Cliff Erosion

A model was developed to calculate the evolution of a notch in a dune or cliff due to wave impact. Analytical solutions were derived to the model for schematized conditions regarding forcing and dune/cliff properties. Comparisons were made with laboratory experiments where the time evolution of the notch was measured. Values of the transport coefficients in the analytical solutions were determined by least-square fitting the solutions to the laboratory data. Some of these coefficients could be related to the ratio between parameters describing the forcing and the dune/cliff strength. The evolution of the dune notch displayed a linear behavior at short times, whereas the cliff notch showed a more complex response for cases where a feedback between the notch and a beach formed seaward of the cliff occurred.

In this paper the cliff shoreline erosion on the coastline between Punta Montijo and the Chipiona Port (Cadiz, Spain) is studied. The reasons which cause this erosive phenomenon and the future erosive tendency of these cliffs are estimated, obtaining magnitudes of recession and the rate at which it will occur. Analysis of the current situation has been carried out by determining its plan shape, the study of the theoretical erosion profile of the cliffs and the verification of their failure. The future evolution of the cliffs shoreline has been analysed through the simulation of its recession and the study of the profile response to storm wave action. Finally, is presented a model to estimate the recession of the cliff shoreline.

In this paper the cliff shoreline erosion on the coastline between Punta Montijo and the Chipiona Port (Cadiz, Spain) is studied. The reasons which cause this erosive phenomenon and the future erosive tendency of these cliffs are estimated, obtaining magnitudes of recession and the rate at which it will occur. Analysis of the current situation has been carried out by determining its plan shape, the study of the theoretical erosion profile of the cliffs and the verification of their failure. The future evolution of the cliffs shoreline has been analysed through the simulation of its recession and the study of the profile response to storm wave action. Finally, is presented a model to estimate the recession of the cliff shoreline.

A quantification of coastal erosion processes on a clay cliff in a cold temperate region was conducted. This study was based on a network of markers that were measured on a monthly basis from 1998 to 2003. During that period, the average retreat rate of the cliff was 1.5 m/y. Our results demonstrate that weathering is a more significant cliff retreat factor than hydrodynamic processes on fine sediment shorelines. This statement opposes conventional understanding. In fact, 65% of the annual cliff retreat took place through the winter season when the waves could not reach the foot of the cliff because of an ice foot. This erosion is caused by cryogenic processes in winter, particularly through freezethaw cycles, whereas desiccation and wave undercutting contributed respectively for 20% and 15% of the total annual retreat. The field measurements conducted before and after major storms, especially on October 29, 2000, illustrated that wave undercutting was negligible for the clay cliff. These results do not corroborate with previous studies showing that cliff erosion is mostly controlled by wave undercutting with negligible winter erosion. In a context of global warming, the intensity of cryogenic processes can become more important due to milder winters, an increase in the number of freeze-thaw cycles, and the reduction of the ice foot and snow cover (especially on south-facing cliffs directly exposed to solar radiation). This study demonstrates that the evaluation of sensitivity of coastal systems to climatic change should not be done just for sea-level rise and increased storminess, but also for other climatic parameters. Future research should also take into account approaches combining the studies of marine and terrestrial erosion processes.

In this paper the cliff shoreline erosion on the coastline between Punta Montijo and the Chipiona Port (Cadiz, Spain) is studied. The reasons which cause this erosive phenomenon and the future erosive tendency of these cliffs are estimated, obtaining magnitudes of recession and the rate at which it will occur. Analysis of the current situation has been carried out by determining its plan shape, the study of the theoretical erosion profile of the cliffs and the verification of their failure. The future evolution of the cliffs shoreline has been analysed through the simulation of its recession and the study of the profile response to storm wave action. Finally, is presented a model to estimate the recession of the cliff shoreline.

In most episodic erosion and deposition systems, knowledge of the timing of geomorphological change, in relation to fluctuations in the driving forces, is crucial to strong erosion process inference, and model building, validation and development. A challenge for geomorphology, however, is that few studies have focused on geomorphological event structure (timing, magnitude, frequency and duration of individual erosion and deposition events), in relation to applied stresses, because of the absence of key monitoring methodologies. This paper therefore (a) presents full details of a new erosion and deposition measurement system-PEEP-3Tdeveloped from the Photo-Electronic Erosion Pin sensor in five key areas, including the addition of nocturnal monitoring through the integration of the Thermal Consonance Timing (TCT) concept, to produce a continuous sensing system; (b) presents novel high-resolution datasets from the redesigned PEEP-3T system for river bank system of the Rivers Nidd and Wharfe, northern England, UK; and (c) comments on their potential for wider application throughout geomorphology to address these key measurement challenges. Relative to manual methods of erosion and deposition quantification, continuous PEEP-3T methodologies increase the temporal resolution of erosion/deposition event detection by more than three orders of magnitude (better than 1-second resolution if required), and this facility can significantly enhance process inference. Results show that river banks are highly dynamic thermally and respond quickly to radiation inputs. Data on bank retreat timing, fixed with PEEP-3T TCT evidence, confirmed that they were significantly delayed up to 55 h after flood peaks. One event occurred 13 h after emergence from the flow. This suggests that mass failure processes rather than fluid entrainment dominated the system. It is also shown how, by integrating turbidity instrumentation with TCT ideas, linkages between sediment supply and sediment flux can be forged at event timescales, and a lack of sediment exhaustion was evident here. Five challenges for wider geomorphological process investigation are discussed. This event-based dynamics approach, based on continuous monitoring methodologies, appears to have considerable wider potential for stronger process inference and model testing and validation in many areas of geomorphology.

Between October 2010 and November 2017, surveys using terrestrial laser scanning (TLS) were carried out every 4-5 months to monitor erosion on three chalk cliff faces with close structural characteristics in Normandy (the two Dieppe sites are abandoned cliffs while the Varengeville-sur-Mer site is an active one). The uniqueness of this paper is the comparison between these cliff sections and the significance of marine and/or subaerial controls in erosion. Beyond the quantification of annual retreat rates, which on the active cliff are currently 36 times greater than on the abandoned cliffs, this paper highlights the fundamental efficacy of marine controls in the current cliff erosion and the removal of falls (analyses of modalities of retreat and profile evolution according to a naturalistic approach). Subaerial processes appear to have a less erosive action than marine ones, because the studied abandoned cliffs show low erosion dynamics and have maintained a subvertical profile despite continentalization for between 30 to more than 120 years.

In this paper the cliff shoreline erosion on the coastline between Punta Montijo and the Chipiona Port (Cadiz, Spain) is studied. The reasons which cause this erosive phenomenon and the future erosive tendency of these cliffs are estimated, obtaining magnitudes of recession and the rate at which it will occur. Analysis of the current situation has been carried out by determining its plan shape, the study of the theoretical erosion profile of the cliffs and the verification of their failure. The future evolution of the cliffs shoreline has been analysed through the simulation of its recession and the study of the profile response to storm wave action. Finally, is presented a model to estimate the recession of the cliff shoreline.

Thermochron iButtons incorporate the latest in digital technology, making them smaller, less expensive, durable and potentially more reliable than many other temperature logging devices. The objective of this study was to test the accuracy of an inexpensive air temperature measurement system, composed of a Thermochron iButton and radiation shield. Sixty-one iButtons were subjected to a sequence of two water baths (0°C and 24·9°C) to assess the absolute accuracy of the sensors. Five solar radiation shields were tested in a greenhouse setting to evaluate the reduction in radiative heating. Significant differences (p < 0·05) were detected between instruments subsequent to both water-bath treatment analyses. The accuracy of the sensors was well within the manufacturer's stated specification of ±1·0°C with a collective temperature variance of ±0·21°C. Temperature responses generated by the Thermochron iButtons in different radiation shields were consistent, but varied significantly (p < 0·05) from 28 to 44°C based on diurnal temperature ranges. Results indicate that the Thermochron iButton is an accurate, inexpensive alternative to more expensive temperature datalogging systems, and is well suited for obtaining quality spatially distributed data for hydrologic and water quality investigations.

. The 3 meter long thermal pins inserted inside unconsolidated deposits allow the monitoring of erosion for a time period sometimes extending over several seasons. The thermocouple or thermocable method allows not only to instrument into the unconsolidated deposits, but also into rocky and cohesive substrate to a depth of 85 cm. An autonomous microclimatic station located nearby the experimental sites simultaneously samples temperature parameters, precipitation, snow cover, wind speed and direction, global radiation, etc. The differential analysis of cliff thermal regime performed simultaneously with the one for air allow to establish the activation periods of coastal erosion processes. The results also allow to establish with precision the actual influence of rapid variations of certain climatic and microclimatic parameters (radiation, presence of snow cover, precipitation, etc.) on the physical state of surfaces and also on the activation of certain physical processes connected to coastal erosion events.

. Seasonal quantification of coastal processes and cliff erosion on fine sediment shorelines in a cold temperate climate, north shore of the St. Lawrence maritime estuary, A quantification of coastal erosion processes on a clay cliff in a cold temperate region was conducted. This study was based on a network of markers that were measured on a monthly basis from 1998 to 2003. During that period, the average retreat rate of the cliff was 1.5 m/y. Our results demonstrate that weathering is a more significant cliff retreat factor than hydrodynamic processes on fine sediment shorelines. This statement opposes conventional understanding. In fact, 65% of the annual cliff retreat took place through the winter season when the waves could not reach the foot of the cliff because of an ice foot. This erosion is caused by cryogenic processes in winter, particularly through freezethaw cycles, whereas desiccation and wave undercutting contributed respectively for 20% and 15% of the total annual retreat. The field measurements conducted before and after major storms, especially on October 29, 2000, illustrated that wave undercutting was negligible for the clay cliff. These results do not corroborate with previous studies showing that cliff erosion is mostly controlled by wave undercutting with negligible winter erosion. In a context of global warming, the intensity of cryogenic processes can become more important due to milder winters, an increase in the number of freeze-thaw cycles, and the reduction of the ice foot and snow cover (especially on south-facing cliffs directly exposed to solar radiation). This study demonstrates that the evaluation of sensitivity of coastal systems to climatic change should not be done just for sea-level rise and increased storminess, but also for other climatic parameters. Future research should also take into account approaches combining the studies of marine and terrestrial erosion processes.

. The 3 meter long thermal pins inserted inside unconsolidated deposits allow the monitoring of erosion for a time period sometimes extending over several seasons. The thermocouple or thermocable method allows not only to instrument into the unconsolidated deposits, but also into rocky and cohesive substrate to a depth of 85 cm. An autonomous microclimatic station located nearby the experimental sites simultaneously samples temperature parameters, precipitation, snow cover, wind speed and direction, global radiation, etc. The differential analysis of cliff thermal regime performed simultaneously with the one for air allow to establish the activation periods of coastal erosion processes. The results also allow to establish with precision the actual influence of rapid variations of certain climatic and microclimatic parameters (radiation, presence of snow cover, precipitation, etc.) on the physical state of surfaces and also on the activation of certain physical processes connected to coastal erosion events.

"Three intrusive systems of detection and quantification of coastal erosion events (using thermocouples and thermal pins) were developed and tested from 2005 to 2008 in different regions of the Gulf and maritime estuary of the St Lawrence (Quebec, Canada). The 3-m-long thermal pins inserted inside unconsolidated deposits allow the monitoring of erosion for a time period sometimes extending over several seasons. The thermocouple or thermocable method allows not only the instrumentation of unconsolidated deposits but also of rocky and cohesive substrate to a depth of 85 cm. An autonomous microclimatic station located near the experimental sites simultaneously samples temperature parameters, precipitation, snow cover, wind speed and direction as well as global radiation.

The differential analysis of cliff thermal regime performed simultaneously with an analysis of air temperature makes it possible to determine the activation periods of coastal erosion processes. The results also make it possible to establish with precision the actual influence of rapid variations of certain climatic and microclimatic parameters (radiation, presence of snow cover, precipitation, etc.) on the physical state of surfaces and also on the activation of certain physical processes connected to coastal erosion events. The automated thermal erosion pin system (ATEPS) allows high temporal resolution (i.e. continuous) monitoring, enabling a real coupling of coastal erosion rates and climatic parameters. Preliminary results with the ATEPS system indicate that mild winter temperature and direct solar radiation are significant factors controlling cliff retreat rates. Moreover, the melting of segregation ice during the spring thaw contributed for more than 70% of cliff retreat against only 30% for frost shattering."