Willow Planting Suitability Model for the Shasta River, CA

 This analysis is comprised of several models. First, the Relative Elevation Surface Model was developed to create a DEM that is normalized to the elevation of the surface water in the immediate vicinity. In other words, a river is always running downhill, so the elevation of the surface water is always decreasing as you move downstream. This first model essentially flattens out the river, and uses those small incremental changes in elevation to normalize the adjacent bank elevations, so that a given point at one location on the stream bank can be directly compared to a point at a different location downstream. 

 The Relative Elevation Surface Model was then used to develop a Willow Planting Suitability Model, which categorizes each pixel of stream bank along the waterways as suitable, marginal, or unsuitable for willow survival, depending on the elevation of the bank relative to the water surface. 

 Finally, a Solar Loading Model was developed to indicate which portions of the waterways were exposed to the most sun on the summer solstice (i.e. the longest day of the year). In other words, the model identifies areas that have the least riparian vegetation that would otherwise provide shade to the water surface for at least part of the day. This can be used to identify areas along the stream where the shade from newly-planted willow trees would provide maximum benefit in terms of stream cooling. 

Thus, we identify where willow trees are most likely to survive, and where they are needed the most to support water temperature reduction. The intersection of these models can be used to identify the highest priority planting areas based on this logic.