Introduction to KINEROS2

Transcription

1 Introduction to KINEROS2 Running KINEROS2 Introduction: Goal: Assignment: In this exercise you will learn about the files and instructions to run KINEROS2 for a simple single overland flow runoff element representing a rainfall simulator plot To familiarize yourself with running KINEROS2 and to understand the how various model parameters influence modeled runoff Run the KINEROS2 model for a natural rainfall simulation experiments and use parameter multipliers to alter modeled runoff to better match observed runoff A Short Introduction to Files Needed to Run KINEROS2 (K2) There are four primary files needed to run KINEROS2. Detailed descriptions for each type of file and their content are available from the on- line KINEROS2 documentation at: (go to Documentation - > Input Parameters ). The main files are: Parameter file (e.g. P205N.par) This contains global variables that apply to all watershed modeling elements (e.g. overland flow, channel, pond, etc.) and variables and parameters describing the characteristics of each model element (e.g. size, slope, soils, cover, and infiltration, hydraulic, and erosion parameters). Many of the variables in this file were measured in the field. Rainfall file (e.g. P205N.pre) This file contains data describing the rainfall hyetograph. Run file* (default: kin.fil) This file contains responses to KINEROS2 prompts and can be edited with a text editor. If it is not supplied the program will prompt you for input. After you run K2 once, the kin.fil file with your prompts is written so you can rerun the simulation with the same responses without typing them in or edit kin.fil to change some of your responses. Executable file (k2.app (Mac); k2.exe (PC)) Run this file from a: 1) Mac terminal (Go to Applications - > Utilities -. Terminal.app ; or 2) PC command prompt (Go to: All Programs - > Windows System - > Command Prompt ) Running KINEROS2 with Prompts What are you modeling? You will be modeling the runoff from a natural (unburned) rainfall simulator plot on the Empire Ranch located in southeastern Arizona that was conducted in 2005 (Plot2, 2005, Natural: Associated file names P205N). The vegetation in this area is predominantly desert grassland with mixed shrubs, mesquite trees, and cactus. The variable rate rainfall simulator applied rainfall with a step- wise increase in rainfall intensity ranging from approximately 65 to 180 mm/hr for roughly 40 min. Adjacent to the natural simulator plot, a plot was established on ground that was recently burned by a wildfire (Plot2, 2005, Burned: P205B). During the rainfall simulation experiment runoff (discharge Q) from the simulator plot was measured using a small Parshall flume. The observed rainfall intensity and discharge is contained in the file named P205N_obs.csv and P205B_obs.csv for natural and burned cases, respectively. The observed data from these files can be imported into a spreadsheet or read by a plotting program (Figure 2). 1

2 Figure 1. Photos of Natural and Burned Patches The observed simulator rainfall intensities and runoff for the natural and burned plots are illustrated in the following figure. Figure 2. Observed rainfall simulator precipitation and runoff from the P205 natural and burned plots. Plot Condition Runoff Volume (mm) Peak Runoff Rate (mm/hr) P205N Natural P205B Burned Table 1. Runoff Volume and Peak Runoff Rate for P205 Rainfall Simulator Plot Experiments. 2

3 Start out by setting up the model to predict runoff on the natural plot (P205N). To simplify running the program without specifying different paths it is recommended that you place the following files in the same directory: K2.app (.exe for PC) P205N.PAR P205N.PRE P205N_obs.csv To execute the program go to a terminal window (command prompt window) and type in./k2.app (./k2.exe) See sample responses reproduced below. User input is highlighted in yellow and comments shown in blue. Temps-MacBook-Air:natural dgoodrich$./k2.app $ Repeat previous run? (If Y the program will read from the N kin.fil file if it exists) KINEROS2 Kinematic Runoff and Erosion Model FESP5 Workshop Version Compiled 1-July-2015 with GNU Fortran U. S. Department of Agriculture Agricultural Research Service $ Parameter file: P205N.PAR $ Rainfall file: P205N.PRE $ Output file: (printed at top of output file) P205N.TXT $ Description: Plot 2, 2005, Natural $ Duration (min): 50 $ Time step (min): 1 $ Courant Adjustment? (y/n): y $ Sediment? (y/n): n $ Multipliers? (y/n/file): n $ Tabular Summary? (y/n): y + Processing PLANE 1 3

4 Event Volume Summary: Rainfall mm cu m Plane infiltration Storage Outflow (Make a note of modeled total runoff volume highlighted in green as you will use this number to adjust model parameters printed at top of output file) Error (Volume in - Volume out - Storage) < 1 percent Time step was adjusted to meet Courant condition Total watershed area = ha Open the P205N.TXT file and have a look at the computer output. For the current print option the output file is very similar to the screen output copied above. For more detailed output select one of the following print option in the P405N.PAR file using a text editor. In the PLANE block look for: PR = 1, FILE=P205N- v1.csv! print flag If PR = 1 the summary output it placed in the output file as shown above If PR = 2 the hyetograph and hydrograph are printed in the output file If PR = 3 the csv file named P205N- v1.csv is created with the following columns "Time" "Rainfall" "Outflow" "Outflow" "(min)" "(mm/hr)" "(mm/hr)" "(cu m /s)" The data from the model output file (P205N- v1.csv) can be imported into a spreadsheet or read by a plotting program to compare the model simulation results to the field observations (Figure 3). 4

5 Figure 3. Observations and modeled runoff from rainfall simulator plot P205N. Original parameter file with KS=50 mm/hr and G = 50 mm. It is readily apparent that the model is underestimating the observed runoff with the observed runoff volume = mm (Table 1) being much larger than the modeled runoff volume (37.01 mm, highlighted in green above). Running KINEROS2 with the kin.fil When you ran the model in the prior example it created a kin.fil file with the values you input at the prompts. Contents of kin.fil file from the natural simulator plot run above (explanatory notes in blue are not contained in the file). P205N.PAR (parameter file name) P205N.PRE (rainfall file name) P205N.TXT (output file name) Empire Ranch Plot 2, Natural, 2005 (model run title) 50 (simulation duration min) 1 (simulation time step min) Y (Courant adjustment y/n) N (Sediment y/n) N (Multipliers y/n/file) Y (Tabular summary y/n) 5

6 The simulation you did above will also create a multiplier file (mult.fil). Open this file. It simply contains seven rows of a single number that are multipliers for the following parameters in the.par file. All the numbers should be equal to 1.0. Saturated hydraulic conductivity, KS Manning/Chezy Coefficient of variation of KS, CV Capillary drive parameter, G Interception Soil cohesion parameter (used for erosion) Rain splash parameter (used for erosion) The following table contains a brief summary of how the KINEROS2 multipliers affect the model results. Even though many of the multipliers have similar descriptions for the effects, the magnitude of the impacts can vary greatly. This point is reflected by the intensity of the color associated with each multiplier in the table, where more sensitive parameters have more intense/darker colors. Upland/hillslope hydraulic conductivity (KS) Upland/hillslope Manning s roughness (n) Upland/hillslope coefficient of variation for KS (CV) Upland/hillslope mean capillary drive (G) Upland/hillslope interception Upland/hillslope Cohesion Upland/hillslope splash Increasing KS results in increased infiltration, decreased peak flows, decreased total outflow, decreased erosion and sediment yield from lower flows. Increasing roughness causes runoff to slow. This results in increased infiltration, decreased peak flows, decreased total outflow, decreased erosion and sediment yield from lower flows, and slows drainage times. This propagates through to the channels, resulting in similar trends. Increasing CV results in decreased infiltration, increased peak flows, increased total outflow, and increased erosion and sediment yield from higher flows. Increasing G results in increased infiltration, decreased peak flows, decreased total outflow, and decreased erosion and sediment yield from lower flows. Increasing interception causes less rainfall to reach the ground. This results in less opportunity for infiltration, decreased outflow, and decreased erosion and sediment yield. This propagates through to the channels, resulting in similar trends. Has no effect on hydrology. Increasing cohesion results in decreased erosion and sediment yield. Has no effect on hydrology. Increasing splash results in increased erosion and sediment yield on the. 6

7 If you do have observed hydrograph data and are attempting to calibrate KINEROS2 using the parameter multipliers we recommend the following procedures: 1. Change the KS overland hydraulic conductivity multiplier until you come close to matching the observed runoff volume with the simulated runoff volume. Increasing the KS multiplier will decrease runoff volume. 2. Change the Mean capillary drive (G) multiplier to alter the shape of the initial runoff response. Increasing G will increase infiltration (delay or decrease runoff) at the beginning of the event 3. Change the Overland Manning s roughness (n) multiplier. Increasing the roughness multiplier will typically reduce Qp and cause the time to peak runoff to be later. NOTE for this tutorial the runoff flow length is short (6 m) so changing n has a very minor effect. Open kin.fil with a text editor and change the last N to Y. Run the program and when asked Repeat pervious run respond with Y. The program will now ask you $ Use previous multipliers?. Respond N and it will prompt you to enter a multiplier for each of the variables. Vary the KS and G multipliers so that the modeled runoff volume and peak runoff rate match observed values. The person obtaining the best match to the observed runoff volume and peak runoff rate will win a fabulous prize!! 7