The global abundance and size distribution of lakes, ponds, and impoundments

TLDR

Fragmentary data have hindered the inclusion of lentic ecosystems in global environmental analyses. The study aims to generate updated global estimates of lakes, ponds, and impoundments. It employs high‑resolution spatial data and novel analytical methods to quantify surface‑water abundance. The analysis shows that natural lakes cover 4.2 million km²—twice the previously estimated area—primarily from millions of bodies smaller than 1 km², while impounded waters cover 0.26 million km² and low‑tech farm impoundments add ≳77,000 km², making ≈4.6 million km² (≈3 %) of continental land water‑covered and highlighting the need to include small water bodies in global studies.

Abstract

One of the major impediments to the integration of lentic ecosystems into global environmental analyses has been fragmentary data on the extent and size distribution of lakes, ponds, and impoundments. We use new data sources, enhanced spatial resolution, and new analytical approaches to provide new estimates of the global abundance of surface-water bodies. A global model based on the Pareto distribution shows that the global extent of natural lakes is twice as large as previously known (304 million lakes; 4.2 million km2 in area) and is dominated in area by millions of water bodies smaller than 1 km2. Similar analyses of impoundments based on inventories of large, engineered dams show that impounded waters cover approximately 0.26 million km2. However, construction of low-tech farm impoundments is estimated to be between 0.1% and 6% of farm area worldwide, dependent upon precipitation, and represents ≫77,000 km2 globally, at present. Overall, about 4.6 million km2 of the earth's continental "land" surface (≫3%) is covered by water. These analyses underscore the importance of explicitly considering lakes, ponds, and impoundments, especially small ones, in global analyses of rates and processes.