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Spatio-temporal variation of soil moisture in a fixed dune at the southern edge of the Gurbantunggut Desert in Xinjiang, China

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Journal of Arid Land 2019年第5期11卷 685-700页

作者： ZHU Hai HU Shunjun YANG Jingsong fidele karamage LI Hao FUSihua State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008China State Key Laboratory of Desert and Oasis Ecology Xinjiang Institute of Ecology and GeographyChinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China Akesu National Station of Observation and Research for Oasis Agro-ecosystem Aksu 843017China Nanjing Institute of Geography and Limnology Chinese Academy of SciencesNanjing 210008China

Soil moisture is critical for vegetation growth in ***,detailed data regarding the soil moisture distribution in space and time in the Gurbantunggut Desert of China have not yet been *** this study,we conducted a series of in situ observation experiments in a fixed sand dune at the southern edge of the Gurbantunggut Desert from February 2014 to October 2016,to explore the spatio-temporal variation of soil moisture content,investigate the impact of Haloxylon ammodendron(***.)Bungeon soil moisture content in its root zone,and examine the factors influencing the soil moisture spatial ***-way analysis of variance,least significant difference tests and correlation analysis were used to analyze the *** results revealed that the soil moisture content exhibited annual periodicity and the temporal variation of soil moisture content throughout a year could be divided into three periods,namely,a moisturegaining period,a moisture-losing period and a moisture-stable *** to the temporal and spatial variability,the 0–400 cm soil profile could be divided into two layers:an active layer with moderate variability and a stable layer with weak *** temporal variability was larger than the spatial variability in the active layer,and the mean profile soil moisture content at different slope positions displayed the trend of decreasing with increasing relative height and mainly followed the order of interdune area>west and east slopes>slope *** mean profile soil moisture content in the root zone of dead *** individuals was significantly higher than that in the root zones of adult and young individuals,while the soil moisture content in the root zone of adult individuals was slightly higher than that in the root zone of young individuals with no significant *** spatial pattern of soil moisture was attributable to the combined effects of snowfall,vegetation and soil texture,whereas the effects of rainfall a

关键词： fixed sand dune soil moisture root zone Haloxylon ammodendron Gurbantunggut Desert

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Monitoring Forest Cover Change and Fragmentation Using Remote Sensing and Landscape Metrics in Nyungwe-Kibira Park

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Journal of Geoscience and Environment Protection 2016年第11期4卷 13-33页

作者： Alphonse Kayiranga Alishir Kurban Felix Ndayisaba Lamek Nahayo fidele karamage Abdimijit Ablekim Haiwen Li Osman Ilniyaz State Key Laboratory of Desert and Oasis Ecology Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Urumqi China University of Chinese Academy of Sciences (UCAS) Beijing China University of Lay Adventists of Kigali (UNILAK) Kigali Rwanda

The objective of this study was to evaluate forest cover change and forest degradation in Nyungwe-Kibira Park, a natural reserve straddling Rwanda and Burundi from 1986 to 2015. Landsat TM, ETM+ and 8OLI images of 30 m spatial resolution were used as primary datasets. Geographic Information System (GIS) techniques were used for forest cover mapping and landscape metrics were calculated by using FRAGSTATS software. Classification and change analysis of forest cover type and landscape patterns analysis were carried out. In addition, to analyze the correlated external disturbances, the buffer zone of 5 Km was delineated outside the boundary of Nyungwe-Kibira Park. The results revealed that in among 5 land cover classes considered within the Park, the dominant one was dense forest class covering over 70% of the entire Park area while in the buffer zone cultivated and open land dominated at over 90% between the years 1986 and 2015. Change detection highlighted that within Nyungwe-Kibira forest, approximately 0.27% (4.97 Km2) of forest cover was cleared while 0.07% (1.22 Km2) was regenerated annually. In the buffer zone, the annual cleared forest cover was about 0.76% (13.02 Km2). The five landscape indices chosen at class level indicated a considerable fragmentation of forest inside the Park and the highest fragmentation in the buffer zone. Indeed, these results shed a bleak image over the future of the Nyungwe-Kibira forest that should be helpful for the policy-makers and managers of these natural parks to establish adequate policies to mitigate the forest loss and degradation by implementing quick and effective solutions.

关键词： Burundi Forest Management Landscape Analysis Nyungwe-Kibira Park Remote Sensing Rwanda

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

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Journal of Environmental Protection 2017年第4期8卷 464-481页

作者： Felix Ndayisaba Hao Guo Alain Isabwe Anming Bao Lamek Nahayo Garee Khan Alphonse Kayiranga fidele karamage Enan Nyesheja Muhire State Key Laboratory of Desert and Oasis Ecology Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Urumqi China University of Chinese Academy of Sciences Beijing China Aquatic EcoHealth Group Key Laboratory of Urban Environment and Health Institute of Urban Environment Chinese Academy of Sciences Xiamen China University of Lay Adventists of Kigali (UNILAK) Kigali 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.

关键词： MODIS NDVI Mann Kendall Test Vegetation Health Rwanda Climate

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The Need for Awareness of Drinking Water Loss Reduction for Sustainable Water Resource Management in Rwanda

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Journal of Geoscience and Environment Protection 2016年第10期4卷 74-87页

作者： fidele karamage Chi Zhang Felix Ndayisaba Lamek Nahayo Alphonse Kayiranga James Kehinde Omifolaji Hua Shao Alice Umuhoza Jean Baptiste Nsengiyumva Tong Liu State Key Laboratory of Desert and Oasis Ecology Xinjiang Institute of Ecology and Geography Chinesee Academy of Sciences Urumqi China University of Chinese Academy of Sciences Beijing China University of Lay Adventists of Kigali Kigali Rwanda College of Science and Technology University of Rwanda Kigali Rwanda Ministry of Disaster Management and Refugee Affairs (MIDIMAR) Kigali Rwanda College of Life Science Shihezi University Shihezi China

Drinking water loss or Non-Revenue Water (NRW) threatens the financial viability of water utilities and sustainable natural water resource management. However, little attention has been paid to quantitative assessment of the spatial distribution of water losses in Rwanda. Therefore, this study focused on the magnitude of water losses, the associated environmental and socio-economic consequences, as well as the potential benefits from water loss reduction in Rwanda. Based on water usage records from the Water and Sanitation Corporation (WASAC) of Rwanda, NRW was calculated for 15 WASAC branches and Provinces, from July 2013 to June 2014, by using the International Water Association (IWA) standard water balance approach. The results highlight an annual NRW of 16,502,198 or 41% of the total water produced, inducing a revenue loss of US$ 8,713,156. In 14 of the 15 WASAC water branches and all Rwandan provinces, the NRW ratios exceed the NRW threshold (10%) recommended by the American Water Works Association (AWWA). Because of the lost revenue, the water facilities may not expand quickly enough to meet the demands of the rapidly growing population. The suggested 50% reduction in NRW would provide additional 8,251,100 m3 of treated water yearly, enough to serve extra 41,925 households or irrigate 661 ha of cropland and save US$ 4,356,579, which would reduce the financial gap in Rwanda’s National Water Improvement Project by more than 24%.

关键词： Non-Revenue Water Water Loss Reduction Sustainability WASAC Rwanda

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