Monitoring Water Quality on Lake Victoria Using MODIS Imagery
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Date
2016
Journal Title
Journal ISSN
Volume Title
Publisher
Int. J. Technosci. Dev
Abstract
Lake Victoria is one of the key ecosystems in East Africa. With a size of 68,800 km2 , it is the largest lake in Africa. It supports the livelihoods of more than 20 million people directly and indirectly as a source of portable water and fish, for recreation, industrial use etc. This renders the monitoring of its water quality of paramount interest. Traditionally water quality testing is carried
out by in-situ measurements or taking of water samples for further testing in the laboratory. This approach has been seen to be costly, cumbersome, it is irregularly carried out and does not give a synoptic perspective of the water quality variation on Lake Victoria, especially given its size. This has motivated the need to explore the use of MODIS satellite imagery in monitoring water
quality on the lake. This paper explores the use of archived MODIS satellite imagery to study Lake Surface Temperature (LST) and Chlorophyl_a (Chl_a) variation from 2003 – 2010. The results show that from the time series dataset, in general the northern region of the lake exhibits annual seasonal LST variation which can be characterized as bimodal. These seasonal peaks
coincide with the occurrence of the region’s rain season, which information could potentially be useful in modeling experiments. The Ocean Color (OC v5) algorithm was used to extract Chl_a from the dataset. The daily Chl_a extracts were averaged over a year and mapped. These annual images were then reclassified according to Carlton’s Index for Chl_a. The results show that on
average, closer to the shores the lake is largely hypertrophic whereas the lake is largely eutrophic. The lake also exhibited traces of Mesotrophic behaviour in some of the years. This has potential implications about the identification of breeding/fishing zones. These results show that the use of satellite imagery in monitoring water quality, its challenges notwithstanding, can be
operationalized for the effective management of Lake Victoria.
Description
Keywords
Chlorophyll_a, Lake Surface Temperature, Lake Victoria, MODIS, Water quality
Citation
Anthony, G., Constance, B., & Angella, N. (2016). Monitoring water quality on Lake Victoria using MODIS imagery. Int. J. Technosci. Dev, 3(1).