Agricultural, industrial, home, recreational, and environmental activities all use water. Almost all of these human needs necessitate the availability of fresh water resources.
Salt water makes about 97 percent of the world’s water. Fresh water makes up only 3% of the total, with little more than two-thirds frozen in glaciers and polar ice caps. The remaining unfrozen freshwater is found mainly as groundwater, with only a small fraction present above ground or in the air.
Despite the fact that fresh water is a renewable resource, the world’s supply of clean, fresh water is constantly diminishing. In many regions of the world, water demand currently exceeds availability, and as the global population grows, so does water consumption.
Sources of Water resources
– Desalination: Desalination is a man-made method for converting saline water to fresh water. Distillation and reverse osmosis are the most popular desalination methods. Desalination is currently more expensive than most other water sources, and it only covers a small portion of total human use. Only high-valued usage in dry locations is economically viable. The Persian Gulf is where it is most often used.
– Frozen water: Several initiatives to use icebergs as a supply of water have been proposed, however they have always been done solely for the sake of novelty. Surface water is referred to as glacier runoff.
The Himalayas, dubbed “The Roof of the World,” are home to some of the world’s most extensive and rugged high-altitude terrain, as well as the world’s largest glaciers and permafrost outside of the poles. Ten of Asia’s greatest rivers originate there, and more than a billion people rely on them for survival.
– Ground water: Fresh water found in the pore space of soil and rocks is referred to as subsurface water or groundwater. It also includes water that flows beneath the water table in aquifers. Seepage from surface water is a natural source of subsurface water.
Springs and seepage into the oceans are two natural outputs of subsurface water.
Uses of Water
-Agricultural: Irrigation accounts for 69 percent of global water use, with 15-35 percent of irrigation withdrawals being unsustainable. To manufacture enough food to meet one person’s daily dietary needs, around 3,000 liters of water must be changed from liquid to vapor. When compared to the amount required for drinking, which is between two and five liters, this is a significant amount. Food production for the planet’s current population of nearly 7 billion people requires enough water to fill a canal ten meters deep, 100 meters wide, and 7.1 million kilometers long enough to round the globe 180 times.
– Industrial: Industrial water usage is estimated to account for 22% of global water use. Hydroelectric dams, thermoelectric power plants that use water for cooling, mineral and oil refineries that use water in chemical processes, and manufacturing plants that utilize water as a solvent are all major industrial users. Water withdrawal can be very high for certain industries, but consumption is generally much lower than that of agriculture.
– Household: Household water consumption is estimated to account for 8% of global water use.
Drinking water, bathing, cooking, sanitation, and gardening are among them. Basic home water requirements, excluding water for gardening, are estimated to be roughly 50 liters per person per day. Water of adequate quality to be ingested or utilized without risk of immediate or long-term harm is referred to as drinking water. Potable water is the term used to describe this type of water. Even while only a tiny fraction of the water consumed or used in food preparation is of drinking water standard in most modern countries, the water provided to residences, commerce, and industry is all of drinking water standard.
Quality of irrigation water
Irrigation water’s appropriateness is mostly determined by the amount and kind of salts present. Calcium, magnesium, and sodium are the most soluble cations, while chloride, sulphate, and bio carbonate are the most soluble anions. Boron, selenium, molybdenum, and fluorine are the other ions present in trace amounts that are toxic to animals fed on plants produced with high levels of these ions.
Criteria to determine quality of Agricultural Water:
• Electrical conductivity is being used to determine the total salt concentration.
• The sodium adsorption ratio expresses the relative amount of sodium to other cations.
• Bicarbonate content, boron concentration, and percentage of soluble sodium
Management practices for using poor quality water
– Application of gypsum: When chemical additions like gypsum are added to water, they raise the calcium concentration, lowering the sodium-to-calcium ratio and enhancing infiltration rates. The solubility of gypsum and the relative concentration of Na, Mg, and Ca ions in irrigation water are used to calculate the gypsum demand.
– Alternate irrigation strategy: Some crops are sensitive to saline during the germination and establishment stages, but become tolerant afterwards. After the vulnerable stages have been watered with high-quality water, the tolerant stages can be irrigated with low quality saline water.
– Fertilizer application: Many soluble salts are present in high concentrations in fertilizers, manures, and soil amendments. The fertilizer may induce or aggravate a salinity or toxicity problem if it is placed too close to the sprouting seedling or growing plant. As a result, care should be made in both the site and timing of fertilization.
Fertilizers applied in tiny dosages and on a regular basis boost absorption and decrease crop plant damage. Furthermore, the lower the fertilizer’s salt index, the lesser the risk of salt burn and harm to seedlings or young plants.
– Method of sowing: Salinity delays or prevents germination, making it difficult to establish a satisfactory stand. During the key germination stage, proper planting procedures, bed forms, and irrigation management can considerably improve salt control. Seeds must be planted in an area with a lower salt concentration. The slope of the ridge and the bottom of the ridge accumulates less salt.
– Drainage: Ensure proper interior drainage. Depending on the crop and the EC of the water, meet the required leaching requirements. This is required to prevent salt levels in the soil solution from rising to the point where crop yields are harmed. Water test findings and tolerance levels of certain crops can be used to calculate leaching requirements.
Methods of irrigation
The type of irrigation has a direct impact on both water efficiency and salt accumulation. Irrigation water of poor quality is not appropriate for use in sprinkler irrigation. Leaf burn occurs when crops are sprayed with waters containing excessive amounts of particular ions such as Na and Cl. Due to the micro leaching effect in the wetted zone, high frequency irrigation in small amounts, such as drip irrigation, improves water availability and uptake.