User Manual - Ohio University
Contents
1. comes full Before there can be Surplus soil Storage must first be brought to field capacity Presumably plants have been utilizing soil moisture as the growing season progresses the soil moisture is then recharged usually through the fall and winter Inputs e Soil AWC grid Soi soil_awc_mm e Storage for previous month e g Storage st_08 mm e Storage for current month e g Storage st_09 mm Output e Storage first full grid for each month values 1 first full or 0 o example C WB Storage st1stfull_09 o Group output monthly grids as ST_Ist_Full 3 Surplus Computes monthly surplus All grids for current month Inputs e Soil AWC grid Soi soil_awc_mm e Average monthly precipitation Climate Precip precip mm_ mm e Monthly actual evapotranspiration AE7 aet_ mm e Monthly Storage Storage st_ mm e Delta Storage grid Delta_ST delta_ST_ mm e Storage first full grid ST stFull_ 1 0 Output e Monthly Surplus mm o C WB Surplus Surplus_ o Group output monthly grids as Surplus Page 9 V Checks To see if water budget is in balance 1 Checks PET AET Deficit Precipitation AET Surplus Resulting annual grids should have all zero values if checks hold Inputs Annual precipitation Climate Precip precip mm_13 mm All monthly AET grids AE7 aet_ mm All monthly Surplus grids Surplus Surplus_ mm All monthly PET grids PET PET_ mm All monthly Deficit grid2. the first model Temp_Factor includes the following output instructions o Group output monthly grids as Climate Temp Factors The slash V indicates the output grouping and its name In this case the twelve t_factor_ grids 1 e t_factor_0O1 t_factor_02 t_factor_12 should be grouped in the Table of Contents with the New Group Layer called Temp Factors Furthermore in this example the group Temp Factors is then placed within the existing Climate group along with the Temp and Precip groups E Climat H O t_factor_o1 H O t_factor_o2 aO t_factor_03 H O t factor_04 O t factor_05 t_Factor_06 t_Factor_O7 oO O O t factor_08 O t factor_09 O t_factor_10 O t factor_11 O t_Factor_12 OO precip mm_01 OO precip mm_02 O precip mm_03 OO precip mm_04 O precip mm_os O precip mm_o6 aO precip mm_07 OO precip mm_08 OO precip mm_o9 O precip mm_10 oO 11 CO precip mm_12 O H re E _ E bs E3 precip mm_ E precip mm_13 E Temp a O temp c_01 HO temp c_02 O temp c_03 a O temp c_04 aO temp c_05 O temp c_06 O temp c_07 O temp c_08 CO temp c_09 O temp c_10 O temp c_11 O temp c_12 O temp c_13 Ae eG DEE Page 4 I Turc PE Calculates monthly PET according to Turc PET 0 013 T T 15 R 50 e NOTE Each monthly temperature grid must be floating point not integer Use Spatial Analyst Tools Math Float if necessary la
3. Geocoding Tools E Geostatistical Analyst Tools E Linear Referencing Tools H Network Analyst Tools ai E Samples E Spatial Analyst Tools E Spatial Statistics Tools H Water Balance soil_awe_mm Coweeta_soils diation rad_01 rad_02 rad_03 rad_04 rad_05 rad_06 rad_07 rad_08 rad_09 rad_10 rad_11 rad_12 imate Precip precip mm_01 precip mm_02 precip mm_03 precip mm_04 precip mm_05 precip mm_06 precip mm_07 precip mm_08 precip mm_09 precip mm_10 precip mm_11 a oKHamnmmmmnmmanAAAKa m 1S S b 2 Forn BETEGA i BHAFRFRFaW E precip mm_12 precip mm_13 Temp temp c_01 temp c_02 temp c_03 temp c_04 temp c_05 temp c_06 temp c_07 temp c_08 temp c_09 temp c_10 temp c_11 temp c_12 temp c_13 p HELNE CECBOBOBCEOBCEOBCBOBCECBCEORG E ge HillShade coweeta_dem i o 2 4 gt 9291128 254 3903076 393 Meters Note that the Water Balance Toolbox has been added to the ArcToolbox and that initial input grids have been added to the Table of Contents Soil Radiation Climate DEM With this
4. T Model first calculates R 50 converting from Whim to cal cm then multiplies by Temp_factor computed in step 1 above Inputs e Monthly temperature factors from above o example Climate Temp Factors t_factor_01 e Monthly radiation from Solar Analyst WH m o example Radiation rad_01 Output e Monthly PET PET_ 4 inmm o example C WB PET PET_OI o Group output monthly grids as PET II P PE Calculates moisture supply demand 1 P PE Inputs e Average monthly precipitation mm o example Climate Precip precip mm_01 e Monthly PET grid PET_ from above o example PET PET_OI Output e Monthly P PE grid P PE_ in mm o example C WB P PE P PE_01 o Group output monthly grids as P PE Page 6 III Storage Model computes soil moisture storage monthly value based on the last day of the month Uses daily time step assuming decreasing availability of soil moisture Curve C from Mather 1974 Climatology Fundamentals and Applications McGraw Hill NY 1 Storage The Storage model is run for each month beginning when soil Storage can safely assumed to be full ST AWC Begin the model on the first month after this full month i e the first month after winter spring recharge in which some grid cells in the P PE_ grid take on a negative value In the demonstration data set for Coweeta begin with month 05 This model runs iteratively computing daily Storage for each day in
5. Temp_Factor or 1b Temp_Factor all positive temps Computes the 0 013 T T 15 part of the Turc equation above If month has any negative temperature values run Temp_Factor PET will be 0 if temperatures are below freezing If temperatures are all positive run Temp_Factor all positive temps Input e Average monthly temperature C o example Climate Temp temp c_01 Output e Monthly temperature factor t_factor_ o example C WB Climate t_factor_01 o Group output monthly grids as Climate Temp Factors te le 3 a TE Pi ti does fe E iea EES a pE E iSe xi Erevorenerts leio a a EE a tf Digig Soave teeda torus wren iowa Mendis PERTE da Sample run of Temp_Factor all positive Result after model run for January In the demonstration temps model After double clicking on the data set all cells in the study area are assigned the same model in ArcToolbox this window is opened temperature value resulting in the single value output for Since model run is for January Input and t_factor_ The output grid can be turned off but once Output grid names end in 01 For February all twelve t_factor_ grids are created they should be grid names should end in 02 etc grouped New Layer Name Temp Factors and the group placed in the Climate Group with the existing Temp and Precip groups Page 5 2 Radiation gt PE
6. User s Guide for Water Balance Toolbox for ArcGIS Revised August 2010 James Dyer Department of Geography Ohio University Before You Start Important Information For ease of use the model executes with default filenames and file locations If you download only the Water Balance Toolbox you will need to create folders organized as described below or alter the models If you downloaded the Toolbox Demo Version these folders have already been created e If you downloaded the Toolbox Demo Version unzip the files to your C Drive By default the program expects files to be located within C WB e If you are not using the Toolbox Demo Version a WB folder needs to be created on the C drive All output grids will be written to C WB o Next subfolders need to be created within C WB AET Checks Climate Deficit P PE PET Storage Surplus Working o Optional folders e g for input grids but not written to Documents DEM Misc Radiation Soil e If you download the Toolbox Demo Version you will see an additional subfolder New_to_Copy This folder contains empty copies of all of the subfolders listed above After you run the model you can copy the entire C WB folder to a new location you may wish to give it anew name e g using the study area name and re create an empty C WB folder to run a new model simply copy the contents of _New_to_C
7. demonstration data set all cells in the study area are assigned the same monthly temperature and precipitation values A Study area shapefile representing a portion of the Coweeta Long Term Ecological Research Site North Carolina USA is the only layer that is visible Expand the Water Balance toolbox We will run the models in E Water Balance sequence by double clicking on the appropriate model name 01_Turc PE ms 4 Temp_Factor Ja B Temp_Factor all positive temps See C Radiation gt PET 02_P PE 03_Storage amp 04_AET 05_Checks e Page 3 For each model in the Water Balance Toolbox the instructions below list the Input and the Output grids e The Input grids must be in the Table of Contents Preliminary grids have already been added to WB_Demo mxd Climate Soils etc and subsequent grids created by the model are added to the Table of Contents by default e Itis important to use the naming conventions given for the Output grids For example for the first model Temp_Factor grid output in the instructions is listed as e Monthly temperature factor t_factor_ Since the model operates on a monthly time step this model will be run twelve times with the output grids named t_factor_01 t_factor_02 t_factor_12 e Itis also important that output grids be grouped in the Table of Contents as indicated in the instructions For example the instructions for
8. meter values When running the model all Input variables should be in the map document s Table of Contents Output variables will be written to C WB Follow grouping and naming conventions in examples below If you are running the Toolbox Demo Version Open the project WB_Demo mxd located in your C WB Folder The Water Balance Toolbox should already be loaded in the ArcToolbox All models in the Water Balance Toolbox can be run by double clicking and entering model parameter values When running the model all Input variables should be in the map document s Table of Contents Climate Radiation DEM and other preliminary Input files are already saved in the Table of Contents for WB_Demo mxd Output variables will be written to C WB Follow grouping and naming conventions in examples below Page 2 From this point forward the User Manual will provide instruction using the example provided in the Toolbox Demo Version After copying the downloaded files to C WB and opening WB_Demo mxd you should see a screen similar to the following amp WB_Demo mxd ArcMap ArcInfo E 218 x Ele Edt view Insert Selection Tools Window Help Deag BBX lo a as 7 32 23 0 Ta amp Projection Plate Carree world Soil E 3D Analyst Tools E Analysis Tools H Cartography Tools H Conversion Tools E Coverage Tools E Data Interoperability Tools E Data Management Tools
9. opy to the new C WB folder A word about the grids used in the model e All grids created for input e g climate soils should be same resolution as DEM e Obviously all grids should also be in the same projection e Cells for all grids should align Subtracting two grids whose cells are misaligned may result in erroneous values such that the water balance final checks fail If you need to align grids zoom into a single pixel and use the Measure Tool to determine the amount of x y shift required Then use the ArcGIS Shift tool to align the grid utilizing the tool s Input Snap Raster option e All grids are floating point Page 1 After starting ArcGIS The Water Balance Toolbox utilizes the Spatial Analyst extension If necessary turn on the extension Tools drop down menus gt Extensions If you are not using the Toolbox Demo Version In the ArcToolbox you will need to Add Toolbox Water Balance Toolbox that you downloaded Since folders will be copied to a new location when water balance computations are completed it is necessary to use relative path names in the map document o File drop down menu gt Document Properties gt Data Source Options gt Store relative path names to data sources o Save the map document mxd file in C WB using a name that identifies the particular study area All models in the Water Balance Toolbox can be run by double clicking and entering model para
10. s Deficit def_ mm Output Annual Actual Evapotranspiration mm o C WB AET aet_ann Annual Surplus mm o C WB Surplus Surplus_Ann Annual Potential Evapotranspiration mm o C WB PET pet_ann Annual Deficit mm o C WB Deficit def_ann P AE Surplus check grid all zeros if checks hold o C WB Checks p_ae_s_1i PE AE Deficit check grid all zeros if checks hold o C WB Checks pe_ae_def_i Glossary of water balance terms Potential evapotranspiration is the evaporative water loss from a vegetated surface in which water is not a limiting factor it depends mainly on heat and radiation Actual evapotranspiration refers to water loss from a vegetated surface given water availability and is equal to available water or potential evapotranspiration whichever is less Deficit refers to evaporative demand not met by available water or the difference between potential and actual evapotranspiration Surplus is excess water not evaporated or transpired that leaves a site through runoff or subsurface flow Available Water Capacity AWC is the maximum amount of water that the soil can store representing the soil s field capacity Page 10
11. th to the next Inputs e Storage for previous month e g Storage st_04 mm e Storage for current month e g Storage st_05 mm Output e Delta Storage Difference in Storage for the current month in mm o example C WB Storage delta_ST_05 o Group output monthly grids as Delta_ST Note if the two Storage grids are equal for consecutive months e g ST_01 ST_02 ST_03 ST_04 you can save time by copying one of the zero Delta_ST grids and renaming it for the other months e g Copy Delta_ST_02 rename as Delta_ST_03 Delta_ST_04 IV AET 1 AET Computes monthly actual evapotranspiration and deficit All inputs for the current month Inputs e Average monthly precipitation Climate Precip precip mm_ mm e Potential evapotranspiration PET PET_ mm e P PE grid P PE p pe_ mm e Delta Storage grid Delta_ST delta_ST_ mm Outputs e Monthly actual evapotranspiration mm o CA WB AET MAET _ o Group output monthly grids as AET e Monthly deficit mm o C WB Deficit Def_ o Group output monthly grids as Deficit Note Some Deficit grids may contain very small negative values lt 0 001 Although negative values make no sense conceptually they are small enough to be ignored Alternatively an if then statement can be added to the model setting negative values to zero Page 8 2 Storage Comes Full This model looks for the month s in which the Storage of individual cells
12. the month it will take a while to run Inputs e Number of days in the current month in two places specify as constant to use in model 01 Jan 31 05 May 31 09 Sep 30 02 Feb 28 06 Jun 30 10 Oct 31 03 Mar 31 07 Jul 31 11 Nov 30 04 Apr 30 08 Aug 31 12 Dec 31 e Soil AWC grid Soi soil_awc_mm e P PE grid P PE p pe_ for current month mm e Storage for the previous month ST_ in mm NOTE for first month run i e the month where Storage come full use the AWC grid SoiAsoil_awc_mm for previous month Storage ST_ since full storage AWC Output e Storage for the current month ST_ in mm o example C WB Storage ST_04 o Group output monthly grids as Storage NOTE Since Storage model involves dividing a grid by AWC the result will be No Data for pixels on the Storage grid where AWC 0 i e where there is water To reduce time avoid unnecessary computations with the model e Model started in month where Storage is full ST AWC Then with soil moisture utilization in summer ST lt AWC e After fall winter soil moisture recharge ST AWC again Computing ST when full is unnecessary and AWC grid can be used for ST_ as long as P gt PE for that month Copy AWC grid and rename as appropriate ST_ grid e g ST_01 ST_02 etc Page 7 2 Delta Storage Computes the difference in Storage from one mon
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