Movement of Water Above Ground

Every watercourse carries both water and sediment.

Practical

My son, who has a Masters in Geology, says a professor told his class it is not worthwhile to try to influence movement of water by bank stabilization, dams, etc. This may be true in the sweep of geological time, but it is not true in the time span of our life. We can make improvements that earn enough more to pay for themselves and benefit us in just a few years. Some of the things you can do above ground (when allowed by law) follow.

The only practical way to preserve a bank where there is cutting on a high gradient intermittent stream is to place stones too big to be moved by the highest flow. We are fortunate to have rocks available on our farm, but it is a hassle to move them from the strip job to streams. I have carried them down when I return from feeding, taking weeks to complete a job, one rock a day.

The creek is, by law, owned by the State of West Virginia, as are all “navigable streams.” This is interpreted as any stream that is not intermittent (does not dry up). Navigable streams are nominally under control of the Army Corps of Engineers. This goes back in common law to a time before the U. S. was a country. The king owned the streams in England. When the American Revolutionary War occurred his ownership fell to the government of Virginia, and when West Virginia broke away, it got the stream ownership. You control the access to it only, but this allows you to keep trespassers out, including fishermen and gas companies who want to pump into their tank trucks or dump out of them.

Presently we have a stream bank erosion plan registered with the U. S. Corps of Engineers and the Soil Conservation folks. You cannot have a (formal, by law) stream crossing without their consent, but we are likely the only farm on Jesse Run (10+ square mile watershed) which does. Other businesses must have one, too, such as a gas company. Materials are not to be filled in or removed from a stream or wetland. Legal use of creek gravel is a thing of the past.

At one time Soil Conservation Service was into straightening streams in a big way, 50 and more years ago. The big stream across from our house had been straightened and put against the south wall of the valley not too long before we came to Jesse Run. John Kolb’s creek (the farm adjacent to ours) had the one big bend cut off, too. If you study the fields, you can find several courses water took in the past. The stream up by the coal road had been straightened, as has the one nearest our house.

There has been an effort to keep cattle from going into steams by conservation interests, because they degrade the banks, and muddy the water. Streams are a great place for cattle to get water, though. What they want you to do is to build watering troughs and fence cattle away from steams. That may be possible for main streams, but not feasible for intermittent streams such as the three that flow south through our property into Jesse Run.

These smaller streams will have a number of crossings. Check dams below the crossings will help to stabilize them, and you may have to maintain a few additional check dams made of rocks, to stabilize these streams. Keep one point along the top of check dams below he surroundings, and let the edges come up to or slightly above the steam bank. Slope the downstream side and/or allow impact of the stream at high flow to hit rocks so the check dam will not be undercut. Go for several small ones, rather than few large ones. Watch and maintain them – usually little is needed.

Where cattle run through heavily used lots you can use rocks in another way. Cattle don’t like to walk on rocks, so you can put large rocks along the streams to control where they walk. The lot where we keep heifers has a stream quite close and parallel to a fence. We place rocks about a foot or so in two dimensions between the fence and the steam to keep them from mashing in the bank between the stream and the fence.

Try using a few piles they won’t want to walk over (one rock thick) every fifteen feet or so perpendicular to the fence and the stream, just so they won’t walk along the fence. If this doesn’t stabilize the banks in some places, you may have to fill piles at shorter intervals.

Particular attention will have to be paid in some areas. We have a stream behind a concrete block well house in the middle hollow, because it is in a very high traffic area. Loss of the block building would ruin a very expensive watering system, which is quite important in a dry year. If it starts to wash, we will build up the watercourse with large rocks so the wall remains intact. The entire channel can be lined with rocks, which is called rip-rap, and you may have to do that in such a location.

If you build a culvert, stabilize the down stream side by using rock or some other method. You don’t need to stabilize the upstream side unless it is quite high. Water piles up against it in times of high water but has little effect. If water flows over the culvert, however, it washes out the fill on the lower side where it splashes over the steep slope, and can make the culvert impassable.

There is a sedimentation basin in one of our small streams near the creek. This is to catch the considerable amount of sediment that comes from the hill. It needs to be cleaned out and the sediment transported every second year or so. We should also have one in the other small south-flowing streams, but there would be some considerable expense in cleaning them and transporting the sediment to some appropriate place. Sedimentation basins should be fenced off to keep the cattle out of them.

Drainage of storm water in small areas is best accomplished by a grassed waterway. The idea is to maintain a broad shallow area that is well grassed over. The grass will contribute to removal of suspended matter, mostly clay and organic debris, from the drainage area above it.

However, if a continuous stream runs for days, several times a year, a channel will develop. This can further develop into a gully if not controlled. Trees along the stream are the easiest control measure. Usually you find them in place. Just don’t remove them. If it is necessary to establish them, Sycamores are a good choice. Willow is easy to establish, just make cuttings three feet long abut the size of your thumb and stick them in place several inches down where they can get plenty of water. I don’t like willows as well as sycamores because they are more difficult to control and the wood is never of any value. Sycamores can be cut and the roots will sprout up again.

Farm roads are a largely ignored area of erosion. Crushed rock is the only real answer. Sometimes you can pick up small rock in your fields, helping both the place where the rock comes from and the place you put it on the road. Water must not be allowed to flow down the road. It washes away the rock and makes gullies. The answer is breakers. Get a technician to help with this. The grade of the breaker and distance apart depend on the grade of the road, and what area drains into the road. The breakers should drain onto established grassland, preferably not too steep. Expect the sediment from the breaker to build up a hump where the breaker ends. Sometimes this becomes too large to allow proper drainage, over a period of decades. In this case the hump must be removed or a ditch maintained through it.

The lower side of a breaker requires special attention, especially if the road is used frequently. If you use the bulldozer to maintain it, and there is plenty of rock, you can push up a lower side of rock. If you don’t have the opportunity to do this put some rock in place, cover it with plenty of dirt and add more rock, building up until you have a pile of rock and dirt well mixed large enough so that it will be high enough to control the flow when it settles. The dirt is necessary to seal the water into the breaker and to keep the rock in place. The rock is necessary to prevent wheel tracks from draining water through the breaker.

The objectives always are (1) to slow the movement of water, (2) to hold the sediment in place, and (3) to prevent gullies and minimize loss of top soil and fertility.

You don’t have to speed up the runoff of water. It can find its own way down hill very well, thank you! When it does speed up, it takes solids with it, and you have erosion.


Descriptive

Streams of intermediate gradient, such as one sees away from the mountains, are a series of pools, each empting into the next. These pools are formed in relatively erodable material, clay or loam, with some smaller rock. The lower end of the pool is blocked by coarser material and the water flows rapidly down a shallow course over riffles into the next pool. This coarser material is sometimes brought into the main stream at the riffles by a smaller side stream with higher gradient (slope) and sometimes it is deposited by a change in direction of the stream. Bars and riffles are constantly changing shape, in large part due to rocks moving down stream. Rock size is an indicator of how fast the water flows over the riffle. Bigger rocks in a deposit mean faster water, because the smaller ones have washed on down stream.


In central West Virgnia all our small streams are high gradient for their size, and are inherently unstable. Over a period of geological time (a very long time) the stream has flowed everywhere between the valley walls – that movement defines where the valley is. Changes in the position of streams come very rapidly, and may seriously disrupt your fields, leaving places you cannot get to, or small irregular fields. In the mountains, where there is a high gradient and sufficient water supply, streams may have a rocky bottom even at normal rates of flow. The sediment in streams, and the deposits along streams may include larger, rounded rocks which have moved some distance. They become rounded by bumping into each other, generating smaller pieces. This rounding down process ends with sand. Sand particles are of such size that in water surface tension of the wetted surface acts as a bumper to form a limit beyond which the size of the particle can not be reduced by bumping. (Very fine grained sand is formed by wind in deserts). Smaller particles in streams are formed by chemical action only.


A basic principle is that in going from a higher level to a lower one, water must dissipate energy. The amount is directly proportional to mass of water moving and distance it drops vertically from one point to another along the stream. At normal flow this is little, but in flood stage it is immense. The stream dissipates this energy by extending its length. It does this by developing meanders (bends). It also dissipates energy by warming the water, but so little you can’t measure it. Loss of energy also happens when the water goes over a falls or riffles, and when it rubs on the banks and bottom or hits other obstructions.

For emphasis, let me repeat, a stream is not uniform in cross section, and does not have uniform grade from higher to lower levels. Considered in the vertical dimension, it is a series of pools, deep quiet spots with riffles between. These riffles are often locaterd where rocky sediment is washed into the main stream by side streams, but appear elsewhere, too. Also, looking down from above, the pools at high flow are not identical with the pools at low flow, riffles having less effect at high flow. Any cross section varies when the water becomes deeper with higher flow.

Changes in the course of streams come at high flow. Double the speed of the flow and the size of rocks that it can move increases by the fourth power (x = awE4 where x is the rate of flow of the steam in any convenient units, such as feet per second, w is the mass (or weight) of the rock and a is a constant relating the units of flow and mass). This relation between rate of flow and mass of the rock that can be moved is one of the highest power laws in nature. The rocks moving at the bottom of the stream abrade (sandpaper) the sides and bottom of the stream. The rocks are more dense than the water (rocks are typically 2.8 times as dense as water), and so are more affected by force of movement (inertia) than water.

Any place water gets up over the land at high water, deposition takes place. If the water is slow and shallow, deposition is slight, and the particles are fine. The presence of grass or tree growth helps deposit solids, because it slows the flow and catches debris. If the water is a foot or two deep, deposition can take place rapidly. I have noticed a lot of sand deposited in some places where it must have been suspended two feet above the low flow level. Notice the elevation of the banks of a stream. I take this to be the equilibrium condition between erosion by the stream propelled sediment on the bottom and the deposition by high water on the surrounding land. Much of the finest sediment, however, goes all the way to the ocean, where the salt water causes it to loose its ability to stay suspended. Deltas (like the Mississippi delta) form where salt causes the suspended small particles to fall out.

If you observe carefully at normal flow, you notice that the outside of a steam curve (the side the stream is thrown against, the cutting side) is vertical, and the other side is slanting from the field level down toward the outside. The outside is being cut away at high flow. Vegetation is an effective barrier to cutting, if it extends to and below the bottom of a steam. Trees are the most important controllable influence on movement of banks. Keep the banks relatively clean, let trees grow where you want the bank to hold, cut them out where you want the bank to be removed. The catch to this last is that the roots do the holding, and they last for years before they rot away, so you have to anticipate, and not let trees get big where you don’t want them. You have to watch the stream banks and cut trees when necessary. It’s an art, not a science. Due to the present environmental-political understanding, it’s best not to cut a lot at a time, especially big, conspicuous trees. The environmental-political group don’t care if the stream changes course and ruins you bottom!

Movement of water below ground

Every watercourse carries both water and sediment.

Most people understand the flow of water underground poorly. The common idea is that water flows in “streams.” When you dig shallow ditches you do observe water flow (if the weather has been sufficiently wet) through crab holes and the like. This is not the major mechanism of movement of water under ground, however.

Imagine a bank of sand along a stream. Water can flow through it moving in the pores between sand grains. These are tiny holes left because the sand grains are irregular in shape. If each was shaped like a brick or a child’s toy block, all the space could be filled in and very little flow permitted. The irregular shapes between sand grains do not completely fill the space, so water is permitted to flow. This is the way water flows down into soil and in some kinds of rock.

Most of the underground water in Central West Virginia (and elsewhere) resides in sandstone (as does the oil and gas). Geologists can measure the porosity of rocks which gives some indication of the space available and the speed liquids can flow through them. Soil is also porous, although not as much as some sandstone. Some rocks are not porous, such as coal and soapstone.

When it rains, water that doesn’t run off seeps down into the soil through pores, some spaces between soil particles, some through earthworm holes, some through spaces caused by plants. It sinks down to some impervious layer, perhaps clay, and there moves laterally (sidewise) through the soil. The process is slow, but it operates through the entire surface. In some places water accumulates due to presence of clay in the soil, and must be drained. Drains must be buried at about 2% grade with no low spots to drain properly. If the work to place drains is not carefully done, the sediment carried by water in drains accumulates in low spots and blocks the drains. Proper design allows for high water in the stream where the outlet is located. The outlet should be far enough above stream level so that there is plenty of time the stream is below the bottom of the outlet. Otherwise the sediment accumulates in the drain. The outlet should be a foot or so above stream level at normal flow. More is better. Anticipate changes in stream level as a result of the processes described in the article “Movement of water above ground.”

An aquifer is a strata of rock which has enough porosity to hold water and allow it to flow into a well bore rapidly enough to be useful. Most aquifers in Central West Virginia are sandstones. To the East there are limestone strata that have enough cracks to allow water to flow in useful amounts.

Water can be pumped readily from the borehole. But the volume of water in the borehole will allow pumping only a brief time. If more than a few gallon is needed, water must be resupplied from the porous rock aquifer. The combination of thickness of the aquifer and porosity determines how rapidly the well will be supplied.

The well may be drilled through a succession of porous and non-porous strata (layers), each aquifer contributing to the production of the well. Aquifers are sometimes held up by some impervious strata, like coal. These are said to be said to be “perched” on the impervious strata. Rarely, drilling through the impervious layer allows the aquifer to drain into an empty porous layer, draining the aquifer.

Some aquifers lie between impervious strata and are replenished from rain percolating down from the soil at some distance from the well at a higher elevation. Drilling into these produces an artesian well. Generally speaking, a well must be in an aquifer thick enough and porous enough to contain a supply of water that will allow the pump to run for several minutes, preferably longer. Often there are several aquifers in an area, in which case the driller should not stop at the first one. The moral of the story is not to stop drilling at the first trickle of water to save yourself money. In some areas, like ours on Jesse Run, go too deep and you get salt water, however. If you have a gas storage field in your area you can expect some of the gas to work its way up through pores toward the surface, away from the pressurized layers to flavor the water. In one of the wells on our farm, gas accumulates above the water, is ignited occasionally by a spark that blows the aluminum well cap off. We know this is the reason, because of the black carbon deposit where the gas-rich mixture explodes.

Aquifers may be thought of as having a lens shape. Not round looking down from above (if you could see through the earth) like a glass lens, nor with a smooth top and bottom, but pinching off in thickness from top to bottom as you move away from the thickest part. When you drill the water well, there is no way to tell where the lens shape of the aquifer is, or how thick it is, in order to best locate the well. The oil and gas people have a way to do this (they only kinda know) looking for their much more valuable target, but such methods are too expensive for water wells. Details of what they do need not concern us here.

The position of the “lens” is unknown and it's shape It can not be found by technology in drilling for small water wells. It bares no relation to surface features with one exception. Very shallow wells may be resupplied by steams in the vicinity. Even when the surface is dry, water continues to follow the unconsolidated material (soil and small gravel) below the surface along streams. If you are a farmer looking to drill a well for a dry time, or a homeowner who doesn’t want to run out of water ever, drilling a well on a hill is a poor choice. The strata tend to drain out in a dry time through the side of the hill into the valley. If you have to drill on a hill, go deep enough to get your water supply below steam level, a few tens of feet.

When you draw water out of the well, the first thing that happens is the water in the bore hole drops. This allows more water from the area of pores around the well to flow toward the hole, refilling it. Then water from further out flows in the newly empty pores, and further out pores resupply those pores. Think about this: When you pump water out of a barrel the water level of the whole barrel goes down, because there is no resistance to the flow of the water. When you pump water out of a hole in a porous strata there is resistance, and so slow flow. The further away from the well the more resistance to flow. Instead of the surface coming down uniformly, like in the barrel, the water nearest the well in the strata comes down most, and further away less. This forms a “cone of depression” in the surface of the water around the well, in the aquifer. If the well is resupplied from above, it is not a good idea to have a shallow well near your septic system, although many people get away with it. The problem is not so much bacteria, but chemicals with molecules nearly as small as water molecules from detergents, cleaners, medicines, etc. that go down the drain. If the water is deep, there is less likelihood of surface water contaminating the resupply.

“Water witching” is an activity that goes back to the time of witches. Although many people “believe” in it, no one has ever been able to prove objectively, that it has any better likelihood of success than pure chance. Drill your well where it is convenient. You are just as likely to hit a lens big enough to meet your needs for a farm or home if you go down until your well is sufficiently deep.

Springs in Central West Virginia (and elsewhere) are most frequently found in the side of a hill or not far from a hill or raised area. They are simply an outlet from an aquifer that can drain, in other words, is above the stream in the valley, and not contained by low porosity rock.. Occasionally they are the result of an artesian aquifer, but not often. If you drill a well in the aquifer above a spring it is likely to reduce the water in the spring.

Fracturing a gas or oil well or blasting by a strip mine or construction job can destroy a well or spring, by making a fracture that lets the aquifer drain below the level of the spring or bottom of the well. If gas or oil well or blasting by a strip mine happens in your neighborhood, it is a good idea to have the production of your well or spring verified in such a way that it can be used in court. In fact it is the law for strip mines to do this. But do it before the work takes place. Afterwards is too late. Consult your friendly lawyer. The company can be expected to fight your claim tooth and nail.