Fluvial Processes Flooding and Change

Tammy Brown

Fluvial Processes

“Flowing water, in streams and rivers or across the land in sheets, is the dominant erosional process in shaping Earth’s landscape…most of the erosional work done by surface water is not done by streams or rivers but instead by falling raindrops and by the resulting unorganized runoff down slopes.”– Science Clarified website

This shaping of the land by water is called “fluvial processes.”  Fluvial processes, flooding, and change are underway at Little Piney, and the process is both fascinating and unsettling.  There is a sense that nature’s processes won’t be stopped, and an opposing sense that they must be stopped.

Down by the lake we are seeing “aggradation,” deposits of sediment that are changing the height and shape of the shore.  At flood levels, Piney Creek rushes toward the Colorado River, gathering sediment, gravel, and human possessions as it goes.  At Little Piney, the creek turns a bend and slows down, depositing inches (or feet) of alluvium in the form of sticky gray mud on the shore.

Deposits of mud on the shore

Close to the house we see a different process–erosion.  Sheets of water pour over the surface, and  tunnels of water gush below,  racing downhill toward the creek.  These combined flows sweep the soil away and carve a  gaping gulley.  Layers of sand, clay, and stone stripe the sides, and a hard, layer of mud or clay swirled by long ago currents lines the bottom.  The gulley is about to slice Little Piney in half, cutting off access to fields and the lake.

Left alone, over time, Little Piney would be reconfigured by fluvial processes.  A new stream might appear where the gulley is now, and down by the lake the shore would continue to rise into a bluff.  The question for us is whether to fight the changes or adapt to them.  I don’t have the answer yet but the effects of another week of flooding will probably make it clearer.


Humans and Change

Without success, I’ve searched for the word that describes how life experiences shape us in the way that water shapes the Earth; “fluvial processes is to earth as ___________is to person.”   “Formative experience” is the best I can come up with and that doesn’t really capture it.  Some life experiences create change as slowly as seeping water; they creep up on us unnoticed, and– for better or worse–we adapt.   Some forces of change are familiar and expected.  We recognize that life has seasons and cycles, and our hope remains intact because we know something about what comes next.   Then there are the  radical, unexpected experiences–the flash floods of life–that we aren’t sure what to do with.  In a moment, we must decide whether to fight, or flee, or surrender.  Perhaps, at its most challenging, life brings on a wall of water, and we stand by immobilized, watchful, feeling our smallness, acknowledging our powerlessness.  Sometimes, we can only witness and wait and hold on to the knowledge that whatever happens, we can survive.   Some Texans have faced this kind of experience in the last two weeks.  Many have lost homes, livestock, cherished possessions, and even loved ones in this latest round of disastrous weather.   We just have a gully to fill, while they have holes in their hearts that will never be filled.









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