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161.
Tony Falkland 《Natural resources forum》1999,23(3):245-260
The water resources of most small island developing states (SIDS) are often very limited and require special consideration to ensure that they are developed and managed in a sustainable manner. Many small islands, typically located in the humid tropics, have no surface water resources and rely on limited groundwater resources in the form of thin freshwater lenses. The exposed location of small islands makes them particularly vulnerable to natural disasters such as cyclones, floods and droughts. Pollution from population centres and from agricultural and other activities is an increasing problem. This article provides an overview of the water resources of small islands, and the main problems and issues related to water resources. Some suggested solutions, based on practical experiences, are offered for water resource assessment and monitoring programmes, and water resource development. Water resource policy, planning and management issues are also addressed, and suggested approaches for resolving some of the major water resource problems presented. 相似文献
162.
Gurnell AM Morrissey IP Boitsidis AJ Bark T Clifford NJ Petts GE Thompson K 《Environmental management》2006,38(4):580-596
A conceptual model of the morphological development of the riparian margins of newly cut river channels is presented, suggesting
early feedbacks between vegetation growth and bank form. To test the model, observations of long and cross profiles, bank
sediment and seed deposition, and bank vegetation development were collected over the first 2 years of river flows through
a reach of the River Cole, West Midlands, UK. The newly created channel had a sinuous planform and varying asymmetric trapezoidal
cross section in sympathy with the planform. No imposed bedforms or bank reseeding were included in the design. Over the 2
years, development of bedforms was rapid, with bed sediment sorting and bank profile adjustment occurring more steadily and
progressively. Six classes of bank profile were identified by the end of the study period, illustrating close associations
with sediment aggradation, vegetation colonization, and growth patterns. Vegetation colonization of the banks was seeded predominantly
from local sources during the summer and from hydrochory (transport by the river) during the winter. Colonizing vegetation
on the riverbanks appeared to act as a significant propagule source by the second summer and as an increasingly important
roughness element, trapping both propagules and sediment, within the second year and providing early feedback into bank evolution.
As a result, the time required for riparian margin development in the conceptual model was found to be considerably longer
than observed in the study river. In addition, the role of surface wash/bank failure in modifying the bank profile and transporting
seeds onto the upper bank face during the first year of bank development was found to be important in initiating rapid bank
vegetation colonization and surface stabilization. This set of processes had not been incorporated in the initial conceptual
model. In relation to channel restoration, this research illustrates that in small temperate rivers of modest energy the provision
of an initial, sinuous corridor is sufficient to induce rapid development of fluvial features and vegetation cover without
the need to construct bed forms or to seed the banks. 相似文献