Land Use as a Predictor of Water Hyacinth (Eichhornia crassipes) Presence on the Entebbe Coast of Lake Victoria, Uganda

Class Year

2023

Document Type

Student Research Paper

Date of Creation

Fall 2021

Department 1

Center for Global Education

Department 2

Environmental Studies

Abstract

Lake Victoria is shared amongst Tanzania, Kenya, and Uganda and has tremendous ecological, economical, and cultural significance. Within the lake system, there are several problems, including the proliferation of an invasive weed, water hyacinth (Eichhornia crassipes). Therefore, this study aims to assess several factors that may correlate with water hyacinth proliferation. The specific objectives are (1) to identify possible correlations of water hyacinth density and land use around Entebbe, Uganda, and (2) to identify annual trends in water hyacinth coverage, to better inform policy and conservation efforts. Entebbe has a coastline of six land cover types: flooded vegetation, trees, grasses, shrub/scrub, crops, and built area. It was hypothesized that coastal areas adjacent to agriculture have a higher density of water hyacinth due to agricultural nutrient runoffs and flooded vegetation and built areas have higher abundances of water hyacinth due to a high amount of waste. The first specific objective employed a systematic sampling method, counting 41,615 water hyacinth around the coast of Entebbe, and was compared in QGIS with Sentinel-2 land use/land cover satellite imagery. The second specific objective employed remote sensing with a normalized difference vegetation index (NDVI). Twelve eMODIS satellite images were created on QGIS to map the percent coverage of water hyacinth in the Ugandan part of Lake Victoria. Flooded vegetation was found to have the highest density of water hyacinth, followed by crops, trees, built area, grass, and scrub/shrub. Additionally, 94% of water hyacinth was found on the left side of Entebbe. The most intense water hyacinth blooms occurred during June and July reaching 10.7% coverage, following the rainy season and maximum annual temperatures. The high densities within flooded vegetation and croplands are likely due to organic pollution runoffs. These results support previous research which found high temperatures and eutrophication to cause water hyacinth proliferation. This study theorizes that several unknown factors cause water hyacinth proliferation and thus controlsolely through mechanical, chemical, and biological means is treating a symptom, not the cause. Future research can explore this, adding to this study’s sample size, analyzing the different water dynamics for each land cover type, and further assessing the observation that water hyacinth presence may act as an indicator of organic pollution runoff.

Comments

Written for Tanzania: Wildlife Conservation and Political Ecology.

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