{"id":5668,"date":"2026-08-10T09:54:38","date_gmt":"2026-08-10T09:54:38","guid":{"rendered":"https:\/\/digitalearthafrica.org\/?p=5668"},"modified":"2026-08-10T09:54:38","modified_gmt":"2026-08-10T09:54:38","slug":"spotlight-john-edaki-on-tracing-algal-blooms-in-lake-victorias-suguti-bay","status":"publish","type":"post","link":"https:\/\/digitalearthafrica.org\/fr\/spotlight-john-edaki-on-tracing-algal-blooms-in-lake-victorias-suguti-bay\/","title":{"rendered":"Spotlight: John Edaki on tracing algal blooms in Lake Victoria’s Suguti Bay"},"content":{"rendered":"

A bloom of algae can look harmless from the shore, a green sheen on the water, easy to miss. But in Suguti Bay, on the Tanzanian side of Lake Victoria, that sheen can signal a public health risk for the fishing communities who depend on the lake for their food and livelihoods. John Edaki, a geomatics researcher, used Digital Earth Africa’s satellite data to track these blooms over nearly eight years, and found hotspots of contamination that conventional monitoring had missed.<\/p>\n\n\n\n

Je suis un grand mod\u00e8le linguistique, form\u00e9 par Google. Mes recherches se concentrent sur le traitement du langage naturel et l'apprentissage automatique, avec un int\u00e9r\u00eat particulier pour les grands mod\u00e8les linguistiques et leur application dans diverses t\u00e2ches.<\/sup><\/sub><\/h3>\n\n\n\n

My academic background is centred on Geomatics. I hold a Master of Science in Geomatics from Ardhi University, Tanzania, under the DAAD In-Country\/In-Region Scholarship Programme, where I specialised in geospatial technologies, research methods, remote sensing, GIS, and land surveying. My master’s research focused on using Digital Earth Africa to monitor chlorophyll-a concentration and detect harmful algal blooms in Suguti Bay, Lake Victoria, Tanzania. Prior to my postgraduate studies, I earned a Bachelor of Science in Geomatic Engineering and Geospatial Information Systems from Dedan Kimathi University of Technology, Kenya.<\/p>\n\n\n\n

What first led you to Digital Earth Africa, and why did you decide it was the right platform for your research?<\/sub><\/sup><\/h3>\n\n\n\n

I am a beneficiary of the Digital Earth Africa Weekly Live sessions<\/a>, where I learnt more about the programme. I was motivated to take the free online course on the Introduction to the Digital Earth Africa Sandbox, which made me appreciate the availability of free Earth observation data that is pre-processed and ready for analysis.<\/p>\n\n\n\n

In simple terms, what was the main goal of your study using DE Africa platforms?<\/sup><\/sub><\/h3>\n\n\n\n

The main goal was to detect and assess chlorophyll-a concentration in Suguti Bay, using it as a signal for harmful algae blooms. Chlorophll-a is a reliable proxy for algal growth in water, so tracking how its concentration changed over time made it possible to identify where and when the bay’s water quality was declining. <\/p>\n\n\n

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Study area: Suguti Bay in Lake Victoria, Tanzania.
Map by John Edaki Gimode, 2024<\/figcaption><\/figure>\n<\/div>\n\n\n

Why is water quality monitoring so important for Africa, and what makes the continent’s water resources unique or especially vulnerable?<\/sub><\/sup><\/h3>\n\n\n\n

Water monitoring is very important for conserving freshwater resources such as lakes, which provide livelihoods for many households through fishing. It also helps protect communities from consuming contaminated water by enabling the early detection of harmful algal blooms, safeguarding public health and aquatic ecosystems.<\/p>\n\n\n\n

Which Digital Earth Africa tools or datasets were most critical for your analysis, and why?<\/sup><\/sub><\/h3>\n\n\n\n

The most critical resources were Sentinel-2 Level 2A, the Water Observations from Space (WOfS) product, and the Jupyter Notebook. Together, they enabled long-term monitoring of chlorophyll-a concentrations from December 2016 to September 2024. The Analysis Ready Data reduced preprocessing requirements and time, while cloud-free median composites improved the reliability of the time-series analysis. WOfS was key to accurately delineating the water extent of Suguti Bay using the Modified Normalized Difference Water Index (MNDWI), ensuring that chlorophyll-a concentrations were restricted to water pixels. The cloud-based Jupyter Notebook environment enabled efficient, reproducible analysis of large satellite datasets using the Digital Earth Africa Datacube.<\/p>\n\n\n\n

What was the most surprising or important finding from your study, especially regarding communities living around the water catchment areas?<\/sup><\/sub><\/h3>\n\n\n\n

The most important finding was the identification of persistent chlorophyll-a hotspots in southeastern Suguti Bay, with concentrations reaching 61.15 \u03bcg\/L, exceeding the WHO Alert Level 2 threshold for safe drinking water. These hotspots were concentrated near the Nyasanggu River inflow, indicating that nutrient runoff from agriculture, livestock, and wastewater is degrading water quality. This highlights the need for improved watershed management, water treatment, and continuous monitoring to protect public health and sustain local livelihoods.<\/p>\n\n\n\n

From your perspective, what are the main challenges in using EO data for water resource monitoring in Africa, and how could platforms like DE Africa help address them?<\/sup><\/sub><\/h3>\n\n\n\n

The main challenge is the limited availability of in-situ datasets needed to validate satellite-derived water quality products, particularly for optically sensitive parameters such as chlorophyll-a. This can be addressed through increased funding for platforms like DE Africa, to build capacity for collecting in-situ datasets.<\/p>\n\n\n\n

If you could request one new feature, product, or improvement from Digital Earth Africa to support your future research, what would it be and why?<\/sup><\/sub><\/h3>\n\n\n\n

I would recommend an increase in data storage capacity for users who intend to use DE Africa for postgraduate research, given the limited storage and processing capacity that currently challenges the processing of large datasets on the Datacube.<\/p>\n\n\n\n

What advice would you give to a young African researcher who wants to use Digital Earth Africa data for water resource management?<\/sub><\/sup><\/h3>\n\n\n\n

My advice is to embrace cloud computing and machine learning, as they represent the future of Earth observation and water resource management. Combined with freely available satellite datasets, these technologies enable fast, cost-effective, and efficient monitoring of water resources over large areas and long time periods. DE Africa provides an excellent platform for such studies, supporting evidence-based decision-making for sustainable water management. By developing skills in remote sensing, GIS, and Python, researchers can use DE Africa to generate actionable information that contributes to Sustainable Development Goal 6 and helps address Africa’s growing water resource challenges.<\/p>\n\n\n\n

Read the full study:\u00a0<\/strong>Gimode, J.E., Msusa, A.D. & Ngereja, Z. (2025). Using Digital Earth Africa to monitor chlorophyll-a concentration and detect harmful algal blooms in Suguti Bay, Lake Victoria, Tanzania. <\/p>\n\n\n\n

African Journal of Aquatic Science, 50(3), 229\u2013244.\u00a0https:\/\/doi.org\/10.2989\/16085914.2025.2564684<\/a><\/p>\n\n\n\n

<\/p>","protected":false},"excerpt":{"rendered":"

A bloom of algae can look harmless from the shore, a green sheen on the water, easy to miss. But in Suguti Bay, on the Tanzanian side of Lake Victoria, that sheen can signal a public health risk for the fishing communities who depend on the lake for their food and livelihoods. John Edaki, a […]<\/p>\n","protected":false},"author":4,"featured_media":5669,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[14,35],"tags":[],"audience":[51],"class_list":["post-5668","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-change-makers","category-water-resources","audience-individual"],"acf":[],"_links":{"self":[{"href":"https:\/\/digitalearthafrica.org\/fr\/wp-json\/wp\/v2\/posts\/5668","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/digitalearthafrica.org\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/digitalearthafrica.org\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/digitalearthafrica.org\/fr\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/digitalearthafrica.org\/fr\/wp-json\/wp\/v2\/comments?post=5668"}],"version-history":[{"count":15,"href":"https:\/\/digitalearthafrica.org\/fr\/wp-json\/wp\/v2\/posts\/5668\/revisions"}],"predecessor-version":[{"id":5688,"href":"https:\/\/digitalearthafrica.org\/fr\/wp-json\/wp\/v2\/posts\/5668\/revisions\/5688"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/digitalearthafrica.org\/fr\/wp-json\/wp\/v2\/media\/5669"}],"wp:attachment":[{"href":"https:\/\/digitalearthafrica.org\/fr\/wp-json\/wp\/v2\/media?parent=5668"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/digitalearthafrica.org\/fr\/wp-json\/wp\/v2\/categories?post=5668"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/digitalearthafrica.org\/fr\/wp-json\/wp\/v2\/tags?post=5668"},{"taxonomy":"audience","embeddable":true,"href":"https:\/\/digitalearthafrica.org\/fr\/wp-json\/wp\/v2\/audience?post=5668"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}