Lowland Coastal Areas Research Articles

Holocene sea-level rise and its effect on the mass balance of coastal deposits

A mass balance study of the Holocene accumulation wedge has been carried out in the lowland area between the Ems and Weser rivers on the German North Sea coast. This region, which comprises various sedimentary environments, such as barrier islands, sheltered and open tidal flats, bay flats, and estuaries, is highly suitable for such quantitative studies and can serve as a model for general mass transport and accumulation processes connected with transgressions over coastal lowlands. Data for the study was taken from borehole records, hydrographic soundings and topographic surveying to prepare structure contour maps and sequence maps at a scale of 1:25,000 showing the outlines and the internal make-up of the Holocene accumulation wedge. The irregularly distributed data was interpolated into a regular grid and the volumes of allochthonous clastic sediments and autochthonous peat, which make up 90% and 10%, respectively, of the coastal Holocene, were calculated. A comparison of the amount of clastic material supplied by the Ems, Weser, and Elbe rivers during the last 7500 years with the total volume of the accumulation wedge shows that about 90% is from marine and only 10% from riverine sources. By comparing the results of the quantitative analysis of the Holocene sedimentation with the present-day morphological and hydrodynamic observations, predictions of the future development of the coastal lowland area can be made.

Land characteristics and plant resources in relation to agricultural land-use planning in a humid tropical strand plain, southeastern Thailand

Recently in humid tropical Asia, human activities have begun to extend toward the coastal lowland areas where widespread peat swamps are distributed. Draining peat swamp areas for agricultural uses creates a high risk of sulfuric acidification. The research site in this paper was a strand plain comprising beach ridges, swales on inter-ridges, and peaty backswamps in southeast Thailand. Thus, the actual and potential acid sulfate soil in the peaty backswamps is a major problem there, but sandy podzols on older beach ridges are also considered an agricultural problem soil. To establish an agricultural landscape plan encompassing the whole of the strand plain, we studied the land characteristics associated with the landforms and soils, their spatial variability related to landscape evolution, and the status of present plant resources in terms of biomass and species diversity for local farmers on peaty backswamps and beach ridges. We found that all spatial attributes of the two soils, such as the locations, profiles, and chemical and physical properties, were closely related to the geomorphic formation process or chronosequence: the landward or older backswamp has ripe clay and the seaward or younger one partly has unripe clay; the degree of spodic horizon development with ortstein is highest in the most landward beach-ridge system and decreases seaward; and the profile positions of the spodic horizons were related to the fluctuations of marine sand sediments, as revealed in a fine-scale survey. Finding these spatial regularities is useful for predicting land characteristics in areas outside of detailed research sites, reducing time and cost as well as forming the basis of landscape planning. Plant resources presently utilized by local farmers on the strand plain are Melaleuca cajuputi forests on both the peaty backswamps and the beach ridges, and home gardens of tropical fruit trees around settlements. Ecological carrying capacity in terms of biomass of M. cajuputi was not significantly different among soil types in the strand plain, but the growth rate and potential biomass of the species appears to be highest in thick, water-saturated peaty backswamps with acid sulfate soils. By comparing the species composition of home gardens in different areas, we found that on the beach ridges, although the ecological carrying capacity in terms of biomass for several types of fruit trees appears lower, a great number of species particular to the shrub layer are maintained. Based on the spatial variability of land characteristics and the ecological carrying capacity in terms of biomass, we identified separate land units and suggested future land-management and land-use systems appropriate to each unit.

The record of climatic change in the geological archives of shallow marine, coastal, and adjacent lowland areas of Northern Germany

The record of climatic change in shallow marine, coastal, and adjacent lowland areas has been investigated by three different approaches. A mass balance study focused on the interaction between sea-level rise and Holocene sediment accumulation in the coastal lowland area between the Ems and Weser rivers on the German North Sea coast. This region, which comprises various sedimentary environments, such as barrier islands, sheltered and open tidal flats, bay flats, and estuaries, is highly suitable for such quantitative studies, which can be used to create a model for general mass transport and accumulation processes connected with transgressions over coastal lowlands.An integrated geochemical and microfacies study was made to assess the response of shallow marine, intertidal, and limnic-semiterrestrial environments to the climate-controlled Holocene sea-level rise. The factors controlling the development of various palaeoenvironments were estimated from the distribution of biomarkers, major and trace elements, diatoms, foraminifera and sedimentary structures observed at high resolution in core sections. These data complement those of conventional geological, lithostratigraphical, archaeological and geobotanical investigations.The extensive raised bogs which occur in the Pleistocene hinterland, adjacent to the coastal zone, provided an excellent opportunity to examine peat formation in response to climatic changes in the past. On the basis of a large number of 14C-age determinations special attention was paid to the onset and regional expansion of raised bogs in this region and to the question of whether or not the formation of raised bog peat started synchronously in one or in a series of different phases.

Policy And Practice The Ecological Values of Traditional Land Use in Low-lying Coastal Environments: The Example of the Aiguamolls de L'Emporda, Costa Brava1

Traditional strategies of resource use in lowland coastal areas may play a very significant role in modern environmental management since, in many ways, the cultural and biological diversity peculiar to these ecoystems that we now wish to protect are the product of human efforts rather than the product of nature alone. We will illustrate this using the example of the so-called closes (enclosures) in the Natural Park of the Aiguamolls de l'Emporda (Catalonia, Spain). Closes are pasture fields surrounded by tree screens that remain inundated part of the year but that can be used for cattle grazing during the rest of the time. Because of agricultural modernization in the 1960s and 1970s many closes were turned into permanent agricultural fields. Since the creation of the Natural Park in 1983, there has been an attempt to recover these traditional land uses although not without some opposition by the farming sector.

Geophysical measurements for archaeological investigation: case studies in Malaysia

Three archaeological sites containing different artifacts were investigated by geophysical methods. The first site is located at Sungai Mas village in Kuala Muda District of Kedah, north west of Malaysia. Since the beginning of the 1980 this site has produced a number of important and interesting archaeological finds relevant to the history of the Bujang Valley ofKedah. The archaeological teams from Universiti Kebangsaan Malaysia and the Museum Depar tment of Malaysia revealed that there were several remains of low mounds of laterite block and brick foundation for 'structures in the village. A geoelectrical profiling method using dipole-dipole array was used to study the artifacts and the preliminary survey was designed to see whether the technique would be u seful for identifying and locating anomalies of archaeological significance in the area. Result of the study indicates that the geoelectrical resistivity method can be successfully used in detecting archaeological anomalies of shallow buried artifacts in the studied area. The second site is situated in a fi sherman's village on the northern bank of Kedah River mouth and it lies in a coastal lowland area of Kuala Kedah Di strict. The site is located approximately 7 kilometres from Alor Star, northern Kedah. It cover s an area of about 3.5 hectares along the river side. Remains of partly buried nineteenth century fort which belong to the for mer sultan of Kedah was excavated by the Museum Department of Malaysia for future conservation plan. The area was gazetted as a museum reserve and planned to be developed as another historical tourist spot in Kedah. Geophysical measurements employing g voelectric profiling (Wenner array) and magnetic surveys were conducted to locate structures of partly ) uried foundation of the fort as a guide for future conservation work. Both the geoelectrical and magnetic surveys have produced results showing several :m omalous areas which appear to coincide well with the locations of-the uncovered artifacts. The third archaeological site is located in the area of Pasir Salak historical complex in Kampong Gajah Di~trict, southern Perak. The site which covers an area of 80 x 60 square metres lies about 200 metres from the Perak River. It was identified to be a site of a former fort built by a Malay warrior to fight the British in the late nineteenth century. The site was developed into a football field for the school nearby before the land was gazetted as a museum reserve. The department of muselJm h as conducted four phases of excavation in December 1990, April 1991, June 1993 and July 1996 but no significant major artifact was found. Detailed geophysical study (geoelectric and magnetic) was carried out to look for artifact. The geoelectrical profiling survey employing dipole-dipole array revealed eight different locations of high resistivity zones wher eas the magnetic measurement indicated two anomalous areas. These anomalous areas could probably be associated with the artifact of archaeological significance and they need to be confirmed by excavation.

Life‐history consequences of predation for a subantarctic beetle: evaluating the contribution of direct and indirect effects

1. Recently, a small predatory beetle, Trechisibus antarcticus (Carabidae), was accidentally introduced onto the island of South Georgia, sub‐Antarctic. 2. From the presumed site of introduction the beetle is invading the coastal lowland area, building up high densities locally in the tussock‐forming grass Parodiochloa flabellata. 3. In the coastal area the endemic detritivorous/herbivorous beetle Hydromedion sparsutum (Perimylopidae) is common, especially in and beneath the tussocks. 4. The first three, out of six, larval instars of H. sparsutum are easily taken prey by the carabid. 5. In sites colonized by the carabid, total abundance and the ratio between larval and adult numbers of H. sparsutum are far lower, and its adult body size clearly larger, than in comparable sites where the carabid is absent. 6. Two hypotheses are proposed for explaining the increase in adult body size of H. sparsutum: (i) the increase is a direct effect of predation: selection by the predator favours large hatchlings and/or larvae with a high growth rate; and (ii) the increase is an indirect effect of predation: by lowering the density of H. sparsutum, predation has increased its per capita food supply, enabling a higher growth rate and a larger adult body size. 7. A food addition experiment in a carabid‐free site showed availability of high quality food to be insufficient for sustaining the initial larval population. 8. In the laboratory, females from the predator‐infested sites produced larger eggs and hatchlings than females from the carabid‐free sites, but mass specific growth rates of the larvae were not higher. 9. Field and laboratory data give stronger support to the food hypothesis than to the size selectivity hypothesis.

Toward a redefinition of resources and hazards in coastal management: Examples from the lowland coastal areas of Catalonia, Spain

Coastal planning and management are experiencing a number of changes that point toward a major shift in emphasis from development to conservation. In this process, natural environments and processes traditionally perceived as hazardous to human occupation will be redefined in terms of being resources to protect for the benefit of present and future generations. This process, however, is neither universal nor conflict free because development pressures maintain their strength in many parts of the world. This article examines the current situation of four lowland coastal areas located in Catalonia, Spain. The transition from development to conservation, and its reflection in planning and management practices is examined for each case in light of the social appraisal of coastal environments and processes as either resources or hazards. We conclude that this appraisal depends strongly on the historical trajectory of each area, the effectiveness of new legal and planning instruments, and the political will of institutions and social agents present in each area.

Hydrochemical Analysis of Ground‐Water Flow and Saline Incursion in the Clarendon Basin, Jamaica

AbstractThe Clarendon Basin of south‐central Jamaica has been recognized for its productive sugar cane industry since the late 1800s. Much of its success is attributed to rich alluvial soils, a year‐round tropical climate and copious supplies of good quality irrigation water from a karstic limestone aquifer of Tertiary age. This aquifer extends throughout the northern part of the basin, but ends abruptly at the South Coast Fault, an east west feature that forms the northern boundary of a deep graben filled with alluvial sediments. These alluvial sediments are the only source of water for the area south of the fault (the Vere Plain). However, the sediments also lap onto the limestone to the north of the fault (the Clarendon Plain) and provide a supplementary ground‐water source. By the early 1970s nearly 200 wells supplied irrigation water for over 20,000 hectares of land. As development increased, the salinity of the ground water increased. Consequently, many wells were closed down and several sugar plantations were abandoned. In the study presented here, major ion (Ca, Mg, Na, K, HCO3, Cl, SO4, and NO3), minor ion (F, Br, and I), and environmental isotope (δ18O,δD) hydrochemistry is used to resolve the hydrodynamics of ground‐water flow in the basin and identify the source and mode of emplacement of the saline water.Oxygen and hydrogen isotope data confirm that while the major well production areas are located in lowland coastal areas, recharge originates almost exclusively as rainfall in the cooler elevated parts of the basin above 750 m (asl). Subsurface conduit flow brings this water to the limestone well fields, and any excess water is able to cross the South Coast Fault to feed the alluvial aquifer of the Vere Plain. The thin alluvial aquifer of the Clarendon Plain also receives limestone water but this water does not enter entirely by subsurface means. Instead data suggest that while some of the water can be attributed to natural upward vertical leakage in the northwest of the Clarendon Plain, the remainder can be attributed to the seepage of irrigation water drawn, at least in part, from wells developed in the underlying limestone.Saline ground waters affect all the aquifers of the basin and several potential sources have been proposed. Major and minor ion data point to a sea‐water source, and a sea‐water wedge extending beneath the thick alluvial aquifer of the Vere Plain is an obvious candidate for the source of salinity observed in wells from this aquifer. Closer examination of the chemical data reveals, however, that wells in the limestone and alluvial aquifers to the north of the South Coast Fault do not derive their salinity from this source location, and instead draw sea water from the east and west along the relatively permeable South Coast Fault zone. This water can move to limestone wells directly; wells in the alluvium of the Clarendon Plain, however, receive most of the saline water indirectly via leakage of irrigation water pumped initially from the limestone. Sea water drawn along the fault may also be the primary source of salinity in the aquifer of the Vere Plain but this cannot be confirmed on the basis of hydrochemical evidence alone.

The invasion of the carnivorous carabid beetle Trechisibus antarcticus on South Georgia (sub-Antarctic) and its effect on the endemic herbivorous beetle Hydromedion spasutum.

Recently two species of carabid beetle were accidentally introduced onto the sub-Antarctic island of South Georgia. Both species are carnivorous and flightless. One of the species, Trechisibus antarcticus, is locally very abundant and in the process of invading the coastal lowland area, where the endemic herbivorous beetle Hydromedion sparsutum (Perimylopidae) is common. Field samples showed the abundance of the endemic species to be much lower, and its adult body size to be larger, in carabid-infested locations than in carabid-free locations. The sample data allowed us to estimate the growth rate of the H. sparsutum larvae and to reconstruct the most likely life-cycle of both species. A laboratory experiment showed a high mortality for the first three (out of six) larval instars of H. sparsutum in groups which had been subjected to predation by T. antarcticus. The duration of the period during which the larvae are vulnerable to predation was shown in a growth experiment to depend on food type. Quantitative and qualitative aspects of the interaction between the introduced predator and the endemic prey, and conditions which allowed the former to invade are discussed.

The Distribution, Status and Habitat Associations of the Satyrine (Lepidoptera: Nymphalidae) Fauna of Northeastern Australia

ABSTRACTThe geographic distribution, relative abundance and habitat associations of tropical satyrine butterflies were studied in north‐eastern Australia in 1990‐92. Three species, Mycalesis evara, Ypthima pusilla and Geitoneura klugii, are excluded from the region so that only 16 species are now recognised north of the Tropic of Capricorn. of these, Melanitis amabilis has not been recorded from Australia since 1910; M. constantia is restricted to Murray Island, Torres Strait; Orsotriaena medus, may now only occur in the Torres Strait islands; while Heteronympha merope appears to be a rare southern vagrant. the remaining 12 species occurred predominantly in the moist coastal lowland area, and few penetrated the drier inland zone. Most intruded into montane areas, but, with the exceptions of Melanitis leda, Hypocysta metirius and Tisiphone helena, were comparatively scarce in this zone. the tropical satyrine fauna, which comprises northern, southern and endemic elements, is relatively species poor compared with that of temperate south‐eastern Australia.

Endemism and speciation in a lowland flora from the Cape Floristic Region

Taxonomic, edaphic and biological aspects of endemism were studied in a phanerogamous flora from the Agulhas Plain, a coastal lowland area of the Cape Floristic Region. Of the 1751 species in the flora, 23.6% were regional endemics and 5.7% were local endemics. Families which were over-represented in terms of endemics included the Ericaceae, Rutaceae, Proteaceae and Polygalaceae. Under-represented families included the Poaceae, Cyperaceae, Scrophulariaceae and Orchidaceae. Highest levels of local endemism were recorded on limestone and colluvial acid sand. Sixty-nine percent of regional endemics and 85% of local endemics were confined to a single substratum. An analysis of the frequency of biological traits associated with species with different categories of endemism enabled the establishment of a biological profile of a local endemic: a dwarf to low, non-sprouting shrub with soil stored seeds which are ant-dispersed and/or form a symbiotic relationship with microbes. It is argued that lineages with these characteristics are vulnerable to severe population reduction or even local extinction. An effect of this would be the promotion of rapid, edaphic speciation as a result of catastrophic selection. Thus, certain traits (e.g. non-sprouting) prevail or even predominate in the flora not because of any adaptive advantage but because high speciation rates of lineages which possess them, overwhelm low survival rates.

Flandrian sealevel changes in the Thames Estuary and the implications for land subsidence in England and Wales

CATASTROPHIC flooding occurred in the Lower Thames and lowland coastal areas of eastern England in 1953. Large-scale investment in port, freight, factory facilities and connected urban development, has centred in these littoral and coastal zones. The effects of changing sealevels, such as seen in 1953, could, therefore, cause even greater economic and human loss in the future, unless government expenditure on flood alleviation schemes, as exemplified by the Thames barrage project, is increased and a coordinated flood protection policy established. Information on the rate of changing relative sealevel in south-east England is thus of great value. (A description is given here of a stratigraphic study upon the interleaved Flandrian biogenic and inorganic deposits of the Lower Thames estuary, carried out between central London and the Isle of Grain (Fig. 1).) From this, the heights of relative sealevel movements were determined and plotted against time to show the rate of relative sealevel change and subsidence trends for the Thames and southern England. The vegetational and environmental history was deduced from pollen, diatom and other micro-fossil analyses, with radiocarbon dating applied to establish an objective chronology.

Lichens from a High Arctic Coastal Lowland, Devon Island, N.W.T.

Lichens from a High Arctic Coastal Lowland, Devon Island, N.W.T.

Some effects of glacial action in Iceland

Introduction The dominant geological features of Iceland are its glaciers and its volcanoes, both of which are developed on a tremendous scale and afford unusual opportunities for detailed study. The island itself is essentially an uplifted plateau country, averaging 500 to 700 meters in elevation, and consisting in large part of basaltic lava flows and associated tuffs and breccias. Fringing this plateau at different points are lowland coastal strips, whose total area is nearly one-fifteenth of that of the entire island; to these all habitation is practically confined, the rest of the island being a barren waste of lava and glacial debris, devoid of forests, and even vegetation, and worthless from an economic standpoint, but valuable to the geologist because of its excellent exposures. Soundings by the Danish government have shown that these lowland coastal areas, in north and west Iceland especially, extend seaward as a coastal rock shelf 100 . . .