When he wanted to emphasize a point while campaigning President Clinton said, “It’s the economy,stupid!”
In much the same way you could answer the question, “Want to know about water?” with “It’s the soils, stupid.” The point is that soils -- soil types, soil retention, soil absorbtion -- are the key to understanding water. Who knew?
This critical factor was the focus of Rebecca MacLeod’s lecture at the Morgan County Water Forum that marked the start of the County’s Source Water Assessment and Protection (SWAP) Program. This SWAP is a citizen-input procedure that is being used to identify threats, alternatives and solutions in three areas: Groundwater, Surface Water and Septic. A final report on findings will be issued by the Rural Water Committee.
Importance of Soils
If you are like most people you think of rainfall as the best indicator of the amount of water
we have in the Cacapon Watershed. However as it turns out, it is the soil that is critical to recharge, run-off, groundwater and river
flow. Soil perviousness or imperviousness relates directly to quantity and quality -- a quanity and quality that is being threatened
by substantial development. The increase in population in
Water Ways
The Cacapon’s watershed is, according to MacLeod’s presentation, dominated by shallow, shale-y top soils that restrict plant root growth and make for poor water holding capacity. This coupled with the fact that rainfall is, on average, 38.7 inches, with 22.7 inches of snow means the watershed is “water poor.” For comparison Terra Alta, WV has a rainfall of 54.32 inches (a high of 78.00 inches and a low of 42.79).
Although 38.7 inches may sound like a fairly good amount one must remember first, that rain doesn’t fall evenly throughout the year; and second, rain doesn’t always come when wanted, such as just after you plant your garden. Most importantly, the total amount of rainfall is never available for human or environmental use. The four critical factors are evaporation, runoff, and two kinds of infiltration (shallow and deep.)--you can think of infiltration as groundwater. Subsequently, these factors vary in percentages according to two basic different types of landscapes: undeveloped and developed.
Undeveloped Landscape
If the watershed remains rural -- meaning the land is covered with rolling fields, a substantial percentage of forest and the river is protected by significant buffers -- the rainfall that does come will be filtered before it infiltrates the groundwater or runs off into the river. This means mainly that the river is cleaner. Here are the statistics: natural, average ground cover generally means that of the 60% of the precipitation that doesn’t evaporate or transpire (evapotranspiration), only 10% will be in runoff with 25% in shallow infiltration and 25% deep infiltration. (See diagram.)
Developed Landscape
If, however, the watershed becomes suburbanized -- meaning there is a significant increase in impervious surfaces (roads, sidewalks, drives, roofs) and increased storm water runoff with its attendant contaminants -- then the river could be in serious trouble.
For example, if there is an impervious surface increase there will be less evaporation, perhaps only 35% and an increased runoff rate of 30%. That leaves only 35% of the total for infiltration instead of 50%. And here the percentages change with more going to shallow infiltration (20%) and only 15% to deep infiltration. (See diagram.)
Watershed estimates
MacLeod took these theoretical percentage figures and applying them to this area and these are the results :
First lets look at runoff:
Out of 38.7 inches we get
3.9 inches of runoff in undeveloped areas
11.6 inches of runoff in developed areas
This means that there is about 2 ˝ times as much runoff in suburbanized situations. This
causes more scouring, more sediment and more contaminants in the river.
Second lets look at infiltration:
Out of 38.7 inches we get
9.7 inches of groundwater in undeveloped areas
5.8 inches of groundwater in developed areas.
Additionally, she considered these factors: while in 2 of 10 years do we have more
rain, up to 44.1” in 2 of 10 years we have less than 29.6” in average precipitation. In these driest years we would get only 4.4 inches
in groundwater. Of course, groundwater gives us our drinking water. More importantly, if there is more development we would get more
runoff, which is bad.
Knowing that there are many new developments “in the works,” as they say, (see sidebar) that will directly
affect the Cacapon we must rationally consider what to do. Close monitoring, education and conservation are certainly three
topics for discussion before we run out of water or have it severly polluted.