How water exchange and seasonality affect the eutrophication of Murchison Bay, Lake Victoria

Abstract

a b s t r a c tMurchison Bay in the Northern part of Lake Victoria has for decades received a daily wastewater load of 0.2% of its volume from Kampala City, through the Nakivubo channel. In spite of this, the Water Treatment Works abstracts raw water from this bay and has been able to produce drinking water of sufficient quality for the capital. This study monitored various physical−chemical components within the bay during 2000−2003 to understand the processes responsible for the acceptable quality of raw water. Four sampling stations were located along a transect from the channel mouth towards the open lake. Results: showed that the wastewater did not accumulate in the bay, instead was already strongly diluted 2.5 km from the channel mouth. This caused an abrupt reduction in conductivity and the concentrations of the nutrients total phosphorus (Tot-P), orthophosphate (PO 4 -P) and total nitrogen (Tot-N).Inshore−offshore exchange of water was mediated by flows from daily and sub-daily water level fluctuations and wind-driven currents. As a daily average, 2% of the Murchison Bay flowed in and out and the incoming wastewater was diluted 9.7 times.During the dry season from June to August (D2), when the weather was influenced by the south-east monsoon, the thermal stratification in the main lake disappeared and cooler and deoxygenated water from deeper depths entered the bay influencing its water quality.The daily flushing of water in and out of the bay due to water level variation was identified as the main factor diluting the bay water.

Determination of the Connectedness of Land Use, Land Cover Change to Water Quality Status of a Shallow Lake: A Case of Lake Kyoga Basin, Uganda

“…Heavy rains in the area caused by climate change as reported in the related study [106], exacerbates LULC impacts into the lake as floods help to deliver sediments and nutrients into Lake Kyoga. This is done through a network of rivers and streams including rivers, Awoja, Mpologoma, and Manafwa, with effects on water quality as has been shown elsewhere [43,80,[107][108][109][110][111][112][113][114]. Most of the forests, grasslands, woodlands and shrublands have been destroyed for different reasons, including agriculture and charcoal burning to provide for the ever-growing human demands for energy in the form of charcoal, timber, and livestock grazing, which has impacted water quality, including reduction of essential DO [115][116][117].…”

Environmental Impact Assessment Follow–Up in Central Uganda’s Processing and Manufacturing Industries: Implications for Achieving Sustainable Development

“…This research used both qualitative and quantitative approaches focusing on a number of categories of EIA stakeholders, including the regulator, the developer, and the public, both affected public and interested public, particularly environmental non-governmental Organizations (ENGOs). The processing and manufacturing industries were chosen because related studies (Akurut et al, 2017;Kabenge et al, 2016;Luyiga et al, 2015;Paul, Walakira;James, 2011;Pierre & Wondwosen, 2016) reveal them as the major source of pollution of lakes particularly lake Victoria, the world's second-largest freshwater lake, rivers, streams aquifers, and soils. Data was collected between 2018 and 2019, the year ending the 24 years of the NEA 1995 regime and its related regulations.…”

“…Here is meant EIA follow-up at both the micro-scale level (applied to operational projects) and the macro-scale level (EIA system). It is for this reason that, this study sought to evaluate the implementation of EIA follow-up in the manufacturing sector which literature (Akurut et al, 2017;Kabenge et al, 2016;Luyiga et al, 2015;Paul et al, 2011;Pierre & Wondwosen, 2016) reveal to be the main source of pollution of Lake Victoria, streams, soils and aquifers in the central region of Uganda; a region which is a habitat to more than half of Uganda's population (UBOS 2016) and with fragile ecosystems.…”

Status and changes of water quality in typical near-city zones of three East African Great Lakes in Tanzania

“…Water quality deterioration of inland freshwater bodies is one of the main ecological and environmental challenges that has been faced by developing countries for decades. This undesirable phenomenon is evident in many areas from Latin America to Asia and Africa (Basturk 2019;Diaz-Casallas et al 2019;Gradilla-Hernandez et al 2020;Lopes et al 2020;Luyiga et al 2015). Increasing pollution in freshwater systems in less-developed regions such as Africa poses risks to public health, food security, and biodiversity (UN-Water 2016).…”