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Here is what I am trying to do using ArcGIS Desktop:

I am studying the coastal area, with several headlands and bays. The goal is to find the best suitable areas to install bee-yards (apiaries). One of the criterion I want to use is the amount of usable forage area that is lost by ocean cover, considering a flight range of 2000 m.

Here some abstract examples to help you visualize what I am trying to explain:

If I would install a bee-yard directly on straight coast I would have a loss of 50% percent of usable forage area.

If I would install a bee-yard in the corner of an bay with an 90º angle I would have a loss of 25% percent of usable forage area.

A 90º headland would be 75% loss.

Of course I would need this coverage not directly over the coastline but land inwards. Is there any way to calculate this in ranges of percentage for the whole area I am studying?

The only way I see is to create grid of point data manually (using the same steps as here Calculating relative share of area covered by water/percentage of polygon area that overlaps in ArcGIS for Desktop?) and then making an interpolation of the data.

  • You had tags for two desktop GIS products but only mentioned one in your question. I'll assume that is the one that you want to ask about. If you are also using and need to ask about the other then just do that in another question. – PolyGeo Dec 15 '16 at 20:04
  • How close to the water are you wanting to put these structures? If you placed them all at least 2000m inland, then you would achieve 100% foraging area. This might be safer anyway, given the risk of damage from storms, high winds, flooding, etc. Do you already have an area of interest polygon within which you'd like to place them? – Priscilla Dec 16 '16 at 14:53
  • Another thought... Given my experience with Mid-Atlantic estuaries, I can tell you that there aren't many consistent pollen producing plants this close to the water either. There'd be a spike in July/August when the Spartina are flowering, but that's about it. I would make sure to research viable vegetation cover as well. – Priscilla Dec 16 '16 at 15:03
  • @ Priscilla I understand your beekeeping concerns about my study. The area I am studying is very unique as it is an Island from the Azores Archipelago. The topography of the Island is very accentuated with protected hillsides and volcanic cones at distance less than 500m from the ocean. The problem of starting from 2000m inland is that altitude and humidity increase very fast. At a distance of 2000m the average altitude is 200m and average humidity is then 92% anything greater then that I consider unsuitable for beekeeping. Nectar abundant trees grow very close to the coast. – Huts Dec 23 '16 at 11:10
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This is how I would solve using ArcGIS software:

Before you start, you’ll need two starting polygons: Area of Interest (AOI) and a water/hydrology polygon. You’ll have to make them if you don’t have them already. Then use some approximation of the following steps.

  1. Create Fishnet

    • Template Extent: Same as area of interest (AOI) layer polygon

    • Cell Size Width: 30 m; Cell Size Height: 30 m (or whatever distance makes sense)

    • Check box: Create Label Points

  2. Select out fishnet points that intersect with AOI

    • Select by Location: Target=fishnet_points, Source=AOI, Method: intersect the source layer feature

    • Selection -> Create Layer from Selected Features

  3. Buffer fishnet points 2000 m

  4. Tabulate Intersections

    • Input Zone Features: fishnet_buffer, Zone Fields: OBJECTID, Input Class Features: water polygon

  5. Add new field in fishnet points called Percent with type float

  6. Join table back to fishnet points via OBJECTID

    • Use field calculator to grab percent from table and transfer to fishnet points

    • Remove join

  7. Interpolate fishnet points with method of choice (IDW, spline, EBK, etc.) using Percents field

  8. Display interpolated raster according to appropriate range buckets (e.g. 90%-100%, 80%-90%), percent of 2000 m range with viable bee habitat not covered by water.

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