eBook Chapters

Water Scarcity Issues
The world is running out of clean water. The subsurface water table decreases and surface runoff rises as a result of deforestation. The amount of water stored underground is decreasing as wells are being dug deeper and deeper. As a result of desertification and deforestation, perennial rivers are turning seasonal. There is not enough potable drinking water because of abuse and overuse.
Conserving Water
• In certain situations, manipulating plants, harvesting water, and other techniques might increase the availability of water supplies.
• Water use reduction achieved by the application of water efficiency or conservation techniques; alternatively,
• Better techniques for managing water can either decrease or increase the useful use of water.
• Any activity, behavioral modification, tool, technology, or better design or procedure used to lower water loss, waste, or use is referred to as a water conservation method.
• One method of conserving water is water efficiency.
Among the Objectives of Water Conservation Initiatives
• The goal of sustainability is to guarantee that water extracted from an ecosystem will not be lost faster than it naturally replaces itself for future generations.
• The pumping, delivering, and treating of water results in energy conservation.
• Habitat conservation includes limiting the amount of water used by humans, which lessens the need to construct new dams and other water diversion infrastructure while also preserving freshwater habitats for nearby species and migratory waterflow.

Soil, climate and water decide the nature of crop to be grown in a particular region. While soil and climate can be manipulated to certain extent, there is no substitute of water. Water is governed by the hydrological cycle. The major source of water is rainfall which has been reduced over the years due to climate change. The per capita water availability in India was 4944 m3 in 1955 which has been reduced to 1750 m³ now and is expected to come down to 1500 m³ by 2025.

Introduction

The climatic elements such as solar radiation, temperature, precipitation, humidity, evaporation, evapotranspiration and wind velocity affect growth and development of saplings. These climatic factors are not favourable for successful propagation of various horticultural crops in arid region. The main climatic features of Indian hot arid agro-ecosystem is high wind speed, sand storm and high temperature during summers up to 48-50oC  and during winter season temperature falls to the 2-3^°C, low atmospheric humidity i.e. 20-30% during maximum period of the year. Moreover the relative humidity goes down to below 10 per cent during summer months.

Abstract

In the emerging era of wide spread use of IT tools, up-to-date information on water resources is the key to support economic development, conserve the nature as well as to improve the quality of life. Due to rapid rise in population  and food demand, growing economy and improving living standards; the pressure on our water resources is increasing and it will become scarce in the coming decades if not managed at this stage in a integrated way. Water resources management requires a multi-disciplinary approach that combines a collection of technical tools and expertise along with stakeholders of diverse interests and priorities in planning and management and an operational water resources information system at national level is the first requirement.

When rocks and minerals under go weathering process large quantities of soluble salts are formed. In humid regions these salts are washed down to the ground water and to the sea. But in arid and semi arid regions they accumulate in the soil. Excessive irrigation and poor water management are the two chief causes of water logging and salt accumulation. An accumulation of salts in soil leads to unfavourable soil water-air relationship and effect the crop production.

The following are the main causes which leads to development of salty soils (salinity or alkalinity)

Water is a critical input for agricultural production and plays an important role in sustainable agriculture and food security. Agriculture is the principal user of water, accounting for around 70% of total withdrawals. Producing each calorie of food requires approximately one litre of water.

Increasing population, declining natural resources, changing climate and political stability are the major threat to our food, nutritional as well as environmental security. It is expected that India’s population will boom to 1.5 billion by 2030 and to feed them we need approximately 341mt food grain including 315 mt cereals and 26mt pulses) (Kumar et al., 2016).

The coastal agro ecosystem is very important among the different agro ecosystems of our country both economically and environmentally. It spans over a length of 8129 sq. km. covering 9 states and 2 Island ecosystems. Agriculture and allied activities constitute the single largest component of India’s economy, contributing nearly 27 per cent of the total Gross Domestic Product (GDP) in the year 1999-2000 (TERI, 2002). Agriculture exports accounts for 13 to 18 per cent of total annual exports of the country (MoF, 2002). However, given that 62 per cent of the cropped area is still dependent on rainfall (MoEF, 2002). Coastal agricultural region comprises of hinterland, which has a varied geometric and topographical features of mountains valley, coastal plains, riverine systems, climatic conditions, different soils and water bodies, vegetation ranging from rich tropical rain forests to coastal mangroves and a wide range of crops that are cultivated in this region (Table 1). The agro climatic conditions of the coastal zones are congenial for growing various field and horticultural crops.

Relationship Between Plant and Water

Water is the most vital component of the living cells and the basis of plant feeding. Water is also characterized with extraordinary physical properties: it has high specific heat, biggest latent heat of vaporization, very high thermal conductivity and greatest surface tension. Large amounts of heat are tied up with water because of very high specific heat, which contribute to both climatic stability and to heat budgets of the plants and other organisms. Water molecules are integral part of living systems being the solvent for metabolites and structural component of proteins and nucleic acids. In fact, biological macro-molecules cannot exist in their complicated secondary folding or spiralled helixes without the support of hydrogen bonding within their water matrix. The water matrix is also critical for metabolic activity because its properties of hydration permit ready reactivity between molecules in solution as well as between enzymes and their substrates, and the biochemical processes are sensitive to tissue hydration. A reduction of only 20-25 per cent below maximum hydration is sufficient to cause metabolic malfunctioning of many enzymes. It is the substrate for photosynthesis and a product of respiration. Water also helps to buffer plant tissue against fluctuations in the external environment. Plant growth including leaf expansion, organ enlargement, reproductive development and stomata function are all clearly associated with moisture status. Hormonal changes (abscisic acid and cytokinins) in plant body occur with brief reduction in water potential. Water is the also major force in shaping the climatic patterns.

Water management in agriculture is a critical component of ensuring sustainable food production and environmental conservation. This article explores various strategies for conserving water in agricultural practices, examining both traditional methods and modern technological innovations. It addresses the challenges posed by climate change, population growth, and resource scarcity, highlighting the importance of efficient water use. Key strategies discussed include irrigation optimization, soil moisture management, rainwater harvesting, and the adoption of drought-resistant crops. The article also considers policy measures and community-based approaches that support water conservation. By implementing these strategies, the agricultural sector can contribute to sustainable water management and enhance food security.

Introduction

Indian agriculture was contributing 70% to total GDP of the country at pre-independent time, but it decreased drastically year by year and contributed 66.8% in 1960, 55.6% in 1994, 27.1% in 1997 and now a days, it reached only to 25% in 2001. With the advancement of civilization our population is increased, whereas, the cultivable lands is decreased side by side, thus, on an average income of agriculture is decreased.

Gujarat is the leading state to concern with the productivity, production and the area of the some crops like Groundnut, Castor, Cotton, etc. in India. The major part of the state is surrounded by sea coast border, which is 1600 km. Gujarat is popular for production of oilseed crops like groundnut, cotton ; horticultural crops like mango, chiku, coconut, banana, papaya, citrus; spices crops like chili, cumin, funnel etc.

1.0 Introduction

Population in dry lands of the world is increasing; more fresh water is required in order to meet the growing demands. To meet this challenging situation developing new technologies for identification of potential sites for rainwater harvesting (RWH) is an important step towards maximizing water availability in semi-arid areas.

Water is a critical input for crop production. Its optimum availability is important in augmenting and sustaining crop productivity. Lack of adequate supply of water can limit crop yields ranging from 10 to 90% or even be subjected to mortality if moisture go below permanent wilting point. It is also observed that the moisture shortage during some critical crop growth stages would cause severe detrimental effect. This necessitates us to provide irrigation to crops at right quantity and frequency. In other words, irrigation schedule plays key role in optimizing or maximizing crop yield. Moreover, judicious use of irrigation water has potential to enhance the agricultural productivity which in turn would lead to food security. As water resources are getting diminished day by day, the application of water saving techniques would be needed for addressing the food security objectives of the nation.

Irrigation is one facet of the inputs which need to be carefully managed so that profits are maximized. Irrigation plays a major role in any agriculture crop production. One should be aware of different types of irrigation adapted in orchards or crop cultivation to become a successful grower. Irrigation is very important component of crop cultivation as sufficient moisture must be maintained in the soil for obtaining the optimum growth and good quality yield. The aim of irrigating a plant should be to wet the entire root zone without allowing any wastage of water beyond the root zone.

Irrigation is one facet of the inputs which need to be carefully managed so that profits are maximized. Irrigation plays a major role in any agriculture crop production. One should be aware of different types of irrigation adapted in orchards or crop cultivation to become a successful grower. Irrigation is very important component of crop cultivation as sufficient moisture must be maintained in the soil for obtaining the optimum growth and good quality yield. The aim of irrigating a plant should be to wet the entire root zone without allowing any wastage of water beyond the root zone. The irrigation systems have to be properly devised so that the water requirements of the trees are met at the minimum expenditure without any wastage of water. Irrigation practices can be improved if a range of important factors like crop type, crop water requirements, climatic conditions, soil type, water quality, method of irrigation are taken into account.

Crop type

The type of horticultural crops grown influences irrigation practices. Annual vegetable and melon crops have high water requirement, hence irrigation management is extremely critical to their productivity during their relatively short life span (10-20 weeks). Perennial fruit crops tend to require less water and management, although critical, is not generally as critical as for annual crops.

Pulses can be grouped into kharif and rabi pulses according to their temperature requirements. In India chick pea, pea, lentil and beans require relatively less temperature and are grown in rabi season, whereas others are confined to kharif season. However, kharif pulses can also be grown in pre-rabi on stored soil moisture or as irrigated crops in rabi and summer seasons.

Pulse crops have long tap root system which extracts soil moisture from deeper layers. Water uptake across the depth of rooting zone is not uniform. In general 40 per cent of the total water uptake occurs from first one fourth of the rooting zone, 30 per cent from the second, 20 per cent from the third and remaining 10 per cent from the last one-fourth region of total rooting depth (Nageshwararao and Writ, 1994). Plants often maintain higher root length densities than required in the surface layers to facilitate rapid uptake of recent rain/irrigation before it evaporates.

India is a major exporter of vegetables with 10th position in the world. In the past, the Dexport of Indian vegetables was restricted to potatoes and fresh onions, however, now, the Government of India finds great opportunities for expanding exports of several vegetables including lettuce, fresh peppers, tomatoes, squashes, gherkins, etc. Under World Trade Organization (WTO) regime, the development of stronger seed industry and improved production technology will give India a competitive edge in global market. New opportunities and challenges are emerging every day in the dynamic and global vegetable-based industries. However, such opportunities can be harnessed only if assured quality, in terms of organic farming and reduced pesticide residues, is maintained (Shanmugasundaram, 2004).

Introduction
Surface irrigation is the distribution of water using open canals in which water flows by gravity. This type of irrigation, which includes flood irrigation, requires relatively flat fields and deep soils.
A good irrigation will ensure a uniform and homogenous distribution of water in small and regular doses. The status of moisture in the soil also aims at maintaining the relative humidity in a plot at a stable level, to limit the development of weeds and pathogens. Irrigation is also used to avoid the transmission of phyto-sanitary problems or the leaching of pesticides.
The volumes of water to apply depend on the climatic conditions, the frequencies of the applications, the soil type and the irrigation method. The choice must take into account the efficiency of each method, the water availability, the installation and running costs, the maintenance needs, the spatial requirements and whether it’s possible to work while the field is irrigated.
Water Management Practices of Different Crops Rice
Total water requirement is 1100-1250
The daily consumptive use of rice varies from 6-10 mm and total water is ranges from 1100 to 1250 mm depending upon the agro climatic situation. Of

17.1 Rice

Rice culture at present dominates irrigated agriculture. About 64% of the irrigation water resources in Andhra Pradesh are used for cultivation of rice. An adequate water supply is one of the most important factors in rice production. In many parts of India including Andhra Pradesh rice plants suffer from either too much or too little water because of irregular rainfall and land topography.

Percolation losses in rice fields

Percolation losses are a function of the local soil and topographic conditions. Therefore, at any time the amount of rainfall or irrigation water entering the soil becomes greater than its water holding capacity, losses by downward movement of free water (vertical percolation) will occur. Percolation is often defined as the movement of water through saturated soils due to gravity, hydrostatic pressure or both.

Thus where the soil is heavy and the water table is close to the soil surface, percolation losses are low, about 1 – 2 mm/day. On the other hand, where the soil is light and the water table is deep, percolation losses may be high, about 8 – 15 mm/day, or more. About 50 to 60% of applied water to rice is lost by deep percolation. The percolation losses can be reduced by adopting following agronomic practices:

4.1. Introduction

Globally, rice is cultivated on about 165 million ha of land, which provides around 787 million tons of paddy annually (FAO, 2023). In Asia, 708 million tons of paddy is produced from nearly 143 million rice-cultivated areas. Rice crop is grown in a wide range of climates, varied soil types, and hydrological situations. Rice is the lone cereal crop that grows well in floods.

The rice habitat can be divided into four groups based on the hydrology of the rice field: irrigated lowland rice (79~80 million ha), rainfed lowland rice (54~55 million ha), upland rice (14~15 million ha), and flood-prone rice (11~12 million ha) (Table 4.1) (Bouman et al., 2006).

5.1. Introduction

Rice-fallows are a rainfed rice mono-crop production system, where only a single crop (rice) is grown and these lands remain without any crop for the rest of the period of the year (fallow). An estimate shows that rice-fallow areas extended over 22.3 M ha in South Asia, maximum in India ( 88.3%) followed by Bangladesh (8.7%), Nepal (1.4%), Sri Lanka (1.1%), Pakistan (0.5%), and Bhutan (0.02%) (Gumma et al., 2016). The eastern part of India accounts for ~ 84% (9.7 million ha) of the country’s total rice-fallow area (i.e. 11.7 million ha) (Ali et al., 2014; Singh et al., 2017), despite high rainfall during rainy / monsoon season. The reasons are that after the rainy season, irrigation facilities are lacking, very fast depletion of the soil residual moisture due to temperature rise, the poor economic condition of the farmers, and a lack of awareness or knowledge of available technologies. Additionally, delayed harvesting of long-duration rice (150-160 days) results in late sowing of winter crops, which, in turn, exacerbates the temperature and moisture stresses in winter crops (Kumar et al., 2018a; 2018b). Overall, the challenges of growing another crop in rice-fallow areas are the lack of irrigation facilities including declining groundwater levels, the dominance of the long-duration rice varieties cultivation, higher evaporative loss of the residual soil moisture, degradation of soil quality, and poor financial conditions of the farming community with diminishing profit. Recently, climate change with erratic rainfall and delayed monsoon arrival added more challenges for these areas in several places. Deficit soil moisture imposes stress on the crops and negatively affects the winter crops productivity in the rice-fallow system, and several times it results in complete crop failure (Singh et al., 2012; Ghosh et al., 2016).

Agricultural water consumes about 85% of the available water. The future hopes to solve world’s food problem lies in irrigation development. Considering the need of efficient management of water, which is crucial at this point understanding of different efficiencies of the irrigation related experiments or projects, is necessary. Irrigation efficiency is used to evaluate how effectively the available water is used in crop production. Water is conveyed through canal system, watercourses and channels to crop fields. Irrigation is applied to store water in the effective root zone of soil for use of crops. A considerable loss occurs after its diversion from sources to its actual use by crops. The extent of water loss in the process decides the irrigation efficiency. Irrigation efficiency declines as the water loss increases. A high efficiency of an irrigation project is always desirable. The efficiency may be estimated for various operations beginning from diversion of water to its actual use by crops, uniformity in its distribution in the root zone, its use for crop productivity, economics and so on.

Introduction

Crop production system includes the components like soil, climate and plant (genetic) material. Within a particular genetic make up of the crop, productivity of the system is limited either by climatic factors, that is, radiation, temperature and rainfall (water), or by inherent edaphic environment that govern the root development and consequent uptake of water and nutrients. Where soils are cultivated over long periods, the edaphic conditions reach at its low levels. When water, nutrients and CO2 are plentiful, yield is determined by radiation and temperature regimes during the growing season. However, under actual field situations, the yields are limited by factors other than climate, which is water and nutrients. These are not only limited in amounts but also are becoming costlier every year. It is, therefore, important that available fertilizers be used efficiently.

Introduction
Water management is a critical aspect of agricultural science and environmental sustainability, influencing not only the efficiency of food production but also the health of ecosystems and the balance of global water resources. This chapter delves into the principles, techniques, and modern advancements in water management, emphasizing its significance in ensuring food security, conserving vital resources, and combating global warming. The chapter begins by exploring the foundational principles of irrigation, a key component of water management in agriculture. Various irrigation techniques, such as surface, sprinkler, and drip irrigation, are discussed in detail, along with the factors that influence irrigation efficiency, such as soil type, crop needs, and climatic conditions. The importance of optimizing irrigation practices to enhance water use efficiency and minimize waste is underscored. Water use efficiency and conservation strategies form the next major focus of the chapter. As global water resources face increasing pressure from population growth, industrialization, and climate change, the need for efficient water use in agriculture becomes ever more critical. The chapter discusses various methods to improve water use efficiency, including advanced irrigation technologies, crop selection, and soil management practices. Conservation strategies, such as rainwater harvesting, groundwater recharge, and the use of drought-resistant crops, are also explored. Effective drainage systems and waterlogging control are essential for maintaining soil health and agricultural productivity. The chapter provides an overview of drainage system principles, techniques for assessing soil drainage, and strategies for controlling waterlogging, a condition that can severely impact crop yields. The benefits of well-managed drainage systems, including improved soil structure, reduced salinity, and enhanced crop performance, are highlighted. Water quality and salinity management are crucial for sustaining agricultural productivity and preventing soil degradation. The chapter discusses methods for assessing water quality, the impact of salinity on soils and crops, and techniques for managing salinity, such as the use of salt-tolerant crops and soil amendments. Effective water quality management ensures that crops receive the nutrients they need while preventing harmful buildup of salts and other contaminants

Summary
 
This chapter explores different approaches to manage water in rain-fed and irrigated agricultural systems. The first methods support the retention of water and reduce soil erosion. These methods include mulching – the application of a surface coating over the soil – which is usually organic mater. This reduces the damage to soil caused by rain and wind and reduces water loss to evaporation and helps with infiltration. The other methods explored are bunding and terracing.  These approaches are about stopping the flow of water across land to increase the amount of water infiltration into the soil and to reduce or prevent soil run off.  These approaches are labour intensive. A less labour -intensive approach is contour ploughing. This approach is about encouraging farmers and tractor drivers to plough across sloping fields not up and down them. The second group of technologies refers to the introduction of water through irrigation methods.

Irrigation/ Drip/ Fertigation

Pomegranate is considered to be drought hardy fruit crop. Supplemental irrigation, however, is necessary for realizing higher fruit yield and better quality. Irrigation is also used to regulate cropping in pomegranate and the total water applied therefore depends on the desired bahar. In Gujarat and Maharashtra, where Ambe bahar is taken, regular irrigation is required during March to July and irrigation is stopped after the fruit harvest until January. For Mrig bahar crop irrigation is not required from July to September. However, in case of prolonged break in monsoon one or two supplementary irrigation at an interval of 10-15 days during October to December are required. In hasta bahar (September flowering) prolonged rainy season helps in reducing requirement for irrigation 3-4 irrigation at monthly interval after cessation of rainfall are must to obtain good fruit size and higher yield.

Water: Water is one of the most important inputs essential for the production of crops. Plants need it continuously during their life and in huge quantities. It profoundly influences photosynthesis, respiration, absorption, translocation and utilization of mineral nutrients etc. Both its shortage and excess affects the growth and development of a plant directly and consequently its yield and quality.

Soil needs the application of water to:

•    Remove stress condition.

•    Release nutrients in the soil solution for absorption by plants.

•    Leach or wash out injurious salts from the soil.

•    Preparation of land for raising crops.

•    To maintain the temperature and humidity of the soil micro-climate and the activity of soil microbes at optimum level.

Water

• Water constitutes about 35–95% of the different portion of the plants. The leaves of the plant contain 35–95% water, Roots 60–90% and Fleshy fruit contain 70–90% water.
• Water is one of the most important inputs essential for the production of crops.
• Plants need it continuously during their life and in huge quantities.
• It profoundly influences photosynthesis, respiration, absorption, translocation and utilization of mineral nutrients etc.
• Soil needs the application of water to:
• Remove stress condition.
• Release nutrients in the soil solution for absorption by plants.
• Preparation of land for raising crops.
• To maintain the temperature and humidity of the soil micro–climate and the activity of soil microbes at optimum level.

12.1 INTRODUCTION

Water is a factor of prime importance in agriculture industry. Water management is one of the largest and most important inputs into an orchard. An efficient water management refers to artificial application of water, i.e., irrigation in crop root zones in case of soil moisture deficit and removal of water, i.e., drainage from the root zone in case of excess so as to provide the crops a most optimum soil moisture regime for best production. It means how best we are in irrigating and dewatering our fields so that plants are protected from stress as well as water logging (Goswami, 2015). Water resources are continuously overburdened with excessive drafts and water sources are shrinking at faster rate. Groundwater levels are falling at the rates faster than ever. Under this type of circumstances, judicious use of water should be given due attention for water conservation and also in increasing water productivity. Area under horticultural plantations is increasing at exponential rate. The unproductive uplands and low productive midlands and lowlands are brought under fruit based horticultural plantations. For a profitable orchard enterprise, a well-planned irrigation system and efficient water management practice are of utmost importance. Horticultural sector, which includes vegetables, f lowers and fruits, has enormous potential for development owing to varying agro-climatic conditions in India. There is tremendous scope for increase in productivity and quality of horticultural crops, which is necessary to compete in this modern competitive world market. There are many production technologies available to increase the per unit vegetable production and also to increase its quality. One of the widely acceptable, reliable and cost- effective technologies is pressurized irrigation.

Water

Water is one of the most important inputs essential for the production of crops. Plants need it continuously during their life and in huge quantities. It profoundly influences photosynthesis, respiration, absorption, translocation and utilization of mineral nutrients etc. Both its shortage and excess affects the growth and development of a plant directly and consequently its yield and quality.

Soil needs the application of water to:

Remove stress condition.

Release nutrients in the soil solution for absorption by plants.

Leach or wash out injurious salts from the soil.

Preparation of land for raising crops.

To maintain the temperature and humidity of the soil micro-climate and the activity of soil microbes at optimum level.

For the normal aeration and functioning of roots and shoots of the plants.

Excess water needs to be removed for the normal aeration and functioning of roots and shoots of the plants

Excess water creates unworkable soil condition.

As water consists of two positively charged hydrogen ions and a single negatively charged oxygen ion, water is arranged as a polar molecule having positive and negative sides. This molecular polarity leads to water’s high dielectric constant (ability to withstand or balance an electric field). Water is able to dissolve many substances because the polar water molecules align to shield each ion, resisting the recombination of the ions.

Water melon is tender to frost and most of cultivars require relatively long growing season. Plant growth and fruit development are fallowed by higher temperature and abundant sunlight. Atmospheric humidity greatly regulates fruit and foliage diseases.

Taxonomy and Origin: Ealier it was classified as Citrullus Vulgaris Schrod. But in 1963 Thieret called attention to the correct name, C. lanatus (Thumb) Mansf. Africa is centre of origin of the genus. In 1857 David Living Stone, the famous missionary explorer found both bitter and sweet melons grown together in Africa and native people used them as source of water. Cultivation is prehistoric as there are pictures made in ancient Egypt. Early cultivation occurred in Mediterranean area and as far as India also and It was brought to USA by European colonist as early as 1629.

6.1 INTRODUCTION

Water in soils is essential to plant growth, being the medium through which inorganic nutrients are translocated to the root surface and carried through the plant. Most of the water in soils at or near field saturation can be considered as equivalent to bulk water, and only bulk properties need be considered in discussing its movement through soil interstices and its retention in soil capillaries; this is the field with which soil physics deals. But, in the first molecular layer in contact with soil particles, and perhaps for several molecular layers beyond, the behaviour of water molecules is very different from that in the bulk. Strong adsorptive forces can reduce the volatility of these molecules and restrict their mobility. Such an adsorbed layer of water competes with other polar molecules for adsorption sites, and so has an important role in determining the release and retention of fertilizers and pesticides. Such strongly adsorbed layers confer wettability on soils, but hydrophobic surfaces can also be present and these lead to non-wettable soils with serious consequences in run off and inefficient use of precipitation. This region of distinctive molecular interactions between water and soil particles falls within the field of soil chemistry.

Abstract

A transect was performed along the Chubut River (Patagonia) from the Atlantic towards the Andes measuring major water parameters of this drainage area. Samples were taken at different locations of the Chubut River, and also brooks several Andes lakes in the Chubut and Río Negro Provinces as well as from several Andes rivers and mountain creeks. For comparison, the Laguna Cacique Chiquichano in Trelew (Chubut) was investigated. Several physico-chemical parameters were determined (pH, oxygen, nitrogen compounds, conductivity, redox potential, water hardness and spectral transmission), as well as photosynthesis by means of PAM fluorimetry. Water toxicity was assessed with a bioassay based on toxicity-induced changes of the movement behavior of a flagellate.

ABSTRACT

Remote Sensing and Geographical Information System play major role in the water planning of river basins. Varahanadhi is one of the 17 major river basins of Tamilnadu, bounded in North by Palar basin, East by Bay of Bengal and West & South by Ponnaiyar basin. It drains through Thiruvannamalai and Villupuram districts. There are three sub basins viz., Ongur, Nallavur and Varahanadhi sub basins. From Survey of India top sheets, Basin boundary, sub basin boundary maps were generated. Administrative map with district, block boundaries was prepared. GIS software - Arc view, was utilized for this purpose. By using ERDAS IMAGINE, Digital Image processing software, satellite image mosaic of Varahanadhi Basin, Geomorphology, Land use, Wasteland, Structural-Lineament maps were generated. IRS P 6 RESOURCESAT, LISS III and PAN data were used for the thematic map preparation. From the collateral data collected, the thematic maps on Geology, Soil, and annual north east, south west. summer, winter rainfall, irrigation system, pre monsoon and post monsoon groundwater levels, ground water quality were prepared using ARC GIS Software. Relief and Drainage map were also generated in GIS environment. The surface water potential was assessed by rainfall run off method for which geomorphology map interpreted by remote sensing and GIS was utilized. Based on geomorphology and land use maps, draft for irrigation was estimated. Geology, geomorphology, depth to bedrock, rainfall pattern, water level maps were used

to asses groundwater potential and draft. Sectoral demand on power, industry and domestic were made based on collected collateral data. Environmental Impact Assessment was assessed using land use maps and ground water quality maps interpreted from remote sensing data for years 1998 and 2004 were prepared and compared. Wasteland map was prepared to know the extent of wastelands and their types as per National Waste Land Board norms. Remedial measures to convert waste lands into productive lands were also suggested. By superimposing geomorphology and lineament maps upon the wastelands, sites suitable for groundwater development in the waste lands were identified. In the same way by using GIS overlay analysis developmental and action plan maps were also prepared with technical recommendations. By applying remote sensing and GIS techniques the basin water resources assessment, draft to meet out sectoral demands and balance of water available for future use can be decided. Varaganadhi basin is a surplus basin as per the study.

Introduction
Water is chemical substance which important for all living organism to survive on this planet. Water is necessary for all cell of the living organism’s body to performance any normal work. Water covers 71% of the Earth’s surface, most like in oceans and other more water bodies, with 1.6% of water below ground in aquifers and 0.001% in the air as vapors, clouds and precipitation. Some observation have estimated that by 2025 more than half of the world population will be facing water-based vulnerability, a situation which has been called a ‘water crisis’ by the United Nations. A recent report suggests that by 2030, in some developing regions of the world, water desire will be exceed supply by 50%. The total volume of water 1,385 million Km3 on the planet earth, 96.5% is salt water (oceans and seas), the fresh water is mostly ice (24 million Km3). The fresh water available as annual stream flow is 46,768 Km3, that is 0.00034% of the total global water. If there is no intake of water into the body, death can ensue in 7-10 days. Water is also essential to man for maintaining personal hygienic and freedom from disease. Today there are many cities worldwide facing actual shortage of water and nearly 40 percent of the world’s food supply is grown under irrigation and a wide variety of industrial processes depends on water. Water is the most vital element among the natural resources, and is critical for the survival of all living any organisms including human, food production, and economic development. The environment, economic growth and developments are highly affected by water is regional and seasonal availability and the quality of surface and groundwater. The quality of water is affected by any human activities and is declining due to the rise of urbanization, population growth, industrial production, climate change and other factors. The resulting water pollution is a serious surrounding to the well-being of both the Earth and its population. The pressures is increasing population, growth of industries, urbanization, energy intensive life style, loss of forest cover, lack of environmental awareness, lack of implements of environmental rule, regulations and environment improvement plans, untreated effluent discharge from industries and municipalities, use of non

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.

Water is indispensable for our life. About 2/3 of earth is covered with water. No organism can survive without water. So keeping water free from any pollutant is very important. Water is said to be  “polluted” when it is hanged in its quality and composition directly or indirectly by man’s activity so that it becomes less suitable for drinking, domestic, agricultural or any other purpose. Polluted water transmits a large number of diseases in man. They are cholera, typhoid, dysentery, jaundice and other bacterial or viral diseases.  Water becomes polluted by the presence or addition on inorganic or organic substances or biological agents. Soil erosion, leaching of minerals from rocks, decaying of organic matter are natural sources of water pollution. There has been an alarming increase in the degradation of water quality in the recent past in the large cities and industrial areas.

Water pollution can be studied under the following heads—  (i) medium in which it occurs (surface water, ground water); (ii) habitat (lakes, estuaries and open seas); and (iii) type of pollutants (bacterial, metallic, thermal and radioactive).

5.1 Introduction

The source of pollution are many and varied. The most critical are domestic sewage and industrial effluent discharging into rivers, lakes, ponds etc. Treatment facilities for domestic sewage in class 1 cities having population of more than 1,00,0000 and class 2 cities having population between 50,000 and 99,999 can process hardly 10% of the wastewater generated. Wastewater treatment facilities are difficult to quantify due to lack of continuous data. On an average, the treatment capacity in class 1 cities can handle only 60% of the wastewater collected and less than 15% of the total volume of wastewater generated.

The Indian industry has grown annually at an average rate of 5.5% during the last 50 years. Among different industrial sectors, water pollution is concentrated with in a few industrial sub-sectors mainly in the form of toxic wastes and organic pollutants. Out of the total pollution contributed by the industrial sub-sectors, 40% to 45% of the total pollutants can be traced to the processing of industrial chemicals and nearly 40% of the total organic pollution to the food products industry alone. Food products and agro-based industries together contribute 65% to 70% of the total industrial wastewater in terms of organic load. Blair T Bower, consultant, the Urban Institute, USA, remarks: "… If substantial further growth of Asia’s cities cannot be avoided and if the environmental disasters that could be associated with that growth are to be prevented, there is only one alternative: urban environmental quality management must be substantially improved throughout the region".

The total quantity of water used by the domestic and industrial sectors is much less than that consumed for irrigation. However, the wastewater released from the above sectors has a great concentration of pollutants, and is discharged at specific disposal points. Thus, the wastewater generated from domestic and industrial projects causes much more water pollution as compared to any other source.

Ours is a Living Planet because ours is a Water Planet. The health of the Living Planet depends on the health of its water resources. Ironically, the health of its water resources is at stake. And so of its life! The waters of the Earth are in the grips of pollution. Much of the water is already polluted and the rest is increasingly becoming polluted. Water pollution, indeed, is one of the worst problems life on Earth is faced with. Water pollution is halting human progress and is phenomenally affecting all walks of human civilization. Water pollution is even putting a question mark on our sustainable future. This chapter presents the causes, magnitude, and consequences of water pollution and also suggests ways and means to prevent and control water pollution and also attempts to manage water resources.

Introduction
In the global perspective, water contamination is a significant issue. Every day, it is the cause of almost 14,000 deaths. The most valuable natural resource on Earth is water, which makes up more than 70% of its surface.
Definitions
• The term “water pollution” refers to the contamination of water bodies by human activity, which can be detrimental to the plants and organisms that call thesem bodies of water home. It can be characterized as any alteration in the quality of water brought about by human activity that makes it less suitable for any of its positive uses, actual or potential. Excess of any substance or heat that could endanger people, animals, or aquatic lifeMan’s actions alter the quality or composition of water, either directly or indirectly, making it unfit for any purpose.
Sources of Water Pollution
• Point source pollution, which is defined as pollution having a distinct source and point of entry into the water, making it easy to identify. It describes impurities that find their way into a waterway by a covert channel, like a ditch or pipe. For instance, contaminants include metals and organics in municipal and industrial discharge pipelines.

It is estimated that the world requires nearly 70 per cent increase in agriculture production to meet the demand for food by the year 2050 based on current trends in population growth it can be achieved either by increasing land under cultivation (which is not possible), increasing the availability of more water for agriculture and efficient utilisation of available land and water resources. The best available option is to increase in productivity of unit of land for unit water. However, the availability of water for agriculture production cannot be presumed to be same year after year as the major source of water is precipitation more known for its uncertainty due to change in weather patterns from season to season and year to year all over the world. The element of uncertainty is increasing since the beginning of the present century due to climate change under the present circumstance, the crop production is practiced -
• In Irrigated Areas
• In Rainfed Areas
• Under Conserved Moisture Condition Without Any Source Of Irrigation
For increasing crop production under irrigated condition, it is necessary to identify crops and varieties that can produce more yield per unit of water even when there is some decrease in availability of water through irrigation. Therefore, the concept of water production function is used for evaluation of water use efficiency of the crops.

16.1 Introduction

Producing more crops, livestock, fish and forest products per unit of water use is an essence of water productivity and is highly essential for both food and environmental security. A variety of options exist for improving the productivity of water in agriculture through breeding, better management practices and supporting policies and institutions. It is imperative to identify a range of means to enhance water productivity in agriculture, assess their potential and the consequences of their adoption. The production systems to be considered can vary from purely rainfed to irrigated, and from dry zones to semi-humid monsoonal areas.

The productivity of water used in agriculture has almost doubled during 1961 to 2001, It is mainly due to increases in crop yields. Irrigated rice yields doubled and rain-fed wheat yields rose by 160% in that period, with little variation in water consumption per kilo of output. Globally, FAO estimates that water needs for food per capita halved from about 6 m³/day to less than 3 m³/day during 1961 to 2001 which is a significant saving and an equally significant gain for other water users.

According to an estimate, a 1% increase in water productivity in food production enables to save about 24 lit/day of water per head of population, while a 10% increase would equal current domestic water consumption. Importance of saving water in agriculture can be realised from the above observation.

The quality of irrigation water is a crucial factor for long-term soil productivity. Poor quality water if used for a long time can make the soil less productive or even barren, depending on the amount and type of constituents present in it and the texture of the soil in question. Low or marginally saline waters sometimes appear to stimulate crop growth because of the higher amounts of nutrient ions present.

Irrigation water always contains some soluble salts irrespective of its source. The suitability of waters for a specific purpose depends on the types and amounts of dissolved salts. Some of the dissolved salts or other constituents may be useful for crops. However, the quality or suitability of waters for irrigation purposes is assessed in terms of the presence of undesirable constituents, and only in limited situations is irrigation water assessed as a source of plant nutrients. Some of the dissolved ions, such as NO₃^- are useful for crops.

Collection of water samples

A representative water sample (500 ml) is collected in a glass or polyethylene bottle, which should be properly washed/rinsed with the same water that is being sampled. Floating debris or any other contaminant should be avoided while collecting the sample. After proper labelling (e.g. source of water, date of collection, and type of analysis required), the sample should be sent to the laboratory without undue delay.
Some of the anions such as SO₄ and NO₃ may be quite low in irrigation waters. Hence, the large volume of the sample has to be first concentrated by evaporating it to about 100 ml in order to obtain their detectable amounts.

Water is a critical and essential nutrient in poultry production, necessary in greater amounts than any other nutrient. It plays a vital role in various physiological processes such as digestion, metabolism, nutrient transportation, enzymatic and chemical reactions, regulating body temperature, and lubricating joints and organs. Water deprivation can have severe consequences on poultry health, impacting growth, egg production, and even leading to increased mortality if prolonged. Therefore, providing cool, clean water that is free from contaminants is crucial for maintaining poultry health and optimizing farm profitability.

Water Consumption in Poultry

Water consumption in poultry varies under different conditions. Generally, under thermo-neutral conditions, birds will consume approximately twice the amount of water as the amount of feed. However, water intake is influenced by several factors, including environmental temperature, relative humidity, dietary salt and protein levels, the productivity of the birds (growth rate or egg production), and the bird’s ability to reabsorb water in the kidneys. In poultry houses, water consumption tends to be higher in areas with more birds and higher ambient temperatures. Studies indicate that birds prefer water at about 10°C; when water temperatures exceed 27°C, both water intake and daily weight gain are significantly reduced.

Introduction

In the 21st century aquaculture has become one of the most important booming industries in the world. With just a mere contribution to the worlds fish production in 1960’s, and able to contribute to about nearly 50% in 2021, production from aquaculture has increased manifolds. Successful aquaculture relies on creating a suitable environment for growth of aquatic animals. Water quality has to be the most important component for successful aquaculture production. Throughout the farming period, it is necessary to maintain good water quality to ensure high survival and fast growth of cultured species. There are numerous water quality parameters that can impact the well-being of fish and crustaceans, most of which are discussed in this chapter.

Factors like salinity and water temperature play a critical role in assessing the suitability of a location for the cultivation of specific species. Additionally, factors such as alkalinity, turbidity, phosphorus, and nitrogen hold significance due to their impact on plant productivity, which, in turn, affects aquaculture production. As the cultivation progresses, factors like dissolved oxygen, carbon dioxide, ammonia, and others gain importance, as they have the potential to create stress for the cultured animals. This chapter offers an overview of the presence and behavior of each of these variables in both natural water environments and aquaculture ponds.

Water is the most important and abundantly required nutrient for poultry. A continuous supply of clean, fresh and wholesome potable water is essential for poultry. Poultry rearing is becoming more and more intensive with which the chances of the infectious diseases being sustained in the different flocks also increase. Consequently, the need for effective disease control measures to be adopted also gains further importance.

Most often, poultry farmers get alarmed only when the mortality level or death rate in a farm is high. However, even the existence of disease at a sub-clinical level may hinder the performance of the birds, in terms of body weight or egg number; such economic losses, sometimes relatively less and unnoticed, may mean the difference between success or failure in the poultry business. Treatment of a sick flock after the onset of any disease becomes costlier and more frequently impracticable. The recovered birds may not regain their production to original levels and may also continue as source of infection to other healthy birds. Hence, the adage ‘prevention is better than cure’ applies more to poultry industry than any other field.

Fish culture is an age old tradition modified and improved by several scientific inventions. Farmers can easily take up fish culture in village ponds, tanks or any water body and can improve their financial position substantially. Pond aquaculture is the most common method of fish culture throughout the world. For successful aquaculture of fish, molluscs, crustacean and even aquatic plants, the water and soil in which fish are grown should have favourable conditions for their growth which, in turn, is intimately linked with several physical, chemical, biological characteristics of water and management practices adopted. Physical and chemical characters of the soil and water will affect the primary and secondary production of water bodies.

The survival and production of fish in a pond is dependent on the primary and secondary production. Primary production depends on the water quality parameters. Phytoplankton make carbohydrate using sunlight and releases oxygen. This is the major source of energy and oxygen in the ecosystem. Zooplankton which feed on the phytoplankton form major source of food for the fishes.

In Indian aquaculture hatcheries, water quality management is crucial for successful fish seed production. It involves maintaining key parameters like pH, dissolved oxygen, alkalinity, and temperature within the optimal range for the specific fish species being bred. Proper management techniques include monitoring water quality, ensuring adequate water flow, maintaining appropriate feeding practices, implementing aeration and oxygenation systems, and implementing effective waste management.
PARAMETERS
Fish health is closely linked to a delicate equilibrium between the host, potential pathogens, and their aquatic environment. Any disturbance—particularly in water quality—can induce stress in fish, making them more vulnerable to diseases. Therefore, understanding and managing key water quality parameters is essential for optimizing fish growth and survival.
Dissolved Oxygen
The optimal range for dissolved oxygen (DO) in pond water is between 5 mg/ litre and saturation, ensuring healthy fish growth. Aeration is an effective method to improve DO levels. Common aerators include paddle-wheel and aspirator types. In high-aeration ponds, improper placement of aerators along pond edges can generate strong currents that erode the pond bottom. Hence, strategic placement is crucial.
Temperature
Temperature governs fish metabolism by affecting molecular properties and biochemical reaction rates. Ideal temperature ranges vary: 14–18°C for coldwater species and 24–30°C for warmwater species. In controlled environments like hatcheries, water temperature can be regulated. In large ponds, aerator operation during calm, warm afternoons helps disrupt thermal stratification. Tree planting for shade may help regulate temperature but can reduce sunlight penetration, thus lowering pond productivity.