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Water is the most precious gift of the nature and it is also the most crucial element for sustainability of the life in the earth. India’s total water consumption alone is the higher than any other continents. The Agricultural sector is the largest consumer of water followed by the domestic sector and the industrial sector. This book addresses several aspects of water scarcity and its management to save the world and for a sustainable life. It discusses about irrigation water quality and criteria to determine water quality. It covers management issues and soil responses to the use of irrigation water of varying quality. To make the best use of water for agriculture and to improve water productivity, it needs to adopt modern efficient irrigation method. Drip and sprinkler irrigation is a solution that reduces conveyance and distribution losses and allows higher water use efficiency. One of the chapters discusses about drip irrigation in detail. Due to over exploitation of ground water and erratic nature of monsoon, there has been depletion of ground water across the world. It is discussed here in this book about the ground water and its proper use. This book emphasizes about the wastewater which must be treated to ensure a safe environment and foster public health. Effluent which meets set discharge standards can be appropriately used for aquaculture and also irrigation. This book highlights different types of droughts and their management. In addition, this book also combines the latest information on water stress and frequently encountered abiotic stress in the terrestrial surface. Its deleterious effects on plant growth and productivity. This book further discusses the strategies to improve the agriculture, especially in the climate change situation.

1.1 Introduction Water scarcity is seen as a major constraint to intensify agriculture in a sustainable manner as an attempt to meet the food requirements of a rapidly growing human population. The ever-increasing human population, climate change due to increased emissions of greenhouse gases (GHGs), and intensification of agriculture, are putting severe pressure on the world’s two major non-renewable resources of soil and water, and thus pose a big challenge to produce sufficient food to meet the current food demand. The present world population of 7.3 billion people is predicted to grow to over 9 billion by 2050, with the majority of this population increase occurring in developing countries, most of which already face food shortages. A 70% increase in current agricultural productivity will be required to produce sufficient food if these human population growth predictions prove to be correct. In this context, concerted efforts are being made globally to improve the effectiveness of water which will be used for enhancing the production of irrigated crops. Additionally, efforts are also being made to improve water harvesting and water conservation in rain-fed agriculture. The injudicious use of saline/brackish water is all too often associated with the development of soil salinity, sodicity, ion toxicity, and groundwater pollution. Because of these negative effects, it is important to have a better understanding of exactly how the quality of water influences the management of irrigated agriculture, especially in arid and semi-arid regions.

2.1 Introduction Water is the most precious gift of the nature and it is also the most crucial element for sustainability of the life in the earth. India is the largest user of freshwater in the world. India’s total water consumption alone is the higher than any other continents. The Agricultural sector is the largest consumer of water followed by the domestic sector and the industrial sector. The role of irrigation water as one of the most essential inputs for crop cultivation can’t be denied. As a traditional productive input, it ensures production by acting as an agent of insurance against inadequate and inconsistent monsoon. Ultimately the outcome provides agricultural production stability. Thus, irrigation is of prime importance in cultivation of vegetable crops as it ensures favourable water balance within the root zone in addition to natural precipitation. It fulfils the crop- water demand and improves the crop production and effectiveness of other agricultural inputs. It is also an important limiting factor of crop yield, because of its association with several factors of plant environment, which directly influence the crop growth and development (Yaghi et al., 2013). The various irrigation methods under different system of irrigation differ with regard to extent of control, timeliness and adequacy of supply of irrigation water for crop cultivation. Consequently, the economic benefits and the costs due to these irrigation methods vary among different irrigation systems. The dominant method of irrigation practiced in large parts of the country is surface irrigation (basin, border and furrow) where the entire soil surface is almost f looded without considering the actual consumptive requirements of the crops. Frequent over or under irrigation create the problems of water stress or water logging leading to reduced irrigation efficiency (less than 30%).

3.1 Introduction Groundwater constitutes about 89% of the total fresh water resources in the planet. But in recent years, due to over exploitation of ground water and erratic nature of monsoon, there has been depletion of ground water across the world. Depletion of ground water has reached to the extent that it is virtually impossible to get the water table back. Even though there is a possibility of recharge of water from the other areas, the process is very slow and may take one year to replenish one meter. In view of this management of ground water has become one of the most significant issues in recent times. Added to it, there are also environmental problems such as aqua for mining, salt water intrusion, stream base flow reduction etc. For several reasons the efficient management of ground water resources through market mechanism has become difficult. Against this context the present article attempts to analyze the need for sustainable ground water management in India. The article also briefly discusses the concept of sustainable ground water management, factors affecting ground water availability, different approaches towards developing and using available ground water without adversely affecting the hydro geological balance. Further, the paper highlights strategies for sustainable groundwater management, including development of aquifers, rainwater harvesting and artificial recharge methods. The article offers some relevant policy recommendations for sustainable groundwater management in India.

4.1 Introduction Water pollution is the contamination of water by an excess amount of a substance that can cause harm to human beings and/or the ecosystem. The level of water pollution depends on the abundance of the pollutant, the ecological impact of the pollutant, and the use of the water. Pollutants are derived from biological, chemical, or physical processes. Although natural processes such as volcanic eruptions or evaporation sometimes can cause water pollution, most pollution is derived from human, land-based activities (Figure 4.2). Water pollutants can move through different water reservoirs, as the water carrying them progresses through stages of the water cycle (Figure 4.1). Water residence time (the average time that a water molecule spends in a water reservoir) is very important to pollution problems because it affects pollution potential. Water in rivers has a relatively short residence time, so pollution usually is there only briefly. Of course, pollution in rivers may simply move to another reservoir, such as the ocean, where it can cause further problems. Groundwater is typically characterized by slow flow and longer residence time, which can make groundwater pollution particularly problematic. Finally, pollution residence time can be much greater than the water residence time because a pollutant may be taken up for a long time within the ecosystem or absorbed onto sediment.

5.1 Introduction Out of the many climatic events that influence the earth’s environmental fabric, drought is perhaps the one that is most linked with desertification. Drought is a natural hazard originating from a deficiency of precipitation that results in a water shortage for some activities or some groups and is often associated with other climatic factors (such as high temperatures, high winds and low relative humidity) that can aggravate the severity of the event. Drought differs from aridity in that the latter is restricted to low rainfall regions and is a permanent feature of the climate. Drought occurrences are common in virtually all climatic regimes. Widespread and severe drought conditions in Asia, Latin America and the Caribbean in 2000 have raised serious concerns about the continuing vulnerability of the world community to extended periods of droughts and water shortages. In 2000, major droughts affected much of south-eastern Europe, the Middle East, and the area through central Asia to northern China. Especially hard hit was Afghanistan, Bulgaria, Iraq and the Islamic Republic of Iran and parts of China. In North America, months of above-average temperature coincided with below-normal precipitation through northern Mexico and much of the southern and western regions of the USA, leading to one of the worst wildfires in the past 50 years. By August 2001, much of Western Asia, Central Asia, and the Middle East was suffering the third year of a continuing drought that severely reduced many countries’ crop yields. The countries most affected were Afghanistan, India, Islamic Republic of Iran, Pakistan, and Tajikistan.

6.1 Introduction Water deficit stress is a serious and frequently encountered abiotic stress in the terrestrial surface. Its deleterious effects on plant growth and productivity are well documented. Plant responses to water stress are believed to be complex as these operate at various levels of plant organization. Several in built physiological and biochemical mechanisms provide resistance to plants against stress. An understanding of the processes linked to these mechanisms is vital for optimizing crop growth and productivity under stress. Plants respond and adapt to water stress by altering cellular metabolism, thus invoking stress tolerance. Alteration in endogenous concentrations of growth regulators along with accumulation of osmolytes, modifications in antioxidant cascade, changes in protein profiles and induction of gene expression in plants under stress are important characteristic metabolic changes that invoke stress tolerance at the cellular level. Alteration in endogenous concentrations of plant bio-regulators under stress helps plants through better turgor maintenance and efficient water usage by influencing stomatal functioning, hydraulic conductivity and morphological adaptation. Progress made in plant adaptation to water stress is an outcome of advances made in analytical techniques on endogenous growth regulator analysis and powerful and reliable molecular and genetic techniques.

7.1 Introduction Water is one of the most essential natural resources of the planet. Water is also the most critical resource for sustainable development in most of the developing countries. The quantities that are needed for drinking and sanitation purpose of humans are relatively small, and much larger quantities of water are required for many other purposes. It is essential not only for agriculture, industry and economic growth of a country, but also it is the most important component of the environment and ecosystem, with significant impact on overall wealth and nature conservation. Agricultural and industrial activities critically depend on a sufficient amount of fresh water that is withdrawn from rivers, lakes and groundwater aquifers. Currently, the rapid growth of world population along with the extension of irrigation dependent agriculture, development of industrial sector and climate change are stressing the quantity and quality of the natural water systems. Due to the increasing problems, human have begun to realize that they can no longer follow “use and discard” methodology either with water resources or any other natural resources. As a result, the need for water management has become evident. Climate change has already started to affect the hydrological cycle and the availability of freshwater for agriculture. So, proper water management practices play crucial roles in the food production and the management of ecosystems. Over the last century global irrigated area has increased more than sixfold from approximately 40 million hectares in 1900 to more than 260 million hectares in 2000. Today more than 40% of the world’s food comes from the irrigated cropland which is 18% of the total cultivated crop land. Irrigated area is increased by almost 1% every year and the demand for irrigation water will increase by 13.6% by 2025 (Jensen, 1993). On the other hand about 8-15% of fresh water supply will be diverted from agricultural sector to meet the increased demand of domestic and industrial use. On the other hand the efficiency of irrigation is very low, only 65% of the applied water is used by the crop (Fig. 1). So, to overcome shortage of irrigation water for agriculture, it is essential to increase the water use efficiency in the crop field and to use marginal water for irrigation.