Aspects of Integrated Water Resources Management in River
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DIE ERDE 142 2011 (1-2) Global Change: pp. 163-186 Challenges for Regional Water Resources • Water yield – Global change – Mining activities – Water transfer Dagmar Schoenheinz, Uwe Grünewald and Hagen Koch Aspects of Integrated Water Resources Management in River Basins Influenced by Mining Activities in Lower Lusatia Aspekte eines Integrierten Wasserressourcenmanagements in vom Bergbau beeinflussten Einzugsgebieten der Niederlausitz With 11 Figures and 3 Tables In Lower Lusatia, eastern Germany, the changing impacts of lignite coal mining and potential climate change have put the naturally low water yield conditions under pressure. Water resources balances describe the hydrological situation in the region and the need for action due to changing boundary conditions. Extended transfer of flood water from neighbouring catchments is considered inevitable for sustainable regional development and the establishment of a quantitatively and qualitatively self- regulated water system. Using the river basin management system WBalMo®, potential water transfer scenarios to compensate for water deficits resulting from regional and global change are analysed. 1. Water Resources Management and are benefits that come from nature and are free Water Resources Balances of costs, including self-purification, biological yield, ecological potential, energy potential, 1.1 Issues of Water Resources Management transportation and flood control potential (Grünewald 2003). However, global and region- Water is a renewable natural resource. Surface and al examples demonstrate that overexploitation of subsurface waters form the water resources of a these potentials causes negative development such landscape, characterised by spatially and as non-sustainable groundwater depletion, the de- temporally changing water yields and by various gradation of rivers to waste water streams and the water-related nature potentials. Nature potentials destruction of landscapes by urban settlements. 164 Dagmar Schoenheinz, Uwe Grünewald and Hagen Koch DIE ERDE The aim of water resources management is to pro- operators must perform yield-oriented operations vide water in a sufficient quantity and quality for OP (Y) or demand-oriented operations OP-1 (D) its several uses and to keep its nature potentials. to minimise costs and maximise sustainability. Furthermore, water resources management in- The continuous changes of natural and socio- volves the effective utilisation and protection of economic boundary conditions additionally water bodies and aims to maintain or re-establish complicate finding the optimum between water a good physical, chemical and biological condition yield and water demand matrices. Because the of water bodies even while the intensity of eco- boundary conditions are randomly distributed system use increases (WFD 2000). and the users have different priorities, an exact mathematic solution does not exist. This com- To meet these aims, water yield and water de- plex task cannot be optimised directly but re- mand must be determined and compared which quires modern techniques of water resources is most practicable by the formulation of both management based on iterative approaches using the state matrix Y of water yield and the state scenario analyses and variant calculations. matrix D of water demand (Fig. 1). Water resources balances are an important tool Both matrices require harmonisation among the to approximate the hydrological situation of a characteristics of water quantity and quality in catchment or region. However, complex bound- space and time with a certain probability. There- ary conditions on the catchment scale change fore, suitable methods, procedures, tools and scenarios, as described in Figure 1, and the sto- Fig. 1 Central issues of water resources management in a catchment under changing framework and boundary conditions (Grünewald 2001a, modified) / Hauptprobleme integrierter Wasserbewirtschaftung im Einzugsgebiet unter sich verändernden Rahmen- und Randbedingungen (nach Grünewald 2001a) 2011/1-2 Integrated Water Ressources Management in Lower Lusatia 165 40 War World II Oil Crisis German Reunification 35 30 /s] 3 25 20 into river Spree 15 Discharge [m 10 5 into river Schwarze Elster 0 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 Year Fig. 2 Groundwater discharge into the Spree and Schwarze Elster rivers (Grünewald 2008, complemented) Grundwassereinleitung in die Spree und die Schwarze Elster (nach Grünewald 2008, ergänzt) chastic character of the input data to hydrolog- the region’s water resources. The analysis of ical systems cannot be incorporated by such bal- groundwater quantities withdrawn and discharged ances. Authorities and decision makers require into surface waters to maintain dry working lev- complex planning systems as support tools, ne- els within the lignite mining pits indicates these cessitating the continuous development of those effects (Fig. 2). Because the ratio between ex- instruments on national and international scales tracted lignite coal and the required groundwater (Loucks and van Beek 2005). pumping is approximately 1 to 7, the temporal be- haviour of groundwater discharge quantities into Global change, the sum of natural (climate, biodi- the adjacent Spree and Schwarze Elster rivers re- versity) and societal (technological, economic, presents the extracted lignite coal quantities. demographic, land use) changes, is the transforma- tion and modification of physical and biological The continuous increase in lignite mining produc- components of the earth system over time. It in- tion and consequently groundwater pumping was volves those changes in nature and society that in- interrupted the first time during World War II. At fluence the livelihood of humans irreversibly and the end of the 1950s, the lignite production of distinctively on a global scale (BMU 2009). the German Democratic Republic (GDR) in- creased immensely. Prior to the oil crisis in In Lower Lusatia, global change has repeatedly 1973, the GDR reduced the lignite production affected the lignite mining industry and thereby due to the low cost of oil imports. With increas- 166 Dagmar Schoenheinz, Uwe Grünewald and Hagen Koch DIE ERDE ing oil prices and other political constraints, the ers under the conditions of naturally low water GDR aimed to implement an energy autarchy, yield. The river basins relevant for management resulting again in increased lignite production measures in Lower Lusatia are those of the Spree and groundwater pumping rates. The most dras- and Schwarze Elster rivers. Because the catchments tic effects on lignite mining were the political do not correspond with federal state boundaries, and economic changes in Europe and particularly negotiations and agreements on management in Germany in 1989. Lignite exploitation in the measures across political boundaries are essential. mining districts of the former GDR dramatical- ly declined, and the sudden cessation of many large open cast mines after 1990 resulted in a 1.2 Water resources balances massive decrease of pumped mining water. 1.2.1 Summary balances Currently, technological change and climate change appear to be the most relevant issues for Water resources balances are the basis for the water resources management in Lower Lusatia planning of water resources management. Such (Koch et al. 2005). balances include the effect of natural and societal conditions and the consequences for wa- Water resources management for Lower Lusatia ter resources. The main principle is the compar- must compensate for the effects of decreasing min- ison of the natural water yield and the realised ing water discharge, potential climate change and and planned immediate or long-term water uses. differing priorities for water demand by various us- From that comparison, the availability of surface Fig. 3 Water resources balance components of a catchment (continuous line) and between two balance sections with sub-catchments (dotted lines), a simplified scheme / Wasserbilanzkomponenten eines Einzugs- gebiets (kontinuierliche Linie) und zwischen zwei Bilanzprofilen mit Teileinzugsgebieten (gestrichelte Linien), Prinzipskizze 2011/1-2 Integrated Water Ressources Management in Lower Lusatia 167 Calculation 1: a) + Natural potential water yield (area A times runoff R) (m³/Δt) – Sum of balance losses (abstraction QA minus return flow QR)(m³/Δt) ____________________________________________________________________________________________________________________________________________________________ = Balance discharge, QB (m³/Δt) b) + Natural potential water yield, A R (m³/Δt) – Sum of water abstraction, QA (m³/Δt) + Sum of return flow, QR (m³/Δt) ± Sum of storage inflow/outflow, QS (m³/Δt) ± Water transfer, QT (m³/Δt) _____________________________________________________________________________________________________________________________________________________________ = Balance discharge, QB (m³/Δt) – Ecologically required minimum discharge (m³/Δt) ____________________________________________________________________________________________________________________________________________________________ = Available water yield (m³/Δt) c) + Natural potential water yield between the balance profiles I and II, . reduced by the catchment of tributaries, (A – AU –AT) R(m³/Δt) ± Balance discharge of the upstream profile II, QIN,U (m³/Δt) ± Balance discharge of tributaries, QIN,T (m³/Δt) – Sum of water abstraction, QA (m³/Δt) + Sum of return flow, QR (m³/Δt) ± Sum of storage inflow/outflow,