All geographic analysis was done in Arc Info Grid version 7.0. All data layers were projected in UTM Zone 18 a common map coordinate..
Climatic data was obtained from ZedX, Boalsburg, PA. The following data were obtained for total monthly precipitation and mean monthly; maximum and minimum temperature and monthly mean daily solar radiation and evaporation. Data on precipitation, mean maximum temperature and solar radiation from October was used to assess harvest conditions. Extreme minimum temperature (10 year interval) and length of growing season were also obtained. The later was based on the time interval between the last 29oF (-1.7oC) day in spring and the first 29oF (-1.7oC) in fall. Data were available at a 1km2 resolution and were based on a 30 year average. Accuracy of the temperature data in comparison with actual stations was +/- 1oF (0.56oC). The data are derived from an elevation based interpolation of climatic records from weather stations across the North East of America. The accuracy of the data is thus dependent upon the density of stations, the variation and height of topography in the grid, the proximity of large bodies of water and the quality of the original data.
More details on ZedX data are avialable
(THIS TABLE NEEDS TO BE REDONE)
|Extreme min. temp.||-26F||-11F||5||50|
|Length of growing season||150d||200d||5||25|
|October solar radiation||210ly/d||60ly/d||4||5|
|October max temp.||44.9F||65.8F||4||5|
|October precipitation||26.6 in||49.7in||4||5|
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Seneca County Soil data was obtained from Cornell University and also from the NY state soil scientist
The mean available water capacity for each map unit was computed by calculating the mean available water capacity for the top layer using the AWCL(low) and AWCH (high) values from the Layer table. The top layer was usually 8 or more inches thick. Given that the majority or root are in the 12 inches of soil, this is a reasonable approximation of awc.
The Hydrologic Soil Group (HSG) class is contained in the HYDGRP variable of the component table. Possible HYDGRP values include A, B, C,D, A/D, B/D, and C/D. . Mixed classes (A/B, B/C etc) were converted to the the lower ranking during processing.
The mean depth-to-bedrock for each soil map unit was computed by calculating the mean depth-to-bedrock for each component using the ROCKDEPL (low) and ROCKDEPH (high) values from the Component table. A weighted average of the mean component values was calculated for each map unit. The map unit polygons were then gridded at a resolution of 1 km.
The mean PH for the map unit was computed by calculating the mean pH for each component using the pH (low) and pH (high) values from the layer table. A weighted average of the mean component values was calculated for each map unit. .
(THIS MAP NEEDS TO BE REDONE)
well or moderate*
|Water holding capacity||0||45||5||20|
|Depth to bed rock||80||120||3||20|
* Percentage of grid unit in either well or moderately well drained drainage classes.
** pH is composed of three classes; I) less than 5, ii) between 5 and 6; and iii) between 6 and 7.3. There were no soils in the state over 7.3.
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Land use data was also provided as a USGS 1:250,000 base map Each polygon in the data base represents a homogenous area and has a minimum area of 4 ha for urban or man-made features and 16 ha for non-urban features Anon (1991). The Land Use and Land Cover map is compiled to portray the Level II categories of the Land Use and Land Cover classification system documented by Anderson and others (1976). More details on the land cover data are available from the USGS condensed users guide.
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The source of digital elevation data was a USGS1:250,000 DEM which has a data point every 3 arc seconds (approx. 92m) with a horizontal accuracy of 130m and a vertical accuracy of 30m (Anon, 1987). The data was projected in lat./long. This DEM was used to calculate aspect and slope information. More information is available from the USGS condensed users guide.
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A simple macro was designed to incorporate threshold values, rescale and weight data values. A slice function was used to assign grid values into a specified number of classes between threshold values, and classes were then scaled between zero and one. A weighting value was then added so that each grid could be given a relative importance in comparison with other grids. The final suitability map was constructed by overlaying a final climatic map, with the finbal soil map and land use map. Suitable land uses were either agriculture or forest classes.
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