PROBLEM: Find the average rainfall by using Isohyetal method for a square catchment area, bounded at the corners by four gage stations. Plot the isohyets as straight lines and assume an isohyet interval of 1 cm. The coordinates of the station and rainfall values are given below. Show the diagram and the tabulated solution in your paper. * (Final answer until 3-decimal places only. Indicate the unit) Station 1 2 3 4 Coordinates, km (50, 80) (100, 80) (50, 20) (100, 20) Rainfall, cm 1 3 3

The 60-year record shows that the annual maximum discharges for a river have a mean of 30,000 cfs, a standard deviation of 28,000 cfs, and a skewness coefficient of 3.15. If the annual maximum discharge can be described by the Extreme-value Type I distribution, what is the probability that the annual maximum discharge exceeds 100,000 cfs at least once in next 10 years? (Note: The sample size is 60. Conduct interpolation using exceedance probabilities or cumulative probabilities.)

Station Rainfall (mm) Annual (mm) ДХ (m) ΔΥ (m) Area (m²) A 42 500 10 25 1500 30 480 15 30 2000 50 558 24 30 830 526 500 E 35 590 40 19 1200 Using a rainfall of 386 mm for rain gauge Station D, determine the average depth of rainfall that fell for the watershed using the arithmetic average, and Thiessen polygon method. The areas for the Thiessen polygon method are given in the table above for each station. B.

Using a rainfall of 386 mm for rain gauge Station D, determine the average depth of rainfall that fell for the watershed using the arithmetic average, and Thiessen polygon method. The areas for the Thiessen polygon method are given in the table above for each station. Determine the average depth of rainfall for a watershed using the isohyetal method given the data below. Isohyet (mm) Area Associated (km²) 30 - 40 20 20 - 30 45 10 - 20 35 under 10