Department of Water and Climate, Vrije Universiteit Brussel (VUB), 1050, Brussels, Belgium.
Water Security Research Group, Biodiversity and Natural Resources Program, International Institute for Applied Systems Analysis (IIASA), Schlossplatz 1, A-2361, Laxenburg, Austria.
Environ Monit Assess. 2024 Oct 25;196(11):1104. doi: 10.1007/s10661-024-13261-2.
Due to the continued increase in land use changes and changing climatic patterns in the Lake Victoria basin, understanding the impacts of these changes on the water quality of Lake Victoria is imperative for safeguarding the integrity of the freshwater ecosystem. Thus, we analyzed spatial and temporal patterns of land cover, precipitation, and water quality changes in the Lake Victoria basin between 2000 and 2022 using global satellite products. Focusing on chlorophyll-a (Chl-a) and turbidity (TUR) in Lake Victoria, we used statistical metrics (correlation coefficient, trend analysis, change budget, and intensity analysis) to understand the relationship between land use and precipitation changes in the basin with changes in Chl-a and TUR at two major pollution hotspots on the lake, i.e., Winam Gulf and Inner Murchison Bay (IMB). Results show that the Chl-a and TUR concentrations in the Winam gulf increase with increases in precipitation. Through increases in precipitation, the erosion risks are increased and transport of nutrients from land to the lake system, promoting algal growth and turbidity. In the IMB, Chl-a and TUR concentrations decrease with an increase in precipitation, possibly due to dilution, but peak during moderate rainfall. Interestingly, changes in land use and land cover (LULC) at 5-year intervals showed no substantial correlation with water quality changes at selected hotspots even though a broader LULC change analysis over the past two decades indicated a notable 300% increase in built-up areas across the Lake Victoria basin. These findings underscore the dominant influence of precipitation changes over LULC changes on the water quality of Lake Victoria for the selected hotspot areas.
由于维多利亚湖流域土地利用变化和气候变化模式的持续增加，了解这些变化对维多利亚湖水质的影响对于保护淡水生态系统的完整性至关重要。因此，我们使用全球卫星产品分析了 2000 年至 2022 年期间维多利亚湖流域土地覆盖、降水和水质变化的时空模式。我们重点关注维多利亚湖的叶绿素-a（Chl-a）和浊度（TUR），使用统计指标（相关系数、趋势分析、变化预算和强度分析）来了解流域土地利用和降水变化与 Chl-a 和 TUR 变化之间的关系在湖的两个主要污染热点，即威尼姆湾和内部默奇森湾（IMB）。结果表明，威尼姆湾的 Chl-a 和 TUR 浓度随着降水的增加而增加。通过增加降水，侵蚀风险增加，陆地向湖泊系统输送养分，促进藻类生长和浊度增加。在内默奇森湾，Chl-a 和 TUR 浓度随着降水的增加而减少，可能是由于稀释，但在中度降雨时达到峰值。有趣的是，即使过去二十年对土地利用和土地覆盖（LULC）的更广泛变化分析表明整个维多利亚湖流域的建成区面积增加了 300%，但每隔 5 年的 LULC 变化与所选热点的水质变化之间没有明显的相关性。这些发现强调了降水变化对所选热点地区维多利亚湖水质的影响超过 LULC 变化的主导作用。
