Yesterday we scanned a 4.5 hectare piece of land at Overgaauw Wine Estate in Stellenbosch with an electromagnetic soil scanner. The scanner is owned by a dynamic new company called Revolute [...]
WHAT IS GIS?
Geographic information describes the locations of features on the Earth’s surface. A geographic information system (GIS) is any system which displays geographic features with related tabular data to allow a user to organize, map and analyze data in a geographic or spatial way. A GIS therefore allows us to understand and interpret features in the real world in a way that would not be possible with tabular data alone. Typically, a GIS can analyze spatial data and visualize results in the form of maps, reports and charts
Base maps to overlay aerial imagery, soil mapping and vineyard observations, vineyard block information.
The normalized difference vegetation index (NDVI) is a simple graphical indicator that shows if a pixel contains live green vegetation or not.
Healthy vegetation (or chlorophyll) reflects more near-infrared (NIR) and green light compared to other wavelengths. It absorbs more red and blue light.
NDVI’s are used to monitor plant stress variation during the growing season. This might include possible soil chemical imbalances (saline soils), pests, diseases, over irrigation/wet areas, excess of nitrogen, broken/faulty irrigation lines.
The data is derived from two separate satellites – Landsat8 and Sentinel 2. Data will only be available if the cloud cover on the selected area is 0% for that specific day.
Area Solar Radiation
In short, Area Solar Radiation is the amount of energy received by the surface of the earth at a specific time. This has a major impact on wine style, quality and yield.
With landscape scales, topography is a major factor that determines the spatial variability of insolation. Variation in elevation, orientation (slope and aspect), and shadows cast by topographic features all affect the amount of insolation received at different locations. This variability also changes with time of day and time of year and in turn contributes to variability of microclimate including factors such as air and soil temperature regimes, evapotranspiration, snow melt patterns, soil moisture, and light available for photosynthesis.
Solar radiation enables you to map and analyze the effects of the sun over a geographic area for specific time periods. It accounts for atmospheric effects, site latitude and elevation, steepness (slope) and compass direction (aspect), daily and seasonal shifts of the sun angle, and effects of shadows cast by surrounding topography.
This is especially profound on the Bordeaux varieties.
The Southern slopes are cooler than the Northern slopes (In the Southern Hemisphere). Aspect analysis can help a lot in choosing sites to plant Sauvignon blanc’s for instance, or to plant Shiraz for the spicy or fruity style.
During aspect analysis factors like choosing the suitable variety, clone, row direction, trellis system, irrigation system etc are determined for the intended wine style and quality.
Slope (inclination of the land from the horizontal) can either be expressed in degrees or in percentage. Determining the slope degree does not only dictate where you can mechanize, but will show potential erosion zones, will impact irrigation planning, row direction, trellis system, soil temperature and will have a massive impact on the potential solar radiation.
Usually, steeper slopes are also at a higher elevation and this combination almost always results in very special and unique wines. This also means handcrafted vines, making handcrafted wines! I think the best example is the Mosel in Germany.
Digital Elevation Models are the starting point of all Terrain Analysis projects. The effect of different altitudes on vineyards can be seen across the globe. It does not only affect the temperature, but a lot of phenological and physiological processes.
The value that atmospheric temperature drops or increase with change in elevation is called the “Lapse Rate”. Under normal atmospheric conditions the average atmospheric lapse rate results in a temperature decrease of 6.4C°/km (this may vary). This means that it is generally cooler the higher you get. This can impact budding, flowering, your ripening period and ultimately your wine style.
Knowing at which elevation your blocks are can give you a comparative advantage to measuring different styles of different varieties in different regions.
Digital Elevation Models visually represent the difference in elevation of a landscape. This elevation changes has a big effect on diurnal temperature shifts which influences factors like ripening of grapes, grape colouration, chemical compound composition and flavour profiles.
In short, higher elevated mountain and hillside vineyards offer three critical contrasts to their counterparts on valley floors: more direct and concentrated sunlight (solar radiation), dramatic temperature shifts, and exceptional drainage.
As elevation increases, sunlight becomes more concentrated. The intense sun exposure in high elevation vineyards causes grapes to develop deeper pigment concentration. Higher solar radiation high altitude grapes receive comes in the form of a thick, tough grape skin which contributes vivid color and strong tannin, essential for making a wine age worthy.