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Jim Kompanek
Introduction & Background:
The purpose of this project is to identify potentially suitable vineyard locations with the use of raster GIS analysis. Napa County, California is used as an example and a variety of geographic, climatIC, and zoning factors are analyzed to determine the most suitable locations. According to King (2006b), California is one of the biggest wine-producing regions in the world (Figure 1).
For the purpose of this project, the following criteria will be used to identify suitable localities (King 2006):
Outside the floodplain and more than 100 meters from a stream;
Agricultural or undeveloped land;
Aspect (slope orientation) between 112 to 337 degrees or on flat land;
Average maximum wind speed of less than 25 mph;
Average minimum temperature greater than 35 degrees Fahrenheit;
Soil depth between 31 and 72 inches;
Medium to highly drained soils (values between 1.5 to 3).
All information presented in this lesson was derived with data from King (2006b). It is intended for academic purposes only and does not represent or imply suitability of actual vineyard locations.
Figure 1. Overview photograph of the Bacio Divino (2006) vineyards in Rutherford, California Copyright Bacio Divino 2006. All rights reserved. Used here for educational purposes only.
Methodology:
As mentioned previously (see Introduction & Background), numerous types of data were used to determine potentially suitable locations for vineyards in Napa County, California. For the purpose of this project, only a sample of the key intermediary steps will be presented. A lack of discussion regarding steps not presented does not indicate a lack of necessity to the final identification of suitable vineyard locations.
Figure 2. Climatic data collection points in Napa County, California with elevation depicted in background.
Figure 2 depicts the location of 25 climatic data collection points. At each of these points, a theoretical weather station collected and recorded climatic data, such as temperature and wind speed, for analysis. Elevation data is also presented for the purposes of providing context. Hillshade is also provided to show the relative terrain.
Figure 3. Interpolated maximum wind speed (mph) data based upon field observations at data points.
Figure 3 represents the interpolated results (determined by ArcGIS Spatial Analyst) of maximum wind speed observations based on field observations. The limited number of observation points is a limitation of this methodology. As can be seen in the above figure, the data points are at times, several miles apart. A more accurate depiction of wind speed could be obtained by more field observation points.
Figure 4. Suitability of land based upon interpolated maximum wind speed (mph) data.
As can be observed in Figure 4, a large portion of the available vineyard locations are considered unsuitable due to maximum wind speed (as defined by wind greater than 25 mph). This was determined by reclassifying the data in Figure 3 into two classes. Suitable wind speed was given a value of 1 and unsuitable a value of 0. This binary system of defining suitability was utilized in order to simplify to process of combing multiple variables into a single layer. When multiplying variables, the results will always be 1(suitable) or 2 (unsuitable).
Conclusion:
Figure 5. Suitable vineyard locations in Napa County, California.
Figure 5 represents suitable vineyard locations in Napa County, California based up seven geographic, hydrographic, and climatic variables (see Introduction & Background). This model portrays a general predictive model of suitable locations and is limited by the geographic data used in the analysis. More precise data, either by adding the number of climatic data observations points, or by more accurate topographic data, would result in a better model. A limitation of the terrain data can be seen in the terrace-like slopes in the above figure, which implies a series of benches, as opposed to continuous slope.
Experiments with Supplemental Data:
Figure 6. Suitable vineyard locations in Napa County, California with overlay of privately owned land.
Figure 6 represents suitable vineyard locations located on private land (see Try This!). This figure also represents experimentation with additional data, utilizing what was learned in Lesson 6 (King 2006a). A road map (California GIS Council 2006, Napa County GIS 2006a) and county overlay (Napa County GIS 2006b), as well as an extent rectangle is provided for geographic reference.
Try This!
Figure 7. Suitable vineyard locations in Napa County, California with overlay of privately owned land.
Figure 7 represents suitable vineyard locations located on private land. Approximately 739 acres were excluded when this prerequisite was applied to the results of Figure 5.
References Cited:
Bacio Divino
2006 Bacio Divino Vineyard Homepage. Rutherford, California. http://www.baciodivino.com/. Accessed 29 April 2006.
California GIS Council
2006 California Spatial Information Library. Sacramento, California. Napa County DLG Roads. http://casil-mirror1.ceres.ca.gov/casil/gis.ca.gov/teale/roads/ Accessed 29 April 2006.
King, Beth
