441: Geography Watershed Systems EX 2: Reservoir Routing Due Date: Wednesday, March 25, 2009. In your AFS course space student directory- Create an EX2 folder. In that folder, save a word document named EX2_YourOnyen answering all 3 questions below. Be sure you have all five necessary files (inflow.dat, flood.m, ex2question1a.m, ex2question1b.m, and ex2question2.m) in your MATLAB working directory Please address any questions to Jon Duncan, [e-mail] Background: Reservoirs are useful flood-control measures because they store a portion of the inflow during a flood, thereby reducing the outflow. As indicated by the continuity equation,
(1.2) the larger the change in volume of water stored, the larger the difference between inflow I and outflow O. The storage capacity of a reservoir depends on its size. The larger the surface area of the reservoir, the more water it can hold before the level of the reservoir rises a given amount. In this exercise, you can explore the effects of reservoir size and initial storage on the outflow hydrograph. Figure 1 on the next page (Figure 5.8 from the text) shows the geometry of the reservoir for this exercise. The height of the spillway crest (hspillway) is fixed at 3 m and the width of the spillway (wc) is 20 m. Adjusting the value of along-channel slope (THETA, in radians) increases or decreases the length of the reservoir. Adjusting the value of across-valley slope (BETA, in radians) changes the reservoir width. In most cases, the value of is considerably larger than the value of , producing a reservoir that is longer than it is wide. The initial depth of the reservoir (HPINIT, as a percentage of the spillway height) can also be specified. When 100% full (HPINIT = 100), the water level in the reservoir is initially at the top of the spillway. Smaller values of HPINIT result in an initially partially full reservoir in which there is no outflow until the water level reaches the top of the spillway. For example, if HPINIT = 50, the water level is initially at half (50%) of the spillway height. Adjusting this value allows you to explore the effect of initial reservoir level on its effectiveness for flood attenuation. The inflow hydrograph for example this has the same shape as the inflow hydrograph shown in Figure 5.10. The peak discharge is determined by the value specified for Q (in m3 s 1) in the input table below. The duration of the flood depends on the value specified for DTHR (in hours) in the input table. A value of DTHR = 2, for example, results in a 2-hour time interval between successive values of discharge in the inflow hydrograph. The higher the peak discharge and the longer the duration of the flood, the more water enters the reservoir during the flood. Therefore, a reservoir with a large storage capacity would be needed to handle the large volume of water associated with a flood of long duration.
Figure 1 Reservoir geometry for the reservoir routing exercise. Assignment: Once you specify your MATLAB working directory to your AFS Ex2 directory that contains all five files, you will only need to enter three lines of command- each one calling a .m file. Each .m file runs a script that generates four graphs. The inflow and outflow hydrographs for each parameter (Theta, Beta, HPINIT) change and one summary graph that displays the outflow hydrographs from the reservoir. These graphs will serve as the basis for your written assignment. Question 1: Effect of reservoir size Simulate reservoir routing under the following conditions and discuss the...