Ponds properly built and maintained have an indefinite life. Microcatchment farming concentrates runoff water from a large area into a small basin. Fruit trees or other crops are planted in the basins. A modification of microcatchment farming involves watershed modification to direct and concentrate runoff water into a designated area. Collecting ditches or low stone walls built on land contours can channel water to the point of use.
Some rainwater infiltrates into the soil where living plants can take it up through their roots.
Structures such as gabions and ponds, which harvest rainfall runoff, increase the amount of subsurface water available to plants. Water infiltrating into deeper soil layers beyond the reach of plant roots is called ground water. Ground water may be widely dispersed among particles of soil, sand, gravel or rock and be unharvestable. Soil type and moisture content determine the rate and amount of soil infiltration, which may vary from a fraction of a centimeter to several centimeters per hour. Eventually, water may reach a porous soil layer saturated with water.