Correlation of Rainfall Anomalies in Rwanda from September to December (SOND) with Indian Ocean Dipole (IOD) and El Nino Southern Oscillation (ENSO) Events

Understanding the relationship between rainfall anomalies and large-scale systems is critical for driving adaptation and mitigation strategies in socioeconomic sectors. This study therefore aims primarily to investigate the correlation between rainfall anomalies in Rwanda during the months of September to December (SOND) with the occurrences of Indian Ocean Dipole (IOD) and El Nino Southern Oscillation (ENSO) events. The study is useful for early warning and forecasting of negative effects associated with extreme rainfall anomalies across the country, using Climate Hazards Group InfraRed Precipitation with Station (CHIRPS), the National Centers for Environmental Prediction (NCEP) National Center for Atmospheric Research (NCAR) reanalysis sea surface temperature and ERA5 reanalysis datasets, during the period of 1983-2021. Both empirical orthogonal function (EOF), correlation analysis and composite analysis were used to delineate variability, relationship and the related atmospheric circulation between Rwanda seasonal rainfall September to December (SOND) with Indian Ocean Dipole (IOD) and El-Nino Southern Oscillation (ENSO). The results for Empirical Orthogonal Function (EOF) for the reconstructed rainfall data set showed three modes. EOF-1, EOF-2 and EOF-3 with their total variance of 63.6%, 16.5% and 4.8%, Indian ocean dipole (IOD) events resulted to a strong positive correlation of rainfall anomalies and Dipole model index (DMI) (r = 0.42, p value = 0.001, DF = 37) significant at 95% confidence level. The composite analysis for the reanalysis dataset was carried out to show the circulation patterns during four different events correlated with September to December seasonal rainfall in Rwanda using T-test at 95% confidence level. Wind anomaly revealed that there was a convergence of south westerly winds and easterly wind over the study area during positive Indian Ocean Diploe (PIOD) and PIOD with El Nino concurrence event years. The finding of this study will contribute to the enhancement of SOND seasonal rainfall forecasting and the reduction of vulnerability during IOD (ENSO) event years.

A Techno-Economical Characterization of Solar PV Power Generation in Rwanda:The Role of Subsidies and Incentives

Standalone Solar PV systems have been vital in the improvement of access to energy in many countries.However,given the large cost of solar PV plants’components,in developing countries,there is a dear need for such components to be subsidised and incentivised for the consumers to afford the produced energy.Moreover,there is a need for optimal sizing of the solar PV plants taking into account the solar information,energy requirement for various activities,and economic conditions in the off-grid regions in Rwanda.This study aims to develop optimally sized solar PV plants suited to rural communities in Rwanda.Likewise,it aims at characterizing the impacts of subsidies and incentives on the profitability and affordability of solar PV plants’energy in Rwanda.In the study,we have developed a model on basis of which the plant power(peak power)and costs of energy can be predicted given the load requirements using PVSyst.The model was validated using data corrected at eight different sites.Our generalized predictive model’s results matched the results obtained using field measurement data as inputs.The models have been able to replicate with a by degree of accuracy the peak powers and the plants’costs for different loads and were used to evaluate the economic viability of solar PV plants in Rwanda.It was found that with incentives and subsidies of 20%,the solar PV systems’costs,the Levelised Cost of Energy would drop from a maximum of 0.098 Euro to a minimum of 0.072 Euro,the payback period was reduced from a maximum of 7.5 years to a minimum of 6.0 years while the return on investments was seen to vary between 425.72 and 615.32 per cent over the plants’lifetime of 25 years.Overall our findings underscore the importance of government subsidies and incentives for solar PV energy generation projects to be significantly profitable.

刚果(金)内战(1996—2003)的背景及发展演变

刚果(金)东部的跨界民族问题有深刻的历史渊源。20世纪90年代以来,民族矛盾激化导致刚果(金)内部及其与周边国家的冲突升级,是引起刚果(金)内战的主要原因。周边卢旺达、乌干达、安哥拉、津巴布韦等非洲国家出于不同的政治经济动机介入冲突,导致刚果(金)内战扩大化和持久化。西方国家尤其是美国态度的变化,也与这场内战的走势密切相关。期间,冲突各方分化重组,转换阵营,进一步增加了刚内战的复杂性和破坏性。

卢旺达农业有害生物防控技术的研究与应用现状

卢旺达是非洲中东部一个以农业为经济支柱的国家,种植的农作物主要包括木薯、番茄、玉米、香蕉、辣椒、相橘与水稻等.农作物在生产过程中易遭受病虫害的持续危害,严重时可导致农民损失惨重,甚至颗粒无收.本文综述了卢旺达主要农作物病虫害的发生与防控技术研究和应用进展,同时对卢旺达农业可持续发展及有害生物可持续防控对策进行了分析,旨在为卢旺达地区农业病虫害的防控提供参考,以期实现在我国援非政策下卢旺达农业的稳定和可持续性发展.

The Impact of Land Reform on Land Market Activity in Rwanda and Suggestions in Support of Sustainable Urban Development

After a trial period between 2008 and 2010, the LTRP （Land Tenure Regularization Program） was implemented in Rwanda. The program is the consequent implementation of the National Land Policy （2004）, which initiated the reform of the administration of land. With the LTRP, titles to land were registered in the name of every landholder to unlock the potentialities for sustainable growth based on a clear framework, equally valid to all landholders. This paper describes the changes in land and property market activity after the reforms and comments on increasing development pressure on land which can be observed. It recalls that this new market activity is intended and policy-made as a result of the Land Policy with the land tenure regularization and changed land tenure principles, the EDPRS2 which clearly focuses on enabling the private sector to participate in and drive economic development, and the new urbanization agenda coming with the Vision 2020 and the EDPRS2. Identified factors are also discussed which contribute to the new market values of land and a case study in Kigali is referenced which identified accessibility to an area as the most influencing factor, besides access to services and levels of investment on the land. The importance is now, to keep ensuring and enhancing the positive impact of the policy directions in a sustainable manner for their maximum positive impact on socio-economic progress. Provided are recommendations of how to strategically guide public policies and investment in support of sustainable land market activity and using geospatial technologies. The supportive application of technologies is explored.

Inter-Annual Vegetation Changes in Response to Climate Variability in Rwanda

Comprehensive studies on how vegetative ecosystems respond to fluctuations in precipitation and temperature patterns are of great necessity for environmental risk assessment and land-use evaluations. The present study examined the annual trends in vegetation greenness in Rwanda from 2000-2015 and assessed the relationship between these dynamics and climate factors by means of MODIS NDVI, air temperature, SOI and precipitation datasets. Mann Kendal trend test has been utilized to determine the direction and the rates of changes, while Spearman’s rank correlation method has been used to determine the levels of associability between NDVI changes and climatic variables. The results indicate that approximately 11.9% of the country’s vegetation has significantly improved (р < 0.05) from slight to significant improvement while 10.4% of the vegetative cover degraded from slight to severe degradation and an estimated 77.6% of the country’s vegetation cover has remained relatively stable. Much of improvement has been detected in the lowlands of eastern province whereas much of degradation has been highlighted in the western highlands of the Congo Nile ridge and Kigali city. There was a weak correlation between NDVI anomalies and SOI anomalies (rs = 0.36) while near surface air temperature was moderately correlated (rs = 0.47) with changes in Mean NDVI. Precipitation was more significantly associated (r = 0.84) with changes in vegetation health in low plains of Eastern Province (Nyagatare District in particular) than in the high altitude regions of the Congo Nile ridge. A strong positive correlation with precipitation was found in rain fed croplands;mosaic vegetation;mosaic forest or shrubland, herbaceous vegetation/grass-land savannah and sparse vegetation. Identification of degradation hotspots could significantly help the government and local authorities galvanize efforts and foster results driven policies of environmental protection and regeneration countrywide.

Heritage trees and landscape design in urban areas of Rwanda

Trees play a key role in neighborhood landscapes, a belief that has been widely held for millennia in areas beyond Sub-Saharan Africa. Unfortunately, awareness of modern landscape architecture was almost absent in Rwanda until the late 20th century. Today, houses with sur- rounding decorative and amenity plants ate a common feature in Rwanda＇s neighborhood landscapes and, as the villagization of settle- ments progresses, new kinds of landscapes are emerging. This paper explores neighborhood tree planting around human settlements in the country. Remote sensing, photogrammetry, photo interpretation, and plant surveys were the core methods used. The average tree cover frac- tion ranged between 10%-35%. As the result of what is hereafter referred to as the ＂luxury effect,＂ a discrete gradient was detected along which the diversity of ornamental and amenity trees increases with the socio-economic status of neighborhoods： from rural settlements to urban residences via a series of intermediate designs, in which different levels of human-built vegetated areas alternate with non-landscaped spaces. Showy, non-productive amenity trees tend to occur more in wealthy quarters of the inner core of cities while edible ornamentals and other productive neighborhood trees prevail in rural and spontaneous settle- ments. In general, the practice of landscape plant design, in spite of its constant improvement, is still striving to get established as a profession in the country.

Local climate changes and the spread of malaria in Rwanda

A population’s health makes it possible to draw conclusions about a country’s general development level. In connection with local climatic changes, for example, we can assess how well a society adjusts to the new conditions. To that effect, it has been observed during the last few years that global climate change can also affect human health in various ways. We can differentiate direct health impacts (e.g. extreme weather events, natural catastrophes caused by the weather) from indirect ones. However, the indirect consequences cause by far the greater damages to health. They are being spread increasingly by vectors (mosquitoes, ticks, etc.). Especially when a vector-carried infectious disease (e.g. malaria) migrates into areas where it is not endemic, considerable societal problems can result. The people living there would be immunologically unprepared.

Trend Analysis of the Mean Annual Temperature in Rwanda during the Last Fifty Two Years

Climate change and global warming are widely recognized as the most significant environmental dilemma the world is experiencing today. Recent studies have shown that the Earth’s surface air temperature has increased by 0.6°C - 0.8°C during the 20th century, along with changes in the hydrological cycle. This has alerted the international community and brought great interest to climate scientists leading to several studies on climate trend detection at various scales. This paper examines the long-term modification of the near surface air temperature in Rwanda. Time series of near surface air temperature data for the period ranging from 1958 to 2010 for five weather observatories were collected from the Rwanda National Meteorological Service. Variations and trends of annual mean temperature time series were examined. The cumulative sum charts (CUSUM) and bootstrapping and the sequential version of the Mann Kendall Rank Statistic were used for the detection of abrupt changes. Regression analysis was performed for the trends and the Mann-Kendall Rank Statistic Test was used for the examination of their significance. Statistically significant abrupt changes and trends have been detected. The major change point in the annual mean temperature occurred around 1977-1979. The analysis of the annual mean temperature showed for all observatories a not very significant cooling trend during the period ranging from 1958 to 1977-1979 while a significant warming trend was furthermore observed for the period after the 1977-1979 where Kigali, the Capital of Rwanda, presented the highest values of the slope (0.0455/year) with high value of coefficient of determination (R2 = 0.6798), the Kendall’s tau statistic (M-K = 0.62), the Kendall Score (S = 328) with a two-sided p-value far less than the confidence level α of 5%). This is most likely explained by the growing population and increasing urbanization and industrialization the country has experienced, especially the Capital City Kigali, during the last decades.

Analysis of Rainfall Intensity-Duration-Frequency Relationship for Rwanda

Global atmospheric and oceanic perturbations and local weather variability induced factors highly alter the rainfall pattern of a region. Such factors result in extreme events of devastating nature to mankind. Rainfall Intensity Duration Frequency (IDF) is one of the most commonly used tools in water resources engineering particularly to identify design storm event of various magnitude, duration and return period simultaneously. In light of this, the present study is aimed at developing rainfall IDF relationship for entire Rwanda based on selected twenty six (26) rainfall gauging stations. The gauging stations have been selected based on reliable rainfall records representing the different geographical locations varying from 14 to 83 years of record length. Daily annual maximum rainfall data has been disaggregated into sub-daily values such as 0.5 hr, 1 hr, 3 hr, 6 hr and 12 hr and fitted to the probability distributions. Quantile estimation has been made for different return periods and best fit distribution is identified based on least square standard error of estimate. At-site and regional IDF parameters were computed and subsequent curves were established for different return period. The moment ratio diagram (MRD) and L-moment ratio diagram (LMRD) methods have been used to fit frequency distributions and identify homogeneous regions for observed 24-hr maximum annual rainfall. The rainfall stations have been divided into five homogeneous rainfall regions for all 26 stations. The results of present analysis can be used as useful information for future water resources development planning purposes.

Upper Gastrointestinal Cancers in Rwanda: Epidemiological, Clinical and Histopathological Features in Patients Presenting to a Tertiary Referral Hospital

Background: Scant data on upper gastrointestinal cancers in Rwanda exist to guide potential prevention efforts. We evaluated the epidemiological, clinical and histopathological data among patients with gastric and esophageal tumors at a tertiary Referral Hospital in Rwanda. Methodology: We performed a retrospective review of histologically-confirmed esophageal and gastric cancers in adults age ≥ 18 yrs. old presenting to a university teaching hospital (Centre Hospitalier Universitaire de Butare) from 2014-2019. Variables included age at diagnosis, sex, clinical presentation, tumor location and histopathological type. Results: There were 149 upper gastrointestinal cancers, of which 137 (92%) were gastric and 12 (8%) were esophageal. Gastric cancer patients had a mean age at presentation of 56.9 ± 12.3 years (range 21 - 87). Presenting symptoms were epigastric pain (78.8%), weight loss (53.3%), post-prandial vomiting (52.6%), early satiety (29.9%), epigastric mass (24.8%), hematemesis (19.7%) and melena (16.8%). The location was antrum 50.3%, corpus 21.8%, fundus 8%, and cardia 8%. Tumor type was adenocarcinoma in 94.1%. Helicobacter pylori infection was present in 108 (78.8%). Esophageal cancer patients had a mean age of 54.4 ± 9.5 years (range 35 - 72). Presenting symptoms were dysphagia (100%) and weight loss (83%). The most common site was lower third esophagus (9/12), and adenocarcinoma cancer subtype accounted for 5/12 (41.6%) cases. Conclusion: Gastric adenocarcinoma was the most commonly diagnosed upper gastrointestinal cancers and was associated with a high prevalence of H. pylori infection. This study lays the foundation for future work to improve cancer outcomes in Rwanda.

Impact Assessment of Hillside Rainwater Harvesting Ponds on Agriculture Income: Case Study of Ntarama Sector in Rwanda

Nowadays, rainwater harvesting (RWH) technology is increasingly adopted as a strategic pathway for reducing poverty in rural drought prone areas for enhancing agricultural productivity and boosting farm income. The aim of this study is to assess the level of adoption and the impacts of RWH ponds on farm income in Ntarama sector of Bugesera District in Eastern Province of Rwanda. Fifteen farm ponds were visited and the level at which households adopted RWH ponds, their impact on farm income and performance in storing water were assessed. Interviews and questionnaires methods were used to farm ponds beneficiaries and the storage capacity of farm ponds was calculated to ensure that they meet irrigation water demand. Then, Microsoft excel was used as a data analysis tool. The results show that 42.5% of households have adopted RWH ponds and the adoption level of RWH ponds fails due to the lack of training about the role and use of RWH ponds before their implementation. Beside this the low level of public involvement during the site selection for ponds associated with social conflicts among water users was observed. However, it is further revealed that the use of RWH ponds positively impacts on agricultural income on 1/4 hectare per year by about 2,325,000 RWF (3100USD). The studied portion of area can bear 222 ponds of 120 m3 each if all the rain is harvested throughout the year instead of being three ponds. Furthermore, we found that the quantity of rainwater harvested of 328.5 m3 as a total of the 3 ponds was still too less to meet irrigation water demand. As negative impacts, the RWH technology can cause dangerous effects such as social conflicts, breeding site for mosquitoes, water related diseases, accidents and others with a level of severity of 32%, 24%, 20%, 16% and 8%, respectively. This happens when the RWH ponds are not properly managed.

The Impacts of Topography on Spatial and Temporal Rainfall Distribution over Rwanda Based on WRF Model

The impact of topography on heavy rainfall during two rain seasons was investigated in order to explain their mechanisms on rainfall distribution over Rwanda. Weather Research and Forecasting (WRF-ARW) model was used to study two historical cases of heavy rainfall which took place over Rwanda during two rain seasons, March to May (MAM) and September to December (SOND), from April 7 to 9, 2012 (for MAM) and from October 29 to 31, 2012 (during SOND). The control experiment was done with actual topography, whereas sensitivity experiment was carried out with topography reduced by half. Results show that rainfall distribution over Rwanda significantly changes when topography is reduced. The reduction in topography leads to a decrease in rainfall amounts in both MAM and SOND seasons, with varying magnitudes. This reveals the importance of orography in determining rainfall amounts and distribution over the region. The accumulated rainfall amount from WRF underestimate or overestimate rain gauge stations data by region and by season, but there is good agreement especially in altitude below 1490 m and above 1554 m during April and October respectively. The results may motivate modelling carters to further improve parameterization schemes in the mountainous regions.

The Environmental Impact of Industrial Agriculture in Rwanda:The Case of Mulindi Tea Plantations

The aim of this study is to assess the impact of industrial agriculture on the environment in Rwanda taking Mulindi tea plantations as a case study.Tea is one of the three major crops of Rwandan industrial agriculture apart from coffee and pyrethrum.The results of this study show clearly the impact of tea plantations on the environment in Rwandan in all aspects.Soil samples collected in three zones

Climate Change Impacts in Rwanda:Challenges and Adaptations

Climate change is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is,in addition to natural climate variability,observed over a period of considerable length.Rwanda shares with the world a big challenge of climate change,because climate change is not only an environmental issue,but also an economic issue,a social issue,a security issue and, above all,a moral issue.This paper reviews the origins of climate change and its impacts in Rwanda as they manifest themselves across various sectors

Major Elements in Lake Muhazi,Rwanda,East Africa

The aim of this study undertaken at Lake Muhazi in Rwanda was to determine and analyze the major elements present in water. The presence of many major elements （Al, As, Ba, C, Ca, Cu, Fe, H^＋, K, Mg, Mn, N, P, S, Si, and Zn） was determined by spectroscopic technique. The concentrations of the elements were measured in water samples taken from three different locations of the lake from May to August 2008. The lake is polluted by water flow from mountain sides surrounding the lake. Other causes of pollution could be the use of agrochemicals in the sugar land, which surrounds the lake, and human activities near the lake. Finally, we proposed the strategies that can be applied in order to ensure good conservation of the environment and to prevent augmentation of heavy materials into the lake.

Performance Evaluation of Sediment Basins: Case Study of Keya Hydropower Plant in Rwanda

Keya Hydropower Plant (HPP) is a run-off-river plant which can be an effective green solution contributing to the current energy demand in Rwanda but a huge amount of sediment contained in water of Sebeya River on which this plant is built results in loss of the plant capacity. The aim of this study was to conduct the performance evaluation of Keya HPP sediment basin located in Rubavu district, western province of Rwanda. Specifically, laboratory tests of sediment, efficiency of the basin, assessment of sedimentation problems on HPP operations, proposition of technical options for increasing the removal efficiency of sediment basin and other options for reducing sediment at the source of generation were performed using different methods including interviews and questioning Keya hydropower technicians, field sediment sampling followed by hydrometer and Particle Size Distribution (PSD) analysis. Analysis was made in University of Rwanda (UR) Soil Mechanics laboratory. MICROSOFT EXCEL and Graphisoft Archicad 18 softwares with Massachusetts Institute of Technology (MIT) soil classification were used as data analysis tools. Results showed that the overall efficiency removal of the diversion headwork was 85%. However, after comparing sediment concentration at the inlet and outlet of the sediment basin, it was found that the basin removed only 22% of sediment from diverted water toward the turbine. This means that 78% of sediment escapes the basin to cause erosion on the turbine components resulting in reduction of the plant capacity from 2.2 MW to 900 KW. To ensure sustainable solution to sediment issues in Keya HPP, an upstream sediment trap reservoir is proposed. It is recommended also that Rwanda Energy Group (REG) should work together with Rwanda Natural Resource Authority (RNRA) at national level to ensure sustainable development of erosion control in the Sebeya catchment area.

Adoption of small-scale irrigation technologies and its impact on land productivity:Evidence from Rwanda

In an attempt to identify solutions to the effects of erratic rainfall patterns and droughts that limit agricultural production growth,the Rwandan government has recently increased investments in irrigation development.In this study,we analyze the adoption of small-scale irrigation technologies(SSITs)and its impact on land productivity using cross-sectional data from a sample of 360 farmers in Rwanda.The study uses the propensity score matching technique to address potential self-selection bias.Our results reveal that adoption decisions are significantly influenced by factors such as education,farm size,group membership,gender,extension services,access to credit,access to weather forecast information,risk perceptions,access to a reliable source of water for irrigation,awareness of rainwater harvesting techniques,and awareness of subsidy programs.In addition,the results show that the adoption of SSITs has a significantly positive impact on land productivity.The study concludes with policy implications that highlight the need to promote the adoption of SSITs among farmers as a strategy to improve agricultural productivity and food security in Rwanda.

Phenolic Compound Profiles of Two Common Beans Consumed by Rwandans

Legumes are high-protein, medium-energy and micronutrient-rich food consumed in many parts of the world including Africa. This study evaluated the levels of specific phenolic compounds in three legumes. Two varieties of the common bean, (Phaseolus vulgaris L.) soybeans (Glycine max L.), and peas (Pisum sativum L.) from Rwanda were analyzed using high performance liquid chromatography with diode array detection. The phenolic compounds were identified by comparison to the chromatographic retention times and UV spectra of known reference compounds. This study results clearly shows the presence of 11 different phenolic compounds in common beans: gallic acid, (+)-catechin, (–)-epicatechin, caffeic acid, o-coumaric acid, chlorogenic acid, quercetin, 4-hydrobenzoic acid, syringic acid, ferulic acid and vanillic acid. The concentration ranged from 0.59 to 2.27 mg/kg for epicatechin. High levels of catechin (13.5 to 57.9 mg/kg) ferulic acid (26.1 to 47.6 mg/kg) were also observed. Therefore, the results of this study show that Rwandan common beans are a good source of phenolic acids in particular catechins and ferulic acid.

Assessment of Genetic Diversity of Coffee Accessions in Rwanda and Its Implication for Coffee Breeding

Genetic variation is important in breeding programs because it determines the amount of gain from selection. This study was conducted to determine the magnitude of genetic diversity in coffee (Coffea Arabica L.) accessions for developing superior cultivars in Rwanda. Twenty-one coffee accessions established in 1990 in an un-replicated field experiment at the Rubona Experimental Station of the Rwanda Agriculture Board (RAB) located in the mid-altitude zone of Rwanda, were used in the study. Data were recorded on three randomly selected trees on eight quantitative morphological traits in each accession in 2013. One-way analysis of variance (ANOVA) indicated highly significant (p 0.01) differences among the accessions for number of primary branches, number of leaves per branch, number of cherries per internode and % coffee leaf rust disease rating;and significant (p 0.05) for yield, but not for internode length, weight of 100 cherries, and number of internodes per branch. Multivariate analysis showed that the first three principal components contributed cumulatively to 78.3% of the total variation. The PCA biplot grouped all the accessions into three different clusters and one singleton. The first and second PCs accounted for 43% and 21%, respectively. Cluster I and II grouped accessions with valuable quantitative agronomic traits while accessions in cluster III exhibited poor agronomic performance. The highest inter cluster distance of 475 was observed between cluster I and II, and the highest intra-cluster distance (62) was in cluster II. The phenotypic markers provided a useful measure of genetic distances among the coffee accessions and identified potential donors for future breeding efforts.