Lake Victoria Basin Research Articles

Linking land use and precipitation changes to water quality changes in Lake Victoria using earth observation data

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.

Unveiling the determinants of the spatial variability of nitrogen sources use in the Lake Victoria basin, East Africa

As nitrogen pollution increasingly threatens water quality in the Lake Victoria Basin, it is essential to investigate the spatial factors influencing nitrogen source use. Understanding these determinants is crucial to inform effective strategies to combat eutrophication, enhance nutrient management, ensure food security and promote sustainable ecological development. This study investigated spatial variation of N sources, the farmers' socio-demographic and farm characteristics factors influencing farmers' choice of nitrogen sources. Data was collected from 1500 farmers between October and December 2020. The farmers were randomly selected in Kenya, Rwanda, Uganda, Burundi and Tanzania country sub-basins within the Lake Victoria basin (LVB). Spatial autocorrelation was used to evaluate the spatial variation of the nitrogen sources while the Optimized Parameter Geographical Detector (OPGD) model was used to identify the factors influencing the choice or use of N sources. The OPDG results indicate that the country of residence and livestock ownership are the primary factors accounting for 31.9% and 22.1% of the variation in nitrogen sources across the entire Lake Victoria Basin, respectively. The major sub-basin factors influencing the use of N sources were both farm characteristics (types of crops grown and farm size) and social socio-demographic factors of the farmer (education). These findings highlight the need for tailored strategies, accounting for geographical variations, farm characteristics and socio-demographic factors are essential when formulating nitrogen management strategies and policies at local and regional scales within the LVB.

Prevalence and genotype distribution of potential high-risk and high-risk human papillomavirus among women attending selected reproductive health clinics in lake victoria basin-kenya: a cross-sectional study

BackgroundPersistent human papillomavirus (HPV) infection is considered the primary etiological factor for invasive cervical cancer. Understanding the epidemiology of circulating potential high-risk (HR) and HR HPV strains is essential in updating epidemiological knowledge and recommendations on genotype-specific vaccination development. This study determined the prevalence and factors associated with Potential HR/HR HPV among women attending selected reproductive health clinics in Lake Victoria Basin.MethodsA cross-sectional facility-based survey made up of 434 women aged 16–68 years was carried out in two selected facilities. Structured questionnaires were administered to collect participant clinical and social characteristics. Cervical specimens were collected and HPV genotyping was carried out using RIATOL HPV genotyping qPCR assay. Descriptive statistics followed by logistic binary regression was done using R version 4.3.2.ResultsThe overall prevalence of potential HR/HR HPV among women attending the selected reproductive health clinics was reported at 36.5% (158/434). Specifically, in the rural setting, Gobei Health Center, the prevalence was 41.4% (41/99) while in the urban setting-JOOTRH, it was 34.6% (117/335). The most prevalent potential HR/HR HPV are 52, 67, 16, 31, 39, 45, and 31 among women. Age was the main factor associated with HPV infection with women between the age of 30–39 having the highest risk (AOR = 0.3, CI:0.2–0.7, p < 0.001).ConclusionIn both rural and urban regions, potential HR/HR HPV infection among women attending reproductive health clinics at the selected facilities remains common. The study identifies the need for effective implementation and clinical follow-up process of cervical cancer control program in the LVB.

Spatial–Temporal Analysis of Impacts of Climate Variability on Maize Yield in Kenya

This study examined the spatial temporal impacts of climate variability on maize yield in Kenya. The maize yield data were obtained from the Kenya Maize Yield Database while climatic variable data were obtained from the Climatic Research Unit gridded Time Series (CRU TS) with a spatial resolution of 0.5° × 0.5°. The non-parametric Mann–Kendall and Sen’s slope tests showed no trend in the data for maximum temperature, minimum temperature and precipitation. The spatial maps patterns highlight the rampancy of wetter areas in the Lake Victoria basin and Highlands East of Rift Valley compared to other regions. Additionally, there is a decreasing trend in the spatial distribution of precipitation in wetter areas and an increasing trend in maximum temperature in dry areas, albeit not statistically significant. Spearman’s rank correlation test showed a strong positive correlation between maize yield and the climatic parameters for the Lake Victoria basin, Highlands East of Rift Valley, Coastal Strip and North Western Regions. The findings suggest that climate variability has a significant impact on maize yield for four out of six climatological zones. We recommend adoption of policies and frameworks that will augment adaptive capacity and build resilience to climatic changes.

Assessment of Fish Consumption Patterns in the Lake Victoria Basin of Uganda

Assessment of Fish Consumption Patterns in the Lake Victoria Basin of Uganda

Managing Transboundary Water Resources At the Edge of Human Interface: A Case of Kagera River Basin, Tanzania

Globally, water concerns stemming from human factors are evident, and the Kagera River Basin exemplifies this challenge. This study investigated the influence of human elements on transboundary water resource management in the Kagera River Basin. Utilizing focus group discussions, household surveys, key informant interviews, and field observations, the study analysed land use changes via remote sensing; and processed quantitative data using SPSS 20 and ArcGIS 10.4. Results highlighted economic, political, and social factors as key factors influencing transboundary water resource management. The institutional analysis identified major players to include the Ministry of Water, Lake Victoria Basin Water Board, NELSAP, Ministry of Agriculture, village governments, and CONCERN/OXFAM. Non-climatic factors such as water infrastructure management, socio-economic factors, conflicting water uses, agricultural practices causing soil erosion, and land use/cover changes were identified as central to transboundary water resource challenges. Agricultural expansion and land use shifts in the basin in 1986, 2000 and 2021 were pinpointed as contributors to water resource challenges, impacting availability, access, and quality. Anthropogenic-driven land use changes emerged as significant contributors to pollution, habitat loss, and alterations in water quality. While human factors substantially influence water resources, their impact is exacerbated by anthropogenic activities. Thus, fostering collaborative planning and stewardship initiatives at the local level is crucial for sustaining transboundary water resources. This involves engaging community members and leaders in developing resilience plans and initiating international cooperation, and innovative participatory approaches for effective transboundary water resources management.

Access and Use of Information for Enhanced Adoption of Climate Smart Agricultural Practices among Smallholder Farmers in Lake Victoria Basin, Kenya

The value of information in agricultural production cannot be overemphasized given the challenges caused by the impact of climate change. This study evaluated the importance of accessing and using information for enhanced adoption of climate-smart agriculture (CSA) practices in sorghum production among smallholder farmers in Lake Victoria Basin, Kenya. The study used a quantitative research method with a correlation design, collecting data from 382 farmers through a questionnaire. A pilot study was conducted with a 10% sample size to assess reliability and validity achieving a CVI value of 0.877445696 and Cronbach’s alpha (α) value of 0.809. Descriptive statistics were used to determine information access and use, while correlation analysis examined associations between age and education and information access and use. The findings showed that farmers obtained information primarily from television, radio, extension workers, and neighbors and friends. The accessibility and use of this information were influenced by age and level of education. The findings are significant since they can help agricultural stakeholders identify and use appropriate channel and context-specific information to disseminate information that would enhance the adoption of CSA practices for improved sorghum yield. This may increase farmers' resilience to climate variability and improve their farming knowledge and skills, potentially leading to better livelihoods for the farming communities in the region. By advocating the provision of easily accessible and relevant information in the appropriate format and media, the findings may aid in policy formulation by providing policymakers with insights when formulating agricultural policies and legislation.

A hybrid ensemble learning merging approach for enhancing the super drought computation over Lake Victoria Basin

This study introduces a novel Hybrid Ensemble Machine-Learning (HEML) algorithm to merge long-term satellite-based reanalysis precipitation products (SRPPs), enabling the estimation of super drought events in the Lake Victoria Basin (LVB) during the period of 1984 to 2019. This study considers three widely used Machine learning (ML) models, including RF (Random Forest), GBM (Gradient Boosting Machine), and KNN (k-nearest Neighbors), for the emerging HEML approach. The three SRPPs, including CHIRPS (Climate Hazards Group Infra-Red Precipitation with Station), ERA5-Land, and PERSIANN-CDR (Precipitation Estimation from Remotely Sensed Information using Artificial Neural Network-Climate Data Record), were used to merge for developing new precipitation estimates from HEML model. Additionally, classification and regression models were employed as base learners in developing this algorithm. The newly developed HEML datasets were compared with other ML and SRPP products for super-drought monitoring. The Standardized precipitation evapotranspiration index (SPEI) was used to estimate super drought characteristics, including Drought frequency (DF), Drought Duration (DD), and Drought Intensity (DI) from machine learning and SRPPs products in LVB and compared with RG observation. The results revealed that the HEML algorithm shows excellent performance (CC = 0.93) compared to the single ML merging method and SRPPs against observation. Furthermore, the HEML merging product adeptly captures the spatiotemporal patterns of super drought characteristics during both training (1984–2009) and testing (2010–2019) periods. This research offers crucial insights for near-real-time drought monitoring, water resource management, and informed policy decisions.

A Review on Nitrogen Flows and Obstacles to Sustainable Nitrogen Management within the Lake Victoria Basin, East Africa

The Lake Victoria Basin (LVB) is located in the upper reaches of the Nile River Basin and is shared by five East-African countries. The population in the catchment is growing rapidly and the lake is facing several environmental problems. During the past few decades, numerous efforts have been made across the five countries, with the coordination of the Lake Victoria Basin Commission (LVBC) to reduce the loading of reactive nitrogen (Nr) into the lake and Lake Watershed. However, most of the measures envisaged to ensure long-term sustainable N management are not as easily adopted as planned. This paper reports on a review study on N flows and obstacles in achieving sustainable N management in the LVB, with the objectives of improving the understanding of the N cycle and examining the N management practices and policies that can help reduce the loss of Nr in the region. The scientific literature related to a range of N flows, N management obstacles, and options to overcome obstacles has been analyzed using N prospects developed at the global level for their potential applicability across the LVB. The study showed that an unbalanced use of N input is a serious threat to agricultural productivity leading to extreme soil N mining and degradation, with the majority of LVB farms operating within negative N balances and above the safe operating boundary for N in production systems. From the projections in N input as recommended by various stakeholders, there would likely be changes in both current yield and N use efficiency (NUE) values; however, most small-scale farmers will continue to experience low yields, which remains a challenge for food security in the area. These results suggest that scientists as well as those involved in decision-making and policymaking processes should formulate new targets for fertilizer increment to reduce the yield gap for sustainability, focusing on more integrated soil fertility as a package for nutrient management in cropping systems.

Group-based Education and monitoring program delivered by community health workers to improve control of high blood pressure in island districts of lake victoria, Uganda

BackgroundIndividuals living in communities with poor access to healthcare may be unaware of their high blood pressure (BP). While the use of community health workers (CHWs) can address gaps in human resources for health, CHWs in Uganda have not been used previously for BP screening and management. We report the results of an initiative to train CHWs to evaluate BP and to administer group-based education in Kalangala and Buvuma Island Districts of Lake Victoria, Uganda.MethodsWe randomly selected 42 of 212 villages. We trained CHWs based in island districts on measuring BP. CHWs visited all households in the selected villages and invited all adults ≥ 18 years to be screened for high BP. We used the World Health Organization’s STEPwise tool to collect data on demographic and behavioral characteristics and BP measurements. High blood pressure was defined as systolic BP (SBP) ≥ 140 mm Hg and/or diastolic BP (DBP) ≥ 90 mm Hg over three readings. CHWs created and led fortnight support groups for individuals identified with high blood pressure at baseline. At each group meeting, CHWs re-measured BP and administered an intervention package, which included self-management and lifestyle education to participants. The paired t-test was used to compare mean values of systolic blood pressure (SBP) and diastolic blood pressure (DBP) before and after the intervention. Generalized estimating equations (GEE) were used to model longitudinal changes in BP.ResultsWe trained 84 CHWs to measure BP and deliver the intervention package. Among 2,016 community members, 570 (28.3%) had high blood pressure; of these, 63 (11.1%) had a previous diagnosis of hypertension. The comparison of SBP and DBP before and after the intervention revealed significant reductions in mean SBP from 158mmHg (SD = 29.8) to 149 mmHg (SD = 29.8) (p < 0.001) and mean DBP from 97mmHg (SD = 14.3) to 92mmHg (p < 0.001). GEE showed decreases of -1.133 (SBP) and − 0.543 mmHg (DBP)/fortnight.ConclusionHigh BP was common but previously undiagnosed. The CHW-led group-based self-management and education for controlling high BP was effective in the island districts in Uganda. Scaling up the intervention in other hard-to-reach districts could improve control of high BP on a large scale.

Mixed-methods community assessment of drowning and water safety knowledge and behaviours on Lake Victoria

BackgroundDrowning is a major cause of death in Uganda, especially among young adults with water-based occupations and livelihoods. Information about drowning and other water-related deaths and injuries is limited. To...

ICDP workshop on the Lake Victoria Drilling Project (LVDP): scientific drilling of the world's largest tropical lake

Abstract. Lake Victoria, which is bordered by Uganda, Tanzania, Kenya, and has a catchment that extends to Rwanda and Burundi, is home to the largest human population surrounding any lake in the world and provides critical resources across eastern Africa. Lake Victoria is also the world's largest tropical lake by surface area, but it is relatively shallow and without a major inlet, making it very sensitive to changes in climate, and especially hydroclimate. Furthermore, its size creates abundant habitats for aquatic fauna, including the iconic hyper-diverse cichlids, and serves as a major geographic barrier to terrestrial fauna across equatorial Africa. Given Lake Victoria's importance to the eastern African region, its sensitivity to climate, and its influences on terrestrial and aquatic faunal evolution and dispersal, it is vital to understand the connection between the lake and regional climate and how the lake size, shape, and depth have changed through its depositional history. This information can only be ascertained by collecting a complete archive of Lake Victoria's sedimentary record. To evaluate the Lake Victoria basin as a potential drilling target, ∼ 50 scientists from 10 countries met in Dar es Salaam, Tanzania, in July 2022 for the International Continental Scientific Drilling Program (ICDP)-sponsored Lake Victoria Drilling Project (LVDP) workshop. Discussions of the main scientific objectives for a future drilling project included (1) recovering the Pleistocene and Holocene sedimentary records of Lake Victoria that document the dynamic nature of the lake, including multiple lacustrine and paleosol sequences; (2) establishing the chronology of recovered sediments, including using extensive tephra fingerprinting and other techniques from deposits in the region; (3) reconstructing past climate, environment, lacustrine conditions, and aquatic fauna, using an integrated multi-proxy approach, combined with climate and hydrologic modeling; and (4) connecting new records with existing sedimentary snapshots and fossils exposed in deposits around the lake, tying archaeological, paleontological, sedimentological, tectonic, and volcanic findings to new drilling results. The LVDP provides an innovative way to address critical geological, paleontological, climatological, and evolutionary biological questions about Quaternary to modern landscapes and ecosystems in eastern Africa. Importantly, this project affords an excellent opportunity to help develop conservation and management strategies for regional responses to current and future changes in climate, land use, fisheries, and resiliency of at-risk communities in equatorial Africa.

Satellite rainfall bias correction incorporating effects on simulated crop water requirements

ABSTRACT Satellite rainfall estimates (SRE) offer spatial-temporal rainfall representations in regions with limited ground-based gauge rainfall measurements. However, differences exist between SRE and gauge measured rainfall, which needs assessment and reduction. This study presents a method to correct errors in SRE to make their use in agro-hydrological applications and models meaningful. The main scientific objective is the determination of effective window sizes for SRE bias correction. To conclude on effective window sizes, the crop water requirement satisfaction index (WRSI) for gauged rainfall, uncorrected SRE and bias corrected SRE were estimated and propagation effects of SRE errors on respective WRSI estimates were assessed. WRSI indicates how much of the crop water needs are satisfied by rainfall. The Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) SRE was bias corrected using gauged rainfall data from 20 stations in the Lake Victoria basin of Kenya from 2012 to 2018. The results show that the error in WRSI can serve to determine effective window sizes for SRE bias correction rather than using SRE bias error itself. This proposed correction method resulted in improved estimates of WRSI.

Possible role of anthropogenic climate change in the record-breaking 2020 Lake Victoria levels and floods

Abstract. Heavy rainfall in eastern Africa between late 2019 and mid 2020 caused devastating floods and landslides throughout the region. These rains drove the levels of Lake Victoria to a record-breaking maximum in the second half of May 2020. The combination of high lake levels, consequent shoreline flooding, and flooding of tributary rivers caused hundreds of casualties and damage to housing, agriculture, and infrastructure in the riparian countries of Uganda, Kenya, and Tanzania. Media and government reports linked the heavy precipitation and floods to anthropogenic climate change, but a formal scientific attribution study has not been carried out so far. In this study, we characterize the spatial extent and impacts of the floods in the Lake Victoria basin and then investigate to what extent human-induced climate change influenced the probability and magnitude of the record-breaking lake levels and associated flooding by applying a multi-model extreme event attribution methodology. Using remote-sensing-based flood mapping tools, we find that more than 29 000 people living within a 50 km radius of the lake shorelines were affected by floods between April and July 2020. Precipitation in the basin was the highest recorded in at least 3 decades, causing lake levels to rise by 1.21 m between late 2019 and mid 2020. The flood, defined as a 6-month rise in lake levels as extreme as that observed in the lead-up to May 2020, is estimated to be a 63-year event in the current climate. Based on observations and climate model simulations, the best estimate is that the event has become more likely by a factor of 1.8 in the current climate compared to a pre-industrial climate and that in the absence of anthropogenic climate change an event with the same return period would have led lake levels to rise by 7 cm less than observed. Nonetheless, uncertainties in the attribution statement are relatively large due to large natural variability and include the possibility of no observed attributable change in the probability of the event (probability ratio, 95 % confidence interval 0.8–15.8) or in the magnitude of lake level rise during an event with the same return period (magnitude change, 95 % confidence interval 0–14 cm). In addition to anthropogenic climate change, other possible drivers of the floods and their impacts include human land and water management, the exposure and vulnerability of settlements and economic activities located in flood-prone areas, and modes of climate variability that modulate seasonal precipitation. The attribution statement could be strengthened by using a larger number of climate model simulations, as well as by quantitatively accounting for non-meteorological drivers of the flood and potential unforced modes of climate variability. By disentangling the role of anthropogenic climate change and natural variability in the high-impact 2020 floods in the Lake Victoria basin, this paper contributes to a better understanding of changing hydrometeorological extremes in eastern Africa and the African Great Lakes region.

ASSESSMENT OF RAINFALL IMPACT ON GROUNDWATER VULNERABILITY FOR AGRICULTURAL PRODUCTION

The research study was conducted in Northern Lake Victoria basin to assess rainfall impact on groundwater as a fresh water source on 30 farms for agricultural production. Depth Aquifer Recharge and Transmissivity (DART) index quantitative method was applied that revealed that rainfall was directly related to groundwater vulnerability index. Positive DART index was realized during long rainfall season between April and June, and during short rainfall season in September and October. The other months had negative values during dry season. DART indices ranged between -8.40 and 2.50 with positive values representing more resilience to negative impact of erratic rainfall. There were two groundwater vulnerability Index Thresholds of -8.40 and -4.80 that marked onset of long and short rainfall seasons respectively. Mann-Kendall trend analysis and t-test performed indicated a downward trend and a significant difference of groundwater vulnerability index values because of seasonal rainfall changes that caused wells to dry up thus increasing water insecurity. The research study results confirmed the severity of rainfall patterns on groundwater recharge that can affect agricultural production and food security to households.

Integrated Application of SWAT and L-THIA Models for Nonpoint Source Pollution Assessment in Data Scarce Regions

Nonpoint source pollution (NPS) has become the most important reason for the deterioration of water quality, while relevant studies are often limited to African river and lake basins with insufficient data. Taking the Simiyu catchment of the Lake Victoria basin as the study area, we set up a NPS model based on the soil and water assessment tool (SWAT). Furthermore, the rationality of this model is verified with the field-measured data. The results manifest that: (1) the temporal variation of NPS load is consistent with the variation pattern of rainfall, the average monthly output of total nitrogen (TN) and total phosphorus (TP) in the rainy season was 1360.6 t and 336.2 t, respectively, while in the dry season was much lower, only 13.5 t and 3.0 t, respectively; (2) in view of spatial distribution among 32 sub-basins, TN load ranged from 2.051 to 24.288 kg/ha with an average load of 12.940 kg/ha, and TP load ranged from 0.263 to 8.103 kg/ha with an average load of 3.321 kg/ha during the 16-month study period; (3) Among the land use types, the cropland contributed the highest proportion of TN and TP pollution with 50.28% and 76.29%, respectively, while the effect of forest on NPS was minimal with 0.05% and 0.02% for TN and TP, respectively. (4) Moreover, the event mean concentration (EMC) values of different land use types have been derived based on the SWAT model, which are key parameters for the application of the long-term hydrological impact assessment (L-THIA) model. Therefore, this study facilitates applying the L-THIA model to other similar data-deficient catchments in view of its relatively lower data requirement.

Modeling the impacts of land use and land cover changes on streamflow and sediment yield with SWAT model in Migori River watershed, Lake Victoria basin region, Kenya

Modeling the impacts of land use and land cover changes on streamflow and sediment yield with SWAT model in Migori River watershed, Lake Victoria basin region, Kenya

Evaluation of a financial incentive intervention on malaria prevalence among the residents in Lake Victoria basin, Kenya: study protocol for a cluster-randomized controlled trial

BackgroundIn the Lake Victoria basin of western Kenya, malaria remains highly endemic despite high coverage of interventions such as mass distribution of long-lasting insecticidal nets (LLIN), indoor residual spraying (IRS) programs, and improvement of availability and accessibility of rapid diagnostic tests (RDT) and artemisinin-based combination therapy (ACT) at community healthcare facilities. We hypothesize that one major cause of the residual transmission is the lack of motivation among residents for malaria prevention and early treatment.MethodsThis study will aim to develop a demand-side policy tool to encourage local residents’ active malaria prevention and early treatment-seeking behaviors. We examine the causal impact of a financial incentive intervention complemented with malaria education to residents in malaria-prone areas. A cluster-randomized controlled trial is designed to assess the effect of the financial incentive intervention on reducing malaria prevalence in residents of Suba South in Homa Bay County, Kenya. The intervention includes two components. The first component is the introduction of a financial incentive scheme tied to negative RDT results for malaria infection among the target population. This study is an attempt to promote behavioral changes in the residents by providing them with monetary incentives. The project has two different forms of incentive schemes. One is a conditional cash transfer (CCT) that offers a small reward (200 Ksh) for non-infected subjects during the follow-up survey, and the other is a lottery incentive scheme (LIS) that gives a lottery with a 10% chance of winning a large reward (2000 Ksh) instead of the small reward. The second component is a knowledge enhancement with animated tablet-based malaria educational material (EDU) developed by the research team. It complements the incentive scheme by providing the appropriate knowledge to the residents for malaria elimination. We evaluate the intervention’s impact on the residents’ malaria prevalence using a cluster-randomized control trial.DiscussionA policy tool to encourage active malaria prevention and early treatment to residents in Suba South, examined in this trial, may benefit other malaria-endemic counties and be incorporated as part of Kenya’s national malaria elimination strategy.Trial registrationUMIN000047728. Registered on 29th July 2022.

An analysis of the Lake Surface Water Temperature evolution of the world’s largest lakes during the years 2003-2020 using MODIS data

The Lake Surface Water Temperature (LSWT) evolution is analysed in ten of the largest lakes in the world: Caspian Sea, Superior, Victoria, Huron, Michigan, Tanganyika, Baikal, Great Slave Lake, Erie and Ontario. The time span selected is 2003-2020 and the satellite product, MODIS Level 3 SST Thermal IR 8 Day 4km V2019.0. Results show warming trends ranging from 0.012⁰C/yr. in the Victoria Lake to 0.083 ⁰C/yr in the Baikal Lake. Results have been validated with the product MOD11L2 LSWT estimations for the years 2003-2014 in the Laurentian Great Lakes, obtaining correlations between 0.962 and a 0.998. The validation has been enlarged by considering Sentinel 3 observations from the Issyk-Kul lake, with a 0.99 correlation. The validation shows that the MODIS SST product is capable of estimating the LSWT parameter with a high precision.

Historical climate impact attribution of changes in river flow and sediment loads at selected gauging stations in the Nile basin

The Nile basin is the second largest basin in Africa and one of the regions experiencing high climatic diversity with variability of precipitation and deteriorating water resources. As climate change is affecting most of the hydroclimatic variables across the world, this study assesses whether historical changes in river flow and sediment loads at selected gauges in the Nile basin can be attributed to climate change. An impact attribution approach is employed by constraining a process-based model with a set of factual and counterfactual climate forcing data for 69 years (1951–2019), from the impact attribution setup of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP3a). To quantify the role of climate change, we use the non-parametric Mann-Kendall test to identify trends and calculate the differences in long-term mean annual river flow and sediment load simulations between a model setup using factual and counterfactual climate forcing data. Results for selected river stations in the Lake Victoria basin show reasonable evidence of a long-term historical increase in river flows (two stations) and sediment load (one station), largely attributed to changes in climate. In contrast, within the Blue Nile and Main Nile basins, there is a slight decrease of river flows at four selected stations under factual climate, which can be attributed to climate change, but no significant changes in sediment load (one station). These findings show spatial differences in the impacts of climate change on river flows and sediment load in the study area for the historical period.