The study identified spatial variations in flood vulnerability levels in Port Harcourt metropolis with the use of GIS （geographic information systems）. This study considered four factors and these included landuse t...The study identified spatial variations in flood vulnerability levels in Port Harcourt metropolis with the use of GIS （geographic information systems）. This study considered four factors and these included landuse types, drainage, residential densities and elevation. The elevation data and drainage data were derived from the topographical map of scale 1：35,000, while the land use types were derived from the imagery of Port Harcourt metropolis downloaded from Google Earth, 2010 version. Both the topographical map and imagery were geo-referenced to geographic coordinates and geographic features were digitized in form of shapefiles using both ArcView GIS 3.3 and ArcGIS 9.2 versions. AHP （analytical hierarchical process） was adopted in this study whereby many flood factors were ranked and overlaid for decision making. The contour data was used to generate the DEM （digital elevation model） through the process called kriging in ArcGIS 9.2. Based on the ranking index, factors considered were reclassified to three levels of vulnerability namely highly vulnerable, moderately vulnerable and lowly vulnerable through ranking method and these reclassified factors were then overlaid using an addition operator. The analysis shows that communities like Eagle Island, Ojimbo, Kidney Island were highly vulnerable to flood while communities like Choba, Ogbogoro, Rumualogu were moderately vulnerable. Communities like Rumuigbo, Rumuodomaya etc. were lowly vulnerable to flood. The highly vulnerable places covered 98.18 km2, moderately vulnerable was 220.46 km2 and lowly vulnerable areas covered 330.77 km2.展开更多
Trends in land use and water consumption are crucial components in understanding the changing nature of agricultural production and water use in- the Northern Jordan Valley. The objective of this study is to examine c...Trends in land use and water consumption are crucial components in understanding the changing nature of agricultural production and water use in- the Northern Jordan Valley. The objective of this study is to examine current agricultural land uses in the Jordan Valley and their water consumption patterns as well as to examine the changes in land use and water consumption that occurred between the years 2002 and 2010. Farm level cropping patterns and total annual water use were analysed in order to examine inter-basin land use and water consumption characteristics as well as to estimate the amount of water consumed by each respective crop in total and per unit of land devoted to its production. It was found that citrus production dominated both land and water usage in every basin of the Northern Jordan Valley and that between 2002 and 2010 there were shifts toward increasing citrus production in almost every basin surveyed. It was found that agricultural irrigation water usage decreased overall between 2002 and 2010 by approximately 15 percent and irrigated land usage in the Jordan Valley increased by 5 percent. The role of citrus farming is becoming more important in the Jordan Valley as Jordan＇s agricultural economy shifts away from subsistence farming for staple food crops like wheat and vegetables toward more financially lucrative crops grown for an increasingly international market. This trend is at least partly due to the increasing cost of agricultural irrigation water from Jordan＇s national canal system.展开更多
文摘The study identified spatial variations in flood vulnerability levels in Port Harcourt metropolis with the use of GIS （geographic information systems）. This study considered four factors and these included landuse types, drainage, residential densities and elevation. The elevation data and drainage data were derived from the topographical map of scale 1：35,000, while the land use types were derived from the imagery of Port Harcourt metropolis downloaded from Google Earth, 2010 version. Both the topographical map and imagery were geo-referenced to geographic coordinates and geographic features were digitized in form of shapefiles using both ArcView GIS 3.3 and ArcGIS 9.2 versions. AHP （analytical hierarchical process） was adopted in this study whereby many flood factors were ranked and overlaid for decision making. The contour data was used to generate the DEM （digital elevation model） through the process called kriging in ArcGIS 9.2. Based on the ranking index, factors considered were reclassified to three levels of vulnerability namely highly vulnerable, moderately vulnerable and lowly vulnerable through ranking method and these reclassified factors were then overlaid using an addition operator. The analysis shows that communities like Eagle Island, Ojimbo, Kidney Island were highly vulnerable to flood while communities like Choba, Ogbogoro, Rumualogu were moderately vulnerable. Communities like Rumuigbo, Rumuodomaya etc. were lowly vulnerable to flood. The highly vulnerable places covered 98.18 km2, moderately vulnerable was 220.46 km2 and lowly vulnerable areas covered 330.77 km2.
文摘Trends in land use and water consumption are crucial components in understanding the changing nature of agricultural production and water use in- the Northern Jordan Valley. The objective of this study is to examine current agricultural land uses in the Jordan Valley and their water consumption patterns as well as to examine the changes in land use and water consumption that occurred between the years 2002 and 2010. Farm level cropping patterns and total annual water use were analysed in order to examine inter-basin land use and water consumption characteristics as well as to estimate the amount of water consumed by each respective crop in total and per unit of land devoted to its production. It was found that citrus production dominated both land and water usage in every basin of the Northern Jordan Valley and that between 2002 and 2010 there were shifts toward increasing citrus production in almost every basin surveyed. It was found that agricultural irrigation water usage decreased overall between 2002 and 2010 by approximately 15 percent and irrigated land usage in the Jordan Valley increased by 5 percent. The role of citrus farming is becoming more important in the Jordan Valley as Jordan＇s agricultural economy shifts away from subsistence farming for staple food crops like wheat and vegetables toward more financially lucrative crops grown for an increasingly international market. This trend is at least partly due to the increasing cost of agricultural irrigation water from Jordan＇s national canal system.
