The water footprint related to reservoir operation on a global scale

Knook, L. (2016) The water footprint related to reservoir operation on a global scale.

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Abstract:Reservoirs are used to generate electricity, supply water to irrigation, drinking water companies and the industry, to manage the water level in rivers to prevent flooding, to recreate and to catch fish. The water stored in reservoirs will be partly lost due to evaporation and this means that products and services produced by reservoirs have a water footprint. The objective of this study is to determine the water footprint related to the production of goods and services produced by man-made reservoirs. Based on the WRD and the GRanD reservoir databases, a reservoir database is created with 2235 reservoirs. This corresponds to 3,8% of the reservoirs and 30,1 % of the total reservoir volume in the ICOLD database. The economic value of reservoirs is determined by multiplying the annual average production per purpose with the economic value per unit of production. No production data was available for the purpose residential and industrial water supply and therefore this was estimated based on the reservoir volume. The evaporation was determined on a daily basis using 4 different methods: Jensen and Haise, Hamon, Penman and a method provided by Kohli and Frenken. With the first 3 methods, the evaporation was estimated based on climatological data provided by the ERA Interim database. Using the method of Kohli and Frenken, the evaporation is determined based on data from the FAO global evapotranspiration map and assuming that the crop coefficient for open water is 1. The evaporation volume is determined by taking the average of the 4 evaporation figures and multiply this, with the reservoir area and a factor to correct the reservoir area for the reservoir fullness. The total water footprint per reservoir is the sum of both the water footprint related to evaporation and the water footprint related to reservoir construction. The water footprint of reservoir construction was based on the water footprint of construction materials and the dam body volume of the dam. Allocation coefficients based on the economic value of the reservoirs are used to allocate the water footprint to each reservoir purpose. There can be concluded that all reservoir purposes treated in this study have a water footprint. The total annual water footprint from the reservoirs in this study is 1,04 x 1011 m3 and the total annual economic value of the reservoirs purposes in this study is $ 311 billion, in 2014 U.S. Dollars. The total annual water footprint related to reservoir construction is 3,96 x 107 m3. The global water footprint related to: hydropower generation by reservoirs is 7,18 x 1010 m3y-1, for irrigation water supply by reservoirs is 8,28 x 109 m3y-1, for flood prevention by reservoirs is 8,7 x 109 m3y-1, for open water recreation on reservoirs is 2,01 x 109 m3y-1, for residential and industrial water supply by reservoirs is 1,32 x 1010 m3y-1 and for commercial fishing on reservoirs is 2,08 x 108 m3y-1. Lake Nasser has the highest water footprint of all the individual reservoirs in this study. Brazil has the highest water footprint related to reservoir operation for the reservoirs in this study. The differences in water footprint can be partly explained by the location of the reservoir. Reservoirs located in equatorial and arid climates have, in general, a higher evaporation figure than reservoirs located in other climates. The largest part of annual water footprint related to reservoir operation, is located in river basins with a low water scarcity level and the main reservoir purpose in these reservoirs is hydropower generation. A smaller part, 44%, of the water footprint related to reservoir operation is located in river basins with 1 to 11 months of water scarcity and the importance of hydropower as reservoir purpose decreases as the number of months with moderate to severe water scarcity increases. Only 1% of the water footprint of the reservoirs in this study is located in river basins with 12 months moderate to severe water scarcity. For these reservoirs, residential and industrial water supply is the main purpose
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering and Management MSc (60026)
Link to this item:http://purl.utwente.nl/essays/71946
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