II PERMACULTURE IN HUMID LANDSCAPES BY BILL MOLLISON Pamphlet II in the Permaculture Design Course Series PUBLISHED BY YANKEE PERMACULTURE Publisher and Distributor of Permaculture Publications Barking Frogs Permaculture Center P.O. Box 52, Sparr FL 32192-0052 USA Email: [email protected] http://www.permaculture.net/~EPTA/Hemenway.htm Edited from the Transcript of the Permaculture Design Course The Rural Education Center, Wilton, NH USA 1981 Reproduction of this Pamphlet Is Free and Encouraged Pamphlet II Permaculture in Humid Landscapes Page 1. The category we are in now is hu- mid landscapes, which means a rain- fall of more than 30 inches. Our thesis is the storage of this water on the landscape. The important part is that America is not doing it. The humid landscape is water con- trolled, and unless it is an extremely new landscape- volcanic or newly faulted--it has softly rounded out- lines. When you are walking up the valley, or walking on the ridge, ob- serve that there is a rounded 'S' shaped profile to the hills. Where the landscape turns from convex to concave occurs a critical Having found the keypoint, we can now treat the whole landscape as if it were a roof and point that we call a keypoint.* a tank. The main valley is the main flow, from the horizontal, we put in a nomically store water. It is a rather with many little creeks entering. At groove around the hill. This is the deep little dam, and we need a fair the valley head where these creeks highest point at which we can work amount of Earth to build it. It is not start, we locate the major keypoint. with mechanical tools. Above that, it the most economical dam that we will From there on, the keyline starts to is too steep. We make a little shelf have, but it gathers all the water fall from one in 1,000 to one in 2,000 around the hill leading to the keypoint. from the top of the hill to that point. below contour. The dams we make in No matter where this water was go- We can make that keypoint dam as the lower valleys will be slightly low- ing, we have now started to divert it, large as we can afford. It will enable er at each point. They will not be at bringing it right around the hill to the us at any time of the year to run wa- the keypoint. keypoint. In effect, we have put a ter right around this contour and let it Rain falling on the hilltop runs off. gutter around our roof, a very gently fall on any area that we want. We lead The paths described by single rain- falling gutter. We started at the key- the water out through the wall of the drops, wherever they fall, are simi- point and extended a line that we lift- dam, either by siphon or a lock-pipe, lar in that they cross contours at ed one foot at every 2,000 feet. We allowing it to enter a contour drain. right angles, because that is the want to create a very, very gentle We control the flow in the drain by a shortest drop between two contours. fall. Water just moves along it, and sheet of canvas or plastic, fastening Water takes the shortest path across that is all. We have directed the wa- it like a flag to a very light plastic the landscape from where it falls to ter to our keypoint. pipe. A chain attaches to the other end where it hits the river line. It is along At the keypoint, we put a little of the flag, serving as a weight. We this path that raindrops are doing dam; for it is the highest point in the may peg that flag down within the their thing. As soon as they are in the profile of the valley that we can eco- drain, holding back the flow until the river valley, they are off to the sea. It is possible to locate the keypoint from a contour map. Find where the contours start to spread. That is the keypoint. Having found the keypoint, we can All runnoff from now treat the whole landscape as if it above the diversion were a roof and a tank. In a fairly de- drain is collected at scending line, falling gently away the keypoint. This can be directed from *Bill's treatment of keyline differs signifi- an irrigation channel cantly from that of P. A. Yeomans, origi- to any other point nator of the keyline plan. For a more de- below. Slopes of tailed and more accurate treatment of these channels range keyline, see Water for Every Farm-- from 1:200 to Yeomans Keyline Plan, an updated ver- 1:2000. sion of Yeomans' work available from Yankee Permaculture at the address on the cover. Pamphlet II Permaculture in Humid Landscapes Page 2. catch the water; it also defines the point above which you should probably consider forestry, while using the land below for irrigated pasture, croplands, orchards, or even irrigat- ed forest. If you are dealing with a fairly wild forest of walnut and other nuts, it is very useful to be able to pour water on just about the time you are going to harvest. Then all your husks split and the nuts drop out. Be- low the keypoint lies the potential for cultivation. All this that I have been giving you is just a model. I don't expect the "One person can water hundreds of acres this way with no effort at all." drain has filled behind the flag. Then On large property, taking in a whole the water spills over, sheeting down watershed, we may go on construct- across the hillside. About twice a ing further dams on a descending con- year, in summer, this will usually be tour. Away we go, dam to dam to enough to keep the countryside very dam, falling all the way on this one to green. two thousand keyline. As long as your If you want to put out a bush fire main dam is the highest, you can come you just walk backwards with the down to all the little valleys, taking in flag, and you douse the whole hillside. both sides of the watershed. The key- countryside to be like that, for here One person can water hundreds of point should fall to both sides of the we may have rocks and falls and acres this way with no effort at all. watershed. In the next valley, the trees, and maybe a small pasture-- It is very light work. No pumps. dam is a little lower, and the next one but just as a model, that is the way For very large dams, holding five or a little lower. As for the river, it will we would do it. six million gallons, you merely put a flow quite continuously. The more The slope with which we are work- sliding gate or lock-pipe in the dam storage you have on the hills, the ing varies between sand and clay. wall, generally about 18 inches longer that river will flow in summer. Even with sand, if the drop is one foot square. This water will flow out about You can also find situations in which in 2,000, we hardly shift a grain of as fast as you can walk, walking fair- one side of the valley is very, very sand in these ditches. We ran an eight ly slowly. The drain being filled will steep, and the other side very gentle. mile ditch recently in northeast Tas- follow you along. The most restful In this case, it is possible to put stor- mania. We got five or six miles along way to irrigate a large area in this ages on the gentler slope. with one of these ditches--it was in way is to have two people and two Sometimes, again, the keypoint is the summertime and it hadn't rained flags. We peg here, and our friend well up-slope on very gentle, low for months--and there came a light, goes 100 feet ahead and pegs. When sloping country. misty rain. We walked back a couple we have soaked our part of the field, What we are up to is taking water of miles and the ditch was running in we just pull our flag, and our water off non-agricultural land, and prefer- the sand. It had been a guess, sort of flows on to his flag. ably forested land, collecting the wa- a bet. We were doing it with a back- The depth of your ditch depends on ter and the snow melt that has fil- hoe. It was just in sand, and it the size of your dam. If you have a tered through this forest. We don't worked. We filled the first dam on the 5,000 gallon dam and a little garden, want to cultivate those upper slopes. first day of light rain. a small market garden, you can have a They are too steep, and they shouldn't Here you are saying, you have small ditch, and you can control the be cultivated. Depending on your soil, rocks all over the place. Yet, it is flow just by putting a spade in it. don't cultivate beyond a 19 degree very easy to go around outside them, Alternately, you can have some- slope. You can get guidance on this or to bank up on outside of them.