Laserfiche WebLink
in the table of map polygon attributes). This digital coverage and the necessary database files <br />muid <br />. <br />(comp and layer) were copied to the computer workspace <br />/crdss_arc/scs/awc <br />In this exercise, the database file comp identified the different soils comprising each mapping unit and <br />their percentages within the unit. Each unit was identified internally by its coded mapping unit identifier <br />( ). <br />Several additional soil attributes were stored in this file, the most important being and <br />muid Seqnum <br />. <br />identifies which soils correspond to a particular mapping unit since more than one <br />comppct Seqnum <br />soil can occur within a polygon. A soil describes a soil type. It consists of the sequence of soil <br />Seqnum <br />layers, their depths and thicknesses, textures, and other characteristics that are typical for the soil. Each <br />polygon on a soil map represents the occurrence of one or more kinds of soil as typified by their sequa. <br />identifies the percentage composition of each soil within the mapping unit. <br />Comppct <br />An additional database file, layer, describes each soil layer or ?horizon.? This file contains several items <br />. , , <br />comprising a single and are the most important. These <br />Seqnum Laydepl laydeph awch awcl <br />describe depth to the upper boundary of the soil layer, depth to the lower boundary of the soil layer, and <br />the maximum/minimum AWC for the layer. A number of other soil attributes were imported into the <br />files comp and layer from the STATSGO database, but these were not of use to the AWC evaluations. <br />The following steps describe the process by which an AWC for each mapping unit was calculated using <br />ARC/INFO and information from these database files: <br />1.Delete unnecessary items from comp using the ARC macro language (aml) using the following: <br />2.DPCOMP.AML - Delete unnecessary items from layer using the aml <br />3.DPLAYER.AML - Add the following items (and their definitions) to layer: <br />awcformatted as 5 5 N 3 <br />laydepformatted as 2 2 I <br />layawcformatted as 9 9 N 3 <br /> + ) <br />4.Calculate equal to ( / 2. <br />awc awcl awch <br /> - ). <br />5.Calculate to ( <br />laydep laydeph laydepl <br /> * ). <br />6.Calculate to ( <br />layawc awc laydep <br />7.Generate a summary of for unique occurrences of and in layer, <br />layawc muid seqnum <br />. . <br />resulting in an AWC for each The summary database file is <br />sequum museawc <br />. <br />8.Copy the item (and its contents) from comp to <br />comppct museawc <br />. <br />9.Add the item (formatted as 9 9 N 3) to is the polygon <br />awc soilw.pat Soilw.pat <br />attribute table within the relational database, INFO. <br />10.Relate to using as the relational key. <br />museawc soilw.pat muid <br />11.Run the aml CALCAWC.AML to calculate an AWC for each mapping unit ( identifier). <br />muid <br /> ( <br />This program multiplies the AWC for each identifier) by its component <br />seqnum seqnum <br />2 <br />A275 01.09.95 1.14-17 CSU IDS <br />