Photo AI
The table and graph below give information on rainfall and runoff, gathered over a twelve-month period - Leaving Cert Geography - Question Question 1 - 2006
Question Question 1
The table and graph below give information on rainfall and runoff, gathered over a twelve-month period. MONTH | RAINS (in mm) | SURFACE RUN-OFF (in mm) -------|... show full transcript
Worked Solution & Example Answer:The table and graph below give information on rainfall and runoff, gathered over a twelve-month period - Leaving Cert Geography - Question Question 1 - 2006
Step 1
In how many months did rainfall exceed 80mm?
Answer
To determine the number of months with rainfall exceeding 80mm, we can analyze the rainfall data:
- J: 120mm
- F: 110mm
- M: 75mm (not exceeding 80)
- A: 90mm
- M: 150mm
- J: 95mm
- J: 80mm (not exceeding 80)
- A: 55mm (not exceeding 80)
- S: 95mm
- O: 120mm
- N: 150mm
- D: 80mm (not exceeding 80)
Rainfall exceeded 80mm in the following months: J (120), F (110), A (90), M (150), J (95), S (95), O (120), N (150).
This results in a total of 8 months.
Step 2
Calculate the average monthly rainfall for the last three months of the year.
Answer
To find the average rainfall for the last three months (October, November, December), the total rainfall can be calculated:
- October: 120mm
- November: 150mm
- December: 80mm
The sum is:
To find the average: ext{Average} = rac{ ext{Total Rainfall}}{ ext{Number of Months}} = rac{350}{3} ext{ mm} \\ = 116.67 ext{ mm}
Therefore, the average rainfall is approximately 116.67mm.
Step 3
Name the month when rainfall and surface run-off were closest.
Answer
To find the month when rainfall and surface run-off were closest, we can compare rainfall and surface run-off values:
- January: Rainfall 120mm, Run-off 120mm (equal)
- February: Rainfall 110mm, Run-off 65mm
- March: Rainfall 75mm, Run-off 45mm
- April: Rainfall 90mm, Run-off 50mm
- May: Rainfall 150mm, Run-off 35mm
- June: Rainfall 95mm, Run-off 0mm
- July: Rainfall 80mm, Run-off 15mm
- August: Rainfall 55mm, Run-off 30mm
- September: Rainfall 95mm, Run-off 20mm
- October: Rainfall 120mm, Run-off 15mm
- November: Rainfall 150mm, Run-off 35mm
- December: Rainfall 80mm, Run-off 90mm
The closest values are in January, with both being 120mm.
Step 4
Select the most likely explanation for run-off being almost equal to rainfall in that month.
Answer
In January, the rainfall was 120mm, and the surface run-off was also 120mm. The most likely explanation for the run-off being almost equal to rainfall is:
(b) evaporation was low
This suggests that there was less evaporation, allowing for a greater proportion of the rainfall to become surface run-off.