Handbook for Irrigation of Wine Grapes in South Africa

Chapter 2

The dynamics of water in and around vineyards

2.1 INTRODUCTION Sufficient water is essential for irrigated agriculture. Irrigation water can be obtained from a number of resources. In addition to rainfall, water for vineyard irrigation may be abstracted from rivers or collected in on-farm dams (Fig. 2.1). In some regions, irrigation water is allocated from government irrigation schemes where water from large reservoirs is distributed via extensive canal systems (Fig. 2.2). Groundwater may also be abstracted from aquifers deep below the Earth’s surface by means of boreholes or wells (Fig. 2.3). All the water resources form part of the Earth’s hydrological cycle. Therefore, it is important to understand the hydrological cycle, and how irrigation water resources are created. Since plant root systems absorb water from the soil, its ability to absorb, conduct and store water is also an important consideration when it comes to practical irrigation management. Due to the variability in climate and soils, the dependency of viticulture on water resources may differ substantially between grape growing regions, or even within such a region.

A

B

FIGURE 2.1. River water (A) and water collected in on-farm dams (B) can be used for vineyard irrigation.

30 CHAPTER 2 – THE DYNAMICS OF WATER IN AND AROUND VINEYARDS