Man-made Barriers Research Articles

Dissolved Organic Matter in the Florida Everglades: Implications for Ecosystem Restoration

Dissolved organic matter (DOM) in the Florida Everglades controls a number of environmental processes important for ecosystem function including the absorption of light, mineral dissolution/precipitation, transport of hydrophobic compounds (e.g., pesticides), and the transport and reactivity of metals, such as mercury. Proposed attempts to return the Everglades to more natural flow conditions will result in changes to the present transport of DOM from the Everglades Agricultural Area and the northern conservation areas to Florida Bay. In part, the restoration plan calls for increasing water flow throughout the Everglades by removing some of the manmade barriers to flow in place today. The land- and water-use practices associated with the plan will likely result in changes in the quality, quantity, and reactivity of DOM throughout the greater Everglades ecosystem. The authors discuss the factors controlling DOM concentrations and chemistry, present distribution of DOM throughout the Everglades, the potential effects of DOM on key water-quality issues, and the potential utility of dissolved organic matter as an indicator of success of restoration efforts.

Strategies to Support High-Growth Enterprises in Haiti

Laine’s narrative of the moments following the earthquake of January 12, 2010, will be a poignant reminder of the shock and the sense of uselessness we all felt as we watched the CNN reports live from Port-au-Prince. I was still watching in Dublin in the early hours of January 13, as we attempted to make contact with our colleagues and Haitian friends. AIDG’s response to that emergency was mirrored by other similar organizations, as they cleverly applied their capabilities to suddenly revised priorities and did their best to respond to the new, more urgent, and more extreme needs of the people they served. By applying its skills and connections, AIDG found a way to participate in the immediate emergency response in a highly effective manner. Its support of Shelter2Home illustrates how a business development organization can use its expertise to help provide a response to a real and dire social need. Nature has set some high barriers to the development of Haiti with the risk of hurricanes, tsunamis, and earthquakes, but it is the man-made barriers highlighted in this case that deserve the most attention. While Haiti could be better prepared for and respond more effectively to the inevitable natural disasters, the Haitian leadership, supported by the international community, can and must take steps to remove many of the man-made barriers. One crucial short-term need identified by AIDG is for skilled masons and builders. The devastation in Port-au-Prince was a direct result of low building standards and workers’ poor construction skills. As highlighted in this case, there is a real need to produce more skilled workers as the rebuilding process commences. Building back better will demand stronger construction skills and higher building standards. The case also highlights the gap in support for small and mid-size enterprises (SMEs), a vital sector of Haiti’s future economic success. Many of the current

Alluvial aquifer recharge enhanced by a natural dam: feasibility assessment based on multidisciplinary characterization (Khuzestan, Southwest Iran)

In the Kushkak Valley (Khuzestan, Southwest Iran) an anticlinal structure has partially impounded an ephemeral stream. This natural impounded area has been chosen for an artificial recharge site due to its current rate of recharge, capability to store water and favorable situation for the construction of man-made barriers to stream flow. The aquifer to be recharged is the Kushkak unconfined aquifer which consists of medium to coarse-grained alluvial deposits that overlie consolidated conglomerate rock. In this semi-arid area with infrequent relatively heavy falls of rain, alluvial aquifer recharge can be an important process that sustains shallow, over-exploited groundwater bodies. In this investigation a multidisciplinary approach including: hydrometerological studies, and a detailed hydrogeochemical survey, have been carried out. Other essential prerequisite parameters for the scheme were also taken into account to determine the suitability of this location for groundwater artificial recharge. The assessment has brought out that (1) the proposed reservoir will conserve a major part of the water being lost, (2) annual runoff of about 0.27 MCM can be injected into the aquifer through recharge from impounded water, (3) hydrochemical data from surface water and from the Kushkak aquifer water demonstrates that dilution and change in compositional trend in the groundwater proximal to the impounded alluvial bed areas would be expected based on the infiltration capacity of this site, and (4) cost–benefit ratio of the project is 1:2 and it is assumed to recover the investment within six years.

Feasibility of satellite image‐based sampling for a health survey among urban townships of Lusaka, Zambia

To describe our experience using satellite image-based sampling to conduct a health survey of children in an urban area of Lusaka, Zambia, as an approach to sampling when the population is poorly characterized by existing census data or maps. Using a publicly available Quickbird image of several townships, we created digital records of structures within the residential urban study area using ArcGIS 9.2. Boundaries were drawn to create geographic subdivisions based on natural and man-made barriers (e.g. roads). Survey teams of biomedical research students and local community health workers followed a standard protocol to enroll children within the selected structure, or to move to the neighbouring structure if the selected structure was ineligible or refused enrollment. Spatial clustering was assessed using the K-difference function. Digital records of 16 105 structures within the study area were created. Of the 750 randomly selected structures, six (1%) were not found by the survey teams. A total of 1247 structures were assessed for eligibility, of which 691 eligible households were enrolled. The majority of enrolled households were the initially selected structures (51%) or the first selected neighbour (42%). Households that refused enrollment tended to cluster more than those which enrolled. Sampling from a satellite image was feasible in this urban African setting. Satellite images may be useful for public health surveillance in populations with inaccurate census data or maps and allow for spatial analyses such as identification of clustering among refusing households.

Hydroelectricity and fish: a synopsis of comprehensive studies of upstream and downstream passage of anadromous wild Atlantic salmon, Salmo salar, on the Exploits River, Canada

Government (Fisheries and Oceans Canada) and industry (Abitibi Consolidated Company of Canada) have been working cooperatively to protect and enhance wild Atlantic salmon populations on the Exploits River, insular Newfoundland, Canada. Since the mid-1960s, enhancement programmes and construction of fish passage facilities at natural and man-made barriers in the watershed have expanded the range and increased the returning adult population from 1200 fish (circa 1960) to 22,000 fish, on average. Since 1997, attention has been paid to improving passage and survival of downstream migrating smolts and kelts at two hydroelectric facilities at Grand Falls-Windsor and Bishops Falls. At Grand Falls-Windsor a floating louver and bypass system was installed in a power canal and extensive biological, hydraulic, and modelling studies have been conducted to assess, modify, and optimize fish passage. At Bishops Falls, a retrofitted surface spill bypass system was installed in an existing spill gate and similar studies have been conducted to improve passage success. Studies have also been conducted on the upstream migrating adults at these facilities and associated fishways, using conventional and physiological telemetry, to assess tailrace attraction and residency, and the relative energy cost of upstream migration to bypass the hydro plants and fishways. This article reviews the results of these various studies to demonstrate how cooperative work has improved passage of anadromous salmon in coexistence with hydroelectric development.

Hydrodynamics of a Coastal Bay. Natural and Man-made Barriers

This paper deals with wind-induced flows in a semi-enclosed water body in a microtidal environment that is subject to various wind-wave and river discharge conditions. The resulting currents are analyzed using numerical models supplemented by (and calibrated with) field observations. The emphasis is on the driving efficiency of wind fields in generating steady currents as a function of wind velocity and direction. The circulation generated is analyzed for the actual case of Cullera Bay and for a theoretical case in which the cape (limiting barrier) has been “removed” from the computational domain. The results obtained as a part of the EU research project ECOSUD, allow the barrier effect exerted by the cape to be partially quantified. The river plume dimensions and direction of spread are clearly influenced by the cape barrier. On a more local scale, the effluent discharge from the outfall was also found to be influenced by the two Júcar River jetties. Based on these results, a “retention” index that partly characterizes water quality in the bay is defined. This type of index is also a scientifically based indicator that supports more sustainable management of water quality in coastal bays of this type.

What Drives Price Differentials of Consumables in Europe? Size? Affluence? Or Both?

Prices of many consumables differ substantially across the European Union (EU) due to natural segmentation and to the survival of residual man-made barriers. However, we do not know much about the direction and the cause of deviations among countries differing mainly in size and income of their citizens. Here, we wish to fill this gap. We go through some simple theoretical analysis and show that, in the presence of mild barriers to trade, as those persisting among EU countries, prices should be lower in large countries. On the contrary, prices will be higher where people enjoy better standards of living which translate into higher marginal willingness to pay by consumers. We perform a parallel empirical investigation to assess the relative weight of the two main forces driving prices apart across countries and we test our theoretical proposition through a simple econometric analysis of prices of consumables across the EU. Country size and affluence explain price differentials in a convincing manner. However, the relative importance of the two variables changes as we consider the EU after the establishment of the Single Market or when we analyse a subsample of fast growing EU members.

Population structure and genetic diversity of trout (Oncorhynchus mykiss) above and below natural and man-made barriers in the Russian River, California

The final publication is available at link.springer.com. Link to abstract: http://link.springer.com/article/10.1007/s10592-006-9183-0

What Drives Price Differentials of Consumables in Europe?

Prices of many consumables differ substantially across the European Union(EU) due to natural segmentation and to the survival of residual man-made barriers. However, we do not know much about the direction and the cause of deviations among countries differing mainly in size and income of their citizens. Here, we wish to fill this gap. We go through some simple theoretical analysis and show that, in the presence of mild barriers to trade, as those persisting among EU countries, prices should be lower in large countries. On the contrary, prices will be higher where people enjoy better standards of living which translate into higher marginal willingness to pay by consumers. We perform a parallel empirical investigation to assess the relative weight of the two main forces driving prices apart across similar countries and we test our theoretical proposition in a simple econometric analysis of prices of consumables across the EU. Country size and affluence explain price differentials in a convincing manner. However, the relative importance of the two variables changes as we consider the EU after the establishment of the Single Market or when we analyse a subsample of fast growing EU members.

Genetic differentiation ofCaridina cantonensis(Decapoda:Atyidae) in Hong Kong streams

AbstractCaridina cantonensis Yu 1938 is an atyid shrimp that is widespread in southern China, including Hong Kong. It is a fully freshwater species with an abbreviated larval development lacking planktonic stages. The population genetics of C. cantonensis in Hong Kong streams was studied at inter- and intradrainage scales using random amplified polymorphic DNA (RAPD) markers. Shrimps displayed low levels of within-population genetic variation (≤20% of total genotypic variance) but high levels of among-population variation (>50% of total genotypic variance) at both scales. High interdrainage genetic differentiation indicated that dispersal among catchments was limited, whereas high differentiation among populations at the intradrainage scale mainly resulted from natural barriers such as waterfalls. The effect of man-made barriers on population differentiation at the intradrainage scale was less marked than at the interdraineage scale. Levels of gene flow among populations within and among drainage systems ...

Evaluating economic change

Daedalus Summer 2004 In recent years there have been enormous changes in our technology, our economy, and our society. But has there been progress? From most economists the 1⁄2rst reaction to this question is: Of course there must have been progress! After all, the growth of new technologies expands opportunity sets, what we can do, the amount of output per unit input. We can choose either to have more output, more goods and services, or to work less. However we make the choice, surely we are better off. But what, then, about the sweeping changes we associate with the phenomenon of globalization? For several years I have been actively involved in debates around the world about the costs and bene1⁄2ts of this phenomenon. As a result of globalization, the countries of the world are more closely integrated. Goods and services move more freely from one country to another. This is the result of the lowering of transportation and communication costs through changes in technology, and of the elimination or reduction of many man-made barriers such as tariffs. The countries that have been most successful at both increasing incomes and reducing poverty–the countries of East Asia–have grown largely because of globalization. They took advantage of global markets for their goods; they recognized that what separates developed from less developed countries is a disparity not only in resources but also in knowledge; they tapped into the pool of global knowledge to close that gap; and most even opened themselves up to the flow of international capital. But in the countries that have been less successful, globalization is often viewed with suspicion. As I have argued elsewhere, there is a great deal of validity to the complaints of those who are discontent. In much of the world, there has been in recent years a slowing of growth, an increase in poverty, a degradation of the environment, and a deterioration of national cultures and of a sense of cultural identity. Globalization proves that Joseph E. Stiglitz

Effects of Barriers and Thermal Refugia on Local Movement of the Threatened Leopard Darter, Percina pantherina

Local, short-term dispersal by the U.S. federally-threatened leopard darter, Percina pantherina, was examined in the field and in the laboratory to assess the possible effects of natural versus man-made barriers on movement. Mark-resight studies were conducted in two summers at sites in the Glover River (southeastern Oklahoma, U.S.A.). At one site, patches of 'preferred' habitat were separated by a natural riffle; at the other site, by a low-water road crossing with culverts. At the Natural Riffle site, darters moved downstream across the riffle, but also moved upstream into deeper water when water temperatures exceeded 29°C in the `preferred' habitat. Use of deeper, cooler waters by this species in late summer suggests that thermal refugia may be important habitats for the long-term management of leopard darters. At the Road Crossing site, all documented movement was in a downstream direction, and at least two darters traversed culverts in the low-water bridge. Laboratory studies of movement across several types of culverts suggested that culverts significantly decrease the probability of movement among habitat patches.

Forecasting Transit Walk Accessibility: Regression Model Alternative to Buffer Method

A description is given of a methodology for estimating transit walk accessibility at the home end of transit trips and for forecasting transit walk accessibility at the home end for a future year, given forecast population and employment data, transit route information, and type of street configuration. The methodology for estimating transit walk accessibility overcomes the problems associated with natural and man-made barriers such as water bodies and community walls and the problem of uneven distribution of population. A comparison of the results with those from the traditional buffer method, as well as with network ratio methods that consider actual walk distance along streets, showed that both the buffer method and network ratio methods tended to overestimate transit walk accessibility. Regression analysis also showed that the new transit walk accessibility measure was a stronger predictor of transit use than that produced using the buffer method. The methodologies may be applied to transit planning, urban design for sustainable development, and long-range transit demand modeling.

Rentier States and Geography in Mexico's Development

This paper provides a long-term historical and econometric account of the way in which geography has shaped development in the Mexican states. The emphasis is placed on the way in which the natural geography is reinforced by political decisions, which configure the human geography of population density, urbanization and public good provision, which in turn determine income, growth and poverty. The paper presents brief historical instances of how geography has determined prospects for development at different moments in Mexican history. This anecdotal discussion seeks to highlight the intrinsic link of geography with political institutions, which is central to understanding the economic effects of geography. The paper then presents a descriptive statistical and geographical profile of the relationship between geography and development in Mexico. The paper argues that the main channel through which geography affects development is political. The fragmentation of political jurisdictions in the form of municipal governments constitutes a proxy for man-made barriers to geographic mobility, which explain the interaction between geography, politics and development.

Relationship between hydrology and zonation of freshwater swale wetlands on lower hatteras island, North Carolina, USA

Only a few relatively wide barrier islands support shallow freshwater aquifers. Rare, swale wetlands occur on islands where fresh water inundates, at least seasonally, low-lying troughs between interior dunes. Swale wetlands are dominated by emergent vegetation and submerged aquatic vegetation in the deepest areas and by woody shrubs in more shallow areas. On southern Hatteras Island, wetland shrubs have progressively invaded open water areas over the past 40 years, suggesting a change in hydrologic regime. To determine the relationship between vegetation cover type and length of saturation, water-level fluctuations over time were analyzed to tie boundaries of six wetland cover types to the duration of soil saturation at 20-cm depth. We found that areas dominated by herbaceous vegetation had significantly longer flooding regimes than areas dominated by shrubs (85–95% vs. 12–69% of the growing season, respectively). Only 22–25 cm elevation differences were found to separate emergent marsh from the various shrub cover types, suggesting that lowering the mean water level via drainage has likely been responsible for shrub swamps replacing emergent marsh in swales. Although succession from open water to shrub swamp probably occurs naturally in the absence of drainage through the accumulation of organic matter, natural disturbances such as wildfire and storm-driven surges of saline water would have periodically re-set succession. Therefore, managing for long-term maintenance of freshwater swale wetlands on barrier island should include (1) eliminating or controlling drainage through constructed ditches, (2) eliminating man-made barriers that prevent the transport of saline water into ponds during hurricanes and nor’easters, and (3) initiating a prescribed burning program to mimic the historic, natural fire regime.

Are Man-Made Barriers Influencing Mammalian Speciation?

Are Man-Made Barriers Influencing Mammalian Speciation?

Park-People Relationships: The Case of Damage Caused by Park Animals Around the Royal Bardia National Park, Nepal

Crop damage and livestock predation were a serious problem in three Village Development Committees (VDCs) situated adjacent to the Southwestern Part of the Royal Bardia National Park. The seriousness of crop and livestock losses varied considerably with the distance from the Park's border and the specific location of farms. This was explained by the variations in the distribution of animal wildlife inside the Park, the presence of natural and Man-made barriers, the availability of forested areas outside the Park, and the agricultural cropping pattern. Adjacent to the section of the Park with the highest animal densities, crop losses varied from 47% for Lentil to 24% for Wheat. Farther away, the extent of crop losses was reduced. In the ‘Far’ zone situated 2–8 km from the Park, only 3% of the Paddy was reported lost.Two wildlife species, Chital and Wild Boar, were responsible for roughly half of the total damage to crops by animals. Damage from a newly-introduced population of Rhinoceros unicornis was increasing, with Paddy (Rice) and Lentil the crops most affected by that species. The economic value of livestock loss to wild predators was estimated to be two percent of the value of total crop losses. The estimated value of grasses harvested by local villagers inside the Park, seen as ‘compensation’ for crop losses and denial of access to traditional resources, constituted only 10% of the total economic loss from crop losses and livestock predation.

Radionuclide getters in cement

The ultimate release of radionuclides from a radioactive waste repository will depend upon the natural and man-made barriers surrounding the site. An opportunity exists to enhance natural radionuclide retention through improved sorption, by the use of suitable additives applied to the repository backfill material. This paper summarises a development programme designed to identify problem isotopes, to find suitable materials for their retention and, ultimately, to provide, through batch sorption studies, an understanding of their effectiveness under repository conditions.

Shoreline changes along the Rosetta-Nile Promontory: Monitoring with satellite observations

A study to test the effectiveness of satellite data for monitoring shoreline change is reported, the rapidly changing Rosetta Promontory of the Nile Delta, Egypt, being selected as the study area. Landsat multispectral scanner (MSS) image data in the near infrared (0.8–1.1 μm, 80 m resolution) covering a 15 year period (1972–1987) at roughly 3 year intervals were compiled. These were digitally overlain, registered and differenced relative to the initial 1972 shoreline, and composite changes (erosion and accretion) are mapped. The area studied is one undergoing both aggradation and degradation, depending on location, sediment supply and man-made barriers. It was found that the general trend of the regional processes can be monitored with Landsat imagery due to its repetitive coverage and good spectral contrast of land and sea. Improved satellite imagery with higher resolution should be a valuable tool for complementing traditional shoreline monitoring surveys in easily eroded, lowlying areas such as the Nile Delta.

The role of the canister in a system for the final disposal of spent fuel or high-level waste

A final repository for radioactive waste must isolate the toxic substances or distribute their release over time or space to avoid causing harmful concentrations of radionuclides in the biosphere. The Swedish research has focused on a repository 500 m down in crystalline rock where the geochemical environment can give canisters a service life of the order of a million years. These evaluations are discussed and the safety effect of the canister is compared with that of other barriers available in a repository system. Our conclusions are that a combined protection effect of natural and man-made barriers can be achieved that substantially exceeds what could reasonably be required by society. An actual repository design can then be based on an optimization of the cost to reach a level of accepted safety with due regard for the safety margins and redundancy necessary for achieving public confidence.