Erosion channels run across a lawn toward the house after storms. What do they document?

Erosion channels are a record written by the water itself. Sheet flow across a lawn does not cut channels; concentrated flow does, and the channels form along the path the water actually takes rather than the path the grading was supposed to create. So a channel running toward the house documents two things at once: that surface water is being concentrated somewhere upslope, and that its destination is the foundation. The value to the client is that this is a repeatable, predictable event — every storm sends the same volume down the same path — and the remedy is upstream, in regrading, a swale, or intercepting whatever is concentrating the flow, rather than at the foundation where the water arrives.

Channels form where flow concentrates rather than spreads, and their direction records where that concentrated flow is going. Channels running toward the house document surface water being repeatedly delivered to the foundation.

Site drainage should carry surface water away from the structure. Concentrated flow erodes visible channels, and their direction and depth indicate the volume and destination of runoff, making them a durable record of how a site drains during storms.

Channels Are the Water's Own Map. It drew the route itself, over and over. Read where it starts and where it ends.

Look for what concentrates the water — a missing downspout extension, a neighbouring driveway, or a swale that has silted in. The remedy is usually there rather than at the house.

• •Attributing storm-related channels to a plumbing leak
• •Treating erosion as a landscaping issue rather than a drainage finding
• •Addressing the foundation rather than what concentrates the flow upslope