eChapters

4.1 Defining erosivity and erodibility

Rainfall erosion is the interaction of two items - the rain and the soil. The amount of erosion which occurs in any given circumstances will be influenced by both, and our study of the processes of soil erosion is simplified by considering the two aspects separately.

We know from observation that one storm can cause more erosion than another on the same land, and we also know that the same storm will cause more erosion on one field than on another. The effect of the rain is called erosivity and the effect of the soil is called erodibility. The way they differ is best explained by examples.

Let us imagine an experiment station which has over its whole area exactly the same soil type and slope. Assume also that the whole of the station is covered by a completely uniform crop. If the amount of erosion taking place during each storm were measured, the amount would be influenced only by the nature of the rain. Comparing the effect of one storm with that of another storm would provide a relative measure of the power of each storm to cause erosion, and that is what is meant by erosivity. This will enable us to say that on this imaginary experiment station, storm A caused a soil loss of X kilograms per hectare and storm B caused a soil loss of Y kilograms per hectare. If Y is half of X, then the erosivity of storm B is half of the erosivity of storm A.

3.1 Physical characteristics

There is obviously an association between the amount of rainfall and the amount of soil erosion, i.e. more rain goes with more erosion, and less rain with less erosion, but in statistical terms the correlation between the two is poor. The same total quantity of rain can on different occasions result in widely differing amounts of erosion, and so other more specific measures are required to describe the ability of rainfall to cause erosion. In this chapter we shall establish the known facts about the main physical properties of rainfall, and then in chapter 4 show how these properties are related to the erosive power of rainfall.

3.1.1 Quantity of rainfall

Any measure of rainfall amount is a sample, and so associated with the inevitable problems of sampling, namely, ⁴is the sample representative of the whole?’ and ‘is the sample measured accurately?’ On both counts the data of rainfall which are usually available are of very doubtful reliability. Considering firstly the size of the sample measured, a very intensive network of rain gauges such as that established in an experimental catchment might be as dense as one gauge per 25 hectares, but this corresponds (with a 125 mm diameter gauge) to a sample of about one in 20 million, which would for any other scientific measurement be considered totally inadequate. The density of gauges in a country which considers itself very well provided might be one gauge per 25 square kilometres - a sample of one in 2 000 million, and in an undeveloped country the density of one gauge per 2 500 square kilometres is a sample of 1 in 200 000 000 000! Secondly, the siting of this remarkably small number of gauges is usually arranged primarily on convenience, eg where they can be easily read and contained, with little or no consideration of whether the site is representative of the whole. Thirdly, the accuracy of the measurement is usually unknown and studies have shown that variations in the shape and size of the instrument, and in the height at which it is mounted, and the way it is shielded from the wind, can seriously affect the recorded amount of rainfall. Clearly, even the apparently straightforward question of how much rain falls is not answered as precisely as might be imagined from a survey of rainfall tables and maps.

2.1 Geological and accelerated erosion

Erosion has always taken place, and always will. The surface of the earth is constantly changing, with mountains rising, valleys being cut deeper and wider, the coast line receding here and advancing there. The physical pattern of the surface of the earth which we see today is not the result of some single cataclysmic sculpturing but the result of changes so infinitely slow that only after centuries is the effect noticeable. Erosion is simply one of the aspects of the constant process of change. It is fundamental to the formation of alluvial soils and sedimentary rocks. Man’s activities seldom slow down or halt the process but frequently speed it up. We usually refer to geological erosion or normal erosion, or natural erosion when we mean that which results only from the forces of nature, and to accelerated erosion when the process is influenced by man.

When trying to predict the probable severity of man-made erosion it helps to consider the rate of geological erosion. If the conditions of climate and topography are such that geological erosion is quicker than usual, then these sameronditions will also lead to particularly severe accelerated erosion. Extreme examples of both kinds of erosion are shown in plates 2.1 and 2.2.

1.1 The relation between man and the earth’s resources

The balance between the demand which a community of plants or animals makes on its environment and the ability to satisfy those demands is not the static equilibrium of a laboratory balance with equal weights on either side. It is more like the unstable balancing of a circus acrobat - a series of swings and overcorrections, resulting in an oscillation on either side of the true balance point. Thus a species of wild life increases in number according to the availability of its food supplies, but then goes beyond the optimum number. The natural correcting factors of starvation or migration reduce the population, but there is an overcorrection, and soon the cycle starts again with increasing numbers.

1.1.1 The Malthusian Thesis

In primitive societies the human population also oscillates about a mean as the limiting factors of starvation, disease, and war, maintain an uneasy balance against the natural tendency to increase. A serious imbalance arises when man learns how to modify the limiting factors, but allows the natural increase to go unchecked. The essence of the Malthusian Thesis is that the resulting instability is the inevitable order for mankind. The thesis is named after the English political economist Thomas Malthus who first gave it formal expression in MALTHUS (1966). In an age when significant improvements in health, hygiene, and the standard of living were just becoming possible, Malthus aroused great argument when he pointed out that these very improvements could lead to mi sery through overpopulation. The key point of Malthus’s argument is that population increases in what he called geometric ratio, what today we would call an exponential curve, because whenever there is an increase in population there are more people to produce the next generation, so the rate of population growth accelerates - in modelling terms a positive feedback loop. On the other hand, when we increase food production there is no feed-back loop, the best we can hope for is for a constant linear increase. The natural sequence is therefore for food demand to increase faster than food supply, leading at some point to food shortage.

This is a great Hahnemannian anti- psoric. Its action is centrifugal - from within outward - having an elective affinity for the skin, where it produces heat and burning, with itching; made worse by heat of bed. Inertia and relaxation of fibre; hence feebleness of tone chracterizes its symptoms. Ebullitions of heat, dislike of water, dry and hard hair and skin, red orifices, sinking feeling at stomach about 11.00am, cat-nap sleep; always indicate sulphur homoeopathically. Standing is the worst position for sulphur patients it is always uncomfortable. Dirty, filthy people, prone to skin affections. Aversion to being washed. When carefully selected remedies fail to act, especially in acute diseases, it frequently arouses the reactionary powers of the organism. Complaints that relapse. General offensive character of discharge and exhalations. Very red lips and face, flushing easily. Often use in beginning the treatment of chronic cases and in finishing acute ones.

Imperfect assimilation and consequent defective nutrition, it goes further and produces neurasthenic states in consequence, and increased susceptibility to nervous stimuli and exaggerated reflexes. Diseases of bones, caries and necrosis. In TB it must be used with care, for here it may cause the absorption of scar tissue, liberate the disease, walled in, to new activities. It is a deep acting remedy and slow in action. It is meant for scrofulous children with large head, open fontanels and sutures, distended abdomen, slow in walking. Ill effects of vaccination. It is related to all fistulous openings. Ripens abscesses since it promotes suppuration.

Silica patient is cold, chilly, hugs the fire, wants plenty warm clothing, and hates drafts, hands and feet cold, worse in winter. Lack of vital heat. Prostration of mind and body. Great sensitiveness to taking cold. Intolerance of alcoholic stimulants/Ailments attended with pus formation.

In inflammation with pus formation, which has become chronic, silicea is of great help. It is equally useful in grandular or bony ulceration. Think of silicea in whitlow, unhealthy skin, smelly feet, mammary abscess, mammary cancer, TB of the skin, the bone or of the abdomen,

Acts especially on the portal system, with venous congestion. Stasis and thereby ptosis of viscera and weariness and misery. Weakness, yellow complexion, bearing-down sensation, especially in women, upon whose organism it has most pronounced effect. Pains extend down to back, chills easily. Tendency to abortion. Hot flashes at menopause with weakness and perspiration. Upward tendency of its symptoms. Easy fainting/ Ball" sensation in inner parts. Sepia acts best on brunettes. All pains are from below up. One of the most important uterine remedies. Tubercular patients with chronic hepatic troubles and uterine reflexes. Feels cold even in warm room.

The most important indications of Sepia are in the problems of women relating to the uterus. It has been called the best uterine remedy available. The patient feels that all her internal organs would come out of the pelvic region. She has to sit with legs crossed to relieve this feeling. Sepia is a chronic remedy. It can take care of long standing problems.

It produces contraction of the unstriped muscular fibers, hence a constringent feeling throughout the whole body. This produces an anemic condition, coldness, numbness, mortification and gangrene. A useful remedy for old persons with shriveled skin- thin, scrawny old women. All the Secale conditions are better from cold; the whole body is pervaded by great heat. Haemorrhages continued oozing, thin, fetid, watery black blood. Debility, anxiety, emaciation, though appetite and thirst may be excessive. Facial and abdominal muscles twitch. Secale lowers the flow of pancreatic juice by raising the blood pressure.

Menstrual colic, with coldness and intolerance of heat. Passive haemorrhages in feeble, cachetic women. Burning pains in uterus, brownish, offensive leucorrhoea. Menses irregular, copious, dark, continuous oozing of watery blood until next period. Threatened abortion about the third month. During labor no expulsive action, though everything is relaxed. After-pains. Suppression of milk; breasts do not fill properly. Dark, offensive lochia. Puerperal fever, putrid discharges, tympanitis, coldness, suppressed urine.

The word RHUS means red because its flowers and leaves are red in colour. TOXICODENDRON means poison tree.

The effects on the skin, rheumatic pains, mucous membrane affections, and a typhoid type of fever, make this remedy frequently indicated. It mainly affects fibrous tissues, joints, tendons, sheaths producing pain and stiffness. Ailments from strains, over lifting, getting wet while perspiring. Rheumatism in the cold season.

Rhus Tox is the first remedy one should think of in any muscular pain where the cutting pain and soreness are temporarily relieved by movement. This is in direct contrast to Bryonia where movement aggravates pain.

The word PULSATILLA is derived from PULSATUS meaning to beat or to strike as it pulsates from the blowing winds.

The weathercock among remedies. The disposition and mental state are the chief guiding symptoms to the selection of Pulsatilla. It is pre-eminently a female remedy, especially for mild, gentle, yielding disposition. Sad crying readily; weeps when talking; changeable, contradictory. The patient seeks the open air; always feels better there, even though he is chilly. Mucous membranes are all affected. Discharges thick, bland, and yellowish green. Often indicated after abuse of Iron tonics, and after badly- managed measeals. Symptoms ever changing. Thirstless, peevish and chilly. When first serious impairment of health is referred to age of puberty. Great sensitiveness.

Pulsatilla cures chronic colds, fatty dyspepsia, and painful and scanty menstruation. One of the leading indications for the use of Pulsatilla is a thick, bland, yellowish or green discharge from mucous membranes in the body. Such discharges are to be found in nasal catarrh, in expectoration from the ears, the eyes, the lungs, ulcers, leucorrhoea and in gonorrhoea. In most such cases Pulsatilla leads to a cure. In the vagina, however, this discharge is excoriating and not bland.

Phosphorus irritates, inflames and degenerates mucous membranes, irritates, and inflames serous membranes, inflames spinal cord and nerves, causing paralysis, destroys bone, especially the lower jaw and tibia; disorganizes the blood, causing fatty degeneration of blood vessels and every tissue and organs of the body and thus gives rise to haemorrhages.

Produces a picture of destructive metabolism. Causes yellow atrophy of the liver and sub-acute hepatitis. Tall, slender persons, narrow chested, with thin, transparent skin, weakened by loss of animal fluids, with great nervous debility, emaciation seems to be under the special influence of Phosphorus. Great susceptibility to external impressions, to light, sound, odors, touch, thunderstorms. Polycythaemia, fatty degeneration, cirrhosis, and caries are pathological states calling for this remedy, inflammations of the respiratory tract. Paralytic symptoms. Ill effects of iodine and excessive use of salt, worse lying on left side.

The first indication for Phosphorus is given by an intense sensation of burning in various parts of the body like the mouth, the lungs, the stomach, the small intestines, the anus, up the spine, the palm of the hand, and even the face. The patient craves for cold food, but this food is vomited as soon as it reaches the stomach. There is an insatiable hunger, an empty gone feeling in the stomach, in the whole abdomen.

The common acid " debility" is very marked in this remedy, producing a nervous exhaustion. Mental debility first, later physical. A congenital soil for the action of Phos. Acid is found in young people who grow rapidly, and who are overtaxed, mentally or physically. It is useful when the body is exposed to acute diseases, excesses grief, loss of vital fluids. Useful in relieving pain of cancer.

An excellent use of phosphoric Acidum is made in curing mental and physical debility and in acute and chronic diseases where the patient is tired in mind and body. The mental debility is a result of nervous exhaustion in persons who have been working overtime at a young age. Physical debility comes as a result of acute disease, sexual excesses, grief, and loss of vital fluids from the body. Haemorrhages in typhoid, therefore require Phosphoric Acidum.

The word NUX VOMICA is derived from Latin word NUX meaning nut and VOMERE meaning vomiting because of the peculiar property of the nut.

Is the greatest of polychrests, because the bulk of its symptoms correspond in similarity with those of the commonest and most frequent of diseases. It is frequently the first remedy, indicated after much dosing, establishing a sort of equilibrium of forces and counteracting chronic effects.

Nux is pre-eminently the remedy for many of the conditions incident to modern life. The typical Nux patient is thin, spare, quick, active, nervous and irritable. He does a good deal of mental work; has mental strains and leads a sedentary life, found in prolonged office work, over study and close application to business with cares and anxieties. This indoor life and mental strain seeks stimulants, coffee, wine, possibly in excess; or again, he hopes to quiet his excitement, by indulging in the sedative effects of tobacco, if not really a victim, to the seductive drugs, like opium etc. Nux is preeminently a male remedy. These conditions produce an irritable, nervous system, hypersensitive and over impressionable, which Nux will do much to soothe and calm. Especially adapted to digestive disturbances, portal congestion and hypochondriacal states depending thereon. Nux patients are easily chilled, avoid open air. Nux always seems to be out of tune, inharmonious spasmodic action.

The main action of this drug is on the outlets of the body where the mucous membrane and the skin meet; these pain as from splinters. Marked improvement of symptoms while riding in a carriage. Acts best on the dark complexioned and past middle life. Syphilis after abuse of mercury. Pains appear and disappear rapidly. All discharges very offensive especially urine, faeces, and perspiration. Persons who have chronic diseases and take cold easily and disposed to diarrhoea. Excessive physical irritability.

The human body has many outlets where the mucous membranes and the skin meet. Any pain on account of problems in these regions is severe. It is a sticking pain. It is a pain as if somebody is piercing the surface with splinters. Nitric Acid is the remedy for problems of this type.

The skin and the mucous membrane join at the corners of the mouth, in the nose and at the anus. On the lips the corners crack, get ulcerated and swollen. In the mouth there are blisters with a lot of pus and swelling. The gums are swollen, ulcerated and spongy. Fissures occur in the canthi. Nitric Acid is the first remedy in such cases.

The prolong taking of excessive salt causes profound nutritive changes to take place in the system, and there arises not only the symptoms of salt retention as evidenced by dropsies and oedemas, but also an alteration in the blood causing a condition of anaemia and leucocytosis. There seems also to be retention in the tissues. It is a great remedy for certain forms of intermittent fever, anaemia, chlorosis, many disturbances of the alimentary tract and skin. Great debility; most weakness felt in the morning in bed. Dry mucous membranes. Constrictive sensation throughout the body. Great weariness and weakness. Oversensitive to all sorts of influences. Hyperthyroidism. Goiter, Addison's disease. Diabetes.

According to Dr. E.B. Nash, Nat Mur is one of the best homoeopathic remedies for anemia. This anaemia can be caused by loss of fluids, by menstrual irregularities, by grief or mental diseases. The patient is pale, emaciated and in spite of eating very well he is anaemic. He suffers from a throbbing headache, soreness while climbing steps, exhaustion or physical exertion, constipation to some degree and overall depression. Some women have scanty flow of blood during menses.

Every organ and tissue of the body is more or less affected by this powerful drug; it transforms healthy cells into inflamed and necrotic cells; decomposes the blood producing a profound anaemia. This is converted into useful life saving and life preserving service if employed homoeopathically, guided by its clear-cut symptoms. The lymphatic system is especially affected with all the membranes and glands, and internal organs, bones, etc. lesions produced by Mercury are very similar to those of syphilis. Very often indicated in the secondary stage of syphilis where there is a febrile chloroanaemia, rheumatoid pains around joints, etc. all mercury symptoms are worse at night, from warmth of bed, from damp, cold, rainy weather, worse during perspiration. It is also known as human 'thermometre'. Sensitive to heat and cold. Breath, excretions and body smell foul. Tendency to pus formation, which is thin, greenish, putrid, streaked with thin blood.

The word LYCOPODIUM is derived from LUCOS meaning wolf and PES meaning the foot, as the shoots has an appearance of the wolfs foot. CLAVATUM derived from Latin word CLAVATUS meaning club-like.

This drug is inert until the spores are crushed. Its wonderful medicinal properties are only disclosed by trituration and succussion. In nearly all cases where Lycopodium is the remedy, some evidence of urinary or digestive disturbance will be found. Lycopodium is adapted more especially to ailments gradually developing functional powers, where the function of the liver is seriously disturbed. Atony. Malnutrition. Mild temperaments of lymphatic constitution, with catarrhal tendencies; older persons, where the skin shows yellowish spots, earthy complexion, uric acid diathesis, etc.; also precocious, weak children. Symptoms characteristically run from right to left, act especially on right side of body, and are worse from 4 to 8 PM.

Lycopodium is most useful in troubles relating to digestion. These troubles arise from the consumption of food, which ferments in the digestive system. That is why Lycopodium relieves a bloated and full abdomen wherein the wind is pressing downwards.

Like all snake poisons, Lachesis decomposes the blood rendering it more fluid; hence a haemorrhagic tendency is marked. Purpura, septic states, diphtheria, and other low forms of disease when the system is thoroughly poisoned and the prostration is marked. Delirium tremens with mucfrtrembling and confusion. Very important medicine during menopause and for patients of a melancholic disposition. Diphtheria carriers. Sensation of tension in various parts.

Lachesis treats the worst of throat problems, hot flushes in women during menopause, and diptheric paralysis. It is indicated in high blood pressure with constriction and in heart disease when the face is purple and bloated. Also religious insanity.

As a red inflammation leads us to use Belladonna, so Lachesis is to be thought of when the colour is purple. The face is purple; the eyes are engorged. An inflamed spot is purple and so are the inflamed glands. Ulceration bleeds, blood coagulates and the surface looks purple. There is extreme sensitivity to touch. The throat is purple and not red because the blood under the skin has coagulated. There is nothing like Lachesis if these indications are present.

Kali Bi is one of the finest remedies for the treatment of sinusitis, in diphtheric croup and in chronic, old cases. The mucous membrane of the nose responds to the administration of Kali Bi in acute as well as chronic cases. The discharge is tough, stringy, green and goes inwards into the throat.

The mucus is very difficult to take out. The patient can be heard from a distance trying to take it out but without success. One dose of Kali Bi. loosens this mucus.

There is pain in the sinuses. There is neuralgia in the orbits above the eyes. The sense of smell has been lost. The nose is stuffed. At times, there is violent sneezing. The patient suffers from chronic inflammation of the frontal sinuses. Only Kali Bi. gives relief and cure to such a patient.

Catarrhal laryngitis cough has a brassy sound. True membranous croup, extending to larynx and nares. Cough with pain in sternum, extending to shoulders. Pain at bifurcation of trachea on coughing from midsternum to back.

The name Ipecacuanha is from the Portuguese meaning, 'Road-side-sick-making plant⁷, and mention of it as a remedy for the bloody flux or dysentery goes back as far as the late sixteenth century.

The principle feature of Ipecacuahna is its persistent nausea and vomiting, which form the chief guiding symptom. Indicated after indigestible food, raisins, cakes, etc. especially indicated in fat children and adults, who are feeble and catch cold in relaxing atmosphere, warm moist weather.

One cannot think of treating persistent nausea without Ipecac. This is a nausea in which there is no relief by vomiting. The patient is as sick after as before. The second major problem for which Ipecac is a great cure is a chest complaint, bronchitis in infants, bronchitis with coarse rattling. Ipecac is also a remedy for infections of the upper respiratory tract wherein a peculiar wheezing sound is produced on breathing out. Old incurable cases of asthma are relieved by Ipecac. Ipecac is useful in uterine haemorrhages.