eChapters

Flood-control measures aim to reduce the probability of inundation or limit its harmful consequences. Structural measures physically modify water flow or storage and include dams, reservoirs, levees, floodwalls, diversions, channel improvements, detention basins, and watershed-treatment structures. Non-structural measures reduce exposure and vulnerability through forecasting, warnings, zoning, insurance, preparedness, evacuation, public education, land-use control, and disaster-response planning. This chapter classifies and evaluates both groups of measures, explaining their purposes, benefits, limitations, and selection criteria. It emphasizes that no individual intervention provides complete protection. Effective flood-risk reduction normally requires an integrated combination of structures, sound watershed management, reliable information systems, institutional coordination, and community participation.

Flood diversion redirects part or all of an excessive flow away from a vulnerable river reach, settlement, or agricultural area. Water may be conveyed through diversion channels, floodways, canals, tunnels, spillways, or natural depressions and discharged into another river, reservoir, wetland, or safe storage area. A diversion scheme must have sufficient capacity and a dependable control structure while avoiding unacceptable flooding, erosion, sediment deposition, or environmental damage elsewhere. This chapter explains the purpose, principles, and methods of flood diversion. It covers site selection, diversion routes, hydraulic and structural components, design discharge, operational requirements, advantages, limitations, maintenance needs, and the role of diversions within integrated basin-level flood-control planning.

Flood estimation determines the probable magnitude and frequency of flood events for designing hydraulic structures and managing flood risk. Intense rainfall over a catchment generates excess water after interception, infiltration, evaporation, and depression storage have been satisfied. This runoff reaches the drainage system and may cause flooding when channel capacity is inadequate. Reliable estimates help engineers select suitable dimensions for dams, spillways, bridges, culverts, reservoirs, and other protective works. This chapter describes rainfall-based and streamflow-based estimation techniques, including the Rational and Cook’s methods, unit-hydrograph procedures, frequency distributions, Gumbel, log-normal and Log-Pearson Type III analyses, empirical formulae, flow-mass curves, and partial-duration series.

Hydrology examines the occurrence, circulation, distribution, and properties of water in the atmosphere and on Earth. Solar energy drives the hydrologic cycle through evaporation, condensation, precipitation, infiltration, runoff, and groundwater movement. Rainfall first satisfies interception, depression storage, evaporation, and infiltration before excess water begins flowing across the surface and into channels. When runoff entering a river exceeds its conveyance capacity, flooding may occur. This chapter explains clouds, precipitation measurement, rain-gauge networks, rainfall consistency, infiltration, runoff mechanisms, hydrographs, unit hydrographs, empirical runoff models, and stage-discharge relationships. These concepts provide the scientific foundation required for analysing floods and designing appropriate control measures.

Flood management is a continuing process of assessing flood risk and coordinating prevention, preparedness, response, recovery, and adaptation. Unlike flood control, which often emphasizes physical structures, integrated flood management accepts that floods cannot always be eliminated and seeks to balance their risks and beneficial functions. It protects life and property while considering river-basin development, environmental sustainability, social needs, and economic feasibility. This chapter explains flood-management concepts, objectives, purposes, and techniques. It discusses structural and non-structural actions, forecasting, watershed treatment, afforestation, rainwater harvesting, floodplain zoning, community preparedness, institutional responsibilities, interlinking proposals, and government programmes. Emphasis is placed on coordinated, basin-wide and risk-informed decision-making.

Flood routing predicts how a flood hydrograph changes as it passes through a river reach or reservoir. Storage, channel geometry, friction, inflow distribution, and outlet conditions generally reduce, delay, or otherwise modify the flood peak. Routing results help forecast downstream water levels, determine reservoir releases, design spillways and channels, issue warnings, and evaluate flood-control alternatives. This chapter introduces the continuity and storage principles underlying flood routing and distinguishes reservoir routing from channel routing. It discusses hydrologic and hydraulic approaches, including level-pool, Muskingum, and related techniques. Attention is also given to inflow and outflow hydrographs, routing coefficients, travel time, attenuation, data requirements, assumptions, calculations, and practical engineering applications.

9.1 Introduction

Flood water which is in the form of a hydrograph when passes down a river section undergoes several changes in its form. There may be some addition of water to the river section when the flood wave passes down the river section. There may be some diversion of water from the section. Thus, depending on the addition or abstraction of water to the incoming flood water, shape of the flood hydrograph in the downstream section may change. Sometimes channel storage and resistance to flow of water in the channel section also affects the shape of the flood hydrograph.

A flood occurs when water exceeds the carrying capacity of a river, stream, drain, gully, or another natural or artificial channel and spreads over adjoining land. Its severity depends on water volume, depth, velocity, duration, timing, and the vulnerability of affected communities. Prolonged inundation can severely damage crops, property, infrastructure, water supplies, and human and animal life. Night-time floods may be particularly dangerous because warnings and evacuation become difficult. This chapter introduces flood occurrence and mechanisms, India’s and the world’s flood history, flood-prone regions, flood types and causes, major consequences, and the responsibilities of Indian flood-control and forecasting agencies.

7.1 Introduction

Flood is an unusually high stage in a river resulted due to high rainfall or snow melt which causes large flow of runoff in it. During flood, the river overflows the banks and inundates the adjoining areas. Flood causes heavy damages to buildings and hydraulic structures besides causing catastrophic loss to human life and property. It causes great economic loss due to disruption of many structures and damage to agricultural fields. Many forest and aquatic lives are affected by the flood. Hundreds of crores of rupees are spent every year to control, forecast and manage the flood.

This chapter portrays flooding as a geohazard that can be managed with ease through simple and effective measures. Flooding is a recurrent geohazard that affects vast lands in India and elsewhere. Unlike many other geohazards, flooding event and probable area to be affected could be predicted with fairly accurate levels and hence, proper safety measures could be taken easily. However, as flash floods could not be predicted and the nature of flooding hazard that it brings in added danger of health hazard, crop damage and cutting off of supply and communication networks, flooding is as serious threat as any other geohazard. Scientifically designed urbanization and flood control measures are suggested for minimizing the potential impacts of flooding.

INTRODUCTION

Flooding is defined as a temporary submergence of a large area (that normally remains dry) under water by overflowing rivers and reservoirs as a result of heavy rains, high winds, cyclones, storm surges, tsunami, melting of snow or dam burst (Arya et al. 2005). The term “temporary submergence” denotes a time period ranging from few hours to about few months depending on type and location of flooding. Although flooding is a natural phenomenon that plays a major role in replenishing wetlands, recharging groundwater and supports agriculture, extreme demands on natural resources due to population growth, people and their property move closer to water bodies

6.1. Determination of Hydraulic Conductivity of Saturated Soil: Laboratory Methods

Hydraulic conductivity of a saturated soil indicates the ease with which water is transmitted through the soil pores. If a constant water head (h) is maintained on a saturated soil column of length (L) and the volume of water (V) percolating per unit time (t) through per unit cross sectional area (A) to the other end, then according to Darcy’s Law the rate of flow of liquid or flux (q) is proportional to the hydraulic gradient (ΔH/L) across the length of soil column.

Introduction

Pomegranate (Punica granatum L.) is an important fruit crop of hot arid region of the India. It is grown commercially in the states of Maharashtra, Gujarat, Karnataka, Andhra Pradesh, Tamil Nadu, Madhya Pradesh and Rajasthan. India is one of the largest producers of pomegranate in the world. The pomegranate area in arid region is increasing at faster rate due to its incessant demand, drought hardy nature, low cost management and wider adaptability to arid soils. In Rajasthan it is mainly grown in Jaipur, Ajmer, Alwar, Tonk, Sriganganagar, Tonk, Pali, Kota, Jalore, Banswara, Sawai Madhopur, Bhilwara, Jhunjhunu and Sirohi districts in 12,000 ha area (Rathi, 2017). The pomegranate plants flower and provide fruits throughout the year. In Rajasthan pomegranate is harvested in all three seasons during March-April, Aug.-Sep. and Nov.-Dec. However, it needs to be forced into rest period for prolific harvest at a given time. The basic objectives of flower regulation in pomegranate is to manipulate the natural flowering and fruiting in such a way that it produce high yield of quality fruits in desired season with sustainable use of farm resources. Transition of flower from vegetative phase to reproductive phase is critical phase in pomegranate flowering, which determine production efficiency. The differentiations of vegetative tissue to reproductive tissue decide flowering intensity and production efficiency. Withholding of irrigation (moisture stress), plant growth substances, nutrient content along with canopy management are major horticultural interventions for flower regulation which influence flowering. It is based on principles that pomegranate bears three kinds of flowers namely hermaphrodite, intermediate and male flowers (Fig.1) on both new and old growth in three flushes i.e. ambe bahar (Feb.-March), mrig bahar (June-July) and hasta bahar (Sep.-Oct.).

Fluorescein diacetate (3’ 6’-diacetyl-fluorescein) is a fluorescein conjugated to two acetate radicals. This colourless compound is hydrolysed by both free (exoenzymes) and membrane bound enzymes, releasing a coloured end product, fluorescein. This end product absorbs strongly in the visible wavelength (490 nm) and can be measured by spectrophotometry. The enzymes responsible for FDA hydrolysis are plentiful in the soil environment. Non-specific esterases, proteases and lipases, have been shown to hydrolyse FDA. The hydrolysis of FDA by soil enzymes can be estimated by methods of Adam and Duncan (2001).

Abstract

The anomalies observed in the reverine systems have been demonstrated to be the potential tool in deciphering the tectonically active zones. Such various drainage anomalies viz: radial drainages, anomalous compressed meanders, eyed drainage and the youthful floodplains observed in Annamali – Palani - Varushanad hill ranges of the Western Ghats of Tamil Nadu show that the N-S and NE-SW trending faults are tectonically active in the recent years.

Introduction
 
Arid western part of Rajasthan which contains the Indian segment of the Thar Desert, accounts for ~62% of the country’s hot arid area and is a region of low rainfall. Under such physico-climatic situation, fluvial processes function much less frequently and more episodically than the aeolian processes, but their impacts on landforms and society are large, as noticed on several occasions in arid regions. There is a distinct east-west gradient of rainfall and temperature in the region. Along the eastern margin bordering Aravallies, the mean annual rainfall is 500 mm while in the westernmost part at Jaisalmer, it is less than 150 mm. The rainfall is largely monsoon driven which brings 80 - 90 per cent of total rainfall received during the year. There is large inter-annual rainfall variability of rainfall which leads to climatic extremes of drought and floods of different magnitudes. For example on an average, the Thar Desert in India experiences flood-causing rainfall in 2-3 years in a decade, but a maximum of 5 flood causing rainfall years in a decade was recorded during the 1950s, 1970s and the 1990s (Rao et al. 2006).

Abstract
 
Pop sorghum, apart from popping qualities has also shown the potential fodder yielding abilities. A field experiment was conducted at University of Agricultural Sciences, Dharwad, Karnataka during kharif 2001 under rainfed situation.

Water vapour changes to the liquid water through condensation process. Condensation is the direct cause of the various forms of precipitation. It occurs as a result of changes in air volume, temperature, pressure or humidity. Water vapour can also be converted directly into the solid form through a process called sublimation. The latent heat expended in evaporation is liberated in the process of condensation. Four mechanisms may lead to condensation.

Introduction
Food Chains
Food chains are made up of organisms that eat and are devoured by one another as a means of transferring energy from the source in plants. “The transfer of energy from plants through a series of organisms with repeated eating and being eaten” is one definition of it.
A food chain is the movement of energy from producers at one trophic level to consumers at the next. In a food chain, energy moves only in one direction. An understanding of food chains can provide important insights into how ecosystems work.
• Grazing food chain
Grazing food chains and detritus food chains are the two main categories of food chains.
The food chain known as grazing begins with living green plants, moves through grazing herbivores, and ends with carnivores. Such a food chain places an immediate demand on ecosystems for solar radiation. From an energy perspective, these chains are very significant.

Introduction
Chapter 11 delves into the intricate relationship between food sciences, human nutrition, and their collective impact on food security and global sustainability. The science of sustenance, encompassing food processing, preservation, quality, safety, and nutrition, is crucial for understanding how to feed a growing global population while minimizing environmental impact. The chapter begins by exploring food processing and preservation techniques, which are essential for extending the shelf life of food products and preventing food wastage. Traditional and modern food processing methods are discussed, highlighting their role in maintaining food quality and safety. The importance of food preservation is emphasized, along with emerging trends in food technology that address current and future challenges. Food quality and safety are vital components of the food sciences, ensuring that the food consumed by populations is not only nutritious but also free from harmful contaminants. The chapter examines the factors influencing food quality, including environmental conditions, handling practices, and storage methods. The principles of food safety are outlined, addressing the critical need for stringent measures to prevent foodborne illnesses. The challenges in maintaining food safety in the face of global trade and climate change are also discussed. Nutritional requirements and their role in human health are covered in the next section. This part of the chapter introduces fundamental concepts of nutrition, such as macronutrients, micronutrients, and dietary guidelines that promote health and well-being. The importance of balanced diets is underscored, with an emphasis on the need for proper dietary assessment methods to ensure adequate nutrient intake. The concept of food security is then explored, considering the various factors that influence the availability, accessibility, and affordability of food. The chapter discusses strategies for enhancing food security, including improving agricultural practices, reducing food waste, and addressing socio-economic inequalities. The integration of food sciences and human nutrition is presented as a critical approach to achieving sustainable food security. The chapter also examines the impact of food sciences and human nutrition on global warming. Food production, as a significant source of greenhouse gas emissions, is analyzed with respect to its environmental footprint. Strategies for efficient resource utilization, policy advocacy, and research innovation are