Alphonse Kayiranga

Chinese Academy of Sciences

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Felix Ndayisaba

Ghent University

Fidele Karamage

Nanjing University of Information Science and Technology

Huifang Zhang

Institute of Geographic Sciences and Natural Resources Research

Lamek Nahayo

Chinese Academy of Sciences

Baozhang Chen

Chinese Academy of Sciences

Simon Measho

Institute of Geographic Sciences and Natural Resources Research

Fabien Muhirwa

Institute of Geographic Sciences and Natural Resources Research

Hubert Hirwa

Chinese Academy of Sciences

Christophe Mupenzi

University of Lay Adventists of Kigali

Lifeng Guo

Chinese Academy of Meteorological Sciences

Cooperative Institutions

Chinese Academy of Sciences

University of Chinese Academy of Sciences

Xinjiang Institute of Ecology and Geography

Institute of Geographic Sciences and Natural Resources Research

Research Center for Ecology and Environment of Central Asia

University of Lay Adventists of Kigali

Nanjing University of Information Science and Technology

Joint Research Center

Institute of Ecology and Geography

State Key Laboratory of Desert and Oasis Ecology

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Analysis of Climate and Topography Impacts on the Spatial Distribution of Vegetation in the Virunga Volcanoes Massif of East-Central Africa

Geosciences (2017)

Alphonse Kayiranga Felix Ndayisaba Lamek Nahayo Fidele Karamage Jean Baptiste Nsengiyumva

This paper aimed to investigate the influence of climatic and topographic factors on the distribution of vegetation in the Virunga Volcanoes Massif using GIS and remote sensing techniques. The climatic variables considered were precipitation, Land Surface Temperature (LST), and evapotranspiration (ET), whereas the topographic factors considered were elevation and aspect. The dataset consisted of MODIS NDVI data, satellite-delivered precipitation, ET, and the LST. A 2014 Landsat 8 OLI image was used to produce a vegetation map of the study area, while DEM was used to derive the elevation attributes and to calculate the aspect angles. Moran’s I and Geographically Weighted Regression (GWR) Model was used to analyze the relationships between the climatic factors and NDVI changes over elevation and aspect. The results indicated that among the nine vegetation types inventoried in the area, the Mean NDVI varied from 0.33 to 0.59 and the optimal vegetation growth was found at an elevation between 2000 and 3900 m, with mean NDVI values larger than 0.50. The peak mean NDVI value of 0.59 was found at the elevation from 2100 to 2800 m. Vegetation growth was found to be more sensitive to elevation, as NDVI values were more varied at a lower elevation (<4000 m) than at a higher elevation (>4000 m). Considering the aspect, the greater vegetation growth was found in SE (132°, 148°), SW (182°, 186°), and NW (309.5°–337.5°), with mean NDVI values larger than 0.56. This indicated that vegetation was susceptible to better growth conditions in the lower elevation ranges and in shady areas. The vegetation NDVI in this study area was mostly uncorrelated with precipitation (R2 = 0.34), but was strongly correlated with LST (R2 = 0.99) and ET (R2 = 98). LST (≥18 °C) and ET (1286 mm/year−1) were found to provide optimal conditions for vegetation growth in the Virunga Volcanoes Massif. Empirically, the results concluded that elevation, aspect, LST, and ET are the main factors controlling the spatial distribution and vegetation growth in this area. This information is significantly helpful for biodiversity conservation and constitutes a valuable input to environmental and ecological research.

Elevation (ballistics)

Massif

10.3390/geosciences7010017

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Citations (24)

Reconstructing monthly 0.25° terrestrial evapotranspiration data in a remote arid region using Bayesian-driven ensemble learning method

Journal of Hydrology (2024)

Friday Uchenna Ochege Xiuliang Yuan Ifeanyichukwu Clinton Ezekwe Qing Ling Vincent Nzabarinda

Ensemble Learning

10.1016/j.jhydrol.2024.131115

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Citations (0)

Spatiotemporal variations of forest ecohydrological characteristics in the Lancang-Mekong region during 1992-2016 and 2020-2099 under different climate scenarios

Agricultural and Forest Meteorology (2021)

Alphonse Kayiranga Baozhang Chen Lifeng Guo Simon Measho Hubert Hirwa

Biometeorology

Representative Concentration Pathways

Baseline (sea)

10.1016/j.agrformet.2021.108662

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Citations (13)

Spatial pattern assessment of Lake Kivu basin rivers water quality using National Sanitation Foundation Water Quality and Rivers Pollution Indices

Desalination and Water Treatment (2017)

Christophe Mupenzi Lanhai Li Lamek Nahayo Amobichukwu Chukwudi Amanambu Alphonse Kayiranga

Spatial variation of water quality in rivers is a function of the surrounding environment and land, the reason why water indices are important to reduce the bulk of information into a simplified and understandable manner for specific purposes.This study aimed at assessing the spatial distribution of water quality of 23 Rwandan rivers that drain into the Lake Kivu by using the National Sanitation Foundation Water Quality Index (NSFWQI) and the River Pollution Index (RPI).The study collected field data and analyzed the parameters of the NSFWQI and RPI including suspended solids, turbidity, biological oxygen demand, nitrate, temperature, total phosphorus, pH, fecal coliform and dissolved oxygen.For gathering details related to entities adjacent to rivers, land use and land cover, topography and rainfall have been analyzed.The results showed that good water quality (negligibly polluted) was located in areas dominated by forestland while bad and very bad (39%, 26%) classes of rivers (severely polluted) were influenced by the dominance of farmland.Moreover, 22% of rivers in medium class were equivalent to 26% moderately polluted due to the disturbance of other land use types and other factors such as slope and tropical rainfall.

Turbidity

Dominance (genetics)

Biochemical oxygen demand

Total suspended solids

10.5004/dwt.2017.21566

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Insights on Water and Climate Change in the Greater Horn of Africa: Connecting Virtual Water and Water-Energy-Food-Biodiversity-Health Nexus

Sustainability (2021)

Hubert Hirwa Qiuying Zhang Yunfeng Qiao Yu Peng Peifang Leng

Water is the key limiting factor in socioeconomic and ecological development, but it is adversely affected by climate change. The novel virtual water (VW) concept and water, energy, food, biodiversity, and human health (WEFBH) nexus approach are powerful tools to assess the sustainability of a region through the lens of climate change. Climate change-related challenges and water are complex and intertwined. This paper analyzed the significant WEFBH sectors using the multicriteria decision-making (MCDM) and analytic hierarchy process (AHP) model. The AHP model demonstrated quantitative relationships among WEFBH nexus sustainability indicators in the Greater Horn of Africa countries. Besides, the net VW imports and water footprints of major staple crops were assessed. The composite WEFBH nexus indices varied from 0.10 to 0.14. The water footprint of crops is increasing period by period. The results also revealed that most countries in the study area are facing WEFBH domains unsustainability due to weak planning or improper management strategies. The strong policy constancy among the WEFBH sector is vital for dissociating the high-water consumption from crop production, energy, environmental, and human health system. Thus, this study enhances insights into the interdependencies, interconnectedness, and interactions of sectors thereby strengthening the coordination, complementarities, and synergies among them. To attain sustainable development, we urgently call all public and private entities to value the amount of VW used in their daily activities and design better policies on the complex WEFBH nexus and future climate change.

Virtual water

Water use

10.3390/su13116483

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Citations (35)

Suitability Analysis for Resettlement Potential Sites of Flood Vulnerable Community in Kigali city, Rwanda

Earth Systems and Environment (2024)

David Izere Lanhai Li Richard Mind’je Alphonse Kayiranga Edovia Dufatanye Umwali

10.1007/s41748-024-00387-z

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Citations (1)

Understanding the Spatial Temporal Vegetation Dynamics in Rwanda

Remote Sensing (2016)

Felix Ndayisaba Hao Guo Anming Bao Hui Guo Fidele Karamage

Knowledge of current vegetation dynamics and an ability to make accurate predictions of ecological changes are essential for minimizing food scarcity in developing countries. Vegetation trends are also closely related to sustainability issues, such as management of conservation areas and wildlife habitats. In this study, AVHRR and MODIS NDVI datasets have been used to assess the spatial temporal dynamics of vegetation greenness in Rwanda under the contrasting trends of precipitation, for the period starting from 1990 to 2014, and for the first growing season (season A). Based on regression analysis and the Hurst exponent index methods, we have investigated the spatial temporal characteristics and the interrelationships between vegetation greenness and precipitation in light of NDVI and gridded meteorological datasets. The findings revealed that the vegetation cover was characterized by an increasing trend of a maximum annual change rate of 0.043. The results also suggest that 81.3% of the country’s vegetation has improved throughout the study period, while 14.1% of the country’s vegetation degraded, from slight (7.5%) to substantial (6.6%) deterioration. Most pixels with severe degradation were found in Kigali city and the Eastern Province. The analysis of changes per vegetation type highlighted that five types of vegetation are seriously endangered: The “mosaic grassland/forest or shrubland” was severely degraded, followed by “sparse vegetation,” “grassland or woody vegetation regularly flooded on water logged soil,” “artificial surfaces” and “broadleaved forest regularly flooded.” The Hurst exponent results indicated that the vegetation trend was consistent, with a sustainable area percentage of 40.16%, unsustainable area of 1.67% and an unpredictable area of 58.17%. This study will provide government and local authorities with valuable information for improving efficiency in the recently targeted countrywide efforts of environmental protection and regeneration.

Enhanced vegetation index

Shrubland

10.3390/rs8020129

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Citations (69)

USLE-Based Assessment of Soil Erosion by Water in the Nyabarongo River Catchment, Rwanda

International Journal of Environmental Research and Public Health (2016)

Fidele Karamage Chi Zhang Alphonse Kayiranga Hua Shao Xia Fang

Soil erosion has become a serious problem in recent decades due to unhalted trends of unsustainable land use practices. Assessment of soil erosion is a prominent tool in planning and conservation of soil and water resource ecosystems. The Universal Soil Loss Equation (USLE) was applied to Nyabarongo River Catchment that drains about 8413.75 km² (33%) of the total Rwanda coverage and a small part of the Southern Uganda (about 64.50 km²) using Geographic Information Systems (GIS) and Remote Sensing technologies. The estimated total annual actual soil loss was approximately estimated at 409 million tons with a mean erosion rate of 490 t·ha(-1)·y(-1) (i.e., 32.67 mm·y(-1)). The cropland that occupied 74.85% of the total catchment presented a mean erosion rate of 618 t·ha(-1)·y(-1) (i.e., 41.20 mm·y(-1)) and was responsible for 95.8% of total annual soil loss. Emergency soil erosion control is required with a priority accorded to cropland area of 173,244 ha, which is extremely exposed to actual soil erosion rate of 2222 t·ha(-1)·y(-1) (i.e., 148.13 mm·y(-1)) and contributed to 96.2% of the total extreme soil loss in the catchment. According to this study, terracing cultivation method could reduce the current erosion rate in cropland areas by about 78%. Therefore, the present study suggests the catchment management by constructing check dams, terracing, agroforestry and reforestation of highly exposed areas as suitable measures for erosion and water pollution control within the Nyabarongo River Catchment and in other regions facing the same problems.

10.3390/ijerph13080835

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Citations (61)

Assessment of Vegetation Dynamics and Ecosystem Resilience in the Context of Climate Change and Drought in the Horn of Africa

Remote Sensing (2021)

Simon Measho Baozhang Chen Petri Pellikka Lifeng Guo Huifang Zhang

Understanding the response of vegetation and ecosystem resilience to climate variability and drought conditions is essential for ecosystem planning and management. In this study, we assessed the vegetation changes and ecosystem resilience in the Horn of Africa (HOA) since 2000 and detected their drivers based mainly on analysis of the Moderate Resolution Imaging Spectroradiometer (MODIS) products. We found that the annual and seasonal trends of NDVI (Normalized Difference Vegetation Index) generally increased during the last two decades over the Horn of Africa particularly in western parts of Ethiopia and Kenya. The weakest annual and seasonal NDVI trends were observed over the grassland cover and tropical arid agroecological zones. The NDVI variation negatively correlated with Land Surface Temperature (LST) and positively correlated with precipitation at a significant level (p < 0.05) account for 683,197 km2 and 533,385 km2 area, respectively. The ecosystem Water Use Efficiency (eWUE) showed overall increasing trends with larger values for the grassland biome. The precipitation had the most significant effect on eWUE variation compared to LST and annual SPEI (Standardized Evapotranspiration Index). There were about 54.9% of HOA resilient to drought disturbance, whereas 32.6% was completely not-resilient. The ecosystems in the humid agroecological zones, the cropland, and wetland were slightly not-resilient to severe drought conditions in the region. This study provides useful information for policy makers regarding ecosystem and dryland management in the context of climate change at both national and regional levels.

Biome

10.3390/rs13091668

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Citations (20)

The implementation of genetic algorithm for the identification of DNAPL sources

Groundwater for Sustainable Development (2021)

Telesphore Habiyakare Na Zhang Chuhan Feng Fabrice Ndayisenga Alphonse Kayiranga

Identification

Groundwater Pollution

10.1016/j.gsd.2021.100707

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Citations (7)