Using the Data Validation tool (Optional)
After running the BRAT tool, it can sometimes be useful calculate additional metrics on the output. The Data Validation tool adds and calculates a number of fields that further contextualize the results of a BRAT run.
Running the Tool
Running the tool is fairly simple. The tool takes three inputs:
- The Conservation Restoration Model output network
- An optional shapefile containing points that correspond to observed beaver dams
- The name of the output If not given a beaver dam shapefile, the tool will not produce the fields that rely on dams data. Be warned, the tool will snap the points of the beaver dam shapefile to the nearest reach, which will change the file given to it. If you want to retain the original position of the beaver dams, give the tool a copy of your shapefile.
Output of the Tool
The tool produces eight new fields. Three of these fields are reliant on the dams input. The fields are as follows:
e_DamCt: The observed number of dams per segment (based on the beaver dam shape file).
e_DamDens: The number of dams per kilometer. Calculated by dividing
e_DamCtby the segment length.
e_DamPcC: The ratio between the observed dam count and the calculated existing capacity. Calculated by dividing
Ex_Categor: The category of the calculated existing capacity. It is determined based on the
oCC_EX(the calculated existing capacity), as follows:
- If 0 <
- If 1 <
- If 5 <
- If 15 <
Hpe_Categor: The category of the calculated historic capacity. It is determined based on the
oCC_HPE(the calculated historic capacity), as follows:
- If oCC_HPE = 0, Hpe_Categor = “None”
- If 0 < oCC_HPE <= 1, Hpe_Categor = “Rare”
- If 1 < oCC_HPE <= 5, Hpe_Categor = “Occasional”
- If 5 < oCC_HPE <= 15, Hpe_Categor = “Frequent”
- If 15 < oCC_HPE, Hpe_Categor = “Pervasive”
mCC_EX_Ct: The existing capacity density. Calculated by dividing
oCC_EXby the segment length.
mCC_HPE_Ct: The historic capacity density. Calculated by dividing
oCC_HPEby the segment length.
mCC_EXtoHPE: The ration between existing and historic capacity. Calculated by dividing
Currently the Data Validation tool is limited by the distance and relation that dam capture events to the NHD line. This can result in short reaches being assigned multiple dams and having overestimated dam densities due to the small reach length. While larger reaches adjacent to the short reach which might have been assigned some of the dams are not and have low dam densities.
To remedy this BRAT has integrated multichannel line segments from the original nhd file that warrent the classification of a perennial network. BRAT was previously not able to handle multichannel features. This has not fixed all these cases but many of them, because these slower flows in multichannel clusters can result in refuge from high streampower which can results in blown out or breached dams.