Die Karte „Hydrographische Übersicht“ 1:750 000 im „Atlas DDR“

Summary

This article provides a detailed account of the conception, content, and hydrographic insights of map sheet 10, "Hydrographische Übersicht" (Hydrographic Overview), at a scale of 1:750,000, part of the "Atlas DDR". The map, created under the specialist editorship of L. Bauer, was designed to be consistent with sheet 11, "Hydrologische Übersicht" (Hydrological Overview). The paper first explains the map's key elements: watersheds and catchment areas are shown down to the IVth order, with thresholds for area (>500 km²), mean discharge (>2 m³/s), and flood discharge (>50 m³/s). The river network, derived from the 1:200,000 overview map, includes all perennial watercourses longer than 2 km, supplemented by smaller ones selectively, and is accompanied by 1:250,000 insets illustrating characteristic drainage patterns. Standing waters are represented if larger than 100 hectares, with reservoirs (capacity >1 hm³) distinctly marked. As an innovative feature, the map presents drainage density using area colors and a seven-class geometric scale (thresholds from 0.05 to 3.80 km/km²), with class boundaries adjusted to natural features. The article then offers an overview of the GDR's hydrography, emphasizing that network form and density correlate more strongly with paleogeographic conditions than with runoff levels. It details the evolution of the drainage system from the Late Tertiary, influenced by tectonics, salt dissolution, and multiple glacial stages. The hydrography of major natural regions, from the Baltic coast to the central uplands, is systematically described. A significant portion is dedicated to anthropogenic changes, tracing the impact of historical water management, modern river engineering, and drainage projects, which have fundamentally altered many river systems. The article concludes that contemporary lowland management must balance rapid spring drainage with irrigation needs during the growing season.