Inter-relationship between average precipitation (P), actual (Ea) and potential (ETp) evapo-transpiration and runoff (Q) and how season and climate change could affect this inter-relationship depending on the region. Grape growing areas are represented in both water and energy limited areas and the effect of climate change might be substantially different for different parts of the world. The original curve is known as the Budyko curve [17] and the presented figure is an adaptation from Farquhar and Roderick [8] in an extended version.