Specific Catchment Area （SCA） is defined as the upstream catchment area of a unit contour. As one of the key terrain parameters, it is widely used in the modeling of hydrology, soil erosion and ecological environmen...Specific Catchment Area （SCA） is defined as the upstream catchment area of a unit contour. As one of the key terrain parameters, it is widely used in the modeling of hydrology, soil erosion and ecological environment. However, SCA value changes significantly at different DEM resolutions, which inevitably affect terrain analysis results. SCA can be described as the ratio of Catchment Area （CA） and DEM grid length. In this paper, the scale effect of CA is firstly investigated. With Jiuyuangou Gully, a watershed about 70 km2 in northern Shaanxi Province of China, as the test area, it is found that the impacts of DEM scale on CA are different in spatial distribution. CA value in upslope location becomes bigger with the decrease of the DEM resolution. When the location is close to downstream areas the impact of DEM scale on CA is gradually weakening. The scale effect of CA can be concluded as a mathematic trend of exponential decline. Then, a downscaling model of SCA is put forward by introducing the scale factor and the location factor. The scaling model can realize the conversion of SCA value from a coarse DEM resolution to a finer one at pixel level. Experiment results show that the downscaled SCA was well revised, and consistent with SCA at the target resolution with respect to the statistical indexes, histogram and spatial distribution. With the advantages of no empirical parameters, the scaling model could be considered as a simple and objective model for SCA scaling in a rugged drainage area.展开更多
Taking an example of Majiayu Catchment Area (14.15 ha) in Taoyuan County of HunanProvince, the soil and water resources dynamics, fertility evolution characteristics andland productivity changing situation were studie...Taking an example of Majiayu Catchment Area (14.15 ha) in Taoyuan County of HunanProvince, the soil and water resources dynamics, fertility evolution characteristics andland productivity changing situation were studied. Fixed observation results from 1993to 2002 showed that pools covering about 15% of total area could store up 10% of surfacerunoff, keep 78.1% of eroded soil and 65.4% of lost nutrients. The yearly ratio ofinterception and evapotranspiration in land, storage in pools and drainage was 7:2:1,which ensured the resources and nutrients equilibrium and a benign recycle in thecatchment area system, and benefited the aquatic culture and helped to resist seasonaldrought. Moreover, the results showed that soil erosion modulus decreased significantly,equal to or lower than soil loss tolerance (≤500 tkm-2) in reddish yellow soil regions.Soil organic matter, total and available N content in sloping land, dryland and paddyfield increased steadily (>10%); water storage enhanced by more than 20% in sloping landand dryland in drought season; crop production increased by more than 20%; and productionof trees, fruits, tea and fish as well as land productivity increased yearly.展开更多
Register in the framework of the International Program of Research on Water Resources Management and Protection of Ecosystems, the Congo basin in which lies the catchment area of the Kadey (2647 km2) was selected to b...Register in the framework of the International Program of Research on Water Resources Management and Protection of Ecosystems, the Congo basin in which lies the catchment area of the Kadey (2647 km2) was selected to better assess the impact climate variability on the water surface in the perspective of supply drinking water both in the rainy season and in periods of low water. Based on new data from rainfall and flow rates obtained in the last fifteen years (1998-2013), the major trends in time series and the scope of the “drought” were identified. The historical rainfall in the basin is characterized by two major ruptures rainfall in 1969 and 1999. These have generated an order deficit of 14% respectively and an excess of nearly 19%. These phenomena also affected the recurrence of cumulative rainfall throughout the Kadey basin. Here, the hydrological response to excess rainfall is over 100%. However, it appears that over the period 1970-2012, the number of years that has undergone a “severe drought” is to play down.展开更多
This study describes various groundwater flow systems in mountainous areas where both crystalline and hard sedimentary rock formations can be found.The research was conducted in the Sudeten Mountains,in the Kamienczyk...This study describes various groundwater flow systems in mountainous areas where both crystalline and hard sedimentary rock formations can be found.The research was conducted in the Sudeten Mountains,in the Kamienczyk catchment area,which covers 7.85 km^(2)(south-western Poland).展开更多
The examination of macroelements and natural radionuclides in the bottom sediments of small lakes and soils in the catchment areas of the Baikal region allows for the study of the mechanism of inflow and the source of...The examination of macroelements and natural radionuclides in the bottom sediments of small lakes and soils in the catchment areas of the Baikal region allows for the study of the mechanism of inflow and the source of these materials.On the basis of the results of rentgenostructural analysis lake sediments are divided into four types:terrigenous,carbonate, terrigenous-carbonate and organogenic.Through the analysis of gamma-ray spectrometry and ato-展开更多
The purpose of this research is to define initial parameters of Khyargas Lake-Zavkhan River and its catchment area using satellite images. The study has been done by two datasets: 1) Shuttle Radar Topography Mission (...The purpose of this research is to define initial parameters of Khyargas Lake-Zavkhan River and its catchment area using satellite images. The study has been done by two datasets: 1) Shuttle Radar Topography Mission (SRTM) at a horizontal spatial resolution of 90 meters, 2) The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) at a horizontal spatial resolution of 30 meters, using two different models of ArcHydro and Integrated Land and Water Information System (ILWIS) softwares. Main methods of models, that were used in this research are the Deterministic-8, the steepest slope, the spread, the seek computations and the trace analysis. Moreover, input data of the modeling are digital elevation model (DEM) and lake position, outlet location of the river. DEM based ArcHydro model was run on the both datasets, and ILWIS model was run on SRTM data. Several intermediate results were produced while the models run, and initial parameters of the Zavkhan River, its catchment area have been defined at the end of the model. Moreover, final results of the models were compared with each other and with the result of previous research, and with the reality. The result of this study can be used in baseline and advanced research on the catchment area. Besides of that, the result can define a spatial boundary of study on Zavkhan River and its catchment area. Moreover, it would have support for decision-making on ground and surface water resource, distribution and management. Further research, which will cover the entire territory of Mongolia, has to be done using same methodology. The 332nd decision on “River catchment areas of Mongolia” of the Minister of Nature, Environment and Tourism in 2009 has to renew, if a result of that study would be accepted from vocational organization and experts.展开更多
The purpose of this research is to define basic parameters of Tuul River and its catchment area using satellite images. The study has been done by two datasets 1) Shuttle Radar Topography Mission (SRTM) at a horizonta...The purpose of this research is to define basic parameters of Tuul River and its catchment area using satellite images. The study has been done by two datasets 1) Shuttle Radar Topography Mission (SRTM) at a horizontal spatial resolution of 90 meters, 2) The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) at a horizontal spatial resolution of 30 meters, using two different models of ArcHydro and Integrated Land and Water Information System (ILWIS) softwares. Main methods of models, that were used in this research are the Deterministic-8, the steepest slope, the spread, the seek computations and the trace analysis. Moreover, input data of the modeling are digital elevation model (DEM) and outlet location of the river. DEM based ArcHydro model was run on the both datasets, and ILWIS model was run on SRTM data. Several intermediate results were produced while the models run, and basic parameters of the Tuul River, its catchment area have been defined at the end of the model. Moreover, final results of the models were compared with each other and with the result of previous research. The result of this study can be used in baseline and advanced research on the catchment area. Besides of that, the result can define a spatial boundary of study on Tuul River and its catchment area. Moreover, it would have support for decision-making on ground and surface water resource, distribution and management. Further research, which will cover the entire territory of Mongolia, has to be done using same methodology. The 332nd decision on “River catchment areas of Mongolia” of the Minister of Nature, Environment and Tourism in 2009 has to renew, if a result of that study would be accepted from vocational organization and experts.展开更多
Background:There are only limited studies on access to COVID-19 vaccines and identifying the most appropriate health centres for performing vaccination in metropolitan areas.This study aimed to measure potential spati...Background:There are only limited studies on access to COVID-19 vaccines and identifying the most appropriate health centres for performing vaccination in metropolitan areas.This study aimed to measure potential spatial access to COVID-19 vaccination centres in Mashhad,the second-most populous city in Iran.Methods:The 2021 age structure of the urban census tracts was integrated into the enhanced two-step foating catchment area model to improve accuracy.The model was developed based on three diferent access scenarios:only public hospitals,only public healthcare centres and both(either hospitals or healthcare centres)as potential vaccination facilities.The weighted decision-matrix and analytic hierarchy process,based on four criteria(i.e.service area,accessibility index,capacity of vaccination centres and distance to main roads),were used to choose potential vaccination centres looking for the highest suitability for residents.Global Moran’s index(GMI)was used to measure the spatial autocorrelation of the accessibility index in diferent scenarios and the proposed model.Results:There were 26 public hospitals and 271 public healthcare centres in the study area.Although the exclusive use of public healthcare centres for vaccination can provide the highest accessibility in the eastern and north-eastern parts of the study area,our fndings indicate that including both public hospitals and public healthcare centres provide high accessibility to vaccination in central urban part.Therefore,a combination of public hospitals and public healthcare centres is recommended for efcient vaccination coverage.The value of GMI for the proposed model(accessibility to selected vaccination centres)was calculated as 0.53(Z=162.42,P<0.01).Both GMI and Z-score values decreased in the proposed model,suggesting an enhancement in accessibility to COVID-19 vaccination services.Conclusions:The periphery and poor areas of the city had the least access to COVID-19 vaccination centres.Measuring spatial access to COVID-19 vaccination centres can provide valuable insights for urban public health decisionmakers.Our model,coupled with geographical information systems,provides more efcient vaccination coverage by identifying the most suitable healthcare centres,which is of special importance when only few centres are available.展开更多
This paper tried to analyze the particle size characteristics of the soil samples in Shuifang Spring catchment area,Jinfo Mt.,Chongqing with different land use patterns that are horse race grassland, rhododendron bush...This paper tried to analyze the particle size characteristics of the soil samples in Shuifang Spring catchment area,Jinfo Mt.,Chongqing with different land use patterns that are horse race grassland, rhododendron bush,bamboos,and the grassland near the Shuifang spring.The different land usepattern in karst area is of great affection to the particle size characteristics of soil.The median diameter of the karst surface layer soil becomes gradually smaller and smaller in following sequence:horse race grassland,grassland near the Shuifang Spring,展开更多
This study was carried out in selected districts of Mashonaland East and Central provinces of Zimbabwe in 2011 to determine the effects of soil erosion on arable lands and how this related to catchment management. Res...This study was carried out in selected districts of Mashonaland East and Central provinces of Zimbabwe in 2011 to determine the effects of soil erosion on arable lands and how this related to catchment management. Results show that the highest contribution is 53% and is obtained from arable land codes 5 and 7. These fields show signs of excessive sheet and gully erosion. The least contribution is 0.8% and this is on arable land codes 3, 4 and 8. These fields have properly done conservation works existing. 33% of the assessed arable lands have conservation works in place whilst 67% are not protected and as such the fields are eroded. Soil erosion results in the washing away of the precious top soil, responsible for plant growth and infiltration of rain or irrigation water. This reduces the usefulness of such affected arable lands as crops grown on it can’t thrive due to lack of soil fertility. The paper recommends that government policies focus more on promoting sustainable land use through integrated catchment area management. This will go a long way in achieving sustainable development in Zimbabwe.展开更多
基金Key Project of National Natural Science Foundation of China No.40930531 National Youth Science Foun-dation of China No.40901185 Specialized Research Fund for the Doctoral Program of Higher Education No.20093207120008
文摘Specific Catchment Area （SCA） is defined as the upstream catchment area of a unit contour. As one of the key terrain parameters, it is widely used in the modeling of hydrology, soil erosion and ecological environment. However, SCA value changes significantly at different DEM resolutions, which inevitably affect terrain analysis results. SCA can be described as the ratio of Catchment Area （CA） and DEM grid length. In this paper, the scale effect of CA is firstly investigated. With Jiuyuangou Gully, a watershed about 70 km2 in northern Shaanxi Province of China, as the test area, it is found that the impacts of DEM scale on CA are different in spatial distribution. CA value in upslope location becomes bigger with the decrease of the DEM resolution. When the location is close to downstream areas the impact of DEM scale on CA is gradually weakening. The scale effect of CA can be concluded as a mathematic trend of exponential decline. Then, a downscaling model of SCA is put forward by introducing the scale factor and the location factor. The scaling model can realize the conversion of SCA value from a coarse DEM resolution to a finer one at pixel level. Experiment results show that the downscaled SCA was well revised, and consistent with SCA at the target resolution with respect to the statistical indexes, histogram and spatial distribution. With the advantages of no empirical parameters, the scaling model could be considered as a simple and objective model for SCA scaling in a rugged drainage area.
基金funded by the Knowledge Innovation Program of Chinese Academy of Sciences(KZCX2-SW-415,KZCX3-SW-426).
文摘Taking an example of Majiayu Catchment Area (14.15 ha) in Taoyuan County of HunanProvince, the soil and water resources dynamics, fertility evolution characteristics andland productivity changing situation were studied. Fixed observation results from 1993to 2002 showed that pools covering about 15% of total area could store up 10% of surfacerunoff, keep 78.1% of eroded soil and 65.4% of lost nutrients. The yearly ratio ofinterception and evapotranspiration in land, storage in pools and drainage was 7:2:1,which ensured the resources and nutrients equilibrium and a benign recycle in thecatchment area system, and benefited the aquatic culture and helped to resist seasonaldrought. Moreover, the results showed that soil erosion modulus decreased significantly,equal to or lower than soil loss tolerance (≤500 tkm-2) in reddish yellow soil regions.Soil organic matter, total and available N content in sloping land, dryland and paddyfield increased steadily (>10%); water storage enhanced by more than 20% in sloping landand dryland in drought season; crop production increased by more than 20%; and productionof trees, fruits, tea and fish as well as land productivity increased yearly.
文摘Register in the framework of the International Program of Research on Water Resources Management and Protection of Ecosystems, the Congo basin in which lies the catchment area of the Kadey (2647 km2) was selected to better assess the impact climate variability on the water surface in the perspective of supply drinking water both in the rainy season and in periods of low water. Based on new data from rainfall and flow rates obtained in the last fifteen years (1998-2013), the major trends in time series and the scope of the “drought” were identified. The historical rainfall in the basin is characterized by two major ruptures rainfall in 1969 and 1999. These have generated an order deficit of 14% respectively and an excess of nearly 19%. These phenomena also affected the recurrence of cumulative rainfall throughout the Kadey basin. Here, the hydrological response to excess rainfall is over 100%. However, it appears that over the period 1970-2012, the number of years that has undergone a “severe drought” is to play down.
基金carried out under the research grant DEC-2011/01/B/ST10/05121 funded by the Narodowe Centrum Nauki(National Centre for Science)。
文摘This study describes various groundwater flow systems in mountainous areas where both crystalline and hard sedimentary rock formations can be found.The research was conducted in the Sudeten Mountains,in the Kamienczyk catchment area,which covers 7.85 km^(2)(south-western Poland).
文摘The examination of macroelements and natural radionuclides in the bottom sediments of small lakes and soils in the catchment areas of the Baikal region allows for the study of the mechanism of inflow and the source of these materials.On the basis of the results of rentgenostructural analysis lake sediments are divided into four types:terrigenous,carbonate, terrigenous-carbonate and organogenic.Through the analysis of gamma-ray spectrometry and ato-
文摘The purpose of this research is to define initial parameters of Khyargas Lake-Zavkhan River and its catchment area using satellite images. The study has been done by two datasets: 1) Shuttle Radar Topography Mission (SRTM) at a horizontal spatial resolution of 90 meters, 2) The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) at a horizontal spatial resolution of 30 meters, using two different models of ArcHydro and Integrated Land and Water Information System (ILWIS) softwares. Main methods of models, that were used in this research are the Deterministic-8, the steepest slope, the spread, the seek computations and the trace analysis. Moreover, input data of the modeling are digital elevation model (DEM) and lake position, outlet location of the river. DEM based ArcHydro model was run on the both datasets, and ILWIS model was run on SRTM data. Several intermediate results were produced while the models run, and initial parameters of the Zavkhan River, its catchment area have been defined at the end of the model. Moreover, final results of the models were compared with each other and with the result of previous research, and with the reality. The result of this study can be used in baseline and advanced research on the catchment area. Besides of that, the result can define a spatial boundary of study on Zavkhan River and its catchment area. Moreover, it would have support for decision-making on ground and surface water resource, distribution and management. Further research, which will cover the entire territory of Mongolia, has to be done using same methodology. The 332nd decision on “River catchment areas of Mongolia” of the Minister of Nature, Environment and Tourism in 2009 has to renew, if a result of that study would be accepted from vocational organization and experts.
文摘The purpose of this research is to define basic parameters of Tuul River and its catchment area using satellite images. The study has been done by two datasets 1) Shuttle Radar Topography Mission (SRTM) at a horizontal spatial resolution of 90 meters, 2) The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) at a horizontal spatial resolution of 30 meters, using two different models of ArcHydro and Integrated Land and Water Information System (ILWIS) softwares. Main methods of models, that were used in this research are the Deterministic-8, the steepest slope, the spread, the seek computations and the trace analysis. Moreover, input data of the modeling are digital elevation model (DEM) and outlet location of the river. DEM based ArcHydro model was run on the both datasets, and ILWIS model was run on SRTM data. Several intermediate results were produced while the models run, and basic parameters of the Tuul River, its catchment area have been defined at the end of the model. Moreover, final results of the models were compared with each other and with the result of previous research. The result of this study can be used in baseline and advanced research on the catchment area. Besides of that, the result can define a spatial boundary of study on Tuul River and its catchment area. Moreover, it would have support for decision-making on ground and surface water resource, distribution and management. Further research, which will cover the entire territory of Mongolia, has to be done using same methodology. The 332nd decision on “River catchment areas of Mongolia” of the Minister of Nature, Environment and Tourism in 2009 has to renew, if a result of that study would be accepted from vocational organization and experts.
文摘Background:There are only limited studies on access to COVID-19 vaccines and identifying the most appropriate health centres for performing vaccination in metropolitan areas.This study aimed to measure potential spatial access to COVID-19 vaccination centres in Mashhad,the second-most populous city in Iran.Methods:The 2021 age structure of the urban census tracts was integrated into the enhanced two-step foating catchment area model to improve accuracy.The model was developed based on three diferent access scenarios:only public hospitals,only public healthcare centres and both(either hospitals or healthcare centres)as potential vaccination facilities.The weighted decision-matrix and analytic hierarchy process,based on four criteria(i.e.service area,accessibility index,capacity of vaccination centres and distance to main roads),were used to choose potential vaccination centres looking for the highest suitability for residents.Global Moran’s index(GMI)was used to measure the spatial autocorrelation of the accessibility index in diferent scenarios and the proposed model.Results:There were 26 public hospitals and 271 public healthcare centres in the study area.Although the exclusive use of public healthcare centres for vaccination can provide the highest accessibility in the eastern and north-eastern parts of the study area,our fndings indicate that including both public hospitals and public healthcare centres provide high accessibility to vaccination in central urban part.Therefore,a combination of public hospitals and public healthcare centres is recommended for efcient vaccination coverage.The value of GMI for the proposed model(accessibility to selected vaccination centres)was calculated as 0.53(Z=162.42,P<0.01).Both GMI and Z-score values decreased in the proposed model,suggesting an enhancement in accessibility to COVID-19 vaccination services.Conclusions:The periphery and poor areas of the city had the least access to COVID-19 vaccination centres.Measuring spatial access to COVID-19 vaccination centres can provide valuable insights for urban public health decisionmakers.Our model,coupled with geographical information systems,provides more efcient vaccination coverage by identifying the most suitable healthcare centres,which is of special importance when only few centres are available.
文摘This paper tried to analyze the particle size characteristics of the soil samples in Shuifang Spring catchment area,Jinfo Mt.,Chongqing with different land use patterns that are horse race grassland, rhododendron bush,bamboos,and the grassland near the Shuifang spring.The different land usepattern in karst area is of great affection to the particle size characteristics of soil.The median diameter of the karst surface layer soil becomes gradually smaller and smaller in following sequence:horse race grassland,grassland near the Shuifang Spring,
文摘This study was carried out in selected districts of Mashonaland East and Central provinces of Zimbabwe in 2011 to determine the effects of soil erosion on arable lands and how this related to catchment management. Results show that the highest contribution is 53% and is obtained from arable land codes 5 and 7. These fields show signs of excessive sheet and gully erosion. The least contribution is 0.8% and this is on arable land codes 3, 4 and 8. These fields have properly done conservation works existing. 33% of the assessed arable lands have conservation works in place whilst 67% are not protected and as such the fields are eroded. Soil erosion results in the washing away of the precious top soil, responsible for plant growth and infiltration of rain or irrigation water. This reduces the usefulness of such affected arable lands as crops grown on it can’t thrive due to lack of soil fertility. The paper recommends that government policies focus more on promoting sustainable land use through integrated catchment area management. This will go a long way in achieving sustainable development in Zimbabwe.
