Answer the following questions calculate the crest width w

Question

Question 1) Consider a reservoir with the following data:

S. No.	Variable	Symbol	Magnitude
1.	Average reservoir depth	dr	100 ft
2.	Dam height	H	200 ft
3.	Wind velocity	U	80 mph
4.	Fetch	F	10 miles
5.	Upstream embankment slope	Vertical: Horizontal	1:2

Calculate the crest width (w) and the freeboard (f) for the dam considering gravity and earthen dams.

An additional amount of 1.5m can be taken in areas of low temperatures for frost action. Freeboard can also be estimated as 4 to 5% of dam height. What final values of freeboard would you consider in both the dams?

Question 2) Consider a reservoir with the following data:

S. No.	Variable	Symbol	Magnitude
1.	Average reservoir depth	dr	12.5 m
2.	Wind velocity	U	50 km/hr
4.	Effective Fetch	F	7 km
5.	Angle of wind with the Fetch	α	30°
6.	Dead storage	Sdead	15%
7.	Sediment discharge	Qs	0.01% of Q
			by weight
8.	Spillway crest Elevation	ELcrest	215 m
9.	Length of the spillway crest	L	50 m
10.	Maximum head of water	Hd	3.5 m
11.	Coefficient of discharge	C	2.2

Answer the following questions:

a) Calculate the crest width (w) for the dam.

b) Calculate the safe and best value of freeboard (f) for the dam based on various formulas.

c) Find the total life of the dam.

d) Find the discharge through the spillway.

Question 3) Classify a dam (H = 12 m; Q < 2000 m³/s) as per ICOLD.

Question 4) A highway culvert is to be designed for a service life of thirty years. What value of the return period needs to be associated with the design procedure having a hydrologic risk of twelve per cent?

Question 5) For the dam shown of a height of 210 ft and crest length of 500 ft, find its maximum reservoir capacity considering 10 ft of freeboard. How long would it take for sediments to fill ten per cent of the reservoir capacity if the annual sediment inflow in the river is 0.01 MAF?

Question 6) Find the value of the maximum wave setup possible for a dam reservoir with an effective fetch of 50 km. The maximum wind velocity at 10 m height is assumed to be twice the value blowing on the ground surface which is 48 km/hr and the depth of reservoir is 100 m. Moreover, calculate the maximum wave height, wave freeboard and the significant wave height for the dam.

Question 7) A storage dam is located on a river with an average daily discharge of 1000 cfs. The mean sediment concentration at this site is 0.3% by weight and the average density of the sediment deposit is estimated to be 87 pcf. Calculate the required dead storage for a project life of 100 years.

Question 8) A given area receives 1000 mm of precipitation in a year. Previous study has shown that the area has a runoff ratio of 0.3. How much water is likely to have evapo-transpired in a year?

Question 9) There is a dam site (as shown in the figure) with wide valley of about 200 m and deep overburden e.g. fine glacial soils, alluvium etc., over 500 m deep. Which type of a dam is suitable for this site? Draw its plan and sectional views and profile of the river.

Question 10) Define the term "Drainage Area". An irrigation tank has a catchment area of 30 sq. km. and the annual average rainfall is 90 cm. If only 20% of the dependable rainfall is the runoff available, calculate the capacity of the tank assuming it fills one and half times in a year.

Question 11) A surface float took 10 seconds to travel a straight run of a stream of 20 m. What is the mean velocity of the stream?

Question 12) In a catchment area in Northern England, 621 mm of evaporation was recorded in 1968 using US Class A pan. Estimate the volume of water lost during this period from a reservoir of surface area of 1.4 square km.

Question 13) Find the value of the maximum wave setup possible for the dam reservoir shown in given figure (scale 1:3600). The maximum wind velocity at 10 m height is 96 km/hr and the depth of reservoir is 100 m. Moreover, calculate the freeboard for the dam.

Question 14) An impounding reservoir had an original storage capacity of 740 ha-m. The catchment area of the reservoir is 100 km², from which the annual sediment discharge into the reservoir is at the rate of 0.1 ha-m/km². Assuming a trap efficiency of 80%, find the annual capacity loss of the reservoir in percent per year.

Question 15) Given the following intensity-duration data, find the a and m constants for the equation =

Intensity (mm/h)          50           30

Duration (h)                 0.5          1.0

Question 16) Given the following data, find the total life of the reservoir:

Dead Storage = 15% of the reservoir capacity

Total storage of the reservoir = 20 Mm³

Mean annual clay and silt deposition = 0.075 Mm3

Question 17) Draw a longitudinal section of a river showing a section of a dam and the sedimentation phenomenon. Clearly label the diagram.

Question 18) Given:

An earthen dam

dr = 14 m

Base width of the dam = 90 m

Qmax < 2000 m³/s

Effective Fetch = 5 km

Wind velocity = 50 km/hr

Answer the following:

a) What is ICOLD?

b) Classify the dam.

c) Find the freeboard.

d) Draw the cross-section of the dam.

Question 19) Given the following information about a concrete uncontrolled gravity dam in the form of a spillway only:

S. No.	Variable	Value
1.	Elevation of the bed of the river	185 m
2.	Spillway crest Elevation	215 m
3.	Length of the dam (i.e. spillway crest)	100 m
4.	Maximum head of water over the spillway	1.5 m

SMALL DAMS = w = (H/5) + 3

DAMS (15 m < H < 30m)

w = 0.55√H + 0.2H

DAMS (H > 30 m)

w = 1.65(H + 1.5)^1/3

a) Classify the dam.

b) Calculate the crest width.

c) What freeboard is safe for this dam?

d) Give an estimate for the settlement of the dam.

e) What is the discharge through the spillway? A typical value of the coefficient of discharge can be taken as 2.2.