In the Limpopo River Basin

At the regional level or basin level, virtual water trade can optimise water savings when the spatial differences related to climate, soil productivity and crop production are recognised. Water security in the Limpopo River basin is very low, making virtual water trade an important alternative to improving water security in the basin.

Of the Limpopo River basin countries, Botswana and Zimbabwe are net virtual water exporters while Mozambique and South Africa are net virtual water importers.

Overview of virtual water flows and net virtual water import related to trade in crop, livestock and industrial products of each state in the Limpopo River basin.

Ex=Export, Im=Import
Source: Kort 2010

Crops

Maize is the most important food crop in the SADC region. South Africa has one the highest irrigated yields in the SADC region at 1,42 ton/ha, and the highest yield of the basin states. When compared with the global average of 3,41 ton/ha it is evident that yields in the SADC region are quite low. In the dry rainfed regions of Botswana very little fertilizer is used when compared with other SADC countries and yields are very low.

Botswana has the highest green water footprint (WF) for the production of maize in the SADC region at about 2 700 m³/ton of maize produced. Mozambique and the south of Zimbabwe also have relatively high green WF for maize. South Africa has one of the lowest green WF (with the exception of some areas around the Kalahari Desert). The average WF for maize in the SADC region is 3 146 m³/ton. This is a less efficient value than in other parts of the world where the average is 2 981 m3/ton for green water and 909 m³/ton for blue water.

Cassava is the most important food staple in the SADC region. Cassava is entirely rainfed and therefore its production is concentrated in the humid areas of the region, in the basin this includes some areas of Zimbabwe and Mozambique. The average yield is 7,82 ton/ ha compared with the global average of 10 ton/ha (FAO 2003b). The water footprint is also higher at 682 m3/ton when compared with the global average of 605 m³/ton (Kort 2010).

Rice is produced in Mozambique, South Africa and Zimbabwe with reasonable yields in Mozambique. In South Africa and Zimbabwe almost all of the rice production is irrigated.

Livestock

Botswana, South Africa and Zimbabwe are among the largest exporters of livestock and livestock products in the SADC region. South Africa is also one of the largest importers. The net virtual water exports related to industry are small (8x106 m3/yr) when compared with the imports (1 427x106 m3/yr).

The WF of livestock is mainly based on the WF of the crops used by livestock. Other water demands are assumed to be covered in domestic and industrial water use figures and are assumed to be comparatively small. Of the Limpopo River basin countries, the WF of livestock is highest in Botswana because of the high WF of crops in this country. The WF of livestock and livestock products is largely composed of green water; however, blue water is important in South Africa and Zimbabwe. The grey water WF is highest in Botswana and South Africa.

Industry

The net virtual water exports related to industry are small (8x106 m3/yr) when compared with the imports (1427x106 m3/yr).

When compared with the WF of agriculture, the WF of industry is quite low and in general considered to be more efficient than the global average. Zimbabwe is the exception of the Limpopo River basin countries, with an inefficient industrial WF.

Water dependency

The annual per-capita WF in the basin states (m³/cap/yr) are: Botswana-288, Mozambique- 1 004, South Africa- 826, Zimbabwe- 1 002. These figures are very low when compared with the global average of 1243 m³/capita/yr. Although these values are small when compared to the rest of the world, water security is a concern.

There are several areas in and adjacent to the basin that uses more water than is naturally available in that area. These include: the Pretoria-Johannesburg urban area in South Africa; the urban and irrigated areas in the Maputo-region at the mouth of the Limpopo River in Mozambique; and, the urban area of Bulawayo in Zimbabwe. Of all of the states in the SADC region, Botswana relies the most on virtual water imports (Hoekstra and Hung 2002). In 1998, Botswana exported 16% of its water and imported 61% of its water supply as virtual water (Lange and Hassan 2006).

The table below shows the levels of water self-sufficiency and the levels of water dependency for each of the basin countries.

Average green, blue and blue-grey water scarcity, water self-sufficiency and water dependency of the SADC region and SADC countries for the period 1996-2005.

Source: Kort 2010

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