Estimated truths: water, science, and the politics of approximation.

This article introduces the special issue on 'Estimated Truths' which investigates the role of estimation in knowledge-making about water and, through it, contributes to thinking place as environment in the historical geography and history of knowledge. It argues that while historical geographers and historians of science have paid much attention to precision and quantification, approximation and estimation have also played an important role in knowledge-making and deserve more attention. It discusses the roles played by uncertainty and estimation in the water sciences and makes the case for more sustained engagement with the influence of the environment – understood as a dynamic set of human and non-human actors and forces – on knowledge-making. Finally, the article presents the five papers and discusses their individual and collective contributions to the themes of the special issue and to further investigation into the making and operation of estimated truths. • Introduces the five articles of the 'Estimated Truths' special issue. • Highlights the role of approximation and estimation in knowledge-making. • Emphasizes the persistence of uncertainty and estimation in the water sciences. • Shows the value of taking into account the role of place as environment in shaping science. [ABSTRACT FROM AUTHOR]