Rwanda Journal of Engineering, Science, Technology and Environment

Stabilization of Expansive Subgrade Soil with Cow Dung Ash and Lime

Jacqueline Nikuze — 2024-07-19

This paper presents the investigation made on cow dung ash (CDA) alone and a combination of CDA and lime for stabilizing expansive black clay soil with high plasticity used as a subgrade for road pavement. The study was mainly conducted to assess the performance of expansive black clay soil when stabilized with CDA and lime, and its suitability to solve the issue of structural damage identified on the road. The chemical compositions of lime, CDA, and natural unstabilized subgrade soil (control) were determined using X-ray fluorescence. The plastic limit (PL), plasticity index (PI), liquid limit (LL), linear shrinkage (LS), maximum dry density (MDD), optimum moisture content (OMC), free swell index (FSI), California bearing ratio (CBR) and unconfined compressive strength (UCS) of the control soil, the control soil mixed with varying quantities (0%, 6%, 10%, 14%, 20%, and 25% by dry weight of the soil) of CDA, and the control soil mixed with varying CDA-lime combinations consisting of mixtures of 5% lime with 10%,15% and 20% of CDA were determined experimentally. The experimental outcomes showed that the soil stabilized with the CDA-lime combination is synergistic, improves the CBR and UCS and lowers the PI, and swelling potential of the soil more than the soil stabilization with CDA alone.

Asymmetry of Leaf Plates of Elm Stick under Industrial Zone Conditions

Rahimov Tulkin Ukhtamovich — 2024-07-19

Assessment of the environmental quality of the industrial zones of the Kashkadarya region was carried out using fluctuating asymmetry of the elm leaves of the squat (Ulmus pumila L.). The method used was based on identifying violations of the symmetry of the development of a leaf plate of a tree species under the influence of anthropogenic factors, where the extent of asymmetry reflects the relative strength of impact. Ulmus pumila L. leaf samples were taken at 4 points in the Kashkadarya region at various recreational sites with different anthropogenic loads and remoteness from the main sources of pollution. The leaves of Ulmus pumila L. in the areas surveyed were characterized by the presence of asymmetry to various extents exceeding the relative magnitude of the normal variance. At the same time, in Muborak Gas Processing Plant and Shurtan Gas Processing Plant, the average index of fluctuating asymmetry corresponded to grade IV on the scale of environmental quality assessment, which is characterized as a critical state of the environment.

Ecosystem Services and Land Degradation in Gishwati-Mukura Corridor, Rwanda: Cost-Benefit of Sustainable Land Management Practices

Jean Pierre Bizimana — 2024-07-19

Gishwati and Mukura Forests are among the fragile ecosystems that face high rates of land degradation in terms of deforestation, loss of biodiversity, soil erosion and landslides because of intense agriculture and overgrazing, and mining activities. Sustainable land management practices are therefore needed for restoring ecosystem services within Gishwati-Mukura Corridor. Four scenarios that have been considered include (1) business as usual where costs and benefits of the current land use systems were analyzed; (2) landscape restoration by terracing, agroforestry, use of fertilizers and improved seeds; (3) restoration by planting and retaining exotic species (eucalyptus); and (4) restoration by planting and retaining indigenous species. Data were collected through the Focus Groups Discussions. Geographic Information Systems (GIS) analysis helped to calculate the land area for afforestation, grazing, and cropping. Google Earth image was also used to digitize and estimate the number of households to be compensated. A cost-benefit analysis was performed to compare the implementation costs of sustainable land management against its benefits. Sensitivity analysis was also carried out to determine how target variables are affected based on changes in other variables to know the most sensitive parameters and the land management option that provides the best Net Present Value (NPV). Results show that the restoration by exogenous species offers the highest economic and environmental benefits with a NPV of 40,690,477.7 USD. This is followed by the sustainable land management option with a NPV of 34,048,663.7 USD and the business-as-usual scenario with a NPV of 21,915,102.8 USD. The rehabilitation of the corridor by exogenous species is less profitable as it shows a NPV of - 9494381.7 USD. Under all scenarios, the NPV is more influenced by changes in input and output than the discount rate. However, an increase in input prices leads to higher negative changes in NPV. Moreover, NPV is positively affected by an increase in output prices, implying high demands and high prices for food products (milk and Irish potatoes). Although maize cropping offers high economic returns to local communities, it requires however huge investments. Local communities can bear the costs of soil conservation and fertility improvement when there is a potential for an increased yield and good price of their agricultural products.

Segmentation of Prostate Cancer in MRI Using Deep Learning

Muhayimana Odette — 2024-07-19

Prostate cancer is one of the most causes of cancer deaths for men worldwide and it is still a significant public health problem. However, prostate cancer can be cured if detected at an early stage. Due to its ability to produce detailed anatomical structures, Magnetic Resonance Imaging (MRI) is one of the most used modalities for prostate cancer diagnosis and treatment. The accurate segmentation of the prostate from MRI is crucial for diagnosis and treatment planning of prostate cancer. Deep learning has provided important support in early disease detection, and image processing analysis, especially in image classification, image registration, image segmentation and medical treatment plans. In this paper, we propose an automatic segmentation of the prostate in MRI based on deep learning methods. A convolutional Neural Network special type named 3D UNet is used to segment the prostate in MRI. We conducted the 10-fold cross- validation experiments on the public Promise 12 Data set of 50 prostate images and achieved a mean Dice similarity coefficient of 84.92% and a mean Hausdorff distance of 5.3 mm. The experiments proved that the proposed algorithm performed with promising results.

Ethnobotany Survey of Medicinal Plants in Home Gardens around Volcanoes National Park, Rwanda

Fabien Rizinjirabake — 2024-07-19

Home gardens show evidences of medicinal plant use and are good places to provide information about plant health practices and biocultural knowledge transfer. In Rwanda there no enough information related to home gardens of medicinal plants. This ethnobotanical study of medicinal plant in home gardens was conducted in that perspective to document medicinal plants in domestic gardens. The study was conducted in home gardens around Volcanoes National Park (VNP) in Musanze and Burera Districts of the Northern Province of Rwanda. The study was conducted in Kinigi Sector in Musanze District, and Cyanika and Gahunga Sectors in Burera District. The objective of the study was to document medicinal plants used to treat human diseases in home gardens around VNP. This is fruitful for biodiversity conservation as domestication of medicinal plants found inside the park, reduces park encroachment and local communities and park manager conflicts. Data were collected by using stratified sampling method, semi-structured interview, and field observation. About 200 households were surveyed and adult household members, men or women, interviewed. A total of 40 medicinal plant species existing in the VNP and belonging to 22 plant families were recorded in home gardens in study area. Lamiaceae, Asteraceae, Rubiaceae and Euphobiaceae were most frequent plant families. Regarding used plant organs, leaves were the most plant organ used whereas barks, roots and fruits were the least used plant organs in study area. Maesa lanceolata was the medicinal plant species for which all stated plant organs are used. The medicinal plants recordee in home gardens in the study area were found to play a vital role in treatment of human diseases include malaria, kidney diseases, stomach diseases, aches, liver diseases, skin diseases, Influenza, gonorrhea, diarrhea and asthma and more others.

Perception and Knowledge of Local Community on the Use of Indigenous Tree Species for Ecosystem Restoration in Gasabo District, Rwanda

Mukeshimana Elias — 2024-07-19

Ecosystem restoration assists in the recovery of ecosystems degraded or destroyed by anthropogenic. This degradation poses significant negative impacts on ecosystem services and restoration is a mandatory approach to reverse the situation. This study aimed at assessing the perceptions and knowledge of the local community on utilization of indigenous trees for ecosystem restoration in order to optimize the delivery of ecosystem services and boost the collaboration among community members. The study was conducted in Gasabo District in seven sectors of Bumbogo, Gatsata, Jali, Kimihurura, Kacyiru, Gisozi, and Nduba. Semi-structured interviews, self- administered questionnaires and group discussion techniques were used to explore the perceptions and knowledge of local communities on the use of indigenous tree species for ecosystem. Data analysis was performed using Excel Microsoft and descriptive statistics was used to calculate the frequencies and percentages. The study indicated that most of the trees are used as agroforestry and that trees are mainly propagated by planting seedlings (72.9%) The most dominant agro-forestry trees are Ficus thoningii (73.6%), Vernonia amygdalina (54.3%) and Dracaena afromontana (52.1%). Other identified indigenous trees used to restore the ecosystem Croton megalocarpus, Markamia luthea, Maesopsis eminii, and Erythrina abyssinica. The local communities prefer indigenous trees that are identified most resistant to the climatic condition stress such as Euphorbia tirucalli (77.1%), Markhamia lutea (42.9%) and Dracaena afromontana (40%). The study found that two of these resistant trees (Markhamia lutea and Dracaena afromontana) are disappearing together with Ficus thoningi and at the rate respectively of 70%, 64.3%, and 75%. The main constraints faced by the local communities are lack of seeds or seedlings (83.6%), urbanization (82.9%), and high demand for medicinal use (75.7%). Regarding the importance of the ecosystem services, the local communities mentioned adventure and ecotourism exploration (41.8%), agriculture and erosion control (31.4%) and Wildlife conservation (24.3%). The ecosystem restoration using indigenous trees is accepted by local communities but it is threatened mainly by the lack of indigenous seedlings. All people should be then mobilized to avail indigenous tree seedlings for ecosystem restoration, biodiversity conservation and ecosystem services.

Assessment of Awareness Level of Green Building Concepts in Kigali Commercial Property Development

Marc Minani — 2024-07-19

The construction industry is one of the main energy consumers and emitters of greenhouse gases (GHG), generating about 23-40% of the world's greenhouse gas emissions. Recently, the construction industry has performed poorly in terms of environmental protection. The construction sector in developing countries, including Rwanda, is characterized by excessive resource consumption, resulting in habitat loss, land degradation, air and water pollution. This has exacerbated the global warming crisis and led to the development of green buildings. The objectives of this study is to analyze the level of awareness of green building concepts by building construction players between 2013 and 2018 in Kigali; to examine to which extent the green building concepts have been adopted in the Kigali City by the construction industry and to identify the factor impeding the implementation of green building concepts with the aim of identifying appropriate strategies for implementing sustainably these concepts. The study was conducted using a questionnaire, interviews, and observations for green building concepts data collection. Data from survey questionnaire were assigned numerical values and analyzed quantitatively using mean item score and percentages. For closed ended questions, the data analysis involved the use of statistical program for social sciences and Microsoft office excel. The Data from interview schedules were transcribed, coded and categorized to facilitate the analysis of the information provided. It also reviewed secondary data from existing green building concepts documents, including journals and books. The study findings showed that 90.2% of the players in construction industry participated in the recently constructed commercial buildings in Kigali and were aware of the green building concepts and regulations. However, only 17.9% of the concepts were taken into account in building process. The findings reveal a lack of enforcement of sustainable building policies. Stakeholders in construction are unaware of green building concepts; didn’t benefit neither empowerment not incentives from the government. This constitutes the biggest obstacles faced by practitioners in the adoption of green building concepts. Some strategies were recommended to promote uptake of the concepts including the development of sustainability checklist by local authority, availability of financial incentives like green loans, recognizing and certifying sustainable buildings as well as improved enforcement by local governments. The study concluded that administrative management and policies are needed to implement sustainable building concepts as well as introduction of incentives.