WINETECH Technical Yearbook 2019

the seasonal growing temperatures have showed significant increases . This trend is continuing and is shifting the climate zone demarcations for viticulture. However, in the context of climate change, seasonal summations are not enough to quantify the impact of temperature shifts on the grapevine. A higher temporal resolution of weather conditions are required, as the most significant increase in temperatures are in the months of December, January and March . Compounding this is an increase in seasonal variability, which is changing the tempo of growth and ripening, grape composition and occurrence of diseases . Over recent years, the seasonal adaptations required to meet these conditions have resulted in the average industry production cost being higher than the producer’s income, often resulting in reduced new investment, long-term vineyard establishment and in extreme cases, farm closure/sales. Temperature data required at a daily/hourly interval are needed to better understand these changes and to inform adjustments of existing practices. UNDERSTANDING PROCEEDS ACTION In view of climate change, economic pressures and limited water availability in the agricultural sector, information about the suitability of land for viticulture is paramount to aid long- and short-term decision-making. A 2017 survey conducted among researchers, consultants and producers highlighted the need for accessible data that can support decisions at farm and field level. The absence of a single, integrated database with a user-friendly interface, where viticulturists can obtain pertinent information about climate, as well as terrain and

soils, was cited as one of the main obstacles for preparing for the transition of the South African wine industry, necessitated by climate change. However, continuous monitoring of environmental conditions is hampered in the Western Cape by four factors, namely: • The expense and logistical difficulties in performing frequent ground-based surveys over an extensive production area. • The sparse and irregular distribution of existing weather stations. • The inaccessibility (cost) and poor quality of existing weather station data. • The prov i nce ’s comp l ex ter ra i n, wh i ch complicates the modelling of the dramatic local climatic variations observed in many wine producing areas. THE EDGY DIFFERENCE Wi th the cont i nued goa l to improve the understanding of how the climate in the Western Cape is changing and how the grapevine is responding to these changes, the primary aims of the TerraClim project are threefold: 1. To create a comprehensive database of long- term climate data [in collaboration with weather station custodians, namely iLeaf ( http://www.ileaf.co.za/ )], standardised in a flexible, query-ready format. 2. To use this database, in conjunction with very high resolution digital elevation models (DEMs) developed by Stellenbosch University and GeoSmart Space, to interpolate wall-to-

FIGURE 1. Description of the possible high resolution climatic and topographic data that can be extracted from TerraClim online spatial decision support system at the selection of a specific field.