Problem 9.8 The following data are the maximum and minimum air temperatures for Pagosa Springs, Colorado, for 10 days in April 1979. Determine the daily number of degree-days, the melt (in./day). the volume rate of melt (acre-ft) from a 79 mi² watershed. Compare the melt, assuming that the watershed has (a) extremely low, (b) average, and (c) extremely high runoff potential.

Final score in Blackboard will be shown as a percent (100% full mark).4. A temporary cofferdam has been built to protect homes in a floodplain until the channel project is completed. The coffer dam was designed to defend a 50-year flood event. The channel project will require 5 years to complete, Compute the following probabilities.[5*4=20] (1) The probability the cofferdam will be overtopped (flooded) in any year. (2) The probability (reliability) the cofferdam will not be overtopped during the project period. (3) The probability (risk) the cofferdam will be overtopped at least one time during the project period. (4) The probability the cofferdam will be overtopped in the 5thyear only.

The 2.4 kN wooden brick (A) as shown below is 0.7 m wide (into paper). The stone weight (B)(specific weight = 23. 6 kN/m³) is suspended from the wooden brick as shown. Determine the volume of the stone weight.

Calculate the hydrodynamic reaction of the curved wall of an open horizontal rectangular channel,knowing the volumetric flow rate Qy [m³/s], width b [m] and the water filling height h [m]. The width of the outlet channel is 0,7b [m]. For the calculations, take: Q_{V}=0,12+0,01 \cdot N r\left[m^{3} / s\right]= b=0,3+0,01 \cdot N r[m]= h=0,2+0,01 \cdot N r[m]= \rho=1000\left[\mathrm{~kg} / \mathrm{m}^{3}\right]

2. An aquifer test is performed on a well in an aquifer of practical infinite aerial extent (nohydrogeologic boundaries in the nearby vicinity). The aquifer is confined with no vertical leakage.The pumped well is pumped at a constant rate of 400 gpm. The draw down is measured in an observation well located 35 feet from the pumping well. The data from the aquifer test are given in the table below. Analyze the data below and determine T (30 Pts).

.3 The storage existing in a river reach at a given time is 13 acre-ft, and at the same time, the inflow to the reach is 450 cfs and the outflow is 500 cfs. One hour later, the inflow is 500 cfs and the outflow's 530 cfs. Calculate the change in storage during the hour in cubic meters and acre-feet.

P5. A spar buoy is a buoyant rod weighted to float and protrude vertically as in Fig.P.5. It can be used for measurements or markers. Suppose that the buoy is maple wood (SG=0.75), 4 in by 3.5in by 15 ft, floating in seawater (SG=1.125). Calculate h in ft if 30 pounds of steel (SG=7.35) is added to the bottom end of the buoy. (Answer:1.277 ft) (Hint: Item 4.1)

Suppose an underground storage tank has been leaking for many years, contaminating the groundwater and causing a contaminant concentration directly beneath the site of 0.30 mg/L. The contamination is flowing at the rate of 1.5 ft per day toward a public drinking water well 2 mile away. The half-life of the contaminant is 10 years. If the PF for the contaminant is 0.02 (mg/kg-day), estimate the cancer risk if a 70-kg person drank 2 L of this water per day for 10years. If the cancer risk is equal to X in 1 million population, find the X.

2. Water flows in the channel shown below. The bottom slope of the channel is 0.003.The dimensions and the Manning coefficients for the surfaces of the different subsections are shown in the figure. Determine the flow rate through the channel.

5. What is the value (cfs) at elevation 5.0 feet (top of pond) of the stage-storage-discharge curve (deltat=0.1 hours) assuming a detention pond with volume, weir, orifice, and infiltration as identified in Questions 1 thru 4? (a) < 750 cfs (b) 750-1500 cfs (c)1500-2500 cfs (d) > 2500 cfs \text { Stage-storage-discharge curve (cfs) }-25 / d t+0 Storage (S) is the total volume (cf) at the elevation in question Delta time (dt) is the time step (seconds) which is given Outflow (O) is the total outflow rate (cfs) at the elevation in quêstion