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. However, their impact will be enhanced by alterations in land use. Micro-storms can produce significant increases in erosion and sediment delivery to streams which in turn will cause geomorphic change, but these changes will be more drastic for developed than for undeveloped watersheds. The literature shows that changes in land use were associated with significant changes in biological communities.