methodology
Post on 14-Dec-2014
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Controlled Assessment Methodology
What do the examiners say?
Hypotheses
1. Channel size or Cross Sectional area will increase with distance downstream.
2. Channel efficiency will increase with distance from the source.
3. Channel gradient will decrease with distance downstream.
Methodology AreasPRIMAY DATA
Cross Sectional Area (width and average depth)Channel Velocity Discharge (CSA x Velocity)Wetted perimeter of channel (channel efficiency)Hydraulic radiusChannel gradientChannel bed roughness
Methodology AreasSECONDARY DATA
What types of secondary data may be useful in your investigation? What might they tell you about the river?
Climate of the area?Human management of the river?Vegetation & Geology of the area?
Risk Assessment
You must complete your own risk assessment for the fieldwork.
Should include environmental, human and equipment hazards and risks
Needs to be a clear link to your methodologies
Annotated Photograph
Ranging poles placed at the wetted edge of the current river channel.
Tape measure held taut at 90° to the river channel attached to ranging poles to measure channel width
Depth measured at 11 evenly distributed points across the wetted river channel starting from the left bank
Tape held about 20cm above water level so a metre rule could be used to measure depth evenly across the channel.
Large irregular rocks associated with the upper course throughout the channel.
Channel edge during the wet season
Measurements taken from left to right as you look down stream
CROSS SECTIONAL AREADescription & Explanation of Method Justification
Risk Assessment
Channel width and depth will be measured at each site using the equipment and method as outlined below.
By calculating the channel width and average depth we are able to work out the cross sectional area (CSA) of the channel at each site. This is worked out using the below formula.
CSA = Width x Average Depth
This method will give an approximation of how channel size changes downstream and will show variations in depth across the channel.
By calculating the cross sectional area of the river, along with the wetted perimeter, we are also able to determine the channel efficiency (Hydraulic Action). It will also provide us with valuable supporting evidence when compared to river velocity and also discharge.
Linked to Risk 1a, b, 2b, 3d
Use of GIS
Clear use of GIS and well linked to the chosen question
Area of Study & Location Maps – Google Earth
Risk Assessment
Secondary Data collection
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