Fig. 6.

Additive model defining settlement volume by precipitation and river catchment size. (A) Bivariate histogram (Left) of the average size of a site with the given precipitation and river value [yellow indicates low values (“dry”), green high (“wet”), gray are not observed], and volume as a function of precipitation (Center) and as a function of surface water (Right) with the same colors as indicated in the bivariate histogram. (B) Average size of a site as estimated in the additive model (Left), precipitation term of the additive model (Center), and river size term (Right), correlating well with observations from above; both additive terms are nearly linear, gray areas indicate 90% intervals from cross-validation; dotted lines in the background correspond to the linear model terms reported in the text. (C) Estimated settlement potential using the model in B, with settlements exceeding the potential indicated by dots.