Which scenario best describes the effect of texture layering on water movement?

Which scenario best describes the effect of texture layering on water movement?

• A. Water moves faster through fine over coarse
• B. Water movement is unpredictable
• C. Water movement is dramatically impeded when fine-textured soil overlays coarse-textured soil
• D. Water movement is unaffected by texture

Answer: (C)

Texture layering matters because different soil textures have different pore sizes and hydraulic conductivities. Fine-textured soils, like clays and silts, have small pores and strong capillary forces but low overall water movement, while coarse-textured soils, like sands, have large pores and drain water quickly. When a fine-textured layer sits on top of a coarser layer, a capillary barrier forms at the interface. Water in the fine top layer is held more tightly and doesn’t easily move downward into the coarser layer beneath, so downward flow is greatly impeded and water can accumulate near the boundary. This is why this scenario best describes the effect: layering creates a barrier to drainage rather than letting water flow freely. The other statements don’t capture that barrier effect or instead describe outcomes that don’t align with how capillary forces and permeability contrast operate in layered soils.

Texture layering matters because different soil textures have different pore sizes and hydraulic conductivities. Fine-textured soils, like clays and silts, have small pores and strong capillary forces but low overall water movement, while coarse-textured soils, like sands, have large pores and drain water quickly. When a fine-textured layer sits on top of a coarser layer, a capillary barrier forms at the interface. Water in the fine top layer is held more tightly and doesn’t easily move downward into the coarser layer beneath, so downward flow is greatly impeded and water can accumulate near the boundary. This is why this scenario best describes the effect: layering creates a barrier to drainage rather than letting water flow freely. The other statements don’t capture that barrier effect or instead describe outcomes that don’t align with how capillary forces and permeability contrast operate in layered soils.