Risk management in agricultural water use

Natural resources of sunlight ,water and land constiute the primary life support systems for all forms of life-microbes,vegetation,animals and human beings.The inter-relationship and inter-dependencies among water, land,vegetation and animal resources determine the nature and kind of livelihood support systems.
To balance the natural resources, water play a major role in nature.
Now a day's in India (karnataka (state)) the distribution of rainfall in the state is highly erratic. The annual normal rainfall is 1138mm received over 55 rainy days. It varies from as low as 569mm in the east to as high as 4029mm in west. About 2/3rd of the geographical area of the state receives less than 750mm of rainfall. Even assured rainfall areas of the state experience scarcity of water in recent years.
Average annual surface water flow available in the country is estimated at around 1869 billion cubic meter (bcm). But only about 690bcm of this can be utilized in the addition to the annual replenishable ground water resources of 432bcm.Thus, the total utilizable water resource in the country is assessed at 1122bcm.At the national level the availability of water is declining. Annual internal renewable water resources in India fell by 652 cubic meter per capita just in two years from 1869cubic meter in 1998 to 1244 cubic meter in 2000. It is estimated that our total annual renewable water resources are of the order of some 350 million-hectare meter(mhm) of which around 160 mhm find their way back to the sea as river flow.
Most of the rainfed lands have undulating topography which generates huge proportion of rainfall into run-off (surface flows). This happens even in low rainfall areas (Northern Karnataka and adjoining areas of Andhra Pradesh and Maharashtra with annual rainfall in the range of 300-600mm).
In areas with high run-off, even if the rainfall is very high there is acute water shortage even after rainy seasons, and particularly so in summary months. The drinking water problem has persisted largely due to adoption of cropping pattern with high water demanding crops in some parts of the rainfed areas.
The water resources in the country are unevenly distributed.some regions have abundance while others suffer from acute scarcity. Rainfall in India, the primary source of sweet water is characterized as erratic in quantum intensity and distribution.
The single most important task before the country in the field of India's water resource management is to pay special attention to rainwater conservation, especially which falls on our vast rainfed lands but most of which flows away from it.
The hydrological challenge is: how to relocate rainwater in time so that 4 months' rainwater can be utilized for 12 months' for multiple uses: human and livestock drinking, domestic consumption and life-saving irrigation, on which depends food-security in rainfed areas. Under the low rainfall situation in tropical/subtropical conditions and in the present scenario of depleting water resources, urgent attention is needed for sustainable development and utilization of water resources.
A drought is an extended period of below average precipitation and depleted soil water storage. It is a normal, recurrent feature of the climate, although many consider it a rare and random event. It occurs in virtually all-climatic zones although its characteristics vary. Droughts don't destroy buildings but can have an economically, socially and environmentally devastating effect. They can result in decreased crop yields, decreased drinking water quality and availability, and food shortages.However, they also cause severe economic and social problems due to serious losses in rural productivity and the widespread long-lasting degradation of land and other natural resources.
To overcome this sever problem in the world today, first we must think up recharging rainwater, and protecting the soil fertility.
[1] To recharge the rainwater there must be contour bunds compalsary, by applying bunds we can control soil erosion, reduce speedy surface-flow .It will heal to recharge rainwater.
[2] Speed-breaker type gabion structures to regulate the flow/velocity at appropriate points.
[3] Check-dams to streams.
[4] Gully-control measures with vegetative systems.
Drainage: Different types of drainage Drainage can be either natural or artificial. Many areas have some natural drainage; this means that excess water flows from the farmers' fields to swamps or to lakes and rivers. Natural drainage, however, is often inadequate and artificial or man-made drainage is required. There are two types of artificial drainage: surface drainage and subsurface drainage. Surface drainage. Surface drainage is the removal of excess water from the surface of the land. Shallow ditches, also called open drains normally accomplish this. The shallow ditches discharge into larger and deeper collector drains. In order to facilitate the flow of excess water toward the drains, the field is given an artificial slope by means of land grading. Subsurface drainage. Subsurface drainage is the removal of water from the rootzone. It is accomplished by deep open drains. i. Deep open drains: The excess water from the rootzone flows into the open drains the disadvantage of this type of subsurface drainage is that it makes the use of machinery difficult. ii. Pipe drains :Pipe drains are buried pipes with openings through which the soil water can enter. The pipes convey the water to a collector drain. Drain pipes are made of concrete or plastic. They are usually placed in trenches by machines. In concrete pipes (usually 30 cm long and 5 - 10 cm in diameter) drainage water enters the pipes through the jointsFlexible plastic drains are much longer (up to 200 m) and the water enters through perforations distributed over the entire length of the pipe. iii. Deep open drains versus pipe drains :Open drains use land that otherwise could be used for crops. They restrict the use of machines. They also require a large number of bridges and culverts for road crossings and access to the fields. Open drains require frequent maintenance (weed control, repairs, etc.). In contrast to open drains, pipes cause no loss of cultivable land and maintenance requirements are very limited. The installation costs, however, of pipe drains may be higher due to the materials, the equipment and the skilled manpower involved.
Iv) The drainage’s must come from high lands to low lands. The main trench must be connected to big stream.
v) The government or the donor agency must take pipes manufacture &distribution.
vi) Drip & sprinkler must take into place.
vii) Food storage must be given to grass-root level.
viii) Cropping pattern: cropping pattern must be maintained according to the soil and climate condition. Government must take responsibility of cash&food crops marketing. And see that there must be no huge difference between cash&food crops. Because after green revolution in India, all farmers turned towards cash crops (cotton, sugar cane, wheat, tobacco, arecanut, maize, ECT...) and all traditional crops & vegitable were vanished. Today all agricultural land is degraded due to heavy irrigation. It has already been noted that in the beginning of the water use from canals, there has been a rapid growth, in cropping programs, resulting in increased yields of cereals, millets and oilseeds, sugarcane and other crops. Later, with advent of water as a perennial source in the command areas, it has become a habit to grow constantly paddy and sugarcane as a major crop, irrespective of the land suitability. Monocropping has been the order of the day, which has not only brought soil exhaustion by continuous mining of the same minerals and degrading the soil of the leguminous flora and fauna, but also depriving the best land. Which otherwise would have brought richer dividends with strategy of alternate leguminous and oilseed crops. Salinity, alkalinity, loss of bases like Calcium and Magnesium, structural destruction of the soil, increasing toxic salts and other soil properties have been on a constant increase making these irrigated lands into degraded lands. Degradation has become a natural phenomenon with heavy human interference in the command areas by his thumb rule of applying higher doses of synthetic fertilizers, pesticides, insecticides, weedicides and other quick money devices by increasing the yield of a crop. In this race of higher production, the symbiotic living with nature and keeping a balanced ecosystem has been lost. Soil, which is a living heritage and sustenance of food fodder fiber and fuel have been totally neglected and is used only as a base without any protection and preservation. As a consequence of this, though water has been playing a vital role in increasing crop production has more or less become a factor in soil degradation, resulting in imbalance. The depletion can be seen in many forms. It is physical with the loss of soil structure referred to as physical degradation, chemical with loss of cations and becoming an acid soil referred to as chemical degradation and biological with loss of soil, flora and fauna referred to as biodegradation. In the command areas, all these forms of degradation and a combination of them can be evidenced in the irrigated tracts. Water use efficiency and health of the soil for crop suitability should be coupled up with soil management practices to bring a revolutionary change in LAND USE. Then only, the pedosphere, lithosphere & hydrosphere will be in harmony with the environment.