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Integrated water resources management in the Orange-Senqu-Fish Catchment

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Abstract
Social, economic and environmental issues which influence the water resources management in the Orange-Senqu-Fish catchment, one of the largest rivers in South-Africa, have been researched. The historical flow regime of the Orange River, with a length of 2200 km the longest river of South-Africa, is characterised by strong variability, with very low discharges during the dry local winter and high discharges combined with flood events during the wet summer months. River flow control for water supply to industry and population as well as for agricultural and hydropower demands resulted in an artificial hydrological regime characterised by a lack of flow variability and decreased total volumes. The present gentle flow regime harms many forms of life which have evolved to cope with severe hydrological conditions. As a result, the ecosystem quality of the Orange River Mouth has severely degraded. There is a threat on the number and diversity of birds, while stagnate water results in ideal conditions for black flies to reach pest densities. The numerical model STRIVE (STReam RIVer Ecosystem) is used to model discharges and water levels of the Orange River which can contribute to a sound water resources management. A river reach of 1110 km is subdivided into 7 sections. The total difference in altitude is 943 m. Recorded discharges are used as an upstream boundary condition and a weir rating curve determines the downstream boundary condition of each reach. Lateral inflow and outflow of water depends on rainfall events, flood events (resulting in floodplain and groundwater interaction) and water abstractions, evaporation and evapotranspiration. A mathematical function defining the relation between flood events, rainfall and the resulting lateral flow was developed. The hydraulic model is calibrated by adjusting Manning’s coefficient for each reach. The hydraulic model serves as a useful tool for planning water releases in order to meet urban, industrial, agricultural and environmental water demands along the river. It will help to determine possible scenarios for sound water releases leading to upgrading the river environment.

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Chicago
Putteman, Jan, Kerst Buis, Liesbet De Doncker, Renaat De Sutter, Dieter Meire, Bert Schepens, Peter Troch, and Ronny Verhoeven. 2011. “Integrated Water Resources Management in the Orange-Senqu-Fish Catchment.” In World’s Large Rivers.
APA
Putteman, J., Buis, K., De Doncker, L., De Sutter, R., Meire, D., Schepens, B., Troch, P., et al. (2011). Integrated water resources management in the Orange-Senqu-Fish Catchment. World’s large rivers. Presented at the International conference on the Status and Future of the World’s Large Rivers.
Vancouver
1.
Putteman J, Buis K, De Doncker L, De Sutter R, Meire D, Schepens B, et al. Integrated water resources management in the Orange-Senqu-Fish Catchment. World’s large rivers. 2011.
MLA
Putteman, Jan, Kerst Buis, Liesbet De Doncker, et al. “Integrated Water Resources Management in the Orange-Senqu-Fish Catchment.” World’s Large Rivers. 2011. Print.
@inproceedings{1897956,
  abstract     = {Social, economic and environmental issues which influence the water resources management in the Orange-Senqu-Fish catchment, one of the largest rivers in South-Africa, have been researched. The historical flow regime of the Orange River, with a length of 2200 km the longest river of South-Africa, is characterised by strong variability, with very low discharges during the dry local winter and high discharges combined with flood events during the wet summer months. River flow control for water supply to industry and population as well as for agricultural and hydropower demands resulted in an artificial hydrological regime characterised by a lack of flow variability and decreased total volumes. The present gentle flow regime harms many forms of life which have evolved to cope with severe hydrological conditions. As a result, the ecosystem quality of the Orange River Mouth has severely degraded. There is a threat on the number and diversity of birds, while stagnate water results in ideal conditions for black flies to reach pest densities.
The numerical model STRIVE (STReam RIVer Ecosystem) is used to model discharges and water levels of the Orange River which can contribute to a sound water resources management. A river reach of 1110 km is subdivided into 7 sections. The total difference in altitude is 943 m. Recorded discharges are used as an upstream boundary condition and a weir rating curve determines the downstream boundary condition of each reach. Lateral inflow and outflow of water depends on rainfall events, flood events (resulting in floodplain and groundwater interaction) and water abstractions, evaporation and evapotranspiration. A mathematical function defining the relation between flood events, rainfall and the resulting lateral flow was developed. The hydraulic model is calibrated by adjusting Manning{\textquoteright}s coefficient for each reach.
The hydraulic model serves as a useful tool for planning water releases in order to meet urban, industrial, agricultural and environmental water demands along the river. It will help to determine possible scenarios for sound water releases leading to upgrading the river environment.},
  author       = {Putteman, Jan and Buis, Kerst  and De Doncker, Liesbet and De Sutter, Renaat and Meire, Dieter and Schepens, Bert and Troch, Peter and Verhoeven, Ronny},
  booktitle    = {World's large rivers},
  isbn         = {9788073995188},
  language     = {eng},
  location     = {Vienna, Austria},
  title        = {Integrated water resources management in the Orange-Senqu-Fish Catchment},
  year         = {2011},
}