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Sediment transport and water quality in Machovo Lake [Czech Republic]

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Dostal T., Krasa J., Vrana K., Dockal M., Koudelka P., David V., Vokurka A.
Annals of Warsaw University of Life Sciences - SGGW. Land Reclamation
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2010
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tom 42
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nr 1
139-148
Máchovo Lake is a historical reservoir founded by Czech King Charles IV. in 14th century. Located in northern part of central Bohemia it has been widely used for recreation purposes for many decades (or even centuries). Its catchments (ca 100 sq km) consist of intensively used agricultural land (ca 25% of area) and of large forested area under nature protection. Several other lakes (ponds) are chained on the two reservoir’s inlets. Irrespective of its great recreation potential Máchovo Lake is one of the Bohemian lakes known for its problems with eutrophication and water quality. The project was set up to point out sources of nutrients and to search for proper solutions. Sediment loads in every lake within the catchments were measured and sampled in order to quantify the nutrients and other pollution. Point and non point sources of phosphorus and other nutrients were searched. Sediment transport within catchments was modelled using WaTEM/SEDEM model. Interestingly, the water quality in the particular ponds varies signifi cantly even though each one of several hundred years old ponds is heavily silted. Soil erosion protection measures within catchments were proposed altogether with flood protection measures in the stream valleys and waste water treatment facilities in surrounding villages. Setting up water quality sampling devices in selected stream profi les was tested and designed. The continual proper management should lead to water quality improvement.
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Dominant discharge in the Indus river from downstream of the Kotri barrage dam

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Radecki-Pawlik A., Laszek W., Plesinski K., Khan Lashari B.
Acta Scientiarum Polonorum. Formatio Circumiectus
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2014
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tom 13
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nr 4
Hydraulic data of the Indus River, downstream of Kotri Barrage dam are analyzed. An attempt has been made to determine the dominant discharge, which is defined as that discharge which over a long time period transports the most sediments and could be used to predict the shape of river cross-section. For dominant discharge calculation Wolman and Miller’s approach has been applied. Since the transport of sediment concentration could be a more effective variable for forming the shape of the river cross-section, suspended sediment concentration has been introduced, because more than 85% of total load is in suspension. We show in the paper that water discharge Q = 1000 m³ · sˉ¹ of water is a frequent discharge and carries maximum sediment load. This discharge we call here the dominant discharge (Qdd) for the Kotri dam cross section.
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Ecohydrological status of Lake Tana – a shallow highland lake in the Blue Nile (Abbay) basin in Ethiopia: review

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Ligdi E. E., El Kahloun M., Meire P.
International Journal of Ecohydrology and Hydrobiology
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2010
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tom 10
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nr 2-4
This paper is based on a country report for Ethiopia prepared as a part of the ecohydrology component of IHP UNESCO’s FRIEND/Nile-phase II Project. It reviews past and current research in the Lake Tana sub-basin around the lake. The objective of the study was to determine the ecohydrological status of the Lake as a tool for integrated water resource management in improving the sustainability of the quantity and quality of freshwater resources in the Nile basin. The preliminary results show that reduced lake water level with its annual fluctuations and seasonal floods associated with high flows are becoming amplified and frequent, and the total average annual sediment load of the four major tributaries shows an increasing trend. Source pollution from urban waste and rural agriculture, and degradation of biota in the catchment are the two main environmental threats for the lake ecosystem. Knowledge gaps were identified and future research needs were recommended along with suggestion of some potential phytotechnologies to be applied in the study area.
4
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The changing sediment loads of the world’s rivers

80%
Walling D. E.
Annals of Warsaw University of Life Sciences - SGGW. Land Reclamation
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2008
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tom 39
This contribution reviews available evidence of recent changes in the sediment loads of the world’s rivers and identifi es the key drivers of such change. Land clearance, land use change and other facets of catchment disturbance, soil conservation and sediment control programmes and dam construction are shown to have resulted in signifi cant recent changes in the sediment loads of many world rivers. Some rivers have been characterized by signifi cant increases in sediment load, whereas others show signifi cant decreases. Interpretation of the resulting trends requires consideration of aggregation and storage and buffering effects within a river basin, such that the downstream response of a river may not clearly refl ect the changes occurring in the upstream basin and in the loads of tributary rivers.
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