Water is an essential part of all life on the globe. Plant and animal could not live without water. Water ensures food security, livestock security, maintain organic life, industrial production and to conserve the biodiversity and environment. Hence, there could no life without water. With the God’s gifted earth is the only planet, so far we know that it posses water and this makes it fit for human living and other living organisms to exist on it.
This precious substance which are not properly utilize by mankind and increasing demand due to growing population and unsuitable lifestyle, many countries are facing sever water crisis. Year by year per capita availability of water is decreasing which threats to human life in many ways. If proper planning and corrective measures are not taken up in the proper place and proper time many developing countries including India will have to face declining in food production and water security in the near future.
India has enough potential for water resources, but due to improper management of water, destruction of many of our available natural resources which conserves the water, unsuitable lifestyle, over-exploitation of some sectors of available water which lead extreme situation in many parts of the country. At this movement we need to give immediate attention to make sustainable use of the available water resources.
Global Freshwater Scenario
Global freshwater reserves are rapidly depleting and this is expected to significantly impact any densely populated areas of the world. Low to middle income developing regions as well as highly developed countries will face water stress in the future, unless existing water reserves are managed effectively. The total volume of water on planet is 326,000,000 cubic miles. Out of the total water on the earth 97.5% is in the oceans and only 2.5% of the water on earth is freshwater. Nearly 70% of the freshwater on earth is permanently frozen in glaciers and at the polar ice caps. Less than 1% of the world’s fresh water (~0.007% of all water on earth) is accessible for direct human uses. This is the water found in lakes, rivers, reservoirs and those underground sources that are shallow enough to be tapped at an affordable cost.
India’s Water Budget
The basic source of water is precipitation in the form of rainfall or snowfall. India’s average annual rainfall is about 119.4 cm which falls over the geographical area of 328 million-ha, which makes total amount of water to 392 million ha-m. If we include snowfall, if may be rounded off to 400 million-ha-m (M ha-m). Out of the total volume of water 300 M ha-m receives during monsoon months and rest receives during non monsoon months. Out of the total precipitation immediate loss to the evaporation is 70 M ha-m, percolation into the soil is 215 M ha-m and contribution to the surface water is 115 M ha-m.
Total annual available surface water flows in the country is 180 M ha-m. It includes about 20 M ha-m brought in by streams and rivers from catchments lying outside the country. About 45 M ha-m pertains to generate flow from ground water as assessed from river flows during non rainy months. The remaining 115 M ha-m constitutes direct contribution by precipitation of which about 10 M ha-m is received as snowfall.
Utility of surface water
Out of the total surface water of 180 M ha-m available in the country, about 15 M ha-m are stored in various forms of reservoirs and tanks and out of this 5 M ha-m are loss to evaporation and 10 M ha-m are available as utilizable water. The remaining 165 M ha-m of total surface water flow in streams and rivers and about 15 M ha-m are utilize through direct pumping and diversion works, the remaining 150 M ha-m goes to the sea and some adjoining countries.
Soil moisture and ground water recharge
About 215 M ha-m volume of water infiltrates into the soil and about 165 M ha-m volume of water retained in the soil as soil moisture which is essential for the growth of vegetation and remaining 50 M ha-m volume of water percolates to water table and adds to ground water reservoir. Some river water seeps in the adjoining area and adds to ground water. About 5 M ha-m of water are added annual to ground water through seepage from flowing rivers and 12 M ha-m of water are recharge to ground water from different irrigation systems and which makes total ground water available annually to 67 M ha-m.
Out of the total ground water available about 13 M ha-m are extracted for various uses, 45 M ha-m are regenerated to rivers and rest about 9 M ha-m loss through evapotranspiration. The soil moisture available is about 170 M ha-m which consist of 165 M ha-m from precipitation and 5 M ha-m from irrigation. Out of this total 170 M ha-m evaporation losses are 60 M ha-m and evapotranspiration losses are 110 M ha-m. Again out of total evapotranispiration losses from forest and other vegetation constitute 55 M ha-m losses, un-irrigated crops constitute 42 M ha-m and irrigated crops constitute 13 M ha-m.