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The study addresses population dynamics in Ghana on the urban and regional levels between 1984 and 2000. At the urban level,
the development trends are analyzed for urban localities (population above 5,000) on the basis of geo-coded census data. Potential
driving forces for rapid population growth related to size, location, accessibility and facility counts are examined using
bivariate and multivariate analysis. An index of weighted accessibility relative to other urban localities provides significant
explanation at the national level, as does initial locality size. At the regional level, population development is analyzed
to provide insight into the rural–urban relations. The level of urbanization is steadily increasing but varies considerably
between regions. Areas of high population growth are found in some rural areas that have a remote location relative to the
large urban centers. This seems to indicate the existence of ‘frontier’ regions, i.e. areas that experience a high degree
of in-migration by people aiming to undertake specific farming activities. A high proportion of the population growth in these
areas appears to take place in relatively small towns. The paper concludes with a more in-depth discussion of the development
characteristics of Ghana’s Western Region. This region has experienced one of the highest regional population growth rates,
mainly due to its status as a ‘frontier’ for cocoa production.
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| Lasse Moller-JensenEmail: |
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Simple yet physically based models to evaluate stream–aquifer interactions during a flooding event subject to triangular stream stage variation were developed in this study. The results from the developed models were compared with other analytical and numerical solutions and noted to be very accurate. The study fills an important gap with regard to available analytical and semi-analytical solutions for modeling stream–aquifer interactions, which can be used for evaluating numerical codes. In particular, the developed models are very useful to obtain preliminary insights with regard to bank storage in ungaged watersheds as required for watershed management and planning studies in rapidly urbanizing watersheds. The utility of the model is illustrated by applying it to study the effects of urbanization on stream–aquifer interactions in the Arroyo Colorado River Watershed along the US–Mexico border region. The results indicate that increased urbanization reduces the amount of influx into the banks. The reduction in flood passage time was noted to have a greater impact than the associated rise in stage. The presence of a semi-permeable barrier was seen to mask the effects of urbanization. The model results also implicitly highlight the importance of how water quality variations caused due to urbanization can affect stream–aquifer interactions. 相似文献
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Based on more than 2,000 data points reflecting various meaningful aspects of urban systems and water-resource systems, and using a quantitative measurement model and ArcGIS, this study discusses the temporal-spatial variations of water resources constraint on urbanization in the Gansu section of China. The conclusions were: (1) from 1989 to 2007 the water resources constraint intensities (WRCIs) of Gansu section and its 9 cities have been generally decreasing, albeit with much fluctuation, and the decrease has been more rapid since 2000, with Lanzhou and Jinchang as the most representative cities. There is, however, a great deal of variation of WRCI among the 9 cities: Lanzhou changed from intensive constraint to relatively strong constraint, with a significant decline in its WRCI; 5 cities changed from extreme constraint to intensive constraint, including Wuwei and Jiuquan with significant declines in their WRCI, Jiayuguan and Jinchang with no dramatic declines and Dingxi with a fluctuating decline; and 3 cities remained at the same level of water resources constraint, including Zhangye and Baiyin with extreme constraint, and Tianshui with intensive constraint. (2) Looking at the 20-year average of WRCI, there are three types of spatial variations among the 9 cities in the Gansu section: Lanzhou, the capital city of Gansu Province, belongs to the relatively strong constraint-high type; 4 cities—Jiuquan, Jiayuguan, Jinchang and Tianshui—belong to the intensive constraint-high type; and the remaining 4 cities—Zhangye, Wuwei, Baiyin and Dxingxi—belong to the extreme constraint-low type. These results show that the Gansu section will continue to be affected by water resources constraint on urbanization and local economic development for some time to come. 相似文献