In the first Psalm, the righteous person is compared to "a tree set into the ground near streams of water, which yields its fruit in its season, and whose leaf does not wither; and in whatever he does he will succeed."
When G-d created the world, the world was first entirely water, chaotic and primeval. Once dry land was brought forth from the water, water was subdued and order reigned. The unleashed and uncontrolled forces of water spell disaster, as they did in the days of Noah, with the flood, and in our days, with the tsunami. But water is the "sine qua non" of life; without it, all of nature is lifeless. The blessing given to the righteous person is one of balance and purpose. A tree set into the ground near water has its life force within reach, and is productive and fruitful. The righteous individual will have his/her needs readily to hand, and will merit timely and fruitful success for his/her efforts.
The metaphor of the tree is a timely one for a tree does not bear fruit immediately. Instead the tree matures and over time becomes a source of fruit and shade. We need patience and faith to sustain us through these trying times, bearing in mind that the trees planted today will sustain us in the future.