3 practice sets · Page 1 of 1
a mean annual runoff 1 m3/s from a catchment of area 10 km2 represents an effective rainfall of
10.0 cm
315.4 cm
100 cm
31.54 cm
150 cm
Correct Answer: B — 315.4 cm
Explanation:
Given: Runoff = 1 m3/sec Catchment area = 10 km2 Calculations: Effective rainfall = Mean Annual Rainfall = 1 m3/sec × 365 × 24 × 60 × 60 Catchment Area = 10 km2 = 10 × 106 m2 Effective rainfall =
The area between the isohytes 0.45 m and 0.55 m is 100 Sq.km and between 0.55 m and 0.65 m is of 150 Sq.km. The average depth of annual precipitation over the above basin of 250 Sq.km will be
0.50 m
0.55 m
0.56 m
0.60 m
1.0 m
Correct Answer: C — 0.56 m
Explanation:
Concept: Isohyetal method: The isohyetal method is used to estimate the mean precipitation across an area by drawing lines of equal precipitation. The method uses topographic and other data to yield reliable estimates. Isohyets are contours of equal precipitation analogous to contour lines on a topographic map.
Consider the factor affecting the evaporation losses:
The rate of evaporation increases as the wind speed decreases.
The rate of evaporation decreases with the increase in atmospheric pressure.
The rate of evaporation increases with an increase in salt concentration in water.
The rate of evaporation increases as the saturation vapor pressure increases.
Choose the incorrect statement:
1, 2
2, 3
1, 3
2, 4
Correct Answer: C — 1, 3
Explanation:
Concept: Evaporation losses: According to Daltons law: E = C (Es – Ea) C = a + bV a=b=constants. V=wind velocity in km/hr ES=Saturation vapor pressure at the water surface Ea=Actual vapor pressure. Factors Affecting Evaporation losses 1.
