. In this presentation, we discuss the development of the LOCSS project, which has engaged more than 1400 citizen scientists and collected more than 6200 water level measurements since 2017. We also use LOCSS data from the United States to test the level of correlation between paired lake storage time series in regional clusters. We find that lakes that are closer together are, on average, more hydrologically coherent than lakes that are far apart, but there remain many pairs of lakes that are close together and have very different hydrographs. We conclude that both local and regional factors are important in driving variations in lake water storage. This result suggests that it is not sufficient to monitor only one or a few lakes in a region in order to understand all such lakes, at least without carefully selecting a representative regional sample.