Third straight night of clouds here in the Delta, but they aren’t really thick. The moon must be getting close to full because enough moonlight made it really light outside after we got back from the city in the dark.
Wind is from the North-east meaning rain will probably continue and cold is coming. One thing the Delta outpost has going over Meadowcreek is you can see the fronts coming and you can feel the wind direction in any open area. Down in Meadowcreek’s protected valley you don’t get much wind and you can’t see the storm systems until they are almost on you.
Looks like the Delta will get more rain out of the current system than the Ozarks. That’s good for Meadowcreek’s leaf lovers because fall rains tear the colors off the trees. We don’t have such a mess of fine fall trees in the Delta, but we have other pleasures.
First geese of the year flew over the Delta outpost just after the rain began. Amazing what a couple of inches of rain will do. Geese don’t ever really invade till the temps drop a lot more. Still in 70s when they passed over. I was out making biochar for the first time in months. It had just been too dry to risk it.
Tomatoes are still going great guns with the high temps. Anyone with fall tomatoes should have tons this year. Nothing better than cooking up some tomato sauce. Tomatoes, onions, and garlic bubbling on the stove filling the house with a delightful aroma and making it hot enough in the kitchen we can leave the door open to the cool outside air.
V’s of geese and tomato sauce. A lot to look forward to soon. Nice to contemplate, but we like to focus on what’s here and now and enjoy that to the fullest. Right now the activity at Meadowcreek is getting the greenhouses ready for winter production and, watching for oyster mushrooms to flush after the rain. A little more rain and we can dig some more beds.
We’re building a new hoop house on some beds we dug and biocharred this summer. (If you missed the story on biochar, you have to click this link and learn all about it.) Also building some berms and swales to cut erosion, build soil and catch water.
Swales, the way we build them at Meadowcreek, are the shallow flat-bottomed depressions behind water-harvesting berms, built on the contour of a landscape. The bottom of the depression follows a very modest slope, usually between 200 feet of berm for one foot drop in elevation to 400:1. Swales are nearly flat on the bottom because they’re designed to slow water down to a standstill, eliminate erosion, infiltrate the surrounding area with water, and recharge the groundwater table. When water moves along the flat bottom of a swale, it fills it up almost like a bathtub — that is, all parts of the bath tub fill at the same rate. The water in a swale is therefore nearly passive; it doesn’t flow the way it would on a slope.
To install a swale, we have to find a contour line. A contour is a horizontal line with a constant elevation. To better understand contour, imagine walking on a hill. If you are walking up the hill you will be putting most of your weight on your toes, if you are walking down a hill you will be putting most of your weight on your heels and if you are walking along the contour of the hill, you will be placing an even amount of weight on your heels and your toes. It is this contour line that we need to find when designing and building swales.
A variety of survey tools such as transits, laser levels, water levels or A-frame levels are used to find contour lines. I like the old fashioned transits, like my father used, but laser levels are so much easier and faster and less difficult to master.
Transits were the tool of choice in a cautionary story on how pride goes before a fall. This is one of my favorite stories of surveying contour lines for swales and involves this city girl fresh our of college and a high priced urban consulting firm. She thought she knew everything. She had already burned her bridges at Meadowcreek when she became an intern at a sister project to Meadowcreek. She’d been there only a couple of weeks when she and a few others volunteered to help an experienced surveyor lay out countour lines and learn how to survey in the process.
Instead of learning how to survey, she took over the job from the sweet surveyor/teacher and proceeded to botch the job and alienate everyone who had volunteered to help survey as the learned to survey.
Some people have such a need to show that they are boss that they destroy all possibility of learning. To learn you have to be able and willing to admit you don’t know something. That’s hard for some to admit. Especially politicians, but sometimes even young millennials graduated from high priced schools with fancy degrees.
The swales whose surveying she disrupted have yet to be built, her behavior and attitude cast a pall over the whole project. Amazing how one bad apple can spoil the whole barrel.
Water is not quite so sinister a force. But like a sinister force, it always goes to the lowest possible point. Coming down off Angora Mountain to the West and the East Ridge of Meadowcreek, lots of water rushes down to the low point which is Meadow Creek and then the Little Red River. We want to slow down and catch as much of this water as we can, so the berms have to be high. But more important, the swales behind the berms have to be as level as possible as they slow water as it moves.
When we have gentle rains, all the water follows the swale behind the serpentine berm. But when rains are too intense, there must be an outlet, an escape ditch, a waterfall over rocks. The escape waterfall is built at the beginning of the berm/swale system, usually at the outlet of a pond or where a stream flows off the mountainside. The escape waterfall is made just a little lower than the top of the berms. When built below a pond, water first fills the pond till it reaches the outlet. Once the pond is full, the extra water will sit in the swale almost imperceptibly flowing into the soil or along the swale to a slightly lower portion of the swale. Once the available water has reached an equilibrium, meaning it has filled the lowest point and has no where else to go, it just sits there, unmoving. And as it sits, it slowly seeps into the surrounding landscape, hydrating the soil and recharging the water table below.
The swale prevents the pond from overflowing by acting as a channel away from the pond. But in extremely high rainfall events, an outlet is needed to prevent breach of the berm.
Usually the tops of the berms are just as wet at the swales. This is due to capillary action pulling water from the swale into the soft mound of the berm. (Capillary action is the phenomenon where liquid flows upward through narrow spaces against gravity — you can see this phenomenon when you dip the end of a paper towel in water and watch the water climb up it.) Because the capillary action is so effective in good soils, these berms along the swale can provide enough water to establish a tree system with irrigation only needed in extremely dry years. Trees established top of a berm with a swale below will get more moisture than trees in the middle of a field. The trees roots will also slow down water runoff in high rainfall events.
Down here, the Delta is one big swale system. Since we have a hard clay pan beneath us and virtually no slope, most of the water just sits. The only way it disappears is when the sun comes out and evaporates it or vegetation sucks it in and transpires it.
Such a contrast and such a delight to have the two exact opposite topographies to work with.