China
Africa
Explore chapters and articles related to this topic
The Baltic States
Published in Enzo Pranzini, Allan Williams, Coastal Erosion and Protection in Europe, 2013
Hannes Tõnisson, Kaarel Orviku, Jānis Lapinskis, Saulius Gulbinskas, Rimas Žaromskis
(till) had been dispersed. During the ensuing regression sand, gravel and boulders on the emerging sea floor formed beaches, beach ridges and dunes by wave and wind activity. Postglacial isostatic movements since the Ancylus Lake period resulted in land uplift ranging from circa 45 m in southern Estonia up to 75 m on the northern coast. Beaches formed are often backed by beach ridges and dunes and tilting has continued on either side of a zero isobase that runs SW-NE through Riga in Latvia, with land uplift of about 1 mm/yr at Pärnu, 2 mm/yr at Tallinn and 2.8 mm/yr on the northwestern coast (Vallner et al., 1988). Main agents causing erosion Waves and currents (especially during heavy storms), longshore drift, onshore winds, and human activity are the main agents of coastline evolution. Tides are negligible on the Estonian coast (<5 cm), with sea level generally higher in winter than summer. Rivers are small and alluvial deposition is very limited. Westerly and south-westerly winds predominate, producing waves from these directions on westfacing coastal sectors, but wave energy is low, especially in places where the nearshore is shallow and boulder-strewn. During storm surges, onshore
Sedimentary Environments and Facies
Published in Supriya Sengupta, Introduction to Sedimentology, 2017
In areas of strong wave action the delta sediments are continuously reworked and the sand bodies are reoriented into a series of beach ridges paralleling the coastline. These are called ‘strike-oriented’ ridges. In areas dominated by longshore drifts the entire delta assumes an asymmetric (‘skewed’) shape. The delta of the Nile is a typical example of wave-dominated delta (Fig. 6.30B).
Risk assessment of human exposure to radionuclides and heavy metals in oil-based mud samples used for drilling operation
Published in International Journal of Environmental Health Research, 2022
Emmanuel E. Okoro, Chidiebere Ochonma, Samuel E. Sanni, Omeje M., Kevin C. Igwilo, Olukunle C. Olawole
The study area is Field X located in Bayelsa State, Nigeria. A lowland state characterized by coastal beaches, beach ridge barriers, tidal flats, and flood plains. The climate for Bayelsa State can be classified as Tropical and the location is classified as Am under the Köppen and Geiger standard. The state experiences three weather conditions which are the humid rainy, warm and dry seasons. The state climate can be seen as an equatorial type towards the southern parts, and the northern parts experience tropical rain. They experience a heavy downpour of rain every month but it decreases from parts of the south down the north. The temperature is said to be uniform in the state, and it is between 26°C and 31°C. The height decreases downstream. It is bound by latitudes 4° 44ʹ 59.99” N and longitudes 6° 04ʹ 60.00” E; and the town where the oil and gas field is located is confidential and protected by Nigeria Law. The geology of Niger Delta covers about 256,000 km. Initially, it was the older transgressive Paleocene prodelta that transformed into discreet minibasins. These minibasins exhibit several tectonic configurations ranging from extensional, translational and the compressional toe-thrust region. The Niger Delta outcropping units comprise of the Imo Formation and the Ameki Group (Adebiyi 2015).
Quantifying blue carbon for the largest salt marsh in southern British Columbia: implications for regional coastal management
Published in Coastal Engineering Journal, 2021
Maija Gailis, Karen Elizabeth Kohfeld, Marlow G. Pellatt, Deborah Carlson
Despite historical modification of the marsh, the western portion of the Boundary Bay marsh is growing (Figure 5). Marsh expansion is a rare event in coastal marshes and is usually due to anthropogenic land changes and accumulation of debris from hydraulic mining (Watson 2008). Kellerhals and Murray (1969) hypothesized that western Boundary Bay marsh is prograding in response to tidal influence, sedimentation and vegetation growth, and ecological interactions that influence the growth of hummocks and eventual cohesion with the marsh. They surmised that the large quantities of eelgrass and algae are rafted onto hummocks and then covered with sand from strong winter storms. The new relief is then colonized with blue-green algal mats which then allow for typical sediment trapping and eventual halophyte propagation. The farthest western portion of the marsh contains a large beach ridge that was not present in the 1930s (Figure 5 and A6) (Engels and Roberts 2005). The area contained large logs and flotsam that blocked a large channel and has since been overgrown by vegetation (Kellerhalls and Murray 1969).
Geoheritage values of consanguineous wetland suites on the Swan Coastal Plain, Western Australia
Published in Australian Journal of Earth Sciences, 2019
The size and shape of wetland basins vary according to their geomorphic setting and the shape of the depressions that will become wetland basins. Thus, there are beach-ridge swale depressions, linear limestone-ridge depressions, karst depressions, ovoid depressions, inter-star-dune depressions and so on. The composition of surface sediments and the stratigraphy of the wetland fills also varies according to geological and geomorphic setting, climate, and host-water chemistry, and hence there is a pattern of stratigraphic sequences in relationship to geologic/geomorphic setting. For sediments and stratigraphy, variation can occur in an east–west transect, and from south to north on the Swan Coastal Plain. The east–west distribution can be related to consanguineous suites, and the south–north distribution is related to consanguineous suites and to climate.