Rainfall and Turbidity!

March 22nd, 2007

With Spring comes the rain… this year it came quickly!  Today we had a major thunderstorm, with 1-2 inches of rainfall in a few hours.  We needed the rain… just not all at once, as the saying goes.  It’s a mixed blessing, because with the helpful water comes the force of water and the erosion of hills and gullies.  Sometimes you work for months to plant and grow, and the rain simply washes it all away.  I noted several of the draws leading to the pond have washed out completely, exposing bare rock and muddy ditches.  Some of the lily plants and grasses I hoped would grow have been undercut by the force of the water.  And where does it go?  To the pond!  The watershed is about 30 acres, which is perfect for keeping the pond at a sustainable level.  But with too much water the pond becomes the repository of the “organic detritus” and soil particulates.  Over time and years, this organic and inorganic matter can accumulate and actually fill up the pond in many shallower spots.  So my journey for the next few years will be try and mitigate this process, perhaps to grade areas that need it, and re-plant grass if it can take hold.  Time will tell, but I will not give up!  So here are a few pictures of the rainfall, and how the pond looks during and after.

During periods of heavy rain, the water from the higher pastures washes down to the house area and then down the hill to the pond.  I am doing battle with the moles… they create enormous tunnel systems and pathways for the water to travel and erode the soil.

Rain washing down the hillsides and grass towards the pond

This almost looks like a pretty creek washing down the hill. But really it only has visible water during heavy rainfall… and then it cascades down the draw, washing mud and leaves into the pond.  The water is nice… the mud is not!

The œcreek washes into the pond during heavy rain

The pond is filling up!  You can see the leaves in the corner after being washed into the pond, and the brownish coloration from the muddy water.   In the parlance of a limnologist, or a scientist who studies the the life and properties of fresh water ecological systems, the water’s turbidity has increased.  Turbidity is a measure of water clarity, and because of the silt and soil particulates, the water clarity will be much reduced for a time.  Normally, turbidity is influenced more by the presence of phytoplankton.  But not today!  The silt and brown coloration will settle to the bottom with time.

The pond is slowly colored with the brown of mud from the heavy rain

After the rainfall, the pond will begin to clear… but it may take a few days.  The “creek” is no longer washing into the pond.  It’s not all bad… the nutrients from the sediment and vegetation will help fertilize the pond and allow phytoplankton and other microscopic life to grow.  Especially with the warming weather and increased sunlight, the food chain in the pond will benefit from the rich diversity of life that will grow.  But too much mud and sediment can be detrimental over time, so I will try to work with the land to control any erosion problems.

Pond after the rainfall the soil sediments have colored the water brown for a few days

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