Maps of inland waters in national atlases

Summary

This article outlines principles for designing and organizing inland-water maps in national atlases. Hydrographic-network maps should use the same scale as other physical-geography maps, because drainage patterns reveal key characteristics of relief, watersheds, and terrain dissection. Runoff and discharge maps should be coordinated closely with precipitation maps to support analysis of regional water balances. Seasonal runoff, for example, should be accompanied by corresponding seasonal precipitation data, with comparable indicators, representation methods, detail, and scale. Hydrological regionalization should be developed in conjunction with maps of climate, relief, soils, and vegetation, preferably at a somewhat smaller but readily comparable scale. Flood maps should also include information on causal factors such as ice conditions, snowmelt, precipitation, wind-driven surges, and earthquakes. Because economic activity substantially alters surface-water and groundwater regimes, hydrographic maps should depict reservoirs, canals, and related infrastructure, while the economic section should provide fuller coverage of water use. A map of integrated multipurpose water utilization is particularly valuable for arid regions and for linking the atlas’s physical and economic sections. The article concludes that inland-water maps should be arranged compactly on two or three atlas sheets and placed immediately after the climate-map section.