Author: Mary Knapp

Several parts of the state have seen some rains. A question asked is just how effective are these rains in restoring the soil moisture? Not surprisingly the answer starts with it depends. It depends on the slope: steeper terrains will produce runoff more quickly. It depends on the soil type: water percolates through sands much more quickly than loams or clay soils. It depends on the rate that the rain is falling: heavy intense rains result in runoff, while light rains less than a 10th of an inch generally evaporate. Water infiltrates sands at a rate of 2-6 inches per hour. In loams, the infiltration rate can be as high as 2 inches per hour and as low as 6 tenth of an inch, while the range for clays runs from 6 tenth of an inch to as little as 2 tenths of an inch per hour. For a loamy soil, you would need from an inch and a half to two inches of moderate rainfall to wet the soil to 12 inch depth.

Mary Knapp, Weather Data Library