Human-induced land use changes cause various hydrologic and geomorphic adjustments, including alterations in the size and timing of flood peaks and in the magnitude and type of soil erosion. Changes in land use and land cover affect the magnitude-frequency relationship of runoff by reducing the infiltration capacity of the soils in the watershed. These land use changes are subsequently expressed in significant changes in stream channel characteristics. These hydrologic changes generate significant geomorphic adjustments as stream channels tend to get deeper, steeper, and wider and transport a greater volume of sediment as accelerated soil erosion also tends to occur with the development of watersheds. In general, the changes in stream hydrology and morphology are due to a disequilibrium in the channel caused by increases in sediment and water discharge.
Urbanization creates impervious surfaces within a watershed.
The infiltration capacity of the land surface decreases and water is able to run off more quickly, which alters the hydrologic regime. Impervious surfaces and storm sewerage associated with urbanization enhance the peak discharges and therefore the mean annual floods. Channelization can restore low flows and reduce flooding upstream. However, downstream effects of channelization have been shown to include greater flooding, larger stream gradients and increased channel velocity. High intensity, short duration storms, or micro-storms may have some geomorphic impact in watersheds.