Geography Independent Investigation “To what extent is the rate of erosion equally distributed at Durdle Door and Lulworth Cove
Geography Independent Investigation
“To what extent is the rate of erosion equally distributed at Durdle Door and Lulworth Cove?”
Coastal landforms can be views as the most dynamic structure on earth and hence most catastrophic. The rate in which coastal landforms change can occur significantly faster than others. At one area of land there can be erosion in one season and deposition in another. The majority of changes along the coasts are accomplished by waves, which can be either constructive (slow rate of erosion) or destructive (fast rate of erosion). Weathering plays a vital role in the formation of Landforms. This process is stated to be of natural events which break down pieces of rocks to give the coastline its shape. These natural events include wind or rain, freeze thaw and salt crystallisation which have minimal effects on the landforms at a short period of time whereas colossal hazards/ events such as hurricanes and storms can have a dramatic effect of the erosion rate at landforms. May, (1971), remarked that the most substantial losses occurred in winter where rainfall and winds were at their peak. In coastal areas such as Dorset, which is concordant, immense winds and waves of long fetches break off soft or less resistant material and rocks which leaves the more resistant rocks exposed therefore channelling the formation on landforms demonstrated at the Cliffs of Moher, County Clare, Ireland. The definition of a concordant coast is when coastline has alternating layers of hard rock and soft rock that run parallel to the coast. The soft rock in usually protected from erosion as the hard rock acts as a protective barrier. Landforms such as Coves can be formed if the hard rock has been ruptured through therefore leaving the soft rock exposed to erosion (e.g. Lulworth Cove).
Furthermore, previous coastal studies carried out by Johonnessen et al (1982) concluded that heat of salts on salt crystallisation was possibly the main erosive mechanism above high tide on sunny, south facing sandstone landforms for example east cliff in Dorset. The average surface reading of NaCl are 27ppm (De Wolf, 2001). This study was constructed in Brighton therefore results will approximately be similar in Dorset.
Many studies have been carried out to investigate what factors which put certain landforms at risk of rapid erosion. A variation of landform response occurs according to material strength. Hard rock coasts erode very slowly due to the constraining factors of material strength and rock mechanics (ALLISON, 1989). Therefore the more resistant rock landforms should remain essentially stable when erosional processes act upon them. In contrast, soft rock landforms are subject to additional weakening by weathering and degradation by mass movement; these processes are likely to operate more rapidly in the wetter, warmer climate predicted for regions such as Southern England due to global warming (Department of the Environment, 1991). Conclusively the landforms present in the south of England are more susceptible to erosional/ weathering processes. (Richard and Lorriman, 1987) pointed out that taller landforms erode more rapidly because they generate higher shear stresses and suffer larger landslides, however they also yields more sediment per unit of recession. Whilst reading the article on BBC news ‘UK storms: Extreme weather caused years of erosion’ (21 February 2014) an interesting fact caught my attention which stated “more than 3m of the cliff at Birling Gap has been lost to the sea this year”. This is where I felt that a wider range of studies can be beneficial to investigate the reasons why this unpredictable event occurred, and also encouraging more people to undergo investigations to arrive at reliable conclusion.
Locations for Study
West bay is a small coastal harbour settlement and resort situated on the English Channel coast in Dorset, England. It is approximately 1.5 miles (2.4km) south of Bridport in West Dorset. Coordinates are 50.7116?N 2.763750?W. The coast of West Bay is also part of the Jurassic Coast, which is a World Heritage site which stretches for 98 miles which includes most of the Dorset coastline. West Bay is surrounded by an Area of Outstanding Natural Beauty which is an organisation whose aims are to conserve and enhance the natural beauty of the landscapes around the UK.
Durdle Door is a costal landform (arch) on the south of Dorset. It is a natural limestone/chalk arch. It is situated on the Jurassic coast near Lulworth in Dorset, England. Coordinates are 50?37’16N 2?16’36W. The development of the area around Durdle door and landform itself is directly related to the geology of the area, which comprises of alternating resistant and less resistant rock parallel to the shoreline also known as a concordant coastline.
I have chosen these two locations as they show several significant differences such as geology, coastal landforms, wave speed etc., which will allow me to compare and contrast and determine which factors are the most significant which contribute to erosion.
The title of my investigation is “To what extent is the rate of erosion equally distributed at Durdle Door and Lulworth Cove.”
In the planning stage I split this title into 3 other research question/ sub questions; (1) “To what extent do wave characteristics contribute to the distribution of erosion at Durdle Door and Lulworth Cove?”, (2) “To what extent do geological features such as faults and bedding planes (lithology) contribute to erosion at Lulworth Cove and Durdle Door?” and finally (3) “How and why does beach profile vary between Durdle Door and Lulworth Cove.
• For sub-question (1) I would expect to find as wave speed and wave frequency increases (destructive waves) the rate of erosion at the landforms will be significantly higher than coastlines with low energy for example Holderness coast. This is due Weymouth being a high energy coastline which therefore means that destructive waves will be the most foremost wave, causing the landforms to erode and recede at a higher rate. In addition I expect the area around Durdle Door to erode significantly faster than the area around Lulworth Cove, due to geology characteristic and change in wave speed.
• For sub-question (2) I expect lithology to be a major contributor to rapid erosion. Feature such as faults and bedding planes can determine whether a coastline is susceptible to erosion or firmly resistant to erosion. This therefore implies that these features also determine the shape of a coastline and what landforms can be created.
• For sub-question (3) I expect the measurements of the beach profile to be equal at both investigation points due to the prevailing wind coming from the same direction, therefore the wave frequency should also be equal. However I believe the waves at Lulworth Cove will have a lower magnitude which means the rate of deposition will exceed the rate of erosion which leads to a flatter beach profile. Furthermore there are limitations and they will be addressed in the data analysis.
Secondary information, if needed, and background research will be carried out in order for me obtain a greater understanding of the subject area. This will be executed by reading information from geography booklets supplied by the instructors which contain a wide variety of geographical literature which will help me complete my independent investigation to a high standard. All the information I obtain from secondary sources will be referenced.
In this investigation I will be involved in the collection of primary data about wave type, beach profile at the different investigation points, longshore drift/distance and the speed of longshore drift at both points. Sediment size at each landform will be collected and measured to determine if there is a correlation between sediment size and rate of erosion. Secondary data in the likes of weather forecast of that day and wind speed will be gathered and used to ensure all the variables that might provide inaccurate measurements are accounted for. This data may be gathered from the internet from website such as “Weather.com”. Specific geology landscape information will also be gathered from the internet.
Specific data will be collected and thus specific instruments of recording are required. Ranging poles will be used to measure the beach profile at both points of the investigation. The method will be executed by using the following steps. 1) Attach the string to both pole A and B at the same height and place the spirit level in the middle of the string. 2) Place pole A closest to the sea and pole B up the beach. Place a third pole C towards the top of the beach to act of as a marker.3) Line up pole A and pole B to resemble the position of pole C. 4) Ensure the string is kept tight and 1m in length. Move it up and down on pole B until the bubble in the spirit level is centred. 5) Measure the change in height from the strings starting point. The longshore drift/distance will be calculated by throwing a buoyant object into the sea and measuring the distance it travels at a given time. With this information, we can find out how fast the object moved which would be equivalent to how fast some waves hit the face of the landforms which therefore contributes to rapid erosion. To distinguish which waves were present at the landform wave counts were constructed. If there are 6-9 waves breaking on the shore in one minute then the waves are constructive. If there are 10-14 waves breaking on the shore in one minute then the waves are destructive. The sediment size will be recorded by picking out 5 sediments by a random sampling technique and using callipers to measure their size. As the majority of the data I am collecting is quantitative recording sheets will be created for each data collection method to ensure all the data is easily distributed and understandable.
(cm) Cumulative height change (cm) Distance between poles (cm) Sediment size (cm)
There are a number of ways of presenting collected data. Methods of presenting data include a line graph to show the cumulative height change at increasing distance in Lulworth Cove and Durdle Door. A bar graph could be used to show the mean sediment size at increasing distance at the two investigation points and for qualitative data radar graphs can be used. Proportional arrows could be used to show the direction and intensity of weed speeds at the different sites.
Risk assessments will be carried out throughout the whole investigation and the main risks will be identified. One of these risks could be getting lost. Avoiding this can be done by exchanging phone numbers with instructors or teachers and staying within a large group of piers. Another risk is tripping and slipping. Avoiding this involves wearing sensible and suitable footwear. And finally traffic accidents. This can be avoided by wearing a seatbelt.
The title for my investigation is: “To what extent is the rate of erosion equally distributed at Durdle Door and Lulworth Cove?” This is the predominate question and it has been split up into 3 different sub questions each needed to target specific questions of the main question, therefore this ensures the main question is more accurately answered. The 3 sub questions are; “To what extent do wave characteristics contribute to distribution of erosion at Durdle Door and Lulworth Cove?”, “To what extent do geological features such as faults and bedding planes (lithology) contribute to erosion at Lulworth Cove and Durdle Door?” and “How and why does beach profile vary between Durdle Door and Lulworth Cove?”.
The destination selected for the investigation was the Coast of Dorset which was an area that had enough variation of landforms that would enable me to construct and gather primary data to help me gain evidence to fabricate a conclusion. Some areas were easily accessible and relatively safe. The primary data collected includes wave type, beach profile, longshore drift and sediment size. Secondary data collected includes weather forecasts and wind speed for that day will be obtained from the internet website such as “weather.com”. Overall, a vast quantity of different data was gathered to ensure enough data was available to accurately show contrast between the two investigation points, and to also ensure the main investigation question if fully answered to the best of my ability.
The destinations needed for me investigation was Lulworth Cove which was near the village of West Lulworth on the Jurassic Coast World Heritage Site in Dorset, southern England and Durdle Door which is a natural limestone arch also on the Jurassic Coast. The maps under “location of study” show accurately the area under investigation.
The primary data was collected from the two sites on the same day however at different times and the results were noted on a data collected sheets so they were easily understood when forming a conclusion. The sampling techniques used were random sampling and pragmatic. Random sampling involved picking 5 different rocks at each ranging pole to obtain information for sediment size. This technique avoids any potential bias that could cause unreliable results, such as picking the largest and smoothest rock you can find. Therefore this technique is effective when implemented correctly. The sampling was also pragmatic as we had to avoid dangerous situations such as not going too close to the cliff face, and had to distinguish which areas were accessible as there was a high density of people at the investigation point at certain times.
Durdle Door landscape:
Lulworth Cove Landscape:?
Advantages and Disadvantages of data presenting strategies
The majority of the data presented in my investigation was primary data and they have been displayed using numerous graphical and presenting techniques. These include; bar graph (to sites in one), table of columns and rows, line graphs (2 lines) and annotated pictures of the two sites that my investigation depends upon, Durdle Door and Lulworth Cove.
Each technique contains its various advantages and disadvantages, some of which are listed below:
Bar graph: Used to show the average sediment size at increasing distance from the sea.
? Exact Figures are reasonably easy to read off.
? Construction is easy.
? Comparison of sediment size at the different sites is easy.
? Significant differences can be easily identified.
? Easily understood due to its common usage in businesses and media etc.
? Additional/ information needed to show exact reasons for variation in sediment size at each site.
Line graph: Used to show to cumulative height change on beach profile at increasing distance. The two lines show a variation between Lulworth Cove and Durdle Door.
? Very effective method to portray quantitative and continuous data in likes of beach profile.
? Tends and patterns can be identified easily.
? The two lines allow multiple sets of data to be analysed.
? Construction such as plotting points is time consuming.
? Theoretical value may be plotted as exact values may be difficult to deduce due to scale size.
Annotated photographs: Used to show the different investigation points, Lulworth Cove and Durdle Door. Information such as characteristics of both sites were annotated which could help determine which coastline erodes at a greater rate.
? Excellent visual representation of each site.
? More accurate than field sketches.
? They can support collected data.
? Secondary data photographs are not always reliable and accurate.
? The more attractive areas are annotated whereas unattractive areas are left out and they are just as important.
Table/list: Used to show comparison between the two types of data collected. For example wave count at both investigation points.
? Very easy to understand.
? Easily to compare information across rows or columns.
? Not effective when finding/ determining trends or correlations.
The main title of the investigation is “To what extent is the rate of erosion equally distributed at Lulworth Cove and Durdle Door. This main question has been split into 3 sub questions to ensure the question is answered to its fullest. “To what extent do wave characteristics contribute to the distribution of erosion at Durdle Door and Lulworth Cove?”, “To what extent do geological features such as faults and bedding planes (lithology) contribute to erosion at Lulworth Cove and Durdle Door?” and “How and why does beach profile vary between Durdle Door and Lulworth Cove. During the investigation data was collected, tables and graphs were constructed which contained primary evidence to help answer the sub question. However secondary data was required to answer the sub question “To what extent do geological features such as faults and bedding planes contribute to erosion at Lulworth Cove and Durdle Door”. This is due to not having enough time and reasonable equipment to gain the correct evidence.
“To what extent do wave characteristics contribute to the distribution of erosion at Durdle Door and Lulworth Cove?”
Tables/ lists were used to represent the data for this method comparing both Lulworth Cove and Durdle Door. The wave count table displays a tally chart which shows that the wave frequency at Lulworth Cove is lower than that in Durdle Door in general. At Durdle Door we counted 11 waves in 1 minute whereas in Lulworth Cove we concluded with a figure of 9 in 1 minute. These numbers mean destructive waves are the most predominant wave at Durdle Door, due to there being more than 10 waves breaking on the shoreline in 1 minute. Constructive waves are the most frequent at Lulworth Cove as only 9 waves broke at the shoreline in 1 minute. This data therefore suggests that the rate of erosion at Durdle Door; compared to Lulworth Cove, is higher. Geographically, this implies that the beach profile at Durdle Door should be steeper. With the values obtained from the longshore drift method, an approximate speed was calculated to determine the velocity at which sediments and rocks may hit the landform. Using the formula speed = distance/time we can figure out the speed in which the buoyant object travels. In this case it was an orange. The buoyant objects represents rocks and sediments however the results gained are indefinite as other factors such as friction and mass are not accounted for. Rocks don’t float on the sea surface they roll on the sea bed (traction) which would decrease speed. Therefore the speed presented is an approximate value. 0.047m/sec is the speed in which the orange travelled at Durdle Door and 0.041m/sec was the speed of the orange at Lulworth cove. It can already be seen that the difference in sediment/wave speed between Durdle Door and Lulworth cove is 0.006m/sec which isn’t significant on a small scale. However this event occurs on a large scale therefore will have a dramatic impact. These results imply Durdle Door to be the landform with the higher rate of erosion as the speed in which rocks and sediments hit the landform (abrasion) is greater than that at Lulworth Cove.
Furthermore, while gathering the results for these two methods there were some limitations and ethical issues that were established, one being the frequency of waves to determine if the waves were constructive or destructive. As the investigation areas were densely populated the nearshore and offshore were never isolated at that time therefore distinguishing between waves and ripples was difficult. To improve the results the investigation could have been constructed at a time in the year where it was less busy. As wind speed the equal at both investigation points it had no effect on the final results. Ethical considerations that were established were to use a buoyant object that was biodegradable and not to impede the flow of individuals.
“To what extent do geological features such as faults and bedding planes (Lithology) contribute to erosion at Lulworth Cove and Durdle Door?”
Secondary evidence such as rock type was needed to configure this sub question. From the booklet given by the instructor we can see that Durdle Door consists of a rock called Portland Limestone which is extremely vulnerable to erosion and weathering processes such as freeze thaw, hydraulic action and carbonation. This is due to its physical characteristics. Limestone is commonly known to contain a drastic amount of faults and bedding planes which makes it vulnerable to erosion. Therefore it is acknowledged as a less resistant rock. On the other hand, Lulworth Cove consists of a narrow limestone entrance and Wealden Beds being the predominant rock type. Wealden Beds is known to be the less resistant rock in the scenario and its physical characteristics are similar to that of Portland Limestone however its chemical properties make it a lot weaker, therefore the rate of erosion at Lulworth Cove should exceed that of Durdle Door. Conclusively, we can establish that lithology in this aspect doesn’t have a massive contribution to the rate of erosion due to the physical properties being extremely similar and to truly discover significance the rocks need to be viewed at a microscopic scale.
While gathering information about this method the only ethical consideration that I came across was copyright. Reliable images and website on Google were used to avoid any copyright claims.
“How and why does beach profile vary between Lulworth cove and Durdle Door?”
A line graph was used to show the cumulative height change at increasing distance at a Lulworth Cove and Durdle Door. The line graph displays two colour coded lines that represent the two different investigation points. Blue being Lulworth Cove and red being Durdle Door. The graph shows that Durdle Door contains a steeper beach profile compared to Lulworth Cove. This is due to the height change at every point being significantly higher at Durdle Door. For example at 3m away from the sea Durdle Doors height change increased by 33.5cm whereas Lulworth only increased by 8cm. The greatest height change at Lulworth Cove was 20.5cm compared to that of Durdle Door which was 33.5cm. These figures show that in general Lulworth Cove has a flatter beach profile than Durdle Door. Wave type can be viewed as one of the most important factor that contributes to a variation on beach profiles and using past and present geographical knowledge the primary evidence I have collected have shown positive results. For example destructive waves provide a steeper beach, which my result evidently illustrates. Furthermore, I took to knowledge that sediment size might have an effect on the beach profile. The bar chart shows the average sediment size at increasing distance from the sea. In general, the bar graph shows at Durdle Door when you go up the beach the sediment size increasing whereas at Lulworth Cove the sediment size decreases. At initial the average sediment size was measured to be 1.2cm at Durdle Door and finishes at 2.1cm, which is a 0.9cm increase. On the other hand, at Lulworth 1.4cm was the initial and ended with ;0.1cm, which is a significant decrease in value. The results on the bar chart show on average Lulworth Cove contains the larger sediments which implies less erosion occurring. These results provide evidence that beach profile increases as wave magnitude/frequency decreases.
In addition to gathering evidence limitations and ethical considerations were established one being the average sediment size. The investigation areas were densely populated which implies throughout the whole day sediments may have been moved by individuals intentionally or purposely which will have a negative impact on the results as the sediments aren’t distributed in the natural positions. The ethical consideration was not blocking the path and view/ disturbing individuals on the beach.
The main title of the investigation is “To what extent is the rate of erosion evenly disturbed at Lulworth Cove and Durdle Door?” This main question was then split into 3 sub questions; “To what extent do wave characteristics contribute to the distribution of erosion at Durdle Door and Lulworth Cove?”, “To what extent do geological features such as faults and bedding planes (Lithology) contribute to erosion at Lulworth Cove and Durdle Door?” and finally “How and why does beach profile vary between Lulworth cove and Durdle Door?”. During the investigation relevant data was collected and they were displayed and presented on tables and graphs, thus allowing a valid conclusion to be reached.
“To what extent do wave characteristics contribute to the distribution of erosion at Durdle Door and Lulworth Cove?”
From the data collected we can establish, that in general, the type of waves present at the two investigation sites are different. The waves that have a high frequency at Durdle Door are destructive waves whereas at Lulworth Cove, the predominant wave is constructive waves. This conclusion was made due to the amount of waves counted per minute. At Durdle Door the maximum amount of waves counted were 11 therefore destructive. On the other hand at Lulworth Cove the maximum amount of waves counted were 9. The conclusion is further supported by the speed of longshore drift, which also implies the speed at which sediments move along the coastline affecting the rate of erosion at the landforms. The speed at which sediments move along both investigation points is a theoretical value as mass, friction and any other important factors are not accounted for. The approximate speed at which rocks and sediments move along Durdle Door is O.O47m/s whereas at Lulworth Cove the approximate speed is 0.041m/s. The difference is not significant however on a large scale it can cause vital change to a landform. This therefore implicates that the rate of erosion at Durdle Door exceeds the rate of erosion at Lulworth Cove, which was what I expected to find.
Geologically, the results the can be explained using geological terms. Wave refraction and geology are two important factors that contribute to the rate of erosion at both investigation points. Wave refraction reduces the wave intensity and magnitude due to the waves being concentrated at one area, which is the narrow entrance. The headlands in front of the cove absorb the majority of the wave’s energy resulting to an increase amount of constructive waves at the cove. One the other hand Durdle Door is vulnerable to all kinds of waves as there is no natural or artificial barrier in front of the landform to absorb wave energy thus rate of erosion is higher. Geology also contributes to the rate of erosion at both landforms. If the geology is at a high resistance the rate of erosion will be slow. In this case Portland limestone and Wealden beds have the same physical properties. They both contain significant amounts of faults and bedding planes which is a large contributor to the rate of erosion.
“To what extent do geological features such as faults and bedding planes (Lithology) contribute to erosion at Lulworth Cove and Durdle Door?”
It can be concluded from my finding that the presence of faults and bedding planes have a significant impact on the rate of erosion at Lulworth Cove and Durdle Door. As the geology and lithology at both investigation points is quite similar it was difficult to construct primary evidence for the sub question. Thus, secondary information and research was required obtain relevant information about the geology and lithology at the two investigation points. Landforms with completely different geology characteristics would improve the results and provide reliable results. However in this scenario Portland limestone can be views as the resistant rock and Wealden bed as the less resistant rock.
My findings conclude; depending on lithology the rate of erosion should be equal at both investigation points as the lithology present is extremely similar which implies whatever weathering process that occurs at Durdle Door should also occur at Lulworth Cove.
“How and why does beach profile vary between Lulworth cove and Durdle Door?”
In general, despite fluctuating results, we can establish that Durdle door has the steeper beach profile compared to that of Lulworth Cove. At Durdle Door the greatest height change was 33.5cm and the lowest height change was 0cm. The figure 0 was obtained due to there being no more accessible area to measure as we were met by the cliff face. At Lulworth the largest height change was 20.5cm and the lowest height change was 8cm. It can be seen by through the figures obtained that every point measured was greater at Durdle door which implies that the beach profile is steeper. This can also be supported by the wave type present at the two investigation points. At Durdle Door destructive waves was the most predominant wave. When destructive waves break at a beach they possess the characteristics of a weak swash and a powerful backwash. As a result, material is strip from the beach producing a steep beach. Evidently Lulworth Cove should portray the opposite as the most frequent wave present is constructive waves. They have a strong swash and a weak backwash which means the rate material is deposited exceeds the rate at which material is removed. Thus, overtime material builds up and the beach flattens out.
Initially, I took into consideration that sediment size contributed and had an effect on the beach profile. However sediment size was evenly distributed at both investigation points but the arrangement of sediments was different due to the types of waves present. At increasing distance from the sea at Durdle Door the average sediment size increases, whereas at Lulworth Cove the average sediment size decreases. Conclusively, the results present on the bar chart displays on average Lulworth Cove contains the larger sediments which indicates less erosion at the coast in contrast to Durdle Door.
To conclude, the main question “To what extent is the rate of erosion evenly distributed at Lulworth Cove and Durdle Door?” can be answered by starting with the most important factor which is waves. You can state that the velocity at which sediments travel at Durdle Door is greater by 0.006m/sec in contrast to Lulworth Cove. However the value is approximate as mass, friction and other factors weren’t accounted for. Some aspects such as beach profile can also determine the rate of erosion at both investigation points. Overall it can be concluded that the rate of erosion at Durdle Door exceeds that of Lulworth Cove.
There were 4 main stages to undergo completion of the investigation; “To what extent is the rate of erosion evenly distributed at Durdle Door and Lulworth Cove?” The stages included introduction, planning/method, data presentation and conclusion. Evidently, each stage had both positives and negatives aspects in attempting to fully answering the main investigation question.
The introduction stage was carried out to ensure that a relevant and worthwhile investigation could be conducted that allowed a wide variety of results to be collected and analysed to ensure that a valid conclusion could be drawn. The introduction section contained a vast amount of positives. The background research/reading conducted provided the necessary knowledge of understanding the significant factors that contributed to rapid erosions at coastlines and to ensure the results I gathered were geologically correct. The Location of study section provided precise information on the destination of the investigation, which allowed secondary research to be carried out such as wind speed and weather forecast on the particular day.
The planning stage was also carried out to ensure that my investigation question was effective and that the means of gathering results were reasonable and assessable. The breakdown of the main investigation question allowed me to assess the question in depth to ensure it was fully answered. The risk assessment that was carried out reduced the risks of injuries as we possessed the knowledge of the potential accidents that could occur when data was being collected out in the field. For example tripping and clipping was a risk which was resolved by wearing sensible footwear. A recording sheet was constructed to allow neat and tidy data collecting, which also reduced the time spent understanding and figuring out which data represented what method. The recording sheet also allowed data presentation to be reasonably easier as we could distinguish what type of graph would be suitable to the chosen data. Finally, gathering and understanding how the equipment’s and methods function allowed effective and accurate data collection. However some of the equipment enabled some recording to be inaccurate. For example the 1 metre string between the two ranging poles was not fully stretched which means the distance from the sea may have been less than we expected. To obtain better and accurate results a metre stick could have been places between the two ranging poles to ensure the string was fully stretched to 1 metre.
The data collection stage provided both positive and negative points whilst collecting data. The investigation was constructed in reasonable amount of time that enabled us to obtain relevant results, however for my investigation question the area chosen was too small/compact to show great contrast. Wind speed, geology and other factors were quite similar which means only a hand full of factors could be analysed. However a large quantity of successful data was collected which indicated my investigation was worthwhile and successful as I could identify areas of contrast between the two investigation points. To obtain approximate sediment speed the longshore drift values were required to calculate a velocity which represented the speed rocks and minerals moves along the sea bed. How hard the sediments hit the landforms depend on how fast they are travelling. Therefore a greater speed equals a more vicious impact. Finally, the wave count to distinguish if constructive waves or destructive waves were the most frequent waves had its limitations. The area of investigation was densely populated at the time which means it was difficult to distinguish actual waves from ripples. Preventing this could involve underdoing the investing at a different time of the year that doesn’t attract a vast quantity of individuals.
Data presentation showed a lot of positives. A bar graph was constructed to show the average sediment size at increasing distance from the sea. The graph contained two bars on the same distance, blue representing Lulworth Cove and red representing Durdle Door. This data presenting technique was advantageous it was quite easy to compare the sediment size between the two investigation points. Also construction of bar graphs is easy and provides the sufficient data comparison. By including the two investigation points in one bar graph significant differences can be identified, thus aiding in answering segments of the main question.
Line graphs were used to show the cumulative height change on beach profile at increasing distance from the sea. The two lines showed variation between Lulworth Cove and Durdle Door. The two sets of lines allowed multiple data two be analysed. The line graph was an effective method in that, the data collected was quantitative which means a large range of data could be plotted at once and the values were continuous. Unfortunately, the technique was time consuming as plotting some points required a large amount of concentration to avoid plotting in the wrong area. Theoretical values may have been plotted due to exact values being difficult to deduce due to the scale size.
Tables and lists were made to hold data neatly and show comparison between the two types of data collected. Initially this method of presenting data was very effective as it was very easy to understand and information was really easy to compare however there are some complications with this sampling technique. It was not effective when finding or determining trends and correlations. If more time was spent constructing the investigation more values could have being obtained for wave frequency which means the data would be more representative and a suitable graph could have been drawn, therefore a more accurate conclusion.
Finally, annotated photographs were used to show the visual contrast between the two sites. It provides a general overview on the surroundings and what the environment was like on that day. This technique can be viewed as advantageous as it provides excellent visual representation of the sites and they can support the data collected to some aspects. One the other hand, they do provide some negative points. Individuals are keener to annotate the most attractive areas on the photograph and leave out the least attractive aspects which can also provide important information. The reliability and accuracy of secondary photographs is not always guaranteed, which provides irrelevant information and may lead to incapability’s of understanding results.
They data collected provided evidence for conclusions to be reached on each of the sub questions. The relevancy of the conclusions was at a high as they were drawn directly from the data collected. These conclusions provided explanations for each of the sub questions which made answering the main question easier. However, some flaw were identified which may set some minor draw backs. Some data collected were not 100% accurate meaning the conclusions drawn weren’t 100% reliable. For instance, distinguishing between waves and ripples was difficult as the investigation sites were densely populated. Results were collected and inaccurate conclusion may have been drawn. The quality of the conclusions can also be viewed as inadequate standards as they were based upon data collected from one day and a certain time of the day. Undergoing data collected for a large period of time would improve the conclusions drastically.
Overall, the entire investigation contained a vast amount of positives and negative which may provide opportunities for other researchers to improve and gain a better understanding of the subject matter coastline erosion.