THE complete understanding, classification and use of the shapesof land for agricultural advantage is, along with climate, the basic structure ofKeyline.
The shape of our land as it is today has been determined byclimate which moulded and modified it. The movement of water over land is a constantforce. If this force with equal volume or power acts on land of uniform hardnessand erodability, then it produces various shapes that possess constantly repeatedand geometrically uniform patterns. But the differences in rainfall and run-off rateon the widely-differing basic geological shapes of land, and the degree of hardnessand erodability of its structure, have produced, together with other climatic forces,what appears to be an infinite variety of land forms yet which lie within a few basicgeometrical patterns.
The variety of these shapes and patterns as they are producedin areas of similar climate, but on different geological bases, displays distinctiveforms according to the geological structure beneath the surface. The large low formsof the soft granite country are very distinctive. The land could be classified asgranite from its shape or outline alone from as great a distance as can be seen bythe eye.
Granite country often increases in hardness as it approachesan area of geological change and the gradually-changing form of the country may clearlyindicate the approach of the major geological break. How often does one reach thetop of a hill to see a complete change in the shape and form of the land. While granitecountry, with great rounded hard domes appearing, changes from the large low formto the small, steeper, harsher shape, it is succeeded by a new shape. It is wide,gentle, expansive, probably with a soft shale base. We look at the skyline--the profileof the hills--and see from their lines that it is a soft, sedimentary formation.At the same time we may note if it is lying horizontally or well off the horizontalplane. The profile of the hills may change again. They may be flat-topped, in lineand the same height. Almost anyone may pick this as old basalt flow country.
There is no doubt that the broad, wide view of land could beclassified with the various major shapes related to their geological form. Some miningmen and geologists develop a facility for judging these matters, but this particularstudy of land shape could be extended to a new agricultural study. I have noticedthat farmers with mining experience tend to think of the potential of the land againstits mineral and geological background.
Our interest in land shape is agricultural. We are looking foragricultural advantage in this study. Can we find a unit area suitable for observation?Can we find a logical start or finish, or beginning and end, to a suitable land form?Now since water is a major factor in the final shape of land, we may reasonably beginby studying the behaviour of water flow on land surfaces.
Progressively more run-off water flows over land from the centreof the ridge or hill to the centre of the valley. This is true whether we refer tothe watershed of the smallest valley or the valley of a major river. But agricultureis the intimate use of the land and the water which falls as rain on the land, withman in close partnership. Therefore our consideration should start with the smallestvalley and not with the watershed of the river.
Run-off water caused by heavy rainfall has a path or a patternof flow according to the shape of the land over which it flows. Every hill or ridgeon which run-off water flows, directs by its shape the path of the run-off waterto its first place of concentration, and here at this first concentration of wateris found the first feature of land shape. It is the smallest valley and it is called"the primary valley" in Keyline. This valley is a rounded or grassed valleydown which the first concentration of run-off water flows to join another valleyor flowing stream. As water flow is the guide in this examination of land shape,then the area of land from which run-off flows to the primary valley is the firstor primary catchment area, and it will be classed in these pages as the "primaryland unit".
There is a definite boundary to the catchment area of the primaryvalley where rain falling only inches away will flow to another valley. This boundaryline is the centre or high line of a ridge.
In this new approach I classify the centre line of the hillor ridge as a "neutral line of no flow" and the start, beginning or boundaryof a land unit in relation to water. The "neutral line of no flow" hasbeen referred to in the past as a water divide or water parting. Accepting run-offflow as the guide, then the bottom or end of this land unit is found where it meetsanother stream of flowing water. This second flow may also be in a valley of roundedshape or it may flow water in a confined stream with banks on either side such asa creek. This, then, is the end or finish of the primary land unit.
The lateral boundaries of the primary land unit are the neutrallines of no flow of the ridges on either side of the primary valley. These smallerridges, sometimes referred to as spurs, differ from the main ridge which carriesthe steep heads of the primary valleys, and will be named "primary ridges".
We now have a land unit with both a start and a finish. Itsupper limit is the main ridge, its sides are the primary ridges and it ends at thevalley or stream course below.
A start and a finish indicate that land can have length, e.g.,length of slope. There will be all lengths of land, but for convenience these maybe classified into short, medium and long. Short-length land may indicate a distanceof one quarter of a mile from the neutral line of the main ridge down the valleyto the line of the watercourse below. This is the length of land at "Nevallan"where Keyline originated. Where the distance is one mile this is medium length. Longlength land may be two or more miles. Again, the length of land agriculturally signifiesthe unbroken length of the primary land unit from the neutral line of its main ridgeto the first valley or watercourse below.
The length of land as it exists now represents a balance ofall the factors that have affected it from the past--climate, geology and vegetation.
If the top of the main ridge is the start of a land unit, andthe stream course below the end of a land unit, we then have agricultural land unitsthat may be small in area or very large. In some shapes of country, the primary valleyarea or the primary land unit may occupy only an acre or two; in other types of countrythis same land unit may comprise upwards of one thousand acres. In the smaller formseveral associated units within one larger watershed may need to be grouped togetherto make a satisfactory agricultural working area or paddock. The larger unit mayitself have to be subdivided to form suitable-sized paddocks. Indeed, some primaryvalleys may be too small to consider, but as these land features are to be used asguides for the planning and the working of the farm, then the primary valley mustbe given another quality or grading which may be called "significance".A primary valley which is too small or unsuitably shaped for a dam therefore hasno planning "significance" if the plan of development includes the maximumconservation of run-off. It may still, however, have "significance" inKeyline cultivation. Again, it may be too small to enable the farm tractor to followa cultivation pattern, and so loses all "significance".
Within the area enclosed by the line of the top of the mainridge and the line of the stream course below, and bounded laterally by the neutralline of the primary ridges on either side, we have a section of land which may includeall or many important agricultural shapes. Several primary valleys may fall fromthe one main ridge to the stream course below; for convenience two such adjacentvalley areas or primary land units are included for examination. Our map then showstwo complete primary land units, combining a part of the main ridge and includingall the land in the watersheds of the two adjacent primary valleys. It is seen thatthe two primary land units now include two primary valley forms and a primary ridgeform between them. Within this area of land, as seen depicted simply on the contourmap, are typical shapes of ridge and valley: (1) the main ridge from which the twoprimary valleys form; (2) the primary ridge formed by the primary valleys on eitherside of it; and (3) the primary valleys themselves.
The steep heads of the primary valleys fall or form from themain ridge shape; a primary ridge shape then is formed by and between the two primaryvalleys. The valleys have a standard geometrical pattern which can be seen in thecontour lines of the contour map. The main ridge and the smaller primary ridge alsohave a regular geometrical pattern, again as seen in their contours. There is a typicalgeometrical pattern in the ridge form and there is a different but typical geometricalpattern in the valley form.
These two general patterns in land shape are of great agriculturalimportance in the ultimate development of land by Keyline.
There is an infinite variety of land shapes within these regulargeometrical patterns of the contour of land, but if the significant features of themore or less regular forms depicted are fully appreciated, then all land shapes canbe used to their best agricultural advantage.
These geometrical patterns of land, as illustrated by theircontours, are markedly consistent in a region of uniform geological character. Ageological change may break the pattern, but it will generally re-form below thebreak until it finally ceases at the watercourse below.
The primary valley form is probably the most important agriculturalland shape. To repeat these points: It has a start in the main ridge where the steephead of the valley forms; it has its Keypoint in the valley bottom at the end ofthe steep head formation where the valley slope changes to form the second or flatterslope; it has a finish where the valley itself flows into a lower watercourse. Ittherefore has a top and bottom or high and low boundary.
The primary valley also has a boundary on each side of it. Lookingat the contour form of the primary valley below the Keyline, the points or the areawhere the contour lines on the sides of the valley are closer together forms thelateral boundary of the valley shape.
The primary ridge shape between the two primary valleys in mostcircumstances is bounded by lines similar to those of the valley boundaries. Thisridge has a top boundary at the top of the main ridge and a lower boundary at thestream course below. It has lateral boundaries represented by the boundary linesof the primary valleys on either side of it. The area of land on the sides of thevalley where the contour lines are close together forms the line or boundary betweenthe primary valley and primary ridge.
The varying relative positions of this boundary between theprimary valley and primary ridge on differing land shapes enable us to make two furtherland, shape classifications. These are "valley shaped" and "ridgeshaped". Where the boundary is close to the valley the land is classified as"ridge shaped", and where the boundary is towards the neutral line of theprimary ridge the land is "valley shaped". In a land form that is dominantlyvalley shaped the boundary up and down the ridge--where the contour lines are closest--willsometimes fall along the neutral line of no flow of the primary ridge. In this formthe horizontal interval between the contour lines in the valley--below the Keyline--graduallybecome closer together as they leave the valley, reaching their narrowest point inthe centre of the ridge; then the contour lines gradually widen out, reaching theirgreatest distance apart again in the next adjacent primary valley. In these circumstancesof land shape the whole of the land is classified as valley shaped, with the neutralline of the primary ridge forming the boundary line between the valleys. (SeeFig. 3, Upper )
In the variety of these forms the boundary of the primary valleysmay be anywhere from the neutral line of the primary ridge to close against the valley.
These geometrical patterns, as displayed in the contour illustrationsof land, will influence decisions on water conservation, farm roads, timber clearing,tree planting, cultivation procedures and much of the general working and managementof the property.
As stated earlier, the land forms may be very large or verysmall. And again if one primary valley form is too small to be of significance forwater conservation--too small for a dam--it may still be large enough to have significancein cultivation patterns. Valleys smaller again may have to be completely disregardedbecause their size is such that they are too small within their natural boundariesfor a valley pattern of cultivation. In these last circumstances, the very smallvalleys are disregarded in planning, but, in the cultivation or the treatment ofland, the operator may consider them by slightly altering a plowing pattern. Sucha valley may be a small tributary valley to a slightly larger primary valley. Thevalley form that still has significance as far as a cultivation pattern is concernedmay not have significance as a water conservation valley.
The man who puts in Keyline on his property may make many decisionsof this nature in his early planning, but once he grasps the basic concept that thewhole is more important than the part, these decisions will give him no difficulty.For instance, water supply is third on the Keyline scale. If this involves, in hiscircumstances, farm dams for irrigation, then his planning decisions are directedby his primary valleys which have water conservation significance.
Areas of land may be considered as dominantly valley shaped,that is in the circumstances where the boundary of the valley or the up and downhill line through the points where the contours closely approach each other, arewell away from the valley towards the centre of the ridge.
Other areas of land may be considered as typically ridge shapedwhere the natural valley boundary is closer to the line of the bed of the valley.A very large ridge may be enclosed then by the boundary line of a valley on eachside of it. The typical shape of this type of ridge has ridge sides which becomesteeper towards the valley floor. The sides progressively flatten out away from thevalley to the neutral line of the ridge. Their typical contour pattern is illustratedby even-shaped sweeping curves in their contour lines, which are close together nearthe valley on either side of the ridge and gradually become further apart towardsthe neutral line of the ridge. This land shape is one of the basic geometrical patterns.It is of outstanding value as irrigation country in any circumstances where appreciablevolumes of water can be made available near the middle length of the up-and-downslope.
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This precise Keyline classification of land shape for agriculturalpurposes is my own. It has been necessary for me to apply suitable names to the variousunits. The names are therefore new in this application. New names were not selectedfor the sake of being different but because there were no land classifications ornames suitable for my purposes. Land sciences, such as Geography in its various branches,Geology, Morphology, Geomorphology, Hydrology and others, cover wide fields all associatedwith land shapes, but they do not provide a suitable nomenclature for the intimatestudy of land in Keyline. These sciences are chiefly concerned with the origin anddevelopment of major land surfaces and continental structures. Rivers and their valleysare examined, measured and classified. Their slopes and thalwegs are related to majorworks for dams, roads and railways. But the more general the concept the less thedescription and descriptive name is applicable to the specific smaller unit whichis a fundamental in the Keyline concept.
In my approach I have taken the smallest significant featureof land shape, which is the rounded, grassed or smooth valley of the farms, grazinglands and forests and called it the "primary valley". This unit includesthe two slopes of the valley, the first steeper slope from the ridge in which itforms and the second flatter slope below to the watercourse where it ends. This primaryvalley is a gully to many, a re-entrant to others, a secondary valley, a headwatervalley, and many other more picturesque names. But to take one of these names, headwatervalley, which seems to be descriptively suitable, in many references it indicatesthe mountain catchment of rivers. This headwater valley then may have a catchmentarea of up to 1000 square miles and contain 10,000 to 20,000 primary valleys.
In Keyline the first land shape then is the primary valley.
This was considered from the point of view which is indicatedby water flow. The area of land around the primary valley which sheds water to itthen becomes the primary agricultural land unit, and it finishes at the stream coursebelow, the lower boundary of the primary land unit. The primary land unit is synonymouswith the primary valley area or primary valley watershed.
The purpose in selecting a primary land unit is to examine thewider aspects of agricultural land in a small representative unity.
The primary valleys of several primary land units may fall intothe watercourse of a larger valley named a "secondary valley". The topboundaries of the watersheds of the primary valleys combine to form a catchment areawhose boundary is that of the secondary valley area, and thus the secondary landunit. Every point in the secondary land unit is a point in a primary land unit. Otherprimary valleys flow from adjacent hills and ridges directly to the larger creeksand rivers, and to lakes. By summation all agricultural land is contained in primaryland units; therefore all agricultural land is represented in our primary land unitwith the exception of stream beds.
Every primary valley falls or flows from higher land--from thehill or the ridge. The ridge from which the primary valley falls is the most importantridge to that primary valley and generally of other adjacent or nearby primary valleys.It is therefore named the "main ridge". It may be large or small, highor low, and short or long, or any combinations. of these, but it is still the mainridge of those primary valleys which fall from it.
Between two adjacent primary valleys lies a ridge having similarhigh and low boundaries to that of the primary land unit. This was named the "primaryridge".
The boundaries of watershed or catchment areas, whether theyare of the smallest primary valley or the largest river valley, are ridge lines.These are generally called divides, water divides, or water partings. Such namesdo not indicate any particular size but will be used in this text in their generalsense for the larger areas of land. The descriptive term, "neutral line of noflow" was used in describing these divides when they belong to the primary andsecondary valleys of this study. The shorter term "neutral line" will generallybe employed in relation to the divides of these two valley watersheds.
These are the new land classifications and the names of theagricultural land features. I hope they may be found suitable for general agriculturaluse.
The final significance of land shape will become increasinglyapparent with the further description of the various Keyline techniques.
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In farm planning, the natural length of land is to remain stable.It must not be shortened by planning or farming practices which would cause morewater flow and higher velocities. These may break the land in a new place, formingan erosion gutter or gully.
The final shape of the primary valley itself, the rounded, grassedor timbered valley which the farmer can travel with his farming equipment, was formedby the balance of influences that collectively affected it, but most of all by waterflow. It could be said to have been designed, constructed and developed with infinitecare by a wide variety of natural forces, to perform the special function of drainingthe surrounding land and transporting the excess water to the watercourse below.It was built to transport the water which the climate and the surrounding land gaveto it. If man, in his occupancy of the valley and the land about it, does not deterioratethe valley environment, then the valley will continue to perform its function andremain stable indefinitely. If, as is the aim in Keyline, the environment of thevalley is improved by building the fertility of its soil and the soil of its surroundingcatchment area, the valley continues stable and permanent; it is more capable ofhandling water and in even greater quantities than that supplied by the climate.
When land is cleared there is likely to be slower and less absorptionof rain into the soil, thus causing water to concentrate quicker and flow fasterin the valley. But there are two reasons why this must be prevented. One, the valleystability could be affected, and two, more and longer-lasting moisture is neededin the soil of the whole of the land unit for its development and for the growthof grass and crops. The object is for all the soil to improve in fertility. The extramoisture in the soil should be evenly spread throughout all the land of the valleyarea.
Now rainfall is uniform over the primary land unit, as it fallsevenly enough to satisfy the desire for uniform moisture, but immediately rain reachesheavy run-off proportions the volume of water moving over various parts of this landunit varies. It follows its natural flow path, which is governed by the shape ofthe land. The volume of flowing water progressively increases from the neutral lineof the ridge to the valley floor.
We have already seen that straight-line or round-the-paddockcultivation crosses the natural flow lines of water in such a way as to cause earlierconcentration and faster movement of the water to the valley. We may disregard forthe moment, the sometimes increased absorption of rain into the soil from specialtypes of cultivation. It is apparent that the natural flow pattern of water shouldeither be preserved by the furrows left by cultivation or controlled in such a wayas to spread flow water more uniformly. That is also true in the immediate area ofthe valley floor, where the wider spread of water reduces destructive velocities.However, our approach to water is not the negative one of preventing destructivevelocities because it may cause soil erosion, but from the positive aim of controllingwater to provide all the soil with its full requirements from each rain for the continuousimprovement of the soil's climate. By spreading moisture uniformly and so controllingthe type of run-off flow, thus making its path broader in the valley, we are, incidentally,effectively protecting and preserving the shape of the land.
A diagram depicting the flow pattern of water on any shape ofland can be produced on a suitable contour map by drawing lines outwards from pointsat equal distances along the neutral line of a ridge, and crossing each contour atright angles.
A little thought will demonstrate that this is sound reasoning.Water flows downhill by the easiest or steepest path until it reaches a depressionor valley and then it concentrates as a stream. The steepest path from any pointon one contour of the map to the next contour is the shortest line from that pointto the lower contour. The flow lines on the contour diagram therefore represent thepath of the sheet flow of water over that land surface. In my studies of the flowpatterns of water over various land surfaces I have discovered that the completepattern, i.e., the flow pattern from the neutral line of the primary ridge to thebottom of the primary valley, always forms a flat S curve. Whether or not this facthas been recorded earlier by others I do not know, but I have been unable to findany reference of it. If ordinary cultivation procedures are employed, the flow pathis steepened, thus causing water to concentrate earlier and to flow faster. It istherefore desirable to seek some other plan of cultivation that will distribute flowwater evenly.
Contour cultivation, theoretically, is cultivation that leavesa pattern of all furrows on the true contour. However, every run of the tractor andplow would need to follow a true contour line marked on the land with a levellinginstrument or the land must be of perfectly even slope. Contour cultivation, as practised,is neither of these. It is simply a cultivation in the spaces between contour linesthat have been levelled-in and marked on the land by permanent or semipermanent furrowsor banks. It leaves a pattern of furrows half parallelling up from the lower contourand half parallelling down from the marked contour above. This pattern is illustratedon our map-diagram, which is a contour map of an actual land form, typical of countrywith a medium but not hard rock base. It is granite type country.
The pattern of practical contour cultivation is illustratedby the broken lines each representing many actual furrows on the land. Arrow headson the lines illustrate the downhill direction of the furrows. Furrows without arrowsmay be accepted as contour lines.
It is seen that half the lines with arrows fall downhill inthe general direction of the flow path and of the valley, thereby tending to causeearlier concentration of run-off and faster flow to the valley. An approximatelyequal number slope downhill in the opposite direction and away from the valley, opposingthe flow lines, causing the run-off to spread as required. Contour cultivation istherefore much better than straight-line or round-the-paddock work.
Keyline cultivation, however, produces a pattern of furrowsin which all, or a very large majority, break the natural flow pattern of water overland surfaces in such a way as to reverse the direction of flow. The result is awider and uniform spread which prevents quick concentration of flow water. The naturalvalley flow is always reduced and widened.
As long as the influence of land shape on the flow path of flowingwater is understood, it becomes a simple matter to control and evenly spread waterby this Keyline technique. This knowledge influences many decisions.
If true contour cultivation were practical, each furrow wouldthen cross the water flow path at right angles and there would be no tendency toalter the flow path. Water would be held on the land longer by the fact that it wouldhave to surmount the obstruction of each furrow at right angles to the flow path,but when general flow occurs, it still follows the natural flow lines.
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The Keyline conception of land shape is based on the fact thatthe consistent final force--flowing water--which shaped land, produced regular geometricalshapes in the land. The varieties of base hardness and the erodability of land andthe varying amounts and times of water run-off produced infinite varieties withinthese geometrical patterns. The longer the shaping of land by water has continuedthe better are the shapes and the more valuable agriculturally. Since Australia isof great age geologically its land forms for a great period of time were very similarto its land forms today.
There is another primary valley shape in Keyline andit is closely related to the first shape already discussed and which with its surroundingland was classed as the most important unit for agricultural study. Reviewing thefirst type of primary valley we concluded that it starts from the main ridge andfinishes where the rounded primary valley flows to a stream course below. This primaryvalley within a stabilised geological formation is one of the consistent geometricalforms as seen in its contour lines. The other type is the valley that flows froma saddle or low point in the ridge.
We have seen that the primary valley of the farms and grazingproperties is a land form that transports run-off water over a rounded surface toa lower stream course, which may be a rounded valley or yet a creek or a river. Theprimary valley was formed and shaped by the work it does. For water to flow, thevalley bottom must be lower than the land on each side of it at right angles to thedirection of flow, or it would not be a valley and would not transport water. Ifthe valley forms from a line of hills it must first lose height steeply, more steeplythan the hillside. Then it flattens and flows more gently. The valley has a steephead, then a flatter bed. The steep head is generally of uniform slope until it flattensto form the flatter bed, which is the second slope of the valley. This second slope--moregenerally than otherwise--tends to continue as a uniform slope to the stream coursebelow. This type of valley then has two slopes, one, the steep slope from the hill,and, two, the flatter valley floor slope below. The point of change between the steephead slope and the flatter valley floor slope is the keypoint of the valley, andthe contour or grade line through this point is the keyline of the valley. However,the second type of primary valley forms from a saddle between two hills or a lowpoint in a ridge.
It does not have two slopes, but only the second slope, theflatter valley floor slope. This type of valley, by starting in the saddle, has alreadylost height. Its bed is already lower than the land on either side. It thereforemay fall from the saddle as one continuous even slope. The saddle point is the keypointof such a valley and the keyline is the contour or grade line through this point.(Fig. 7.)
This valley, the one slope or saddle valley, has its keypointat the saddle, but this keypoint is also the keypoint of another valley falling onthe other side of the saddle. It is therefore a dual valley formation, with the twovalleys falling in opposite directions from the one saddle or keypoint. This naturalland form, and it is by no means uncommon, can be of outstanding agricultural value.
It does not exist on either "Nevallan" or "Yobarnie",and was not mentioned in my earlier book, "The Keyline Plan". While I wasaware of it then and saw in it the inevitable pattern of the land forms of Keyline,I had no opportunity to use it agriculturally. Of our three newly-acquired properties,two contain wonderful examples of these dual saddle-valleys in valuable agriculturalform.
A dam in such a valley would have the minimum of natural catchment,but if it were located with the top water level right to the saddle keypoint anddesigned and constructed as discussed and illustrated in later chapters in this book,it could have as many as four Keyline water conservation drains, each falling fromdifferent directions to the saddle and spilling into the dam.
We have two such dams now on "Kencarley", Orange,N.S.W. One has a depth of twenty feet of water at the outlet valve of the dam. Thewall of the dam provides three feet clear of freeboard but no spillway. The saddleitself is the natural spillway. When the dam overflows, the water runs out throughthe saddle into the other or second valley of this land formation and finishes upin a large reservoir in a valley a quarter of a mile away. The dam is of seven milliongallons--28 acre feet-capacity, and although the reservoir nearby is nearly fourtimes its size, our visitors all appear to be much more interested in this saddleKeyline dam.
There are also primary valleys which form from a saddle butstill have the two slopes, a steeper head slope from the saddle down to a point ofchange (the keypoint), and then the flatter valley slope below. This latter valleyis of the same class as the first of the two primary valley shapes.
To recapitulate: The particular geometrical form of the firsttype of primary valley, the commonest one in my experience, is seen in the contourmap of the valley. Above the keyline of the valley the distances between contoursin the valley are shorter than the distances between the same contours on each sideof the valley, also the centre valley slope is steeper than the slopes on each sideof the valley. Below, the keyline of the valley this relationship is reversed. Thedistances between the contours in the valley then are greater than the distancesbetween the same contours on each side of the valley, and the slope down the valleybottom is flatter than the slopes on each side of the valley. Again, above the keylinethe centre slope is steeper than the slopes of the sides, and below the keyline thevalley is flatter than the sides.
The saddle keypoint valley only possesses the second relationship,that of flatter valley bottom with steeper valley sides.
Keyline Cultivation and Valley Shape : In order to spreadwater and moisture wider in the first type of primary valley by a cultivation thatproduces furrows opposing the natural flow pattern of water to the valley, it isonly necessary to plow parallel with the keyline up the slope of the land and parallelwith the keyline down the slope of the land. This is Keyline cultivation as it appliesto this valley.
All cultivating implements make a series of parallel lines orfurrows on the land surface. Cultivation which parallels a line marked on the landas a contour remains, as cultivation proceeds, parallel to the contour on the surfaceplane of the land, but not to it on the vertical plane. Keyline cultivation usesthis fact as a device and from a selected contour line previously marked out on theland plows in parallel formation in such a way that all furrows, or the great majorityof furrows, oppose the natural flow paths of water on that particular piece or segmentof land, thereby spreading the water or moisture more uniformly. Or more broadlystill, Keyline cultivation is one that generally parallels a contour in such a waythat water and moisture is caused to move as the farmer plans it for the good ofhis land.
Always the general effect of Keyline cultivation on rains whichare fully taken in by the soil is that the moisture is more uniformly held in thesoil; there is no pronounced drift of moisture to the valleys. With rain that producesrun-off, moisture is uniformly held, run-off is wide and flat, and the first concentrationthat flows in the valley commences lower down the valley. The flow is very much widerand shallower, velocities are cut to the minimum and the valley stability is progressivelyimproved. Erosion of fertility and of soil is therefore not a factor for specialconsideration in Keyline agriculture.
A Keyline appreciation of the various land shapes enables afarmer to control all aspects of water almost at will. The accumulation of powerto control water which is provided by many hundreds of little furrows, all combiningfor one effect, is unbelievable until it is seen. For instance, following a veryheavy storm which fell during the severe flood rains of 1956, one of our lower damson "Yobarnie" overflowed with a stream two feet six inches deep by aboutfifteen feet wide through the flood spillway which emptied into a small flat valley.The valley was in a paddock which was Keyline cultivated three years earlier as apart of an experiment. The experiment, which included two other paddocks, was todetermine the different effects on soil and pasture development of Keyline cultivation;one cultivation in the autumn for one year, one in each autumn for two years, andone each autumn for three years. This paddock, cultivated once only, had been stockedon and off about twenty-five times in the three years. There was no noticeable Keylinecultivation pattern left, as the stock had tramped it out. But within a few feetof the spillway's outflow in the valley the old Keyline cultivation patterns hadcompletely controlled this large water flow. The powerful cumulative influence ofwhat was left of the Keyline pattern spread the water well over three hundred feetwide. The water flowing in the valley centre was not noticeably deeper than thatflowing on the sides of the valley where it extended laterally almost to the ridgebetween this valley and the next.
One place where water never flows naturally is down the middleof a ridge, the neutral line of no-flow, in even the heaviest run-off elsewhere.But a Keyline cultivation designed for the purpose of carrying water down the centreof a ridge will control the water and cause it to flow there.
Water can be induced to flow where it is wanted and as it iswanted--except uphill--if our treatment and management of land is based on a fullappreciation of land shapes. And if water is the critical factor by being in shortsupply or by unreliable rainfall, then the simple logical approach is not to wasteit. However, there was, until Keyline, a serious drawback to this obvious approach.There has been no way of conserving all the run-off profitably. But in water we haveour greatest primary commodity. Water, within itself, can be used for its own distribution.A sound knowledge of land shape, implicit in the complete study of Keyline, enablesone to harness the force of flowing water for its uniform distribution over agriculturalland.
We will assume for the moment that special Keyline techniquessupply the cheapest means of distributing irrigation water in the manner most suitablefor farms and grazing properties, and proceed to examine land shape as an aid inconserving all the run-off rain, but first consider briefly dam size and the possiblecost of water storage.
Water can be conserved almost anywhere on agricultural land;it is just a matter of cost. The higher the storage the more valuable is the water.just how much can a farmer profitably afford to pay for water storage capacity underconditions that permit economical use of the water for irrigation and in conditionswhere run-off is satisfactory? I do not know the limit of the amount he can affordto pay per acre foot of capacity, but the highest cost on any of my own farm irrigationdams is below £50 per acre foot, and this cost under the circumstances statedabove is sufficiently attractive to warrant the outlay to conserve all the availablerun-off. By comparison the lowest cost of any of our dams was £6 per acre foot,on prices and values at time of writing.
The cost of water conservation in farm dams is the least ofthe consideration in most so-called supplemental irrigation projects. Other costssuch as pumping and equipment and labour are the critical ones. This has been saidoften before, but it is worth repeating in this context.
If the cost of water storage capacity to hold all run-off andthe cost of using the water returns a much higher profit than rain, or rain plussupplemental irrigation, then all water should be conserved.
To return to dam sites: The possible conservation sites shouldbe examined starting from the highest to the lowest sites. Here again the land formationof the primary valleys is of major importance.
The highest valley water conservation site is generally justbelow the keypoint of the primary valley, thus leaving perhaps less than 20% of theslope above the keypoint. These sites were not considered for farm irrigation dams,because of their restricted natural catchment, until I started in 1944 building farmdams of from fifteen to forty acre feet capacity and providing special water conservationdrains to fill them. The steep head of the valley above these sites--the true keylinedams--is usually short and collects only comparatively small quantities of flow water.Where the keypoint is a saddle point, the natural catchment of the true keyline damwould be still more restricted.
Now the keypoints of the adjacent primary valleys in a commonwatershed such as a secondary valley are higher as the land rises. The primary valleysthemselves form in the main ridge, so that normally as the country rises the headsof adjacent valleys are higher and the keypoints of the valleys are higher. In aseries of primary valleys flowing into a larger valley or into a creek, in undulatingcountry of uniform geological formation, the keypoints of the valleys generally havethis rising relationship to each other. But before going on, a definition of "generalland slope" is necessary, and so in our primary agricultural land unit, withits lower limit at the stream course or the creek below, the slope of the land isthe fall from the main ridge down the primary valley or primary ridge to the watercourseor creek. General land slope, however, is the direction of the rise of all the land--thehills and the stream course--and it is usually at right angles to the slope of theprimary land unit. The general fall of land then is the direction of the drainageline which is the creek or the watercourse to which the primary valleys fall. Thisdirection is down land. Up land is the opposite direction to this fall.
A series of primary valleys flowing to a creek have a slopeto the creek, but the creek itself indicates the general land slope.
These aspects of land have a very important significance inany circumstance where all the run-off water should be conserved in farm dams forirrigation purposes.
The rising relationship of the keypoints of the primary valleyswithin the one larger catchment area, and in converse a falling relationship, enablesthe siting of a higher series of dams in such a way that all these dams can be filledby the water conservation drains before any run-off water gets away from the highercountry. Slightly more catchment area is turned into the highest dam of he series,so that it will fill quickly. The overflow of this dam is directed into the catchmentarea or the water conservation drain of the next lower dam of the series, and soon down the series of keyline dams.
As a general Keyline rule, all drains, both water conservationdrains and irrigation drains, flow or fall with the general fall of the land. (SeeFig. 9 )
The contour map shows a series of primary valleys falling tothe one creek. The direction of flow of the creek is the general fall of the land-downland. "Up the creek" is the general rise of the land-up land. The contoursare seen to cross the creek as arrow heads or V's pointing upstream-up land.
A study of these contours will show further that if water isto be brought into any of the farm irrigation dams, the conservation drain shouldbe constructed from the dam rising in the direction of the general rise of the land.As the land rises, increasing land area lies above the drain to shed water to thedrain for conservation in the dam. If the drain were to rise from the dam in thedirection of the general fall-down land, then the drain would soon reach the topof the watershed, enclosing very little land which would shed water to the drainand so to the dam.
This principle of water conservation drains rising up land alwaysapplies in the design of drains and their location in respect to water conservationwhere natural valley catchment is to be greatly increased. The only likely departurefrom the principle would be near property boundaries where the next land form ison a neighbour's property. Except where these interruptions may occur, all waterin drains, both water conservation drains and irrigation drains, falls with the generalfall of the land. A drain falling with the general fall of the land is, of course,also rising with the general rise of the land.
The reason for this Keyline rule is obvious. Study of the contourmap shows that contours in the down land direction have increasing land area belowthem as they are followed from the watercourse; in the opposite direction, from aridge to the watercourse, the contours have decreasing land below them and soon reachthe creek. Irrigation drains, which have a fall in the down land direction have increasingareas of land below them which can be irrigated by Keyline flow methods. If theirfall were in the opposite direction there would be a rapidly decreasing area betweenthe irrigation drain and the creek. There would be insufficient land for irrigation.
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Once the eye becomes trained to these simple land shapes, andthe mind has selected and classified one or two of them, there is a fascination inthe continuous broadening of one's understanding and appreciation of the landscape.
Every trip I have in the country becomes more enjoyable, becauseof this added interest, and I have had the pleasure of seeing a like interest developin many others.