From my blog:
Here in Jerusalem, the average rain can be upwards of 500 mm. In the Arava, a portion of the Negev, less than 30 mm of rain fall on average. What grows with 30 mm of rain, not much. As you can see above, plant life is fairly limited.
Jerusalem, which is relatively well supplied with rain during an average rainy season, does not have the ability, for a variety of reasons to grow large quantities of vegetables. However, the area with 30 mm of rain is responsible for 55-60% of all of the vegetables grown in Israel. This is made possible by the technological advances including hot houses and drip irrigation. The Jordanians have begun to copy the Israeli model, as greenhouses are springing up on the eastern side of the border as well.
After spending three days in the desert, I can’t tell you how appreciative I am to have access to potable water. In the States, water flows pretty freely, and without a second thought. That’s not the case here, whether in the desert or in Jerusalem. Quite a contrast.