Influence of Wind on Dynamics and Flushing of Shallow Estuaries

Observations of two small estuaries in Cape Cod, U.S.A. indicate large variations in salinity structure that are forced by variations in along-estuary wind stress. During onshore winds, the estuarine circulation is reduced, and the along-estuary salinity gradient increases as freshwater accumulates. During offshore winds, the surface outflow is enhanced, freshwater is flushed out of the estuary, and the along-estuary salinity gradient becomes weak. Constrictions block the wind-induced flushing, resulting in strong salinity fronts across the constrictions. The residence time of one of the estuaries varies by more than a factor of three in response to variations in wind-induced flushing. The other estuary has little variation of flushing associated with winds, due to a constriction at the mouth that inhibits the wind-induced exchange. The strong influence of winds on the flushing of these estuaries is due in part to their shallow depths, which accentuates the influence of wind stress relative to the effects of the horizontal density gradient. In addition, the residence times of the estuaries are comparable to the time scale of wind forcing, allowing large changes in water properties during wind events.     

Assessment of spatial variation in carbon utilization by benthic and pelagic invertebrates in a temperate South African estuary using stable isotope signatures

Stable isotope analyses (δ¹³C and δ¹⁵N) were used to evaluate the spatial variations in carbon flow from primary producers to consumers at two sites in the temperate and permanently open Kariega Estuary on the southeastern coast of South Africa during October 2005 and February 2006. One site was located opposite a salt marsh while the second was upstream of the marsh. Except for significantly enriched δ¹³C values of Zostera capensis and surface sediments near the salt marsh, the δ¹³C and δ¹⁵N signatures of the producers were similar between sites. The invertebrates were clustered into groups roughly corresponding to the predominant feeding modes. The suspension feeders showed δ¹³C values closest to the seston, whereas the deposit feeders, detritivores and scavengers/predators had more enriched δ¹³C values reflecting primary carbon sources that were likely a combination of seston, Spartina maritima and Z. capensis at the upstream site, with an increased influence of benthic algae and Z. capensis at the salt marsh site. The δ¹⁵N signatures of the consumers showed a stepwise continuum rather than distinct levels of fractionation, indicating highly complex trophic linkages and significant dietary overlap among the species. Consumers exhibited significantly enriched δ¹³C values at the salt marsh site, an effect that was attributed to enriched Z. capensis detritus in this region in addition to increased phytoplankton biomass in their diets compared with invertebrates living upstream. The data reinforce the concept that between-site variations in the stable isotope ratios of consumers can result not only from dietary shifts, but also from alterations in the isotope ratios of primary producers.     

"5.12"汶川大地震震中区映秀镇地震灾情及次生地质灾害遥感初步调查

"5.12"四川汶川8级大地震发生后,中国国土资源航空物探遥感中心立即采用"赛斯纳"高空遥感飞机,携带高清晰彩色数码相机及先进的POS系统,迅速获取了重灾区的航摄图像数据。本文以震中附近的映秀镇地区为例,简要介绍了以该高质量航摄数据为基础,采用数字滑坡技术,快速进行震后重灾区灾情及次生地质灾害遥感调查的成果。     

The impact of residential desegregation on social integration: Evidence from a South African neighbourhood

This paper analyses the potential for social integration in post-apartheid urban South Africa by examining the lives of those already living in desegregated spaces. The case study is a low-cost state-assisted housing project situated in the wealthy southern suburbs of Cape Town. In this social housing project, named Westlake village, coloured and Black African (alongside a handful of white and Indian) residents were awarded state housing in 1999 as replacement for their previous homes (informal and formal), which were demolished to make way for a mixed land-use development, of which their new homes form a small component. Westlake’s desegregation is found to extend beyond mere residential abode, affecting resident’s everyday lives to the extent that apartheid’s history and geography are superseded by other factors (such as proximity and affordability) in decision-making. Furthermore, integration at the everyday level of informal neighbourly mixing is prevalent. Although more formal cross-race friendships are rare, discussion reveals this as a consequence of Westlake’s specific socio-historic identity rather than racial divisions per se. Empirical evidence is used to propose a continuum of social integration experience. This continuum addresses the form of integration, for example greeting in the street, visiting homes, inter-marriage; and also the spaces of integration, for example physical space (shared neighbourhood), economic space (common employment-type), social space (cross-race friendship), political space (common involvement in civic organisations) and cultural space (shared sense of belonging).     

八宝喀斯特山区生态环境问题与治理措施

喀斯特峰丛山区生态系统特征有：结构简单，稳定性差，恢复困难等。其生态系统脆弱性表现为：（1）裸露型喀斯特山地坡度陡峻，土壤贫脊，耕地少而分散，水土保持能力差；（2）地下水文网发育导致地表水大量漏失，地下水位埋藏深，难以开采利用；（3）植被树种单一，生长缓慢，资源开发过程中易产生耕作粗放，水土流失，石漠化等环境问题，对其治理和恢复过程应是渐进式的：水－土－林，即首先要科学开发利用各种水资源，同时合理规划利用土地资源，其次要加速生态系统重建，使其形成良性循环发展方式。     

数字化测绘技术在城镇地籍测量中的应用

数字化测绘是目前较为流行的测量方式，其技术本身也日渐成熟。文章简述了数字化测绘技术在城镇地籍测量中作业流程、实施过程与地籍管理信息系统的建立过程。     

‘Bringing government to the people’: women, local governance and community participation in South Africa

This paper considers the ongoing political transformations in South Africa in the context of debates about good governance and participatory democracy. It first appraises the current transformations of local government in South Africa, focusing specifically on relationships between gender equality and citizenship on the one hand, and local government policy, legislation, and community participation on the other, and then explores meanings of participation and how they inform approaches towards local socio-economic development. The findings of primary research conducted with civil society organisations and black women in communities in the Cape Town metropolitan area are explored through three interrelated themes. First, the model of structured participation that is central to South Africa’s democratic transformation is assessed from the perspective of black women. Second, cultures of alienation, both within local governance structures and amongst black women and the extent to which recent restructuring is combating or contributing to these are explored. Third, how participation policies are dealing with conflict within and between target groups are analysed, whether stakeholder group politics obliterate important differences in interests and whether alternative structures might be more effective in terms of women’s participation and empowerment. Finally, the findings are interpreted in relation to theoretical concepts of good governance and participatory democracy, and the potential and problems of realising South Africa’s transformation process toward developmental local government are assessed.     

浅谈雅江县城南各种地质灾害的关系

对雅江县城南地质灾害的产生原因作了查明，为下一步综合整治提供依据。     

A furrow runs through it: An example of sustainable traditional irrigation in Western Cape Province,South Africa

Water and water related matters are important issues in water scarce countries like the Republic of South Africa. This is especially true for the agricultural sector that relies heavily on the availability of water for irrigation to ensure a secure food supply. In South Africa, present day irrigation projects rely on government subsidies and are usually large undertakings beyond the reach of individuals or small communities. The sustainability of such large irrigation projects is still a matter of debate. A 100 years ago a different set of rules applied. Irrigation could only be achieved by hand-dug furrows that supplied water in relatively small quantities to small farming communities. This paper investigated such a small community, the Leeukloof farming community in the Western Cape Province of the Republic of South Africa. For the past 93 years this community has maintained a furrow that supplies water not only to farms bordering the Perdeberg River, which supplies the furrow with water, but also to farms not bordering the river. The authors try to reconstruct the changes in agricultural practices brought about by the furrow, methods of water extraction during each phase, as well as the development and role of the furrow system. The perception by the community of the necessity of this method of water extraction from the river system is also investigated. This revised version was published online in July 2006 with corrections to the Cover Date.