Areas of backyard flooding—usually after heavy rainfall or even brief rainstorms—indicate problems with backyard drainage. If left unchecked, the problem can get worse and soon not only affects the property owner’s enjoyment of the yard but also nearby structures. Flooded basements or crawl-spaces are not unheard of on properties with improper drainage.
Both rainfall and groundwater impact a backyard’s drainage. Continuous rainfall soaks the ground to such an extent that it cannot absorb any more water. At the same time, the rains replenish the groundwater level. Without a drainage system in place, the groundwater table rises while surface flooding covers the top of the soil. The result is water logging, which suffocates plants' roots that rely on air pockets in the soil for oxygen.
Improving backyard drainage could take one or more methods of draining, depending on how severe a problem water-logging presents. Adjusting the backyard's grading is an initial solution. With the house being the highest point in the backyard, the lawn and other landscape features should gently slope down at a rate of two percent. This protects the basement or crawl-space from flooding and provides natural drainage from the highest part of the yard to the lowest. Secondary solutions to backyard drainage problems are pipe systems, such as a French drain.
French Drain System
Installing a French drain is very easy to do, even as it is somewhat labor-intensive. Plan out a drainage route that transports water from areas with high saturation to lower areas where it can drain. Mark the ground in the yard and dig a trench that will hold hollow pipes and connectors. Fill the bottom of the trench with two inches of gravel, embed one or more porous pipes, fill the area around them with more gravel, add a little soil to the top of the gravel and then top if off with a layer of sod. The water enters the drain from above and below and travels to the lower lying areas. From there it may drain into the street gutters.
Common issues associated with French drains include gradual clogging with soil and garden debris. In some cases there is no good place where the water can drain. Municipal rules about draining water from private properties into gutters and storm drains are usually very strict. Another issue is clay soil, which greatly inhibits proper backyard drainage, even with an adjusted grading and French Drain.
Uninstall any drain strainers that may keep obstructions in place within the pipes. Using landscaping textile around the pipes also inhibits the clogging with sand or soil. If there is no ready place for the water to drain, fix the backyard drainage problem with very long French drains that may snake around the property in an effort to let the excess water drain out along the way. Backyards that are rich in clay soil need a soil augmentation before installing any drains. This prevents problems when digging down later to change the makeup of the soil for landscaping purposes.