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  • 1
    Publication Date: 2015-08-12
    Description: This study investigates the effectiveness of a sensitivity-informed method for multi-objective operation of reservoir systems, which uses global sensitivity analysis as a screening tool to reduce computational demands. Sobol's method is used to screen insensitive decision variables and guide the formulation of the optimization problems with a significantly reduced number of decision variables. This sensitivity-informed method dramatically reduces the computational demands required for attaining high-quality approximations of optimal trade-off relationships between conflicting design objectives. The search results obtained from the reduced complexity multi-objective reservoir operation problems are then used to pre-condition the full search of the original optimization problem. In two case studies, the Dahuofang reservoir and the inter-basin multi-reservoir system in Liaoning province, China, sensitivity analysis results show that reservoir performance is strongly controlled by a small proportion of decision variables. Sensitivity-informed dimension reduction and pre-conditioning are evaluated in their ability to improve the efficiency and effectiveness of multi-objective evolutionary optimization. Overall, this study illustrates the efficiency and effectiveness of the sensitivity-informed method and the use of global sensitivity analysis to inform dimension reduction of optimization problems when solving complex multi-objective reservoir operation problems.
    Print ISSN: 1027-5606
    Electronic ISSN: 1607-7938
    Topics: Geography , Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 2
    Publication Date: 2012-11-06
    Description: Hydrological simulation in regions with a large number of water storages is difficult due to inaccurate water storage data. To address this issue, this paper presents an improved version of SWAT2005 (Soil and Water Assessment Tool, version 2005) using Landsat, a satellite-based dataset, an empirical storage classification method and some empirical relationships to estimate water storage and release from the various sizes of flow detention and regulation facilities. The SWAT2005 is enhanced by three features: (1) a realistic representation of the relationships between the surface area and volume of each type of water storages, ranging from small-sized flow detention ponds to medium- and large-sized reservoirs with the various flow regulation functions; (2) water balance and transport through a network combining both sequential and parallel streams and storage links; and (3) calibrations for both physical and human interference parameters. Through a real-world watershed case study, it is found that the improved SWAT2005 more accurately models small- and medium-sized storages than the original model in reproducing streamflows in the watershed. The improved SWAT2005 can be an effective tool to assess the impact of water storage on hydrologic processes, which has not been well addressed in the current modelling exercises.
    Print ISSN: 1027-5606
    Electronic ISSN: 1607-7938
    Topics: Geography , Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 3
    Publication Date: 2012-03-28
    Description: Hydrological simulation in regions with a large number of water storages is difficult due to the inaccurate water storage data, including both topologic parameters and operational rules. To address this issue, this paper presents an improved version of SWAT2005 (Soil and Water Assessment Tool, version 2005) using the satellite-based dataset Landsat, an empirical storage classification method, and some empirical relationships to estimate water storage and release from the various levels of flow regulation facilities. The improved SWAT2005 is characterised by three features: (1) a realistic representation of the relationships between the water surface area and volume of each type of water storage, ranging from small-sized ponds for water flow regulation to large-sized and medium-sized reservoirs for water supply and hydropower generation; (2) water balance and transport through a network combining both sequential and parallel streams and storage links; and (3) calibrations for the physical parameters and the human interference parameters. Both the original and improved SWAT2005 are applied to the upper Fengman Reservoir Basin, and the results of these applications are compared. The improved SWAT2005 accurately models small- and medium-sized storages, indicating a significantly improved performance from that of the original model in reproducing streamflows.
    Print ISSN: 1812-2108
    Electronic ISSN: 1812-2116
    Topics: Geography , Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 4
    Publication Date: 2015-04-08
    Description: This study investigates the effectiveness of a sensitivity-informed method for multi-objective operation of reservoir systems, which uses global sensitivity analysis as a screening tool to reduce the computational demands. Sobol's method is used to screen insensitive decision variables and guide the formulation of the optimization problems with a significantly reduced number of decision variables. This sensitivity-informed problem decomposition dramatically reduces the computational demands required for attaining high quality approximations of optimal tradeoff relationships between conflicting design objectives. The search results obtained from the reduced complexity multi-objective reservoir operation problems are then used to pre-condition the full search of the original optimization problem. In two case studies, the Dahuofang reservoir and the inter-basin multi-reservoir system in Liaoning province, China, sensitivity analysis results show that reservoir performance is strongly controlled by a small proportion of decision variables. Sensitivity-informed problem decomposition and pre-conditioning are evaluated in their ability to improve the efficiency and effectiveness of multi-objective evolutionary optimization. Overall, this study illustrates the efficiency and effectiveness of the sensitivity-informed method and the use of global sensitivity analysis to inform problem decomposition when solving the complex multi-objective reservoir operation problems.
    Print ISSN: 1812-2108
    Electronic ISSN: 1812-2116
    Topics: Geography , Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 5
    Publication Date: 2015-02-17
    Description: An in-house developed mobile and portable three-dimensional scanning lidar system is discussed in this work. The system uses a stimulated Raman-scattering technique for the continuous observation of atmospheric aerosols, clouds and trace gases. This system has a fast scanning technique with a high-speed data acquisition, and permits the real-time measurement of atmospheric pollutants with the temporal resolution of 1 min. This scanning lidar system provides typical horizontal coverage of about 8–10 km while scanning; however, in zenith mode, good quality backscattered signals can be from 20 km, depending upon the laser power and sky conditions. This versatile lidar system has also overcome the drawbacks which are popular in the traditional scanning lidar systems such as complicated operation, overlap height between laser beam and telescope field of view In this system, the optical damage is reduced by using an integral coaxial transmitter and receiver. Some of the initial results obtained from the scanning lidar system are also presented. This study shows that boundary-layer structure and land–sea breeze circulation can be resolved from the developed scanning lidar system. The application of this lidar system to measure the pollutants over an industrial area is also discussed.
    Print ISSN: 2193-0856
    Electronic ISSN: 2193-0864
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 6
    Publication Date: 2014-04-09
    Description: We present and discuss on an indigenously developed mobile and portable 3-D scanning lidar system. The system utilizes a stimulated Raman-scattering technique for the continuous observation of atmospheric aerosols, clouds and trace gases. The system provides fast scanning technique with a high speed data acquisition, which permits the real-time measurement of air pollutant mobility. The temporal resolution of data retrieval is every one min. The scanning lidar system provides typical horizontal coverage of about 8–10 km when scanning, while the vertical range can be up to 20 km depending upon the laser power and sky conditions. This versatile lidar system has also overcome the drawbacks which are popular in the other scanning lidar system such as complicated operation; overlapping height between laser beam and telescope field of view; and damage of optic detectors for long duration measurement by using an integral coaxial transmitter and receiver. Some of the initial results obtained from the scanning lidar system are also presented. We have shown that the developed 3-D scanning lidar system can resolve the boundary layer structure and land-sea breeze circulation. Discussion is also made on the application of scanning lidar system to measure pollutant over industrial areas.
    Electronic ISSN: 2193-0872
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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