Systematic monitoring of the fluctuations in atmospheric SO2 oxidation efficiency—measured as a molar ratio of SO42- to total SOx (SOx=SO2+SO42-), referred as S-ratio—have been performed during a major long range pl...Systematic monitoring of the fluctuations in atmospheric SO2 oxidation efficiency—measured as a molar ratio of SO42- to total SOx (SOx=SO2+SO42-), referred as S-ratio—have been performed during a major long range plume transport to northeast India (Shillong: 25.67°N, 91.91°E, 1064 m ASL) in March 2009. Anomalously low S-ratios (median, 0.03) were observed during the episode—associated with a cyclonic circulation—and the SO42- and SO2 exhibited unusual features in the ‘relative phase’ of their peaks. During initial days, when SO2 levels were dictated by the long range influx, the SO42- and SO2 variabilities were in anti-phase—for the differing mobility/loss mechanisms. When SO2 levels were governed by the boundary layer diurnality in the latter days, the anti-phase is explained by a ‘depleted OH level’—major portion being consumed in the initial period by the elevated SO2 and other pollutants. Simulations with a global 3D chemical transport model, GEOS-Chem (v8-03-01), also indicated ‘suppressed oxidation conditions’—with characteristic low S-ratios and poor phase agreements. The modelled OH decreased steadily from the initial days, and OH normalized to SO2—referred as OHspecific—was consistently low during the ‘suppressed S-ratio period’. Further, the geographical distribution of modelled OH showed a pronounced minimum over the region surrounding (20°N, 95°E) spanning parts of northeast India and the adjacent regions to the southeast of it—prevalent throughout the year, though the magnitude and the area of influence have a seasonality to it—with significant implications for reducing the oxidizing power of the regional atmosphere. A second set of measurements during January 2010—when prominent long range transports were absent—exhibited no anomalies, and the S-ratios were well within the acceptable limits (median, 0.32). This work highlights the GEOS-Chem model skill in simulating/detecting the ‘transient fluctuations’ in the oxidation efficiency, down to a regional scale.展开更多
A thunderstorm tracking algorithm is proposed to nowcast the possibility of lightning activity over an area of concern by using the total lightning data and neighborhood technique.The lightning radiation sources obser...A thunderstorm tracking algorithm is proposed to nowcast the possibility of lightning activity over an area of concern by using the total lightning data and neighborhood technique.The lightning radiation sources observed from the Beijing Lightning Network(BLNET)were used to obtain information about the thunderstorm cells,which are significantly valuable in real-time.The boundaries of thunderstorm cells were obtained through the neighborhood technique.After smoothing,these boundaries were used to track the movement of thunderstorms and then extrapolated to nowcast the lightning approaching in an area of concern.The algorithm can deliver creditable results prior to a thunderstorm arriving at the area of concern,with accuracies of 63%,80%,and 91%for lead times of 30,15,and 5 minutes,respectively.The real-time observations of total lightning appear to be significant for thunderstorm tracking and lightning nowcasting,as total lightning tracking could help to fill the observational gaps in radar reflectivity due to the attenuation by hills or other obstacles.The lightning data used in the algorithm performs well in tracking the active thunderstorm cells associated with lightning activities.展开更多
The present analysis provided the quality assessment of 65 Continuous Operating Reference Stations(CORS) situated in and around Mexico using the data of about ten years(January 2010 to January 2020).To accomplish the ...The present analysis provided the quality assessment of 65 Continuous Operating Reference Stations(CORS) situated in and around Mexico using the data of about ten years(January 2010 to January 2020).To accomplish the assessment,we considered 4 quality indexes for performing the quality check,incluing the multipath effect on L1 and L2 bands,signal-to-noise ratio in both bands,cycle slips,and integrity.Meanwhile,a new reference parameter named regio nal values for Mexico(RVM) was calculated for the stations situated in Mexico.Additionally,an exhaustive analysis of the quality indicators in the worst and best cases was performed.The signal degradation was proved by a long-term time series and cru stal defo rmation analysis in GAMIT/GLOBK platform.The results showed a stro ng correlation between integrity,cycle slips and daily observations time,and the multipath effect is strong in the case of outdated systems.The study indicates that the estimated quality indexes and values could be the basis for establishing new CORS in Mexico,and the errors corrections which cannot be mitigated in the postprocessing stage would greatly help utilize the data for different scientific applications.The results were supported by deformation analysis in part of Baja California Peninsula in Mexico indicating northern and eastern velocity vector of -3.08±0.02 mm/yr,-7.85±0.02 mm/yr and-0.07±0.03 mm/yr,-9.33±0.02 mm/yr respectively at MPR1 and INEG stations.展开更多
Global Positioning System(GPS)Continuously Operating Reference Station(CORS)data analysis shows that the ionosphere’s electron density variability is linked to the deformation and stress accumulation in the Earth’s ...Global Positioning System(GPS)Continuously Operating Reference Station(CORS)data analysis shows that the ionosphere’s electron density variability is linked to the deformation and stress accumulation in the Earth’s crust.Anomalies in ionosphere total electron content(TEC)variability before 2021 M6.4 Sonitpur,Assam earthquake were detected using L1 and L2 GPS frequencies that showed three distinct abnormalities on April 3,9,10,2021.Pearson’s correlation coefficient(r)of TEC decreases in the CORS that lies away from the earthquake epicenter,indicating the possibilities of a positive relationship between TEC variability and earthquake epicenter.TEC concentration also decreases towards the epicenter within the earthquake preparation zone(EPZ).It is also observed that the Pearson’s correlation coefficient(r)of TEC decreases linearly near the EPZ.The study demonstrates the possibilities of determining the TEC anomalous zone in the ionosphere that coincides with the EPZ in the crustal rocks.The research indicated the possibilities of magnitude estimation of an impending earthquake based on the TEC anomalous zone in the ionosphere using closely spaced dense CORS network data.展开更多
There is growing needs for web based GIS for easy and fast dissemination, sharing, displaying and processing of spatial information which in turns helping in decision making for various natural resources based applica...There is growing needs for web based GIS for easy and fast dissemination, sharing, displaying and processing of spatial information which in turns helping in decision making for various natural resources based applications. In order to make a cost effective implementation, operation and maintenance of spatial information over the web, a cheaper yet feature rich alternative to commercial software is required which can be fulfilled by Open Source GIS software. This paper conveys an efficient approach to customize and integrate an open source web GIS system based on Mapserver as a web GIS server and PostgreSQL/PostGIS as an object oriented relational database management system (ORDBMS) for effective dissemination, sharing and management of spatial information over the internet. An open source web application tool built on top of MapScript using the PHP programming language has been used as for development of interactive user interface. The configurable Web Mapping Client Components (CWC2) tags have been added to HTML template pages in order to deploy the mapping contents to a web application. It is observed that the present system developed using open source software enables user to view, update, customized retrieval, query and analysis of natural resources information for specific needs.展开更多
The first ever land campaign to study the spatial variability of the aerosol characteristics along the Brahmaputra river valley (BRV) in Assam, North-Eastern India, was conducted during 2011. Measurements were made ov...The first ever land campaign to study the spatial variability of the aerosol characteristics along the Brahmaputra river valley (BRV) in Assam, North-Eastern India, was conducted during 2011. Measurements were made over 13 locations for Aerosol Optical Depth (AOD), scattering coefficient, particulate matter, black carbon (BC) concentration and meteorological parameters. The BRV is divided into three sectors longitudinally viz western sector (WS), central sector (CS), and eastern sector (ES). Significant Spatial heterogeneity in AOD and BC concentration was observed (p < 0.05) with the highest values over WS and a continual decrease from WS to ES with aerosol dominance in PM2.5 category along the entire valley. The Angstrom coefficient measured using different wavelength pairs showed spatial variability indicating dominance of fine particles over WS and coarse particles in ES with a probable bimodal distribution. The scattering and absorption coefficient shows dominance of both types of aerosol over WS than other areas. The shortwave radiative forcing was higher over the WS than CS and ES of the valley. The campaign revealed that under favorable wind conditions, the BRV is loaded with significant amount of natural and anthropogenic aerosol during local winter and is influenced by the long-range transport of aerosols from the Indo-Gangetic plain.展开更多
Climatic zone is one of the most important units for horticultural planning. Survival and failure of particular land use or farming system in a given region heavily relies on careful assessment of agroclimatic resourc...Climatic zone is one of the most important units for horticultural planning. Survival and failure of particular land use or farming system in a given region heavily relies on careful assessment of agroclimatic resources. Large variety of crops is being grown in Meghalaya traditionally, based on the needs and cultural practices of people without any consideration to the suitability of the climate. This study attempts to make adjustments with the climate based upon scientific knowledge to make the best use of the natural resources so as to recommend more area under horticultural crops. This has been made by identifying existing land use and appropriate land use strategies mainly for horticultural crops for each agro-climatic region. Modern Geospatial technology such as satellite Remote Sensing (RS) and Geographical Information System (GIS) and GPS have been used effectively to provide newer dimensions in identifying suitable sites for various horticultural crops and also for appropriate monitoring and management of land resources in an integrated manner with reference to agro-climatic condition.展开更多
Characterization and evaluation of land resources of Mawryngkneng block was carried out using IRS-P6 LISS III and LISS-IV data. Five major physiographic units namely structural hills, denudational hills, plateau and i...Characterization and evaluation of land resources of Mawryngkneng block was carried out using IRS-P6 LISS III and LISS-IV data. Five major physiographic units namely structural hills, denudational hills, plateau and intermontane valley were identified. Visual interpretation of satellite data indicated that 32.2% of the total geographical area (TGA) is under dense forest followed by wastelands (28.8%), open forest (16.1%), cultivated area (13.6%), built up area (8.2%) and water body (0.9%). Ten soil series were tentatively identified and the soils belonged to 2 orders (Ultisols and Alfisols), 3 sub orders (Udult, Udalf and Humult), 6 great groups, 8 sub groups. The soils are moderately acidic, deep to very deep and texture varies from sandy clay loam to clay. The soils are very rich in organic carbon. The availability of nitrogen is medium to high and phosphorus availability is low to medium whereas potassium availability is low in the entire study area. The soils were grouped into land capability class II & III and the soils were moderately to marginally suitable for orange and marginally suitable for pine apple. An action plan with suggested land use and interventions has been prepared by using all land resource information generated under the study. The action plan includes areas for afforestation, intensive cultivation in the existing cropped areas with soil conservation measures like mulching, zero tillage etc. and orange and pine apple plantation in open scrub lands which are cultivable wastelands. This might help the farmers and the planner in better management of land resources for sustained productivity.展开更多
Land evaluation procedure given by FAO for soil site suitability for various land utilization types for rainfed agriculture has been used to assess the land suitability for khasi mandarin orange and pineapple in East ...Land evaluation procedure given by FAO for soil site suitability for various land utilization types for rainfed agriculture has been used to assess the land suitability for khasi mandarin orange and pineapple in East Khasi Hills District of Meghalaya. The database on soil and land use/land cover was generated from IRS-P6 remote sensing satellite data, soil survey and laboratory analysis of soil samples to perform an integrated analysis in the Geographic Information System environment. Different soil chemical parameters and physical parameters were considered to evaluate soil site suitability for orange & pineapple. Different thematic layers were derived from soil map by using ArcGIS software. Subsequently all of them were overlaid and integrated in GIS environment and suitability criteria was applied to the resulted composite map and generated land suitability map for orange and pineapple. The result indicated that the soil sites of the study area are highly to marginally suitable for mandarin orange whereas it is marginally suitable for pineapple. The study reveals that highly suitable areas for orange are found in the Cherapunjee and Mawsynram area that covers 34.5 Sq.Km areas. Moderately suitable (37% of TGA) and marginally suitable (24% of TGA) areas are found only because of slope constraint (8%-30% slope). The hills with deep gorges and ravines on the southern portion of the district is found not suitable for orange plantation because of steep slopes (>30%) and stoniness. Land suitability analysis for pineapple showed that 81% area of total geographical area of the district is marginally suitable and 19% area is not suitable to support the crop. The district is marginally suitable because of topography (slope and erosion), soil fertility (base saturation and CEC) and climate.展开更多
Urbanization in recent years plays an important role in increase in impervious areas with reducing in vegetation cover and pervious areas of natural landscape. This leads to a rise in temperature of urban areas, by se...Urbanization in recent years plays an important role in increase in impervious areas with reducing in vegetation cover and pervious areas of natural landscape. This leads to a rise in temperature of urban areas, by several degrees particularly at night [1,2]. A novel geospatial approach has been adopted to determine the maximum temperature areas (hot spots) over Kamrup Metro District of Assam, which is a gateway for seven neighboring north eastern states of India. The G statistics have been calculated for detecting the presence of hot spot or cold spot over the entire study area which is a new approach in urban heat island studies. The resultant z-scores and p-values show the pixels with either high or low values cluster spatially. For statistically significant positive z-scores, the larger the z-score is, the more intense the clustering of high values (hot spot) and vice versa. Land Surface Temperature (LST) anomaly values and percentage of Impervious Surface Area (ISA) along with climatic data are used to conform the hot spot location. It is one of the densely populated areas with more commercial pockets thereby giving rise to anthropogenic heat discharge which accelerates the heat island phenomenon. Incorporation of socio-economic survey data as well as certain biophysical parameters can be used to know about the cause and future impact of urbanization.展开更多
Multi-criteria spatial modeling is one of the important components of spatial decision support system (SDSS). Multi-criteria spatial modeling often requires a common scale of values for diverse and dissimilar inputs t...Multi-criteria spatial modeling is one of the important components of spatial decision support system (SDSS). Multi-criteria spatial modeling often requires a common scale of values for diverse and dissimilar inputs to create an integrated analysis. Weighted overlay function is most commonly used for site suitability analysis which identifies the most preferred locations for a specific phenomenon. However, weighted overlay function gives inconsistent and erroneous results for highly dissimilar inputs as it assumes that most favorable factors result in the higher values of raster, while identifying the best sites. This paper conveys the effectiveness of fuzzy overlay function for multi-criteria spatial modeling. It is based on the principle of fuzzy logic theory which defines membership using Gaussian function on each of the input rasters instead of giving individual rank to them like in weighted overlay function. A case study on preparation of land resources map for Mawsynram block of East Khasi Hills district of Meghalaya, India is presented here. It was observed that fuzzy overlay function has given more satisfactory output in terms of site suitability while comparing with the result of weighted overlay function.展开更多
Coronavirus (COVID-19) disease is a major pandemic which has taken the world by storm. More than 524,000 citizens of the globe have succumbed to the disease as on 3<sup>rd</sup> July, 2020. Accurate modeli...Coronavirus (COVID-19) disease is a major pandemic which has taken the world by storm. More than 524,000 citizens of the globe have succumbed to the disease as on 3<sup>rd</sup> July, 2020. Accurate modeling of the dynamics of the disease spread is required to curb the virus. With the availability of large amount of data made available publicly by the Government agency as well as the other live crowdsourcing media, it is possible to develop an accurate local prediction tool. In this study, we analyze the dynamics of local outbreaks of COVID-19 for few states of India with major outbreaks and for India as a whole. The large amount of data available from the COVID-19 Tracker India platform was utilized to estimate the impact of lockdown in the country and the states with major outbreaks. The effectiveness of the lockdown implementation by the respective states is studied for the analysis. The lockdown was categorized into strict, moderate, and lenient. The model is deployed on a web based platform to disseminate the alert to the public. We further extend the ordinary differential Equation (ODE) based model to generate district level vulnerability index for the whole country based on the rate of change of infected people, breach in social distancing, and population. Around 47% of districts of the country were not found vulnerable;however, 13% of the districts were identified as high risk for the disease outbreak.展开更多
文摘Systematic monitoring of the fluctuations in atmospheric SO2 oxidation efficiency—measured as a molar ratio of SO42- to total SOx (SOx=SO2+SO42-), referred as S-ratio—have been performed during a major long range plume transport to northeast India (Shillong: 25.67°N, 91.91°E, 1064 m ASL) in March 2009. Anomalously low S-ratios (median, 0.03) were observed during the episode—associated with a cyclonic circulation—and the SO42- and SO2 exhibited unusual features in the ‘relative phase’ of their peaks. During initial days, when SO2 levels were dictated by the long range influx, the SO42- and SO2 variabilities were in anti-phase—for the differing mobility/loss mechanisms. When SO2 levels were governed by the boundary layer diurnality in the latter days, the anti-phase is explained by a ‘depleted OH level’—major portion being consumed in the initial period by the elevated SO2 and other pollutants. Simulations with a global 3D chemical transport model, GEOS-Chem (v8-03-01), also indicated ‘suppressed oxidation conditions’—with characteristic low S-ratios and poor phase agreements. The modelled OH decreased steadily from the initial days, and OH normalized to SO2—referred as OHspecific—was consistently low during the ‘suppressed S-ratio period’. Further, the geographical distribution of modelled OH showed a pronounced minimum over the region surrounding (20°N, 95°E) spanning parts of northeast India and the adjacent regions to the southeast of it—prevalent throughout the year, though the magnitude and the area of influence have a seasonality to it—with significant implications for reducing the oxidizing power of the regional atmosphere. A second set of measurements during January 2010—when prominent long range transports were absent—exhibited no anomalies, and the S-ratios were well within the acceptable limits (median, 0.32). This work highlights the GEOS-Chem model skill in simulating/detecting the ‘transient fluctuations’ in the oxidation efficiency, down to a regional scale.
基金The National Natural Science Foundation of China(Grant Nos.41630425,41761144074 and 41875007)supported the researchthe Chinese Academy of Sciences for the CAS-PIFI fellowship grant。
文摘A thunderstorm tracking algorithm is proposed to nowcast the possibility of lightning activity over an area of concern by using the total lightning data and neighborhood technique.The lightning radiation sources observed from the Beijing Lightning Network(BLNET)were used to obtain information about the thunderstorm cells,which are significantly valuable in real-time.The boundaries of thunderstorm cells were obtained through the neighborhood technique.After smoothing,these boundaries were used to track the movement of thunderstorms and then extrapolated to nowcast the lightning approaching in an area of concern.The algorithm can deliver creditable results prior to a thunderstorm arriving at the area of concern,with accuracies of 63%,80%,and 91%for lead times of 30,15,and 5 minutes,respectively.The real-time observations of total lightning appear to be significant for thunderstorm tracking and lightning nowcasting,as total lightning tracking could help to fill the observational gaps in radar reflectivity due to the attenuation by hills or other obstacles.The lightning data used in the algorithm performs well in tracking the active thunderstorm cells associated with lightning activities.
基金data provided by the GAGE Facility, operated by UNAVCO, Inc., with support from the National Science Foundation and the National Aeronautics and Space Administration under NSF Cooperative Agreement EAR-1724794。
文摘The present analysis provided the quality assessment of 65 Continuous Operating Reference Stations(CORS) situated in and around Mexico using the data of about ten years(January 2010 to January 2020).To accomplish the assessment,we considered 4 quality indexes for performing the quality check,incluing the multipath effect on L1 and L2 bands,signal-to-noise ratio in both bands,cycle slips,and integrity.Meanwhile,a new reference parameter named regio nal values for Mexico(RVM) was calculated for the stations situated in Mexico.Additionally,an exhaustive analysis of the quality indicators in the worst and best cases was performed.The signal degradation was proved by a long-term time series and cru stal defo rmation analysis in GAMIT/GLOBK platform.The results showed a stro ng correlation between integrity,cycle slips and daily observations time,and the multipath effect is strong in the case of outdated systems.The study indicates that the estimated quality indexes and values could be the basis for establishing new CORS in Mexico,and the errors corrections which cannot be mitigated in the postprocessing stage would greatly help utilize the data for different scientific applications.The results were supported by deformation analysis in part of Baja California Peninsula in Mexico indicating northern and eastern velocity vector of -3.08±0.02 mm/yr,-7.85±0.02 mm/yr and-0.07±0.03 mm/yr,-9.33±0.02 mm/yr respectively at MPR1 and INEG stations.
文摘Global Positioning System(GPS)Continuously Operating Reference Station(CORS)data analysis shows that the ionosphere’s electron density variability is linked to the deformation and stress accumulation in the Earth’s crust.Anomalies in ionosphere total electron content(TEC)variability before 2021 M6.4 Sonitpur,Assam earthquake were detected using L1 and L2 GPS frequencies that showed three distinct abnormalities on April 3,9,10,2021.Pearson’s correlation coefficient(r)of TEC decreases in the CORS that lies away from the earthquake epicenter,indicating the possibilities of a positive relationship between TEC variability and earthquake epicenter.TEC concentration also decreases towards the epicenter within the earthquake preparation zone(EPZ).It is also observed that the Pearson’s correlation coefficient(r)of TEC decreases linearly near the EPZ.The study demonstrates the possibilities of determining the TEC anomalous zone in the ionosphere that coincides with the EPZ in the crustal rocks.The research indicated the possibilities of magnitude estimation of an impending earthquake based on the TEC anomalous zone in the ionosphere using closely spaced dense CORS network data.
文摘There is growing needs for web based GIS for easy and fast dissemination, sharing, displaying and processing of spatial information which in turns helping in decision making for various natural resources based applications. In order to make a cost effective implementation, operation and maintenance of spatial information over the web, a cheaper yet feature rich alternative to commercial software is required which can be fulfilled by Open Source GIS software. This paper conveys an efficient approach to customize and integrate an open source web GIS system based on Mapserver as a web GIS server and PostgreSQL/PostGIS as an object oriented relational database management system (ORDBMS) for effective dissemination, sharing and management of spatial information over the internet. An open source web application tool built on top of MapScript using the PHP programming language has been used as for development of interactive user interface. The configurable Web Mapping Client Components (CWC2) tags have been added to HTML template pages in order to deploy the mapping contents to a web application. It is observed that the present system developed using open source software enables user to view, update, customized retrieval, query and analysis of natural resources information for specific needs.
文摘The first ever land campaign to study the spatial variability of the aerosol characteristics along the Brahmaputra river valley (BRV) in Assam, North-Eastern India, was conducted during 2011. Measurements were made over 13 locations for Aerosol Optical Depth (AOD), scattering coefficient, particulate matter, black carbon (BC) concentration and meteorological parameters. The BRV is divided into three sectors longitudinally viz western sector (WS), central sector (CS), and eastern sector (ES). Significant Spatial heterogeneity in AOD and BC concentration was observed (p < 0.05) with the highest values over WS and a continual decrease from WS to ES with aerosol dominance in PM2.5 category along the entire valley. The Angstrom coefficient measured using different wavelength pairs showed spatial variability indicating dominance of fine particles over WS and coarse particles in ES with a probable bimodal distribution. The scattering and absorption coefficient shows dominance of both types of aerosol over WS than other areas. The shortwave radiative forcing was higher over the WS than CS and ES of the valley. The campaign revealed that under favorable wind conditions, the BRV is loaded with significant amount of natural and anthropogenic aerosol during local winter and is influenced by the long-range transport of aerosols from the Indo-Gangetic plain.
文摘Climatic zone is one of the most important units for horticultural planning. Survival and failure of particular land use or farming system in a given region heavily relies on careful assessment of agroclimatic resources. Large variety of crops is being grown in Meghalaya traditionally, based on the needs and cultural practices of people without any consideration to the suitability of the climate. This study attempts to make adjustments with the climate based upon scientific knowledge to make the best use of the natural resources so as to recommend more area under horticultural crops. This has been made by identifying existing land use and appropriate land use strategies mainly for horticultural crops for each agro-climatic region. Modern Geospatial technology such as satellite Remote Sensing (RS) and Geographical Information System (GIS) and GPS have been used effectively to provide newer dimensions in identifying suitable sites for various horticultural crops and also for appropriate monitoring and management of land resources in an integrated manner with reference to agro-climatic condition.
文摘Characterization and evaluation of land resources of Mawryngkneng block was carried out using IRS-P6 LISS III and LISS-IV data. Five major physiographic units namely structural hills, denudational hills, plateau and intermontane valley were identified. Visual interpretation of satellite data indicated that 32.2% of the total geographical area (TGA) is under dense forest followed by wastelands (28.8%), open forest (16.1%), cultivated area (13.6%), built up area (8.2%) and water body (0.9%). Ten soil series were tentatively identified and the soils belonged to 2 orders (Ultisols and Alfisols), 3 sub orders (Udult, Udalf and Humult), 6 great groups, 8 sub groups. The soils are moderately acidic, deep to very deep and texture varies from sandy clay loam to clay. The soils are very rich in organic carbon. The availability of nitrogen is medium to high and phosphorus availability is low to medium whereas potassium availability is low in the entire study area. The soils were grouped into land capability class II & III and the soils were moderately to marginally suitable for orange and marginally suitable for pine apple. An action plan with suggested land use and interventions has been prepared by using all land resource information generated under the study. The action plan includes areas for afforestation, intensive cultivation in the existing cropped areas with soil conservation measures like mulching, zero tillage etc. and orange and pine apple plantation in open scrub lands which are cultivable wastelands. This might help the farmers and the planner in better management of land resources for sustained productivity.
文摘Land evaluation procedure given by FAO for soil site suitability for various land utilization types for rainfed agriculture has been used to assess the land suitability for khasi mandarin orange and pineapple in East Khasi Hills District of Meghalaya. The database on soil and land use/land cover was generated from IRS-P6 remote sensing satellite data, soil survey and laboratory analysis of soil samples to perform an integrated analysis in the Geographic Information System environment. Different soil chemical parameters and physical parameters were considered to evaluate soil site suitability for orange & pineapple. Different thematic layers were derived from soil map by using ArcGIS software. Subsequently all of them were overlaid and integrated in GIS environment and suitability criteria was applied to the resulted composite map and generated land suitability map for orange and pineapple. The result indicated that the soil sites of the study area are highly to marginally suitable for mandarin orange whereas it is marginally suitable for pineapple. The study reveals that highly suitable areas for orange are found in the Cherapunjee and Mawsynram area that covers 34.5 Sq.Km areas. Moderately suitable (37% of TGA) and marginally suitable (24% of TGA) areas are found only because of slope constraint (8%-30% slope). The hills with deep gorges and ravines on the southern portion of the district is found not suitable for orange plantation because of steep slopes (>30%) and stoniness. Land suitability analysis for pineapple showed that 81% area of total geographical area of the district is marginally suitable and 19% area is not suitable to support the crop. The district is marginally suitable because of topography (slope and erosion), soil fertility (base saturation and CEC) and climate.
文摘Urbanization in recent years plays an important role in increase in impervious areas with reducing in vegetation cover and pervious areas of natural landscape. This leads to a rise in temperature of urban areas, by several degrees particularly at night [1,2]. A novel geospatial approach has been adopted to determine the maximum temperature areas (hot spots) over Kamrup Metro District of Assam, which is a gateway for seven neighboring north eastern states of India. The G statistics have been calculated for detecting the presence of hot spot or cold spot over the entire study area which is a new approach in urban heat island studies. The resultant z-scores and p-values show the pixels with either high or low values cluster spatially. For statistically significant positive z-scores, the larger the z-score is, the more intense the clustering of high values (hot spot) and vice versa. Land Surface Temperature (LST) anomaly values and percentage of Impervious Surface Area (ISA) along with climatic data are used to conform the hot spot location. It is one of the densely populated areas with more commercial pockets thereby giving rise to anthropogenic heat discharge which accelerates the heat island phenomenon. Incorporation of socio-economic survey data as well as certain biophysical parameters can be used to know about the cause and future impact of urbanization.
文摘Multi-criteria spatial modeling is one of the important components of spatial decision support system (SDSS). Multi-criteria spatial modeling often requires a common scale of values for diverse and dissimilar inputs to create an integrated analysis. Weighted overlay function is most commonly used for site suitability analysis which identifies the most preferred locations for a specific phenomenon. However, weighted overlay function gives inconsistent and erroneous results for highly dissimilar inputs as it assumes that most favorable factors result in the higher values of raster, while identifying the best sites. This paper conveys the effectiveness of fuzzy overlay function for multi-criteria spatial modeling. It is based on the principle of fuzzy logic theory which defines membership using Gaussian function on each of the input rasters instead of giving individual rank to them like in weighted overlay function. A case study on preparation of land resources map for Mawsynram block of East Khasi Hills district of Meghalaya, India is presented here. It was observed that fuzzy overlay function has given more satisfactory output in terms of site suitability while comparing with the result of weighted overlay function.
文摘Coronavirus (COVID-19) disease is a major pandemic which has taken the world by storm. More than 524,000 citizens of the globe have succumbed to the disease as on 3<sup>rd</sup> July, 2020. Accurate modeling of the dynamics of the disease spread is required to curb the virus. With the availability of large amount of data made available publicly by the Government agency as well as the other live crowdsourcing media, it is possible to develop an accurate local prediction tool. In this study, we analyze the dynamics of local outbreaks of COVID-19 for few states of India with major outbreaks and for India as a whole. The large amount of data available from the COVID-19 Tracker India platform was utilized to estimate the impact of lockdown in the country and the states with major outbreaks. The effectiveness of the lockdown implementation by the respective states is studied for the analysis. The lockdown was categorized into strict, moderate, and lenient. The model is deployed on a web based platform to disseminate the alert to the public. We further extend the ordinary differential Equation (ODE) based model to generate district level vulnerability index for the whole country based on the rate of change of infected people, breach in social distancing, and population. Around 47% of districts of the country were not found vulnerable;however, 13% of the districts were identified as high risk for the disease outbreak.
