What scale is right for my project?

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What scale is right for my project?

Post by rcoville » Fri Jul 31, 2015 12:19 pm

i-Tree Hydro is flexible with regard to spatial and temporal scale of inputs. A project can be about a large or small area of land or time.

In terms of project time periods:
i-Tree Hydro works with hourly inputs and outputs. Thus projects are in theory limited to one hour as a minimum project time period. The upper limit for project time periods is dependent on available data and computing power.

In terms of spatial scale:

Watershed areas are what Hydro was initially intended to model. To give some examples of how Hydro may be used on watersheds: the USDA Forest Service uses i-Tree Hydro to model watersheds near major cities in the United States, and in terms of size, those watersheds are roughly in the range of 10 - 100 square miles, with 30 square miles being the target. Some flat regions of the country tend to have larger drainage areas, in which case such projects may be based on drainage areas over 100 square miles.
In theory, i-Tree Hydro is capable of modeling massive watersheds, such as the Mississippi River Basin, or very small watersheds, such as the area feeding one of many puddles in a park. Model developers at SUNY College of Environmental Science and Forestry are experimenting with both extremes and refining the model to be easily adaptable to such a wide range of applications.
In practice for now, care needs to be taken to make sure land cover percentages appropriately represent the intended scenario with respect to project area/scale. To illustrate how problems could arise if land cover parameters aren't appropriate with respect to project scale: a dozen trees are a different percentage of tree cover for the Mississippi River Basin than for a city park; and 10% of tree cover for a project area the size of the Mississippi River Basin represents something magnitudes different than 10% of tree cover for a city park project area.

Non-watershed areas have recently become accessible for modeling in i-Tree Hydro. The potential scale of this feature is a very wide range: from nation-wide to a single tree and everything in between. Most testing and support for i-Tree Hydro has been done on municipality scales and somewhat on state scales. We have seen and experimented with i-Tree Hydro on smaller scales such as college campuses, parking lots, suburban property, and single trees - these applications are possible but often require more technical skill and local site knowledge than the more common applications.

The range of acceptable scales in i-Tree Hydro is vast. What scale is appropriate for your project depends on the project goals:
What is the scale of management activities the project is intended to inform?
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