1G476/576 HydrologySurface Water ExerciseIntroductionSurface water processes are driven by the interplay between meteorological processes and geomorphicconfiguration of the landscape. Watersheds of varying scale represent the fundamental hydrologic unit at the Earth'ssurface. This lab employs data techniques that are commonly applied to the analysis of surface water hydrology. Thedata for this lab are available at the class web site, follow the links to the lab data section and download the "SurfaceWater Data" Excel file. Save to floppy or appropriate folder on your network account. NOTE: You will also need toget a copy of the "Surface Hydrology Equation List" from the web site to work on this lab.Part 1 - Flood ClimatologyTable 1 is a list of world record rainfall intensities (inches of precip.) for specific durations (lengths of time)(data from Patton and Baker, 1977). The rainfall and durations are given as Log values. Remember that Log 10 =10 10XX, so the values listed represent the exponents derived from a base of 10.Task 1. Using excel, create two new data columns in Table 1 and convert the Log exponent values back to10their original, "anti-log" value.Task 2. Plot the data on a scatter chart with a log x axis (duration in days) and a log y axis (total rainfall inches). Format the scatter plot with titles, labels and grid lines.Task 3. Fit a power-function curve to the data.- select / highlight the graph data points (the "series" data)- Chart-Add Trend Line-Select "Power" Trend/Regression Type- click on the "options" tab and check the "Display Equation on Chart" and "Display R squared Valueon Chart" boxes.- click o.k. and proceed, Excel should now fit a line to the data and give you an equation that definesthe relationship between the rainfall-duration data. NOTE: the R square value is a measure of thedegree to which the data fit the function. An R square value between 0.7 - 1.0 suggests a very good fit.-Format the equation and R-square information so that it fits on your graph, print the graph and data toinclude in your lab manual.Task 4 - Answer the "Related Questions" at the end of the lab.Part 2 - Historical Discharge Analysis / Recurrence Intervals.The Luckiamute River at Helmick State Park is gaged by the U.S. Geological Survey. Discharge data havebeen collected at the site since the 1940's. Table 2 is a summary of annual peak discharge data from the Luckiamute /Helmick gaging station.2Recurrence Interval and Gumbel PlotsThe recurrence interval of a given flood discharge is commonly calculated from a set of historical data. The annual peakdischarges for the Luckiamute gaging station are listed in Table 2. The "annual peak discharge" represents themaximum discharge recorded at the station for a given water year. Recurrence interval of annual peak dischargerepresents an estimation, based on the historical record, of the probability of a given flood discharge occurring over agiven time period. For example, the "100 yr flood" is a flood-discharge magnitude that has a probability of occurringonce every 100 yrs. Generally, the lower the magnitude of event, the statistically more frequent the chance ofoccurring, and vice-versa. Once the recurrence intervals for given discharges are calculated, the relations may bevisually plotted on a Gumbel-type graph. This is more-or-less a semi-log graph relation (Gumbel graph paper isavailable in the lab data section of the class web site). Refer to the last page of the "Surface Water Hydrology EquationList" for a list of procedures on how to analyze frequency-discharge data.Methods of Calculation1. Once you've downloaded the discharge data from the internet, open the data set with Excel.2. The data from the USGS are listed in ft /sec, set up a new data column entitled "Discharge m /sec"3 3A. Use Excel cell formula techniques to convert the discharge from ft /sec to m /sec (1 cu. m = 35.313 3cu. ft) for each water year listed.2. Sort and rank the data using Excel in order from highest to lowest discharge.3. Create two other new columns entitled "Recurrence Interval yrs" and "Probability". Then calculate RI and Pfor each flood discharge by using the following formulas:R.I. = (n+1)/m p = 1/(R.I.)where R.I. = Recurrence Interval of a Given Discharge of Rank mm = Rank of Dischargen = total number of observationsp = probability of occurrence(1.0 = 100% chance of discharge occurring, 0.1 = 10% chance)PRINT OUT YOUR COMPLETED DATA SHEETS!4. Using the Gumbel graph paper, plot a Gumbel curve for the Luckiamute, with the recurrence interval on thelog-interval x-axis, and discharge on the y-axis (choose an appropriate linear scale for the y-axis).5. Now repeat the steps for Table 3 discharge data for the Smith River Watershed of the McKenzie Basin. Plot the Smith River data on the same Gumbel graph as the Luckiamute, but use different symbols and colors.6. Using Excel chart methods and Table 3, create a flood rating curve for the Smith and Luckiamutewatersheds. A flood rating curve is a plot of Discharge (y axis-linear) vs. River Stage (x axis-linear). Using theChart-Trend Line routine that you employed in part one, determine a linear equation for each data set that3describes the relationship between discharge and river stage.7. Answer the "Related Questions" at the end of the lab.Part 3 - Watershed Morphometry and Hydrologic RelationsTable 4 is a collection of channel network data from three watersheds in Virginia and West Virginia (Fernow,North Fork, and Little River). The data are organized by stream order and channel segment length for each area. Drainage areas, lengths from divide, and basin relief are also listed for each site.Task 1. Calculate the drainage density for each watershed in m/km . Print and list your results.2Task 2. Determine the Shreve Magnitude for each watershed (M = frequency or count of first order streamsegments). Print and list your results.Task 3.Using the empirical hydrologic relations listed as item 7 on the equation sheet, calculate the maximumdischarge expected for each of the Appalachian watersheds (answer in cubic meters per second).Task 4.Using the empirical hydrologic relations listed as item 7 on the equation sheet, calculate the dischargeexpected for a recurrence interval of 2.33 years at each of the watersheds.Task 5.Using the rational runoff method, assume that each Appalachian watershed is covered with a clayey-soilcolluvium. Now consider a regional rainfall event