• TerrAvion TerrAvion
  • Jul 03
  • 3 min read
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Identifying Crop Damage Resulting from a Weather Related Event

In the unfortunate event of a grower suffering crop damage, whether it be from severe weather, pests or disease infestations, herbicide drift or other chemical or nutrient burns, growers can use their TerrAvion imagery to identify and locate the affected areas, to quantify the range of affected acres and to assess the severity of damage in each area. Imagery, in conjunction with in-field scouting, is the best way to assess and evaluate crop damage to either support insurance claims, calculate the cost of remedial actions or guide recovery actions if they are warranted.

Identifying Crop Damage Resulting from a Weather Related Event with NDVI Imagery
NDVI imagery is a vegetation index that is capable of accurately identifying plant stress. When plants are damaged by weather related events such as a hail storm or extreme wind, they become stressed, and this stress is recognized as low vigor in NDVI imagery. To identify crop damage resulting from a weather related event, growers can compare their most recent pre-storm imagery to their first post-storm images. In the images below, your see a pre-storm image from 6/2/18 showing a healthy corn field in Kansas before a bad hail storm that took place the week of 6/24/18. The first image after the storm taken on 6/26/18 shows crop damage in the from of low vigor zones.
 
The post-storm NDVI imagery of this field not only shows crop damage resulting from the storm, it illustrates the damage in varying levels of severity. Most striking is the reduction in week over week vigor. While TerrAvion NDVI imagery can sense tiny variations vigor, determining the source of that variation almost always requires ground truthing in order to come to the right conclusion about what is causing the vigor variability as well as the potential impact of the variation.
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Scouting Crop Damage with NDVI Imagery
Upon identifying low vigor areas after a weather related incident, growers can use the TerrAvion mobile app to scout their fields and estimate the severity of what they are seeing in their imagery and on the ground. Once on the ground in an area of interest growers can make notes on what they are seeing and determine how the NDVI imagery correlates to what they are observing at that location. They can then estimate potential impact using the NDVI histogram tool to see how many acres are represented by a certain range of NDVI values.
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 Using the TerrAvion NDVI Zoning Tool to Quantify Crop Damage

Once growers have identified crop damage in their imagery and have scouted their fields and correlated their imagery to their NDVI data, they can use this information in conjunction with TerrAvion’s zone creation feature to quantify the extent of damaged acres.
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The Select Parameters section of the TerrAvion zone creation tool allows growers to segment their NDVI imagery into zones. They can use the histogram feature of the zone creation tool to define the range of their zones. Based on what a grower may have found while scouting their NDVI imagery, they can make a zoning map with one zone that contains only the damaged areas. They can set the cutoff point of their zone to stop at the NDVI value that the grower has determined is healthy and has not been damaged by the storm (according to their scouting notes). Once they have defined the NDVI range of their zone that represents the crop damaged acres, they will be able to see the acreage of their zone (in the example above, that number is 65 acres).
 
Growers can then use this information to determine if remedial actions such as replanting or nutrient side dressing are warranted, what the cost of doing so would be, or to inform insurance reports. If they do decide to replant or make an application to the damaged areas, they can complete the zoning map process and use their zoning map to guide any planting or applications they are making to assure that their resources are going to the right places.
For more information on how TerrAvion can help you manage storm damage in your fields, please contact support@terravion.com.

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