The size-distributions of inland water bodies (WB) within different regions often poorly conform to geophysically based theoretical models (power-law: y 5 ax b ); however, the causes of these deviations remain unknown.Therefore, we compared WB abundance and size-distribution parameters (slope [b] and model fit [r 2 ]) in 164 regions in the United States with varying topography, climate, and agricultural intensity. We found all three factors influenced WB size-distributions and their fit to expected models. WB size-distributions in steeper terrain had more small WB and better fit power-law models, while regions with flatter terrain and greater precipitation had poorer fits. Extensive agriculture increased the proportion of small WB, causing distributions in some regions to fall outside theoretically predicted limits (b CDF < 21). Regional variation of WB sizedistributions can help develop and test integrated theory that accounts for geophysical and anthropogenic drivers of WB sizes, which is essential for scaling biogeochemical processes in aquatic systems.The abundance, size, and character of naturally occurring and constructed water bodies (WB) influence ecological and biogeochemical characteristics of inland landscapes (e.g., Herbert et al. 2010;Aufdenkampe et al. 2011;Van Meter and Basu 2015;Holgerson and Raymond 2016). Because small WB are biogeochemically very active per unit area compared to large lakes (Stallard 1998;Dean and Gorham 1998;Bastviken et al. 2004;Harrison et al. 2008;Downing 2010;Goodman et al. 2011;Holgerson and Raymond 2016), the mis-estimation of water body size-distribution (WB SD ) can bias estimates of biogeochemical processes, such as carbon emission and sequestration (Hanson et al. 2007). Understanding the causes and consequences of variation in WB SD is thus central to our macroscale understanding of aquatic ecosystems and the landscapes in which they occur Soranno et al. 2014).Natural WB, including lakes, ponds, and wetlands, occur in diverse geologic settings resulting from different processes (e.g., tectonic, glacial scour, and fluvial) that create This is an open access article under the terms of the Creative Commons Attribution NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
Scientific Significance StatementThe areal extent and size-distribution of inland water bodies have profound effects on regional and global biogeochemistry. Theoretical models assuming fractal landscapes predict the distribution of inland water bodies as a power-law with specific ranges of slopes. Observed regional size-distributions often deviate from these predictions, but the reason is unknown. This study provides empirical evidence that climate, topography, and agricultural land cover alter the areal extent and sizedistributions of water bodies, such that the resulting hydroscapes no longer conform to theoretical predictions derived from simple landscape models.
70Limnolog...