How does Dunne overland flow form near streams and shallow water tables?

In the context of hydrologic sciences, Dunne overland flow occurs when the precipitation rate is lower than the soil's saturated hydraulic conductivity, meaning the surface does not become saturated due to rainfall intensity alone. Instead, this process is driven by the saturation of the soil profile from below.1

Near streams and areas with shallow water tables or shallow impeding layers, the water table rises toward the surface during precipitation events. As the soil moisture storage capacity is exhausted, the rising water table reaches the surface, causing ponding. Once the soil is fully saturated and can no longer accept additional water, any further precipitation results in overland flow.1

This mechanism is particularly common in near-channel areas where the water table is naturally shallowest. Unlike Horton overland flow, which is generated by rainfall intensity exceeding infiltration capacity, Dunne overland flow relies on the vertical or lateral expansion of saturated zones, creating variable source areas that fluctuate based on wet and dry conditions.1