Topic 6 - Fieldwork Flashcards
what was the enquiry question
does urbanisation increase flood risk
what was our hypothesis
urban areas are more likely to flood than rural areas
where did we collect the data from
data was collected from the river tillingbourne in surrey england. the river flows between dorking and guildford. there were two sites. shere and crossways farm
what are the factors that increase flood risk
urbanisation - urban areas have lots of impermeable surfaces e.g tarmac or concrete. the reduces infiltration and increases surface run off which causes flooding
thin soil - there is less surface for water to be absorbed and get saturated. this reduces infiltration and increases surface run off
deforestation - when there are less trees there will be less space for the water to go as there are a lack of roots to absorb the water
what was the location of crossways farm like
located in the middle course of the river. the land was used for horses. the river has been left in its natural state and has lots of meanders. the river has however been straightened in the garden next to the farm to prevent the flooding. land is relatively flat. this area is not likely to flood as there is little urban use and there are lots of trees
what was the location of shere like
located in the middle course of the river. the land is urban, there is a small village with roads and paths. the river has been artificially straightened and has embankments to prevent flooding to nearby buildings. the land is flat. this area is likely to flood because there is lots of urban use and lots of impermeable surfaces.
what is the risk assessment
drowning - not likely - stay in groups
slipping on unstable surfaces - walk , wear sensible footwear
flood risk
rivers carry disease - don’t drink river water, wash hands before eating
what are the data types we used for the investigation
- os maps
- geology maps
- flood risk maps
- measurements
- velocity
what are os maps and why did we choose to use them
- we studied the relief of the land by looking at contours as well as studying the land use to spot rural and urban areas
we chose to use them because they helped us to see if relief affects flood risk at both sites and will help us answer our hypothesis
what are geology maps and why did we choose to use them
we studied the maps to identify rock types and saw sandstone and chalk which is impermeable rock. we used these are they help us to identify a possible factor causing flood risk
what are flood risk maps and why did we choose to use them
we studied 2 maps and found that both sites were in flood zone three so there is a greater annual probability of flooding at both sites. we chose these are they help us to understand our field site and means we have chosen a good site to collect data
what are measurement and why did we choose to use them
we measured the river width and depth and 10 intervals across the channel. we chose there as they help us to measure the cross sectional area and the rivers carrying capacity.
how did we use velocity and why did we decide to use it
we used ping pong balls to measure how fast the river flowed we used timers and took 3 readings then calculated a mean value. we used this to see how velocity affects flood risk, fast rivers means less flood risk
describe the data types used and why they are beneficial
primary data is beneficial as you are able to determine the accuracy is the data is collected by you personally however secondary data allows us to have access to higher quality maps that we would not have been able to create ourselves. quantitative data is good because it can be easily plotted in graphs where as qualitative data gives you a more in-depth idea of what is going on in the area.
describe the sampling types we used and why they are beneficial
when measuring the velocity of the river we used systematic sampling to identify the points in the river we needed to record the depths of. we also used stratified sampling to choose the locations of the rivers.
how did we measure the width of the river
-we collected data from 2 chosen sites. at each site we chose a random location along the river to collect the data from
- to begin with we measured the width using a tape measure held across the river. the ends of the tape were positioned where the water met the river bank to record the occupied channel width.
- the width was divided by 9 to get 10 equal intervals across the river including the starting interval of 0 to create locations to systematically sample depth
- we used a metre rule to measure the depth at each interval ensuring accuracy by making sure the metre ruler was held vertically and the narrow side of the ruler faced upstream to avoid water lapping up it at distorting the reading
how did we measure the velocity of the river
we measured the velocity using a metre ruler to mark out a distance then placed a ping pong ball at one end and timing how long it took for it to get from one point to the next we did this three times and them calculated a mean
