How do erosion, creeks and slopes threaten Oklahoma foundations?

Reviewed by Preston, Oklahoma foundation repair consultant · Updated 2026-10-14

In short: Moving water can remove the soil that holds a foundation up. Runoff can wash out soil under slab edges, creeks can eat into their banks, clay on slopes can creep slowly downhill, and underground flow can carry soil away and leave voids. Steep ground, bare soil and heavy rain all raise the risk.

How does water take soil away?

Undermining

Undermining is the loss of soil from beneath a slab edge or footing, usually from concentrated water such as overflowing gutters, a downspout or a flash flood. It leaves the edge of the foundation unsupported; see exposed slab edge or void under footing.

Creek-bank retreat

Streams cut into their banks during high flows. Oklahoma State University Extension notes that long-term removal of perennial plant cover along streams can cause significant erosion from stream flow, while plant crowns and roots help hold soil in place ². A house near a retreating bank can lose the soil that supports it from the side.

Flood-plain soils show how active these settings are. Port soils, on narrow flood plains in central Oklahoma, flood occasionally or frequently for very brief periods during March to October ⁴. Osage soils lie on flood plains along major streams in eastern Oklahoma ⁵, and Verdigris soils on flood plains in northeastern Oklahoma are described as subject to flooding ⁸.

Slope creep

Creep is very slow downhill movement of soil. On clay, wet and dry cycles bring periods of deep near-surface drying; when intense rain follows, water enters the deep cracks and the soil swells ⁷. Repeated over years, this helps move soil downslope. Common clues are leaning fences, retaining walls and trees; see tilted retaining walls, fences or trees and slope creep and lateral movement.

Piping

Piping is underground erosion in which flowing water carries fine soil out through a channel, gradually forming a tunnel or void. The USGS notes that piping caves have been reported in relatively unconsolidated sediments, which it maps as a form of pseudokarst (karst-like voids not caused by dissolving rock) ³.

What raises the risk?

What are other warning signs?

Besides exposed slab edges and leaning walls or trees, sign pages on this site cover a sudden depression or sinkhole, which can mark underground soil loss, and water ponding near the foundation, which shows where runoff collects.

How are these problems repaired?

Because steep slopes, bare ground and heavy rain drive erosion ¹², repair options focus on the water and the slope as well as the house. They are described on slope and erosion stabilization and drainage solutions. Local rules for work near creeks and floodplains are covered under codes and permits.

Related

• Erosion, Undermining and Washout Voids
• Fill Soils and Lot History
• Gypsum Karst and Sinkholes
• OK Data - Creeks and Flood History
• Working with Engineers