Re-direct the water where you want it.
Save the water that does come into your landscape and channel it so that it soaks in slowly.
Change landscape features by adding swales, terracing slopes, and creating rain gardens to capture the water and channel it where plants need it most. This makes the most efficient use of the water you already have.
If you notice after a rainfall, erosion forming deep rivlets in your driveway, pathways, or hillsides, you need to capture that water. Rivlets are a symptom that the rain is moving too quickly over the landscape. By building swales that cut across the water at right angles, you’ll slow the water down and channel it where your plants can use it best.
Catch and save the water you do get
Adding gutters to direct the rainfall and capturing and holding water in rain barrels or cisterns saves the water when it falls, and holds it for use when you need it to water vegetables and fruit, later. 1 inch of rain falling on 1,000 square feet of roof space yields 600 gallons of water. Estimate the size of catchment that you need based on the annual rainfall you get in your region. You won’t hold a year’s supply of rain at one time. But you won’t need a 20,000 gallon cistern if your annual rainfall is only 15 inches a year.
Create a rain garden
It may seem counter intuitive, but even in dry garden areas, seasonal rains can wash out an area while seasonal drought makes gardening difficult. A rain garden allows water runoff to enter a garden area through a cut in the sidewalk or curb, diverting water from storm sewers, while it directs the water where you want it. Rain gardens need to be lower than the surrounding area, as water will flow where gravity takes it. By creating the rain garden in a basin shape, with gently sloping sides, water that enters the garden at the high point will naturally move to the lowest point. Rain gardens are planted with grasses and perennial flowers that can absorb excess water, while at the same time, once established will do well in drought.
Since run off can also be mixed with chemical toxins from streets, don’t plant food crops in a rain garden, that receives runoff that may be contaminated. Instead use the area for butterfly and pollinator plants. These will attract beneficial insects that will increase fruit and vegetable yields in the long run. Ornamental flowers, like yarrow and coneflower, and grasses also do well in the rain garden area.