Accurate,reliable,and regularly updated information is necessary for targeted management of forest stands.This information is usually obtained from sample-based field inventory data.Due to the time-consuming and costl...Accurate,reliable,and regularly updated information is necessary for targeted management of forest stands.This information is usually obtained from sample-based field inventory data.Due to the time-consuming and costly procedure of forest inventory,it is imperative to generate and use the resulting data optimally.Integrating field inventory information with remote sensing data increases the value of field approaches,such as national forest inventories.This study investigated the optimal integration of forest inventory data with aerial image-based canopy height models(CHM)for forest growing stock estimation.For this purpose,fixed-area and angle-count plots from a forest area in Austria were used to assess which type of inventory system is more suitable when the field data is integrated with aerial image analysis.Although a higher correlation was observed between remotely predicted growing stocks and field inventory values for fixed-area plots,the paired t-test results revealed no statistical difference between the two methods.The R2 increased by 0.08 points and the RMSE decreased by 7.7 percentage points(24.8m^(3)·ha^(−1))using fixed-area plots.Since tree height is the most critical variable essential for modeling forest growing stock using aerial images,we also compared the tree heights obtained from CHM to those from the typical field inventory approach.The result shows a high correlation(R^(2)=0.781)between the tree heights extracted from the CHM and those measured in the field.However,the correlation decreased by 0.113 points and the RMSE increased by 4.2 percentage points(1.04m)when the allometrically derived tree heights were analyzed.Moreover,the results of the paired t-test revealed that there is no significant statistical difference between the tree heights extracted from CHM and those measured in the field,but there is a significant statistical difference when the CHM-derived and the allometrically-derived heights were compared.This proved that image-based CHM can obtain more accurate tree height information than field inventory estimations.Overall,the results of this study demonstrated that image-based CHM can be integrated into the forest inventory data at large scales and provide reliable information on forest growing stock.The produced maps reflect the variability of growth conditions and developmental stages of different forest stands.This information is required to characterize the status and changes,e.g.,in forest structure diversity,parameters for volume,and can be used for forest aboveground biomass estimation,which plays an important role in managing and controlling forest resources in mid-term forest management.This is of particular interest to forest managers and forest ecologists.展开更多
Water is at the core of sustainable development and is critical for socio-economic development, healthy ecosystems and for human survival. This research study has been carried out in Nakuru County, a tropical region i...Water is at the core of sustainable development and is critical for socio-economic development, healthy ecosystems and for human survival. This research study has been carried out in Nakuru County, a tropical region in the Rift Valley of Kenya, bounded between latitude 0.28°N and 1.16°S, and longitude 36.27°E and 36.55°E. The objective of the study has been to use GIS and remote sensing in assessment of water scarcity using Land use Land cover area changes, standard precipitation index and crop yields. Landsat satellite images for the year 1985, 1995, 2005 and 2015 were used. Classification was done using maximum likelihood algorithm while classification accuracy assessment entailed the use of confusion matrix method and ground truth data. Post classification change detection results gave percentage cropland areas as 21% in 1985, 29% in 1995, 53% in 2005 and also 53% in 2015. Eleven (11) ground rainfall stations and TRMM satellite rainfall data from 1985 to 2015 has been used to show meteorological drought. Validation of rainfall data done using correlation coefficient (R2) and root mean square (RMS) methods showed that ground rainfall data and TRMM data correlate. Modelling of 3 months SPI for each of the three seasons (MAM, JJA and OND) has been done using interpolation distance weighted method (IDW). 3 months SPI time scales curves gave October 1987 May 1993, and July 2004 as water scarce and dry seasons and were categorized as either Normal, moderately dry, severely dry and extremely dry. Crop yield trends curves showed crop yield decrease in this identified water scarce and dry years. Conclusion reached is that crop yields is not dependent on size of land ploughed only but mostly on rainfall quantities. Therefore, the findings of this research can be used as drought monitoring tools.展开更多
Urban Heat Island (UHI) is a phenomenon characterized by higher surface and atmospheric temperatures in urbanized areas as compared to the surrounding rural areas. This phenomenon is a consequence of increase in Land ...Urban Heat Island (UHI) is a phenomenon characterized by higher surface and atmospheric temperatures in urbanized areas as compared to the surrounding rural areas. This phenomenon is a consequence of increase in Land Surface Temperatures (LST) as a result of trapped heat energy on the surface. The objective of this study is establishing the trends in and relationship between LST and land use/land cover in Nakuru County as it seeks to achieve the ultimate goal to contain the UHI effect. Urban heat island inference was based on the generation of a time series set of Landsat imagery, with particular emphasis on the thermal band. Land use/land cover mapping was conducted using maximum likelihood classification techniques, and this, like the LST, is generated in a time series fashion from 1989 to 2015. Accuracy assessment was conducted in order to give confidence in the classification results. The accuracy of the development was assessed using observed temperature data as recorded by the ground stations at the Kenya Meteorological Department. This study employed Normalized NDVI and NDBI to investigate the variation land use/land cover. Results revealed that over the years, settlement has been on an upward trend in terms of area whereas forests have been decreasing due to deforestation. Also, the land surface temperatures have been increasing over the years. In order to qualify this, the correlation between LST and Land Use change was conducted and it indicated that changes to settlement/urban increased proportionately with Land Surface Temperature.展开更多
Bilharzia is vector-borne disease carried by a parasite that is hosted by fresh water snails. The distribution of the disease is concurrent with the existence of the freshwater snails and </span></span><...Bilharzia is vector-borne disease carried by a parasite that is hosted by fresh water snails. The distribution of the disease is concurrent with the existence of the freshwater snails and </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">is </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">dependent on certain suitable environmental conditions. It is difficult to identify the specific habitats of the snails as they are often inaccessible on the ground, the snails also migrate by means of flowing water, making it difficult to keep a track of the freshwater snails’ habitat. This paper aimed at using GIS, Remote Sensing and Species Distribution Modelling techniques to model the suitable habitats for the freshwater snails and to prove that the snails migrate when there are sudden changes in water levels whilst showing the population at risk of bilharzia. The SDM used is the Maximum Entropy (MAXENT) for its ability to make right predictions even with small presence sites. The AUC value of the model was 0.951. The research results showed that the environmental variables;brightness Index, elevation, temperatures were negatively correlated with the snails’ presence while the wetness index, MSAVI, greenness index and soil pH were positively correlated. The snails are observed to favor clay soils of the montmorillonite type and the crop-lands land cover. Areas consistently submerged by water especially after flooding are shown to be the most suitable areas where snails migrate by means of river or canal water. The research proves that Mwea is not the source habitat of the freshwater snails. The neighboring sub-counties within Kirinyaga County should be investigated using such models as a likely source-habitat of the freshwater snails. Destroying the source habitats will lead to complete eradication of the freshwater snails within Mwea.展开更多
Soil moisture is an important parameter that drives agriculture, climate and hydrological systems. In addition, retrieval of soil moisture is important in the analysis as well as its influence on these systems. Radar ...Soil moisture is an important parameter that drives agriculture, climate and hydrological systems. In addition, retrieval of soil moisture is important in the analysis as well as its influence on these systems. Radar imagery is best suited for this retrieval due to its all-weather capability and independence from solar irradiation. Soil moisture retrieval was done for the Malinda Wetland, Tanzania, during two time periods, March and September 2013. The aim of this paper was to analyze soil moisture retrieval performance when vegetation contribution is taken into account. Backscatter values were obtained from TerraSAR-X Spotlight mode imagery taken in March and September 2013. The backscatter values recorded by SAR imagery are influenced by vegetation, soil roughness and soil moisture. Thus, in order to obtain the backscatter due to soil moisture, the roughness and vegetation contribution are determined and decoupled from total backscatter. The roughness parameters were obtained from a Digital Surface Model (DSM) from Unmanned Aerial Vehicle (UAV) photographs whereas the vegetation parameter was obtained by inverting the Water Cloud Model (WCM). Lastly, soil moisture was retrieved using the Oh Model. The coefficient of correlation between the observed and retrieved was 0.39 for the month of March and 0.65 in the month of August. When the vegetation contribution was considered, the r2 for March was 0.64 and that in August was 0.74. The results revealed that accounting for vegetation improved soil moisture retrieval.展开更多
When conditions are similar,more water evaporates from forest plantations than herbaceous vegetation,thereby affecting hydrological fluxes and ion transport in the soil.The vertical distribution of CaCO3 and Cl^-ions ...When conditions are similar,more water evaporates from forest plantations than herbaceous vegetation,thereby affecting hydrological fluxes and ion transport in the soil.The vertical distribution of CaCO3 and Cl^-ions shifts due to afforestation.The effect of groundwater depth and clay content were studied in the Great Hungarian Plain where forest area has been increasing for decades by analyzing soil and groundwater samples from stands of black locust(Robinia pseudoacacia,11 plots)and poplar(Populus spp.,11 plots).All study sites contained one herbaceous(control)and one or more forested plots.CaCO3 and Cl^-ions accumulated in the soil profile in greater quantities under tree cover than in the controls.The scale of this process largely depended on the species and on soil and ion properties.Under black locust,Cl^-accumulated between 1.3 and 6.3 m,with a maximum difference of 0.3 pCl unit(pCl is Cl^-activity,the negative of the logarithm to base 10 of the concentration of the chloride ion,determined using an ion-selective electrode,it is a dimensionless quantity.),while the difference in CaCO3 accumulation was at most 3.5%in some layers,compared to control plots.This result may be explained by the difference in the mobility of Ca+and Cl^-ions.Different mechanisms were noticeable under poplar plantations due to their higher water uptake:Cl-accumulation was detected below 0.9 m to the groundwater with a maximum difference of 0.5 pCl units,while CaCO3 accumulation was continuous at depths of 2.3–6.8 m with a maximum difference of 8.4%,compared to the controls.With increasing clay content,there was a discernible effect on CaCO3 and Cl-accumulation under black locust,but not observed under poplars.These differences were explained by the differences in water uptake mechanisms and root patterns of the two species and the different mobility of Ca2^+and Cl-ions.展开更多
The objective of this research was to harmonize political and administrative boundaries in Mavoko Constituency, Machakos County, Kenya, using geo-spatial technology and public consultation in order to address the nume...The objective of this research was to harmonize political and administrative boundaries in Mavoko Constituency, Machakos County, Kenya, using geo-spatial technology and public consultation in order to address the numerous disputes that exist. Specifically, the project focused on analyzing the existing electoral and administrative boundaries in the area of study by identifying all existing gaps and overlaps, rectifying the identified gaps and overlaps and created a web based geo-portal of the harmonized sub location boundaries to enable sharing. This was achieved through first putting the various datasets on the same Spatial Reference System and comparing them in order to identify and rectify them using various geospatial operations, public consultation and field work. The result was a single harmonized layer for the sub location data set for the study area. The project finally developed a customized GIS web based portal for sharing the harmonized Sub location boundary. This was uploaded on an open source platform, which has the capability for offline use in the field. The project worked on a hypothesis that if the sub location boundaries adopted by the various Government and Public organizations and individuals doing any kind of mapping in Kenya was a single harmonized data set, the emerging issues on boundary disputes between Counties, Constituencies and County Assembly Wards (CAW’s) would not occur. This is because there would be authentic, consisted and authoritative geo-information which maintains a harmonized, consistent, reusable and readily available data. The development of the geo portal ensured that the results of the research are easily accessible on www.msc2015boundariesmavoko.info.ke/mavoko.展开更多
The development of a web-based Geographic Information System for mass property valuation was the main focus of this research. The developed web GIS allows effective dissemination, extraction and analysis of mass land ...The development of a web-based Geographic Information System for mass property valuation was the main focus of this research. The developed web GIS allows effective dissemination, extraction and analysis of mass land valuation information over the Internet. It also allows for automation of the mass property valuation process by compiling a centralized mass valuation roll database. The Westlands Constituency, one of the administrative regions of the Nairobi City County was used as a case study. The research focused on automation of the mass property valuation roll by creating a centralized database that is accessible by all users on the web-based GIS portal. This was done by customizing and integrating a web-based GIS system based on open source QuantumGIS, GeoServer and PostgreSQL/PostGIS as a relational database. Leaflets APIs were used for the development of an interactive and friendly geographic user interface. The developed system enables users to view and interact with the spatial data. This improves the efficiency and effectiveness of the decision making process and data sharing for mass property valuation and optimal property taxation purposes.展开更多
Urban land-use modeling has gained increased attention as a research topic over the last decade. This has been attributed to advances in remote sensing and computing technology that now can process several models simu...Urban land-use modeling has gained increased attention as a research topic over the last decade. This has been attributed to advances in remote sensing and computing technology that now can process several models simultaneously at regional and local levels. In this research we implemented a cellular automata (CA) urban growth model (UGM) integrated in the XULU modeling frame-work (eXtendable Unified Land Use Modeling Platform). We used multi-temporal Landsat satellite image sets for 1986, 2000 and 2010 to map urban land-use in Nairobi. We also tested the spatial effects of varying model coefficients. This approach improved model performance and aided in understanding the particular urban land-use system dynamics operating in our Nairobi study area. The UGM was calibrated for Nairobi and predicted development was derived for the city for the year 2030 when Kenya plans to attain Vision 2030. Observed land-use changes in urban areas were compared to the results of UGM modeling for the year 2010. The results indicate that varying the UGM model coefficients simulates urban growth in different directions and magnitudes. This approach is useful to planners and policy makers because the model outputs can identify specific areas within the urban complex which will require infrastructure and amenities in order to realize sustainable development.展开更多
Kenya has amassed a wealth of paper based land information records collected over the duration of more than a century. The National Land Commission (NLC) having the mandate to develop a National Land Information Manag...Kenya has amassed a wealth of paper based land information records collected over the duration of more than a century. The National Land Commission (NLC) having the mandate to develop a National Land Information Management System (NLIMS) for Kenya partnered with the Dedan Kimathi University of Technology on a project to develop a pilot LIMS for Nyeri County. A pilot Land Administration System (LAS) has been developed in this work and utilizes an Africanized Land Administration Domain Model (A-LADM) fitted to the Kenyan context. Various processes involved in land administration that required to be automated were identified. Informed by the numbers of applications made for the change of User service, it was picked as the first workflow to be automated. The key outputs of this work were the A-LADM and pilot LAS. The pilot solution uses a webcentric solution, with the data stored and managed centrally from a PostGIS database backend, using the Python Django framework to implement the server side and client side frontend. This solution demonstrates the importance of automating processes and supporting standards based software development. Stakeholder participation is key when implementing systems and 2 workshops are held to capture requirements and validate the developed solution.展开更多
Water plays a role in sustaining all the biotic elements. Unfortunately, in the recent times with persistent climate change impacts, parts of the world are facing cases of inadequate water causing stress and increased...Water plays a role in sustaining all the biotic elements. Unfortunately, in the recent times with persistent climate change impacts, parts of the world are facing cases of inadequate water causing stress and increased vulnerability among the people. This is the case with urban areas across the globe as their populations keep increasing with little to no attention paid to urban planning that allows sustainable management of resources amidst rapid development. Urban areas are surrounded by high yielding aquifers that have better water services from groundwater. However, the urban sprawl phenomena have limited attempts in assessing ground water potential in urban areas contributing to urban water scarcity. Therefore, the study aims to look at the problem of urban water scarcity, by analyzing the levels and distribution of groundwater in Voi town using remote sensing and GIS techniques, in order to suggest suitable sites for underground water exploration in regard to the overall urban water supply. From the analysis, the results showed that the area majorly has low to potential zones of groundwater. High potential areas were very few and were mostly on the western side of the area. Very low potential zones were seen on the east and north side of the area.展开更多
Fisheries in Lake Victoria have been threatened by declining fish stocks and diversity, environmental degradation due to increased input of pollutants, industrial and municipal waste, overfishing and use of unapproved...Fisheries in Lake Victoria have been threatened by declining fish stocks and diversity, environmental degradation due to increased input of pollutants, industrial and municipal waste, overfishing and use of unapproved fishing <span style="font-family:Verdana;">methods, infestation by aquatic weeds especially water hyacinth, de-oxygenation</span><span style="font-family:Verdana;"> and a reduction in the quantity and quality of water. Remote sensing and GIS are essential tools in detection of fishing grounds which is important in providing fish sustainability for human beings and allows fishing grounds detection at minimal cost and optimizes effort. This research tends to identify the most favorable both environmentally and ecologically satisfactory factors which favor fish breeding and growth. The main aim of the study was to identify habitat variables that promote fish breeding and growth to maturity including the extraction of environmental variables from Landsat 8 images for the study period and using suitability index derived from fishery data. The study concentrated on establishing suitability ratings in different parts of Lake Victoria using lake surface temperature and chlorophyll-a levels. The study was conducted for months;January, May and December 2019 on Lake Victoria (limited by the availability of recent data). The factors were analysed and the favorable regions mapped satisfying the conditions for fish breeding. The output obtained illustrated the availability of suitable and habitable zones within the lake using satellite imagery and the suitability index. The fish catch data and satellite derived variables were used to determine habitat suitability indices for fish during January, May and December 2019. More than 90% of the total catch was found to come from the areas with sea surface temperature of 23.0˚C - 28.3˚C and chlorophyll-</span><span style="font-family:Verdana;">a </span><span style="font-family:Verdana;">concentration between 0.72 - 1.31 mg/m</span><sup><span style="font-family:Verdana;vertical-align:super;">3</span></sup><span style="font-family:Verdana;">. The catch data was used to validate the images. This study indicated the capability of High Satellite Resolution Imageries (HSI) as a tool to map the potential fishing grounds of fish species in Lake Victoria. The variables were affected by climatic change factors like rainfall and temperature of the lake basin and other human activities around the lake and also the species ecosystem like competition or predation.</span>展开更多
Groundwater is one of the important necessary renewable resources of the world. It forms part of the natural water cycle that is present in the underground strata with the principal sources being precipitation and str...Groundwater is one of the important necessary renewable resources of the world. It forms part of the natural water cycle that is present in the underground strata with the principal sources being precipitation and streamflow. Traditionally, information on the potential occurrence of groundwater was obtained using techniques such as drilling, geophysical, geological, hydro-geological and geo-electrical which are time-consuming, costly and lacked full coverage. This study shows that remote sensing and GIS techniques can be utilized to map groundwater potential using a GIS-based model, the Modified DRASTIC Model, which incorporates factors that influence groundwater occurrence. These factors are the surface attributes that infer groundwater potentials and they include geology, soil texture, land use, lithology, landforms, slope steepness, lineaments and drainage systems. A prediction of the groundwater prediction was done by utilizing the MOLUSCE tool, a plugin in Qgis that utilizes ANN, multicriteria evaluation, weights of evidence and LRs algorithms in predicting land changes. The kappa value for prediction was 0.83. The results showed areas in the Southwest region had low to very low potential and the central region had high to very high potential for all the years and there were little changes between the years. The prediction showed that by 2042, the eastern region of Kiambu County will have a decline in groundwater potential.展开更多
Coral reefs have tremendous benefits to both humans and marine biodiversity but are globally endangered. Traditionally, data collection of coral reefs was fieldwork based, which is time-consuming, costly and lacking i...Coral reefs have tremendous benefits to both humans and marine biodiversity but are globally endangered. Traditionally, data collection of coral reefs was fieldwork based, which is time-consuming, costly and lacking in full coverage. This study shows that optical imageries can be utilised to map coral reefs, by fusing visible bands and depth invariant index (DII) to classify benthic features. Overall accuracy of at least 68 percent is achieved. However, to overcome the challenge of cloud cover, which is common in coastal areas, microwave imagery is used to map the emergent coral reefs. Again, remote sensing proves to be reliable in estimation of sea surface temperature (SST) and extraction of water quality parameters through Case-2 Region CoastColour (C2RCC) processor. Thereafter, regression analysis is performed to evaluate the correlation of SST and water quality. It is concluded that higher spatial resolution can improve coral mapping and that there is a need for more research on correlation to its environment.展开更多
One major problem that humanity has been confronting recently is water quality. Just 2.5 percent of the water resources on Earth are freshwater resources. Water is an indispensable resource for all living things, and ...One major problem that humanity has been confronting recently is water quality. Just 2.5 percent of the water resources on Earth are freshwater resources. Water is an indispensable resource for all living things, and it is a vital value. Pollution of limited freshwater resources causes further pressure on freshwater resources. Humans play a major role in the waste and pollution of this essential natural resource. This research project focused on the impacts of water pollution and its effects on agriculture, land and aquatic systems, a case study which was conducted in River Njoro, in Nakuru County. With the aid of questioners for information acquisition, the study determined different pollutants and their impact on agriculture. Results indicated that there is a dire need for conservation efforts in the area. Humanity should receive education awareness-capacity building regarding water contamination in order to mitigate the issues to some extent. By doing so, the world we live in becomes a better place for all.展开更多
The increasing frequency and intensity of forest fires,driven by climate change and human activities,pose a significant threat to vital forest ecosystems,particularly where fire is not a natural element in the regener...The increasing frequency and intensity of forest fires,driven by climate change and human activities,pose a significant threat to vital forest ecosystems,particularly where fire is not a natural element in the regeneration cycle.This study aims to identify the indicators influencing forest fire vulnerability and compare maps of forest fire susceptibility that are based on the Intergovernmental Panel on Climate Change tripartite model,with a focus on the vulnerable Hyrcanian forest region in Golestan Province,northern Iran,where forest fires have caused considerable economic losses.On the basis of expert opinions and a literature review,we used geographic information systems,remote sensing and machine learning techniques to select and weigh 30 biophysical,environmental and socioeconomic indicators that affect forest fire vulnerability in the study area.These indicators were rigorously normalized,weighted and amalgamated into a comprehensive forest fire vulnerability index to analyze forest exposure,sensitivity and adaptive capacity.We thus identified and mapped areas with very high forest fire exposure,high sensitivity and low adaptive capacity for urgent targeted intervention and strategic planning to mitigate the impacts of forest fires.The results also revealed a set of critical indicators that contribute more significantly to forest fire vulnerability(e.g.,precipitation,elevation and factors related to biodiversity,human activity and economic reliance on forest resources).Our results provide insights that can inform policy-making,community engagement and environmental management strategies to mitigate the vulnerabilities associated with forest fires in the Hyrcanian forest.展开更多
Short-term(up to 30 days)predictions of Earth Rotation Parameters(ERPs)such as Polar Motion(PM:PMX and PMY)play an essential role in real-time applications related to high-precision reference frame conversion.Currentl...Short-term(up to 30 days)predictions of Earth Rotation Parameters(ERPs)such as Polar Motion(PM:PMX and PMY)play an essential role in real-time applications related to high-precision reference frame conversion.Currently,least squares(LS)+auto-regressive(AR)hybrid method is one of the main techniques of PM prediction.Besides,the weighted LS+AR hybrid method performs well for PM short-term prediction.However,the corresponding covariance information of LS fitting residuals deserves further exploration in the AR model.In this study,we have derived a modified stochastic model for the LS+AR hybrid method,namely the weighted LS+weighted AR hybrid method.By using the PM data products of IERS EOP 14 C04,the numerical results indicate that for PM short-term forecasting,the proposed weighted LS+weighted AR hybrid method shows an advantage over both the LS+AR hybrid method and the weighted LS+AR hybrid method.Compared to the mean absolute errors(MAEs)of PMX/PMY sho rt-term prediction of the LS+AR hybrid method and the weighted LS+AR hybrid method,the weighted LS+weighted AR hybrid method shows average improvements of 6.61%/12.08%and 0.24%/11.65%,respectively.Besides,for the slopes of the linear regression lines fitted to the errors of each method,the growth of the prediction error of the proposed method is slower than that of the other two methods.展开更多
Cloud computing has emerged as a leading computing paradigm,with an increasing number of geographic information(geo-information) processing tasks now running on clouds.For this reason,geographic information system/rem...Cloud computing has emerged as a leading computing paradigm,with an increasing number of geographic information(geo-information) processing tasks now running on clouds.For this reason,geographic information system/remote sensing(GIS/RS) researchers rent more public clouds or establish more private clouds.However,a large proportion of these clouds are found to be underutilized,since users do not deal with big data every day.The low usage of cloud resources violates the original intention of cloud computing,which is to save resources by improving usage.In this work,a low-cost cloud computing solution was proposed for geo-information processing,especially for temporary processing tasks.The proposed solution adopted a hosted architecture and can be realized based on ordinary computers in a common GIS/RS laboratory.The usefulness and effectiveness of the proposed solution was demonstrated by using big data simplification as a case study.Compared to commercial public clouds and dedicated private clouds,the proposed solution is more low-cost and resource-saving,and is more suitable for GIS/RS applications.展开更多
1.Introduction Crop yield must urgently be sustainably increased to accommodate a rising global population and anticipated climate change in the coming decades,in the face of plant stresses and limited resources[1].Co...1.Introduction Crop yield must urgently be sustainably increased to accommodate a rising global population and anticipated climate change in the coming decades,in the face of plant stresses and limited resources[1].Conventional crop breeding is limited by phenotypic selection and breeding efficiency.展开更多
Geohazards are a recurrent issue in the Kerio River catchment of Kenya, which usually results in life and property loss. This research focuses on mapping geo-hazard risk zones of the region. The risk zones were develo...Geohazards are a recurrent issue in the Kerio River catchment of Kenya, which usually results in life and property loss. This research focuses on mapping geo-hazard risk zones of the region. The risk zones were developed from a combination of land use land cover maps, agroecological zones maps and soil erosion maps using the Analytical Hierarchy Process method of multi-criteria analysis. The final results depict the geohazard risk maps which show the susceptibility of different areas in the catchment (classified as risk zones) to hazards. The zones range from no risk zones to very high-risk zones. The results showed that the lowlands are most susceptible to hazards as they were classified as high-risk zones. These risk zone areas have impacts on the socio-economic development hence negatively impacting livelihoods in the area.展开更多
基金supported by grants provided within the research project»EO4Forest:Use of multi-temporal Sentinel-2 and VHR Pleiades stereo data for sustainable forest monitoring and management«funded by the Austrian Federal Ministry for Climate Action,Environ-ment,Energy,Mobility,Innovation and Technology(BMK)within the FFG Austrian Space Applications Program ASAP 12(grant agreement number 854027).
文摘Accurate,reliable,and regularly updated information is necessary for targeted management of forest stands.This information is usually obtained from sample-based field inventory data.Due to the time-consuming and costly procedure of forest inventory,it is imperative to generate and use the resulting data optimally.Integrating field inventory information with remote sensing data increases the value of field approaches,such as national forest inventories.This study investigated the optimal integration of forest inventory data with aerial image-based canopy height models(CHM)for forest growing stock estimation.For this purpose,fixed-area and angle-count plots from a forest area in Austria were used to assess which type of inventory system is more suitable when the field data is integrated with aerial image analysis.Although a higher correlation was observed between remotely predicted growing stocks and field inventory values for fixed-area plots,the paired t-test results revealed no statistical difference between the two methods.The R2 increased by 0.08 points and the RMSE decreased by 7.7 percentage points(24.8m^(3)·ha^(−1))using fixed-area plots.Since tree height is the most critical variable essential for modeling forest growing stock using aerial images,we also compared the tree heights obtained from CHM to those from the typical field inventory approach.The result shows a high correlation(R^(2)=0.781)between the tree heights extracted from the CHM and those measured in the field.However,the correlation decreased by 0.113 points and the RMSE increased by 4.2 percentage points(1.04m)when the allometrically derived tree heights were analyzed.Moreover,the results of the paired t-test revealed that there is no significant statistical difference between the tree heights extracted from CHM and those measured in the field,but there is a significant statistical difference when the CHM-derived and the allometrically-derived heights were compared.This proved that image-based CHM can obtain more accurate tree height information than field inventory estimations.Overall,the results of this study demonstrated that image-based CHM can be integrated into the forest inventory data at large scales and provide reliable information on forest growing stock.The produced maps reflect the variability of growth conditions and developmental stages of different forest stands.This information is required to characterize the status and changes,e.g.,in forest structure diversity,parameters for volume,and can be used for forest aboveground biomass estimation,which plays an important role in managing and controlling forest resources in mid-term forest management.This is of particular interest to forest managers and forest ecologists.
文摘Water is at the core of sustainable development and is critical for socio-economic development, healthy ecosystems and for human survival. This research study has been carried out in Nakuru County, a tropical region in the Rift Valley of Kenya, bounded between latitude 0.28°N and 1.16°S, and longitude 36.27°E and 36.55°E. The objective of the study has been to use GIS and remote sensing in assessment of water scarcity using Land use Land cover area changes, standard precipitation index and crop yields. Landsat satellite images for the year 1985, 1995, 2005 and 2015 were used. Classification was done using maximum likelihood algorithm while classification accuracy assessment entailed the use of confusion matrix method and ground truth data. Post classification change detection results gave percentage cropland areas as 21% in 1985, 29% in 1995, 53% in 2005 and also 53% in 2015. Eleven (11) ground rainfall stations and TRMM satellite rainfall data from 1985 to 2015 has been used to show meteorological drought. Validation of rainfall data done using correlation coefficient (R2) and root mean square (RMS) methods showed that ground rainfall data and TRMM data correlate. Modelling of 3 months SPI for each of the three seasons (MAM, JJA and OND) has been done using interpolation distance weighted method (IDW). 3 months SPI time scales curves gave October 1987 May 1993, and July 2004 as water scarce and dry seasons and were categorized as either Normal, moderately dry, severely dry and extremely dry. Crop yield trends curves showed crop yield decrease in this identified water scarce and dry years. Conclusion reached is that crop yields is not dependent on size of land ploughed only but mostly on rainfall quantities. Therefore, the findings of this research can be used as drought monitoring tools.
文摘Urban Heat Island (UHI) is a phenomenon characterized by higher surface and atmospheric temperatures in urbanized areas as compared to the surrounding rural areas. This phenomenon is a consequence of increase in Land Surface Temperatures (LST) as a result of trapped heat energy on the surface. The objective of this study is establishing the trends in and relationship between LST and land use/land cover in Nakuru County as it seeks to achieve the ultimate goal to contain the UHI effect. Urban heat island inference was based on the generation of a time series set of Landsat imagery, with particular emphasis on the thermal band. Land use/land cover mapping was conducted using maximum likelihood classification techniques, and this, like the LST, is generated in a time series fashion from 1989 to 2015. Accuracy assessment was conducted in order to give confidence in the classification results. The accuracy of the development was assessed using observed temperature data as recorded by the ground stations at the Kenya Meteorological Department. This study employed Normalized NDVI and NDBI to investigate the variation land use/land cover. Results revealed that over the years, settlement has been on an upward trend in terms of area whereas forests have been decreasing due to deforestation. Also, the land surface temperatures have been increasing over the years. In order to qualify this, the correlation between LST and Land Use change was conducted and it indicated that changes to settlement/urban increased proportionately with Land Surface Temperature.
文摘Bilharzia is vector-borne disease carried by a parasite that is hosted by fresh water snails. The distribution of the disease is concurrent with the existence of the freshwater snails and </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">is </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">dependent on certain suitable environmental conditions. It is difficult to identify the specific habitats of the snails as they are often inaccessible on the ground, the snails also migrate by means of flowing water, making it difficult to keep a track of the freshwater snails’ habitat. This paper aimed at using GIS, Remote Sensing and Species Distribution Modelling techniques to model the suitable habitats for the freshwater snails and to prove that the snails migrate when there are sudden changes in water levels whilst showing the population at risk of bilharzia. The SDM used is the Maximum Entropy (MAXENT) for its ability to make right predictions even with small presence sites. The AUC value of the model was 0.951. The research results showed that the environmental variables;brightness Index, elevation, temperatures were negatively correlated with the snails’ presence while the wetness index, MSAVI, greenness index and soil pH were positively correlated. The snails are observed to favor clay soils of the montmorillonite type and the crop-lands land cover. Areas consistently submerged by water especially after flooding are shown to be the most suitable areas where snails migrate by means of river or canal water. The research proves that Mwea is not the source habitat of the freshwater snails. The neighboring sub-counties within Kirinyaga County should be investigated using such models as a likely source-habitat of the freshwater snails. Destroying the source habitats will lead to complete eradication of the freshwater snails within Mwea.
文摘Soil moisture is an important parameter that drives agriculture, climate and hydrological systems. In addition, retrieval of soil moisture is important in the analysis as well as its influence on these systems. Radar imagery is best suited for this retrieval due to its all-weather capability and independence from solar irradiation. Soil moisture retrieval was done for the Malinda Wetland, Tanzania, during two time periods, March and September 2013. The aim of this paper was to analyze soil moisture retrieval performance when vegetation contribution is taken into account. Backscatter values were obtained from TerraSAR-X Spotlight mode imagery taken in March and September 2013. The backscatter values recorded by SAR imagery are influenced by vegetation, soil roughness and soil moisture. Thus, in order to obtain the backscatter due to soil moisture, the roughness and vegetation contribution are determined and decoupled from total backscatter. The roughness parameters were obtained from a Digital Surface Model (DSM) from Unmanned Aerial Vehicle (UAV) photographs whereas the vegetation parameter was obtained by inverting the Water Cloud Model (WCM). Lastly, soil moisture was retrieved using the Oh Model. The coefficient of correlation between the observed and retrieved was 0.39 for the month of March and 0.65 in the month of August. When the vegetation contribution was considered, the r2 for March was 0.64 and that in August was 0.74. The results revealed that accounting for vegetation improved soil moisture retrieval.
基金founded by a grant from Hungarian Scientific Research Found(OTKA NN 79835) projectthe Postdoctoral Research Program of the Hungarian Academy of Sciences(PD-029/2015)
文摘When conditions are similar,more water evaporates from forest plantations than herbaceous vegetation,thereby affecting hydrological fluxes and ion transport in the soil.The vertical distribution of CaCO3 and Cl^-ions shifts due to afforestation.The effect of groundwater depth and clay content were studied in the Great Hungarian Plain where forest area has been increasing for decades by analyzing soil and groundwater samples from stands of black locust(Robinia pseudoacacia,11 plots)and poplar(Populus spp.,11 plots).All study sites contained one herbaceous(control)and one or more forested plots.CaCO3 and Cl^-ions accumulated in the soil profile in greater quantities under tree cover than in the controls.The scale of this process largely depended on the species and on soil and ion properties.Under black locust,Cl^-accumulated between 1.3 and 6.3 m,with a maximum difference of 0.3 pCl unit(pCl is Cl^-activity,the negative of the logarithm to base 10 of the concentration of the chloride ion,determined using an ion-selective electrode,it is a dimensionless quantity.),while the difference in CaCO3 accumulation was at most 3.5%in some layers,compared to control plots.This result may be explained by the difference in the mobility of Ca+and Cl^-ions.Different mechanisms were noticeable under poplar plantations due to their higher water uptake:Cl-accumulation was detected below 0.9 m to the groundwater with a maximum difference of 0.5 pCl units,while CaCO3 accumulation was continuous at depths of 2.3–6.8 m with a maximum difference of 8.4%,compared to the controls.With increasing clay content,there was a discernible effect on CaCO3 and Cl-accumulation under black locust,but not observed under poplars.These differences were explained by the differences in water uptake mechanisms and root patterns of the two species and the different mobility of Ca2^+and Cl-ions.
文摘The objective of this research was to harmonize political and administrative boundaries in Mavoko Constituency, Machakos County, Kenya, using geo-spatial technology and public consultation in order to address the numerous disputes that exist. Specifically, the project focused on analyzing the existing electoral and administrative boundaries in the area of study by identifying all existing gaps and overlaps, rectifying the identified gaps and overlaps and created a web based geo-portal of the harmonized sub location boundaries to enable sharing. This was achieved through first putting the various datasets on the same Spatial Reference System and comparing them in order to identify and rectify them using various geospatial operations, public consultation and field work. The result was a single harmonized layer for the sub location data set for the study area. The project finally developed a customized GIS web based portal for sharing the harmonized Sub location boundary. This was uploaded on an open source platform, which has the capability for offline use in the field. The project worked on a hypothesis that if the sub location boundaries adopted by the various Government and Public organizations and individuals doing any kind of mapping in Kenya was a single harmonized data set, the emerging issues on boundary disputes between Counties, Constituencies and County Assembly Wards (CAW’s) would not occur. This is because there would be authentic, consisted and authoritative geo-information which maintains a harmonized, consistent, reusable and readily available data. The development of the geo portal ensured that the results of the research are easily accessible on www.msc2015boundariesmavoko.info.ke/mavoko.
文摘The development of a web-based Geographic Information System for mass property valuation was the main focus of this research. The developed web GIS allows effective dissemination, extraction and analysis of mass land valuation information over the Internet. It also allows for automation of the mass property valuation process by compiling a centralized mass valuation roll database. The Westlands Constituency, one of the administrative regions of the Nairobi City County was used as a case study. The research focused on automation of the mass property valuation roll by creating a centralized database that is accessible by all users on the web-based GIS portal. This was done by customizing and integrating a web-based GIS system based on open source QuantumGIS, GeoServer and PostgreSQL/PostGIS as a relational database. Leaflets APIs were used for the development of an interactive and friendly geographic user interface. The developed system enables users to view and interact with the spatial data. This improves the efficiency and effectiveness of the decision making process and data sharing for mass property valuation and optimal property taxation purposes.
文摘Urban land-use modeling has gained increased attention as a research topic over the last decade. This has been attributed to advances in remote sensing and computing technology that now can process several models simultaneously at regional and local levels. In this research we implemented a cellular automata (CA) urban growth model (UGM) integrated in the XULU modeling frame-work (eXtendable Unified Land Use Modeling Platform). We used multi-temporal Landsat satellite image sets for 1986, 2000 and 2010 to map urban land-use in Nairobi. We also tested the spatial effects of varying model coefficients. This approach improved model performance and aided in understanding the particular urban land-use system dynamics operating in our Nairobi study area. The UGM was calibrated for Nairobi and predicted development was derived for the city for the year 2030 when Kenya plans to attain Vision 2030. Observed land-use changes in urban areas were compared to the results of UGM modeling for the year 2010. The results indicate that varying the UGM model coefficients simulates urban growth in different directions and magnitudes. This approach is useful to planners and policy makers because the model outputs can identify specific areas within the urban complex which will require infrastructure and amenities in order to realize sustainable development.
文摘Kenya has amassed a wealth of paper based land information records collected over the duration of more than a century. The National Land Commission (NLC) having the mandate to develop a National Land Information Management System (NLIMS) for Kenya partnered with the Dedan Kimathi University of Technology on a project to develop a pilot LIMS for Nyeri County. A pilot Land Administration System (LAS) has been developed in this work and utilizes an Africanized Land Administration Domain Model (A-LADM) fitted to the Kenyan context. Various processes involved in land administration that required to be automated were identified. Informed by the numbers of applications made for the change of User service, it was picked as the first workflow to be automated. The key outputs of this work were the A-LADM and pilot LAS. The pilot solution uses a webcentric solution, with the data stored and managed centrally from a PostGIS database backend, using the Python Django framework to implement the server side and client side frontend. This solution demonstrates the importance of automating processes and supporting standards based software development. Stakeholder participation is key when implementing systems and 2 workshops are held to capture requirements and validate the developed solution.
文摘Water plays a role in sustaining all the biotic elements. Unfortunately, in the recent times with persistent climate change impacts, parts of the world are facing cases of inadequate water causing stress and increased vulnerability among the people. This is the case with urban areas across the globe as their populations keep increasing with little to no attention paid to urban planning that allows sustainable management of resources amidst rapid development. Urban areas are surrounded by high yielding aquifers that have better water services from groundwater. However, the urban sprawl phenomena have limited attempts in assessing ground water potential in urban areas contributing to urban water scarcity. Therefore, the study aims to look at the problem of urban water scarcity, by analyzing the levels and distribution of groundwater in Voi town using remote sensing and GIS techniques, in order to suggest suitable sites for underground water exploration in regard to the overall urban water supply. From the analysis, the results showed that the area majorly has low to potential zones of groundwater. High potential areas were very few and were mostly on the western side of the area. Very low potential zones were seen on the east and north side of the area.
文摘Fisheries in Lake Victoria have been threatened by declining fish stocks and diversity, environmental degradation due to increased input of pollutants, industrial and municipal waste, overfishing and use of unapproved fishing <span style="font-family:Verdana;">methods, infestation by aquatic weeds especially water hyacinth, de-oxygenation</span><span style="font-family:Verdana;"> and a reduction in the quantity and quality of water. Remote sensing and GIS are essential tools in detection of fishing grounds which is important in providing fish sustainability for human beings and allows fishing grounds detection at minimal cost and optimizes effort. This research tends to identify the most favorable both environmentally and ecologically satisfactory factors which favor fish breeding and growth. The main aim of the study was to identify habitat variables that promote fish breeding and growth to maturity including the extraction of environmental variables from Landsat 8 images for the study period and using suitability index derived from fishery data. The study concentrated on establishing suitability ratings in different parts of Lake Victoria using lake surface temperature and chlorophyll-a levels. The study was conducted for months;January, May and December 2019 on Lake Victoria (limited by the availability of recent data). The factors were analysed and the favorable regions mapped satisfying the conditions for fish breeding. The output obtained illustrated the availability of suitable and habitable zones within the lake using satellite imagery and the suitability index. The fish catch data and satellite derived variables were used to determine habitat suitability indices for fish during January, May and December 2019. More than 90% of the total catch was found to come from the areas with sea surface temperature of 23.0˚C - 28.3˚C and chlorophyll-</span><span style="font-family:Verdana;">a </span><span style="font-family:Verdana;">concentration between 0.72 - 1.31 mg/m</span><sup><span style="font-family:Verdana;vertical-align:super;">3</span></sup><span style="font-family:Verdana;">. The catch data was used to validate the images. This study indicated the capability of High Satellite Resolution Imageries (HSI) as a tool to map the potential fishing grounds of fish species in Lake Victoria. The variables were affected by climatic change factors like rainfall and temperature of the lake basin and other human activities around the lake and also the species ecosystem like competition or predation.</span>
文摘Groundwater is one of the important necessary renewable resources of the world. It forms part of the natural water cycle that is present in the underground strata with the principal sources being precipitation and streamflow. Traditionally, information on the potential occurrence of groundwater was obtained using techniques such as drilling, geophysical, geological, hydro-geological and geo-electrical which are time-consuming, costly and lacked full coverage. This study shows that remote sensing and GIS techniques can be utilized to map groundwater potential using a GIS-based model, the Modified DRASTIC Model, which incorporates factors that influence groundwater occurrence. These factors are the surface attributes that infer groundwater potentials and they include geology, soil texture, land use, lithology, landforms, slope steepness, lineaments and drainage systems. A prediction of the groundwater prediction was done by utilizing the MOLUSCE tool, a plugin in Qgis that utilizes ANN, multicriteria evaluation, weights of evidence and LRs algorithms in predicting land changes. The kappa value for prediction was 0.83. The results showed areas in the Southwest region had low to very low potential and the central region had high to very high potential for all the years and there were little changes between the years. The prediction showed that by 2042, the eastern region of Kiambu County will have a decline in groundwater potential.
文摘Coral reefs have tremendous benefits to both humans and marine biodiversity but are globally endangered. Traditionally, data collection of coral reefs was fieldwork based, which is time-consuming, costly and lacking in full coverage. This study shows that optical imageries can be utilised to map coral reefs, by fusing visible bands and depth invariant index (DII) to classify benthic features. Overall accuracy of at least 68 percent is achieved. However, to overcome the challenge of cloud cover, which is common in coastal areas, microwave imagery is used to map the emergent coral reefs. Again, remote sensing proves to be reliable in estimation of sea surface temperature (SST) and extraction of water quality parameters through Case-2 Region CoastColour (C2RCC) processor. Thereafter, regression analysis is performed to evaluate the correlation of SST and water quality. It is concluded that higher spatial resolution can improve coral mapping and that there is a need for more research on correlation to its environment.
文摘One major problem that humanity has been confronting recently is water quality. Just 2.5 percent of the water resources on Earth are freshwater resources. Water is an indispensable resource for all living things, and it is a vital value. Pollution of limited freshwater resources causes further pressure on freshwater resources. Humans play a major role in the waste and pollution of this essential natural resource. This research project focused on the impacts of water pollution and its effects on agriculture, land and aquatic systems, a case study which was conducted in River Njoro, in Nakuru County. With the aid of questioners for information acquisition, the study determined different pollutants and their impact on agriculture. Results indicated that there is a dire need for conservation efforts in the area. Humanity should receive education awareness-capacity building regarding water contamination in order to mitigate the issues to some extent. By doing so, the world we live in becomes a better place for all.
基金funding provided by University of Natural Resources and Life Sciences Vienna(BOKU).
文摘The increasing frequency and intensity of forest fires,driven by climate change and human activities,pose a significant threat to vital forest ecosystems,particularly where fire is not a natural element in the regeneration cycle.This study aims to identify the indicators influencing forest fire vulnerability and compare maps of forest fire susceptibility that are based on the Intergovernmental Panel on Climate Change tripartite model,with a focus on the vulnerable Hyrcanian forest region in Golestan Province,northern Iran,where forest fires have caused considerable economic losses.On the basis of expert opinions and a literature review,we used geographic information systems,remote sensing and machine learning techniques to select and weigh 30 biophysical,environmental and socioeconomic indicators that affect forest fire vulnerability in the study area.These indicators were rigorously normalized,weighted and amalgamated into a comprehensive forest fire vulnerability index to analyze forest exposure,sensitivity and adaptive capacity.We thus identified and mapped areas with very high forest fire exposure,high sensitivity and low adaptive capacity for urgent targeted intervention and strategic planning to mitigate the impacts of forest fires.The results also revealed a set of critical indicators that contribute more significantly to forest fire vulnerability(e.g.,precipitation,elevation and factors related to biodiversity,human activity and economic reliance on forest resources).Our results provide insights that can inform policy-making,community engagement and environmental management strategies to mitigate the vulnerabilities associated with forest fires in the Hyrcanian forest.
基金supported by National Natural Science Foundation of China,China(No.42004016)HuBei Natural Science Fund,China(No.2020CFB329)+1 种基金HuNan Natural Science Fund,China(No.2023JJ60559,2023JJ60560)the State Key Laboratory of Geodesy and Earth’s Dynamics self-deployment project,China(No.S21L6101)。
文摘Short-term(up to 30 days)predictions of Earth Rotation Parameters(ERPs)such as Polar Motion(PM:PMX and PMY)play an essential role in real-time applications related to high-precision reference frame conversion.Currently,least squares(LS)+auto-regressive(AR)hybrid method is one of the main techniques of PM prediction.Besides,the weighted LS+AR hybrid method performs well for PM short-term prediction.However,the corresponding covariance information of LS fitting residuals deserves further exploration in the AR model.In this study,we have derived a modified stochastic model for the LS+AR hybrid method,namely the weighted LS+weighted AR hybrid method.By using the PM data products of IERS EOP 14 C04,the numerical results indicate that for PM short-term forecasting,the proposed weighted LS+weighted AR hybrid method shows an advantage over both the LS+AR hybrid method and the weighted LS+AR hybrid method.Compared to the mean absolute errors(MAEs)of PMX/PMY sho rt-term prediction of the LS+AR hybrid method and the weighted LS+AR hybrid method,the weighted LS+weighted AR hybrid method shows average improvements of 6.61%/12.08%and 0.24%/11.65%,respectively.Besides,for the slopes of the linear regression lines fitted to the errors of each method,the growth of the prediction error of the proposed method is slower than that of the other two methods.
基金Project(41401434)supported by the National Natural Science Foundation of China
文摘Cloud computing has emerged as a leading computing paradigm,with an increasing number of geographic information(geo-information) processing tasks now running on clouds.For this reason,geographic information system/remote sensing(GIS/RS) researchers rent more public clouds or establish more private clouds.However,a large proportion of these clouds are found to be underutilized,since users do not deal with big data every day.The low usage of cloud resources violates the original intention of cloud computing,which is to save resources by improving usage.In this work,a low-cost cloud computing solution was proposed for geo-information processing,especially for temporary processing tasks.The proposed solution adopted a hosted architecture and can be realized based on ordinary computers in a common GIS/RS laboratory.The usefulness and effectiveness of the proposed solution was demonstrated by using big data simplification as a case study.Compared to commercial public clouds and dedicated private clouds,the proposed solution is more low-cost and resource-saving,and is more suitable for GIS/RS applications.
文摘1.Introduction Crop yield must urgently be sustainably increased to accommodate a rising global population and anticipated climate change in the coming decades,in the face of plant stresses and limited resources[1].Conventional crop breeding is limited by phenotypic selection and breeding efficiency.
文摘Geohazards are a recurrent issue in the Kerio River catchment of Kenya, which usually results in life and property loss. This research focuses on mapping geo-hazard risk zones of the region. The risk zones were developed from a combination of land use land cover maps, agroecological zones maps and soil erosion maps using the Analytical Hierarchy Process method of multi-criteria analysis. The final results depict the geohazard risk maps which show the susceptibility of different areas in the catchment (classified as risk zones) to hazards. The zones range from no risk zones to very high-risk zones. The results showed that the lowlands are most susceptible to hazards as they were classified as high-risk zones. These risk zone areas have impacts on the socio-economic development hence negatively impacting livelihoods in the area.
