Question

Use your calculated discharge results to estimate the probability of flooding, using the following procedure: 1. Use the Annual Exceedance Probability Chart below (also in the Chapter 16 Investigation in your textbook or on the worksheet that corresponds to this exercise). Find the position of your calculated discharge to fill the notch on the vertical axis of the plot. 2. Draw a horizontal line from that value to the right until you intersect the probability line. 3. From the point of intersection, draw a vertical line down to the horizontal axis of the plot, read off the corresponding probability of exceedance, and choose the best answer below. The probability to fill the notch is: Now determine the probability of flooding of the middle terrace, using the same approach as before. Remember you must use the total amount of discharge required to fill the notch and bottomland up to the level of the middle terrace. Choose the best answer below. The probability of flooding the middle terrace is:

Answer 1

Answer:

1) The probability to fill the notch is greater than 95%

2) The probability to fill the middle terrace is 5 to 25 percent

Explanation:

1) The calculated discharge, $D_{ca}$, to fill the notch is given by the relation;

$D_{ca}$ = Width × Depth × Velocity = 8 × 5 × 0.5 = 20 m³/s

From the Annual Exceedance Probability chart, the exceedance probability is greater than 95%, therefore, the probability to fill the notch is greater than 95%

2) The calculated discharge, $D_{mt}$, to fill the middle terrace is given by the relation;

$D_{mt}$ = Width of middle terrace × Depth of middle terrace × Velocity of middle terrace + $D_{ca}$ = 35 × 2 × 1.4 + 20 =  118 m³/s

From the Annual Exceedance Probability chart,  the probability to fill the middle terrace is 5 to 25 percent.