Lake Mcilwaine: The Eutrophication and Recovery of a Tropical African Man-Made Lake

ISBN-13: 9789400979857 / Angielski / Miękka / 2011 / 264 str.

J.A. Thornton

Opis

'And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters. ' Genesis 1:6 Lake McIlwaine is a man-made lake. It was formed in 1952 by the Hunyani poort Dam and is situated on the Hunyani River some 37 km southwest of Salisbury* in the Republic of Zimbabwe**. It is a lake of many aspects: being a popular recreational site, the City's primary water supply reservoir (and the fourth largest impoundment in Zimbabwe), a source of irrigation water to downstream farms, an important fishery, and, until the 1970s, the receptacle of Salisbury's sewage effluent. It is, in short, typical of so many 'urban' lakes in Africa and throughout the world. Lake McIlwaine is also unique, to my knowledge: being amongst the first of the major man-made lakes on the continent to suffer from what is known as cultural eutrophication, and the first to be r: ehabilitated to a mesotrophic state through a rational programme of lake management. This volume synthesizes this process of eutrophication and recovery in terms of the geology and geography (Chapter 2), physics (Chapter 3), chemistry (Chapter 4) and biology (Chapter 5) of the lake, and, whilst discussion of the trophic relationships between these components is beyond the scope of this monograph, discusses its utilisation, conservation and management (Chapter 6). * Subsequent to writing, the name of the Zimbabwean capital was changed to Harare on 18 April 1982. - Ed.

Spis treści

1. Introduction.- The creation of Lake McIlwaine: history and design.- 2. Geology and geography.- Land use survey of the Upper Hunyani catchment.- 3. Physics.- Physical limnology.- The hydrology of the Lake McIlwaine catchment.- 4. Chemistry.- Water chemistry and nutrient budgets.- The sediments.- Sediment chemistry.- Sediment transport.- The effects of urban run-off.- The aqueous phase: nutrients in run-off from small catchments.- The solid phase: a study of pollution benchmarks on a granitic terrain.- Insecticides in Lake McIlwaine, Zimbabwe.- 5. Biology.- An SEM study of bacteria and Zooplankton food sources in Lake McIlwaine.- Phytoplankton, primary production and nutrient limitation.- The algal community.- Primary production of Lake McIlwaine.- An examination of phytoplankton nutrient limitation in Lake McIlwaine and the Hunyani River system.- Zooplankton and secondary production.- Aquatic macrophytes and Eichhornia crassipes.- The benthic fauna of Lake McIlwaine.- The fish of Lake McIlwaine.- Avifauna of Lake McIlwaine.- 6. Utilisation, management and conservation.- Water pollution: perspectives and control.- Water supply and sewage treatment in relation to water quality in Lake McIlwaine.- Fisheries.- Recreation.- Research: perspectives.- 7. Bibliography.- Taxonomic index.- General index.