This paper discusses the integration between GIS and hydrological models and presents a case study relating to the upper section of Moulouya River Basin (UMRB) situated in the east of Morocco. The Basin is an inland w...This paper discusses the integration between GIS and hydrological models and presents a case study relating to the upper section of Moulouya River Basin (UMRB) situated in the east of Morocco. The Basin is an inland water-shed with a total area of approximately 10,000 km2, stretching in the junction between the Middle Atlas, the High Atlas Mountain and the Middle Moulouya basin. From ArcGIS ArcHydro framework data models, different parameters of the Moulouya River and its catchment area have been defined. DEM based ArcHydro model was run on Aster-GDEM V2 data at a horizontal spatial resolution of 30 meters. Several raster and vector products of the Upper Moulouya River and its catchment area have been defined at the end of the model. Final results of the models were discussed and compared with the reality. These results can be used in baseline for advanced hydrology and geomorphology research on the catchment area. They can support for decision-making on ground and surface water resource, distribution and management.展开更多
Digital Elevation Models (DEMs) provide one of the most useful digital datasets for a wide range of users. Both the Shuttle Radar Topographic Mission (STRM V.4.1) topography and the Advanced Spaceborne Thermal Emissio...Digital Elevation Models (DEMs) provide one of the most useful digital datasets for a wide range of users. Both the Shuttle Radar Topographic Mission (STRM V.4.1) topography and the Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER-GDEM V.2) have been widely used in geomorphology, hydrology, tectonic, and others since they were made access to the public. The magnitude of vertical errors of two near-global DEMs—SRTM and ASTER-GDEM is compared and validated against a reference DEM which has a relatively high precision of 1:25,000 scale constructed from topographical map. Moreover, the reference DEM, ASTER-GDEM and SRTM were used as basic topographic data to extract some Morphometric index. The parameters like slope and shaded reflectance maps, were derived from the elevation distribution to provide a more sensitive indication of DEM quality. A square area in the North East of Tunisia was selected as a case study to test and evaluate the elevation accuracy of ASTER-GDEM and SRTM. The relative accuracy approach and absolute accuracy were adopted to evaluate global DEMs. The comparisons show that SRTM overestimates and ASTER-GDEM underestimates elevations, both DEMs can be used to extract the elevations of required geometric data,?i.e.?sub watershed boundaries, drainage information and cross sections. However, small errors still exist in. The lower root mean square errors values indicate that SRTM is comparatively more accurate than ASTER-GDEM.展开更多
Based on the GDEM hydrographic data with a resolution of 0.5°× 0.5°, the current system (Kuroshio south of Japan and Kuroshio Extension east of Japan) is determined by using the P-Vector Method, and its...Based on the GDEM hydrographic data with a resolution of 0.5°× 0.5°, the current system (Kuroshio south of Japan and Kuroshio Extension east of Japan) is determined by using the P-Vector Method, and its seasonal variability is investigated. The Kuroshio Meander south of Japan, the two lee-wave meanders in the Kuroshio Extension and the bifurcation of the Kuroshio Extension are properly presented. The path of the Kuroshio Meander, the position of the second (east) meander in the Kuroshio Extension and the bifurcation of the Kuroshio Extension display evident seasonal variation.展开更多
The propagation of the lightning-radiated electromagnetic field along the real irregular terrain around Yangzhou Direction Finder(DF)site(119°42′E,32°39′N)and Nanjing DF site(118°46′E,32°03′N)o...The propagation of the lightning-radiated electromagnetic field along the real irregular terrain around Yangzhou Direction Finder(DF)site(119°42′E,32°39′N)and Nanjing DF site(118°46′E,32°03′N)of Jiangsu Province in China is estimated.The results show that the rough irregular terrain results in the rapid magnitude attenuation and the increase of the rise-time of the field waveform.For example,for the Yangzhou DF site as the circumference of a radius of 45 km,the root-mean-squared height(RMSH)of the real irregular terrain varies from 7 to 33 m;the extra field attenuation relative to the ideal ground surface ranges from 1%to 11%,and the extra rise-time increment varies from 0.1 to 0.6μs.Therefore,the extracted current peak of lightning return stroke may be underestimated from the remotely measured electromagnetic field,and the error varies along with different azimuths.展开更多
The River Chenab is one of the main western rivers of the Indus River system in Pakistan, which undergoes intensive inundation almost every year during the late monsoon period. The present study performs flood frequen...The River Chenab is one of the main western rivers of the Indus River system in Pakistan, which undergoes intensive inundation almost every year during the late monsoon period. The present study performs flood frequency analyses for the river basin as well as simulates different levels of water flow in the system to speculate all kinds of inundation under different scenarios, i.e., to predict flood hazard and flood extended areas. Flood frequency analyses were performed at MARALA Headworks to Khanki Headworks. Data were collected from the Punjab Irrigation Department, Pakistan and from USGS and ASTER GDEM. The peak discharge of MARALA Headworks had been analyzed for 25 years. The preprocessing was performed in HEC Geo-RAS after preprocessing model run in HEC-RAS. After analysis the data were exported in HEC-RAS to ARCMAP to generate a floodplain and inundation map. Our analysis generated the result that different areas would be under water in different return periods. Flood hazards maps for different return periods 10, 20, 50 and 100 years were conducted using annual peaks flow of 35 years from 1980 to 2016. The maximum discharges at up and down stream for different periods were obtained using Gumbel distribution model results which showed that different areas were predicted under water in different return periods and affected areas after five years’ return period.展开更多
文摘This paper discusses the integration between GIS and hydrological models and presents a case study relating to the upper section of Moulouya River Basin (UMRB) situated in the east of Morocco. The Basin is an inland water-shed with a total area of approximately 10,000 km2, stretching in the junction between the Middle Atlas, the High Atlas Mountain and the Middle Moulouya basin. From ArcGIS ArcHydro framework data models, different parameters of the Moulouya River and its catchment area have been defined. DEM based ArcHydro model was run on Aster-GDEM V2 data at a horizontal spatial resolution of 30 meters. Several raster and vector products of the Upper Moulouya River and its catchment area have been defined at the end of the model. Final results of the models were discussed and compared with the reality. These results can be used in baseline for advanced hydrology and geomorphology research on the catchment area. They can support for decision-making on ground and surface water resource, distribution and management.
文摘Digital Elevation Models (DEMs) provide one of the most useful digital datasets for a wide range of users. Both the Shuttle Radar Topographic Mission (STRM V.4.1) topography and the Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER-GDEM V.2) have been widely used in geomorphology, hydrology, tectonic, and others since they were made access to the public. The magnitude of vertical errors of two near-global DEMs—SRTM and ASTER-GDEM is compared and validated against a reference DEM which has a relatively high precision of 1:25,000 scale constructed from topographical map. Moreover, the reference DEM, ASTER-GDEM and SRTM were used as basic topographic data to extract some Morphometric index. The parameters like slope and shaded reflectance maps, were derived from the elevation distribution to provide a more sensitive indication of DEM quality. A square area in the North East of Tunisia was selected as a case study to test and evaluate the elevation accuracy of ASTER-GDEM and SRTM. The relative accuracy approach and absolute accuracy were adopted to evaluate global DEMs. The comparisons show that SRTM overestimates and ASTER-GDEM underestimates elevations, both DEMs can be used to extract the elevations of required geometric data,?i.e.?sub watershed boundaries, drainage information and cross sections. However, small errors still exist in. The lower root mean square errors values indicate that SRTM is comparatively more accurate than ASTER-GDEM.
基金supported by the Ministry of Science and Technology of China under contract(Grant No.2002CCA00200)by the Ministry of Education of China under contract(Grant No.99075).
文摘Based on the GDEM hydrographic data with a resolution of 0.5°× 0.5°, the current system (Kuroshio south of Japan and Kuroshio Extension east of Japan) is determined by using the P-Vector Method, and its seasonal variability is investigated. The Kuroshio Meander south of Japan, the two lee-wave meanders in the Kuroshio Extension and the bifurcation of the Kuroshio Extension are properly presented. The path of the Kuroshio Meander, the position of the second (east) meander in the Kuroshio Extension and the bifurcation of the Kuroshio Extension display evident seasonal variation.
基金Supported by the Application of the Forecasting Warning System for Lightning Disaster in Yunan Plateau(YNKJXM20190733)National Natural Science Foundation of China(41775006,41575004).
文摘The propagation of the lightning-radiated electromagnetic field along the real irregular terrain around Yangzhou Direction Finder(DF)site(119°42′E,32°39′N)and Nanjing DF site(118°46′E,32°03′N)of Jiangsu Province in China is estimated.The results show that the rough irregular terrain results in the rapid magnitude attenuation and the increase of the rise-time of the field waveform.For example,for the Yangzhou DF site as the circumference of a radius of 45 km,the root-mean-squared height(RMSH)of the real irregular terrain varies from 7 to 33 m;the extra field attenuation relative to the ideal ground surface ranges from 1%to 11%,and the extra rise-time increment varies from 0.1 to 0.6μs.Therefore,the extracted current peak of lightning return stroke may be underestimated from the remotely measured electromagnetic field,and the error varies along with different azimuths.
文摘The River Chenab is one of the main western rivers of the Indus River system in Pakistan, which undergoes intensive inundation almost every year during the late monsoon period. The present study performs flood frequency analyses for the river basin as well as simulates different levels of water flow in the system to speculate all kinds of inundation under different scenarios, i.e., to predict flood hazard and flood extended areas. Flood frequency analyses were performed at MARALA Headworks to Khanki Headworks. Data were collected from the Punjab Irrigation Department, Pakistan and from USGS and ASTER GDEM. The peak discharge of MARALA Headworks had been analyzed for 25 years. The preprocessing was performed in HEC Geo-RAS after preprocessing model run in HEC-RAS. After analysis the data were exported in HEC-RAS to ARCMAP to generate a floodplain and inundation map. Our analysis generated the result that different areas would be under water in different return periods. Flood hazards maps for different return periods 10, 20, 50 and 100 years were conducted using annual peaks flow of 35 years from 1980 to 2016. The maximum discharges at up and down stream for different periods were obtained using Gumbel distribution model results which showed that different areas were predicted under water in different return periods and affected areas after five years’ return period.
