eChapters

3.1 Important Soil Physical Properties

3.1.1 Analysis of Soil Texture

Soil texture refers to the relative proportions of sand, silt, and clay on weight basis. Soil texture was recognized from very early times by experienced farmers from the feel of moist soil placed between the thumb and forefinger. The size groups arbitrarily classified by the International Society of Soil Science (ISSS) into clay (< 0.002 mm), silt (0.002 0.02 mm), fine sand (0.02-0.2 mm), and coarse sand (0.2 2.0 mm). Each soil textural name specifies the weight percent of each fraction falls within certain defined limits. The determination of the percentage of the soil separate present in a sample is called particle-size analysis.

Each type of particle present makes its contribution to the nature of the soil as a whole. Sandy soils are usually quite permeable to air, water, and roots, but they have two important limitations. One is their relatively low water-holding capacity; the second is that they are poor storehouses for plant nutrients. These limitations of sandy soils can, of course, be overcome if both fertilizer and irrigation water are available, but the costs are large.

Clay not only have a large surface area per gram, it also has electrically charged particles. These charges give clay the capacity to attract plant nutrient ions to its surface in forms available to plants, but sand lacks this capacity. Clay holds much more water than sands because they have a large surface area to be coated with water. One important problem with clay soils is their stickiness. When wet, they stick to ploughs, boots, or whatever they contact. Loam and silt loam soils are highly desirable for most uses. They have enough clay to store adequate amount of water and plant nutrients for optimum plant growth but not so much clay as to cause poor aeration or to make working with them difficult.

10.1 Introduction

During rain or heavy irrigation, a part of the rainfall or irrigated water moves below the effective root zone of the crop which moves further below and adds to the water table lying above the impermeable bed or hard rock which is called as  ground  water  reservoir. At  times  the  accumulated  surface  water  is  also recharged to the soil reservoir both naturally as well as artificially that add to the underlying ground water reservoir. This groundwater is an important source of water for irrigation as well as domestic uses. It is the most abundant fresh water resource of the earth. Underground water reservoirs contain large stock of fresh water resources. Total quantity of groundwater within 800 m distance below  the  ground  surface  is  more than  30  times  the  total  water  in  all fresh water lakes, more than 60 times the total water in soil and other unsaturated rock materials, more than 300 times the water vapour in the atmosphere and 3000 times the average volume of all rivers and rivulets in the world (Lenka, 2001). But the distribution of groundwater is not uniform.

11.1 Introduction

The laws governing the flow of water in wells are referred to as the hydraulics of wells. Just like surface water flows from a higher elevation to a lower elevation by gravity, groundwater also flows from a region of higher water table to a region of lower water table. This difference of water table measured by any two piezometers divided by the longitudinal distance between them is called as hydraulic gradient. Hydraulic gradient plays a dominant role in deciding the flow of groundwater. This hydraulic gradient together with the hydraulic conductivity of the aquifer material forms the main law of well hydraulics called as Darcy’s law. An understanding of Darcy’s law together with some other laws as discussed subsequently in this chapter is essential in order to know the discharge of a well in a particular formation. Darcy’s law is valid for studying groundwater flow in alluvial formations. However, it is not valid for aquifers having hard rock areas.

1.    Introduction    302
2.    Raw Materials for Alcohol Production    304

    2.1.    Sugary substrates, 306
    2.2.    Starchy residues (cereal grains), 309
    2.3.    Cellulosic materials (crop residues), 314

3.    Microorganisms for Alcohol Production    316

    3.1.    Comparision of ethanol production by bacteria and yeasts, 318

2.1 Introduction

Precipitation is the general term for all forms of moisture emanating from clouds and then ultimately falling on the land surface. It is the total supply of water derived from the atmosphere in the forms of rain, snow, hail, mist, dew, sleet, fog etc. The liquid form of precipitation is called as rainfall whereas the frozen forms of precipitations are snow, hail and sleet. Of all the different forms of precipitation, rain and snow are the two dominant factors that contribute maximum amount of water. In Indian condition, rainfall is the most important form of precipitation that contributes the highest amount of water causing stream flow. Unless otherwise stated, the term rainfall will be used in this book synonymously with precipitation. It is the primary input vector of the hydrologic cycle. Generally it is expressed as the depth water on a horizontal surface over any specified time interval. If the specified time interval is day, then the amount of precipitation is called as daily precipitation. Similarly, the precipitation being contributed over time interval of a month, season and year is termed as monthly, seasonal or annual precipitation. Its form and quantity are influenced by the action of different climatic factors such as wind, temperature and atmospheric pressure. The study of precipitation forms a major portion of the subject of the hydrometeorology.

2.1    Definition of Droughts
    
2.2    Types of Droughts
    2.2.1    Meteorological Droughts
    2.2.2    Agricultural Droughts
    2.2.3    Hydrological Droughts
    2.2.4    Socio-economic Droughts
    
2.3    Criteria for Classification of Droughts
    Meteorological Droughts
    Agricultural Droughts
    Hydrological Droughts
    
2.4    Data requirements in Drought Analysis
    
2.5    Drought Indices
    2.5.1    Rainfall-based Indices
    2.5.2    Climate Derivate Based Indices
    2.5.3    Remote Sensing Based Indices
    2.5.4    Processes Based Indicators
    
2.6    Assessment of Drought Prone Regions in India
    
2.7    Indicators for Declaration of  Droughts in India
    2.7.1     Rainfall Deficiency
    2.7.2    Area Under Sowing
    2.7.3    Normalized Difference Vegetation Index
    
2.8    Drought Management Procedures in India
    
2.9    Drought Code adopted by Local Governments
    
2.10    Spatial Variability of Droughts and their Frequency of Occurrence in India
    
2.11    Drought Vulnerability Assessment
    
2.12    Vulnerability of Society to Drought
        
References

Key facts

Agriculture
    
·    Agriculture production (plant growth) is highly dependent on climate since crop growth is influenced by solar radiation, temperature and precipitation and sensitive to climate variability and weather extremes (droughts, floods, severe storms).
    
·    Climate change is projected to have an effect on local agriculture and the net result could be harmful (e.g. frequent droughts, salinization of agriculture land due to sea level rise) or beneficial, (e.g. enhance CO₂ and higher yield, longer growing season, increased precipitation) or mixed.
    
·    Climate change or a doubling of GHGs (2 x CO₂) is projected to cause both gains and losses of agriculture land.
    
·    Each crop has a specific temperature range at which vegetative and reproductive growth will proceed at the optimal rate and exposures to extreme temperatures during these phases can impact growth and yield. Higher temperatures during the reproductive stage of development can affect pollen viability, fertilization and grain or fruit formation. 
    
·    Warming generally allow plants to grow faster that are below their optimum temperature, however for cereal crops faster growth means there is less time for the grain itself to grow and mature, reducing yields. 
    
·    Night-time temperatures are rising faster than daytime temperatures and are expected to continue rise in the future. According to International Rice Research Institute (IRRI), Philippines, the rise of night time temperature decreases rice yield by 10% for each 1°C increase in growing-season night time temperature in the dry season.

Key facts
    
•    Pesticides are chemicals that are broadly used to protect crops, livestock and other animals and plants from pests and diseases. They are classified according to the type of pest to be controlled (algicides, herbicides, fungicides and insecticides).
    
•    Commercial production of DDT began in 1943. At that time, DDT was considered to be a wonderful invention. It was cheap to produce, very toxic to insects and much less toxic to mammals and its usage resulted in a sharp decline of mosquito borne diseases. In 1962, it was discovered that DDT was causing egg-shell thinning in bird eggs and thus was leading to the near extinction of bird species such as peregrine falcons and bald eagles.
    
•    Pesticides use has greatly helped to increase and improve the world food production. Use of pesticides also increases farmer’s profits by preventing crop losses due to pest attacks and weed infestation.

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.

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).

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.

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.

8.1 Introduction

The concept of social justice led to a raise the standard of living of the masses. This is only possible by meeting the energy needs of industry, agriculture, transport and domestic use. The energy of demand has been increasing tremendously all over the world science mid – nineteenth century due to rise in industrial and agricultural activities and was being met to a great extent by fossil fuels.

Three factors led the mankind to look for alternative renewable sources of energy like solar, wind, hydro etc. (1) there is a danger that the rate at which the non renewable sources of energies are being consumed presently may lead to a global shortage in the near future. This has already happen in case of oil. (2) Use of fossil fuel involves emission of toxic gases polluting the environment causing health hazards of living being. and (3) the demand and supply gas of energy is continuously widening, thus necessitating to exploit renewable sources of energy.

Out of various renewable energy sources, solar energy has been a promising one and lot of development has been taken in its technology for various uses. The numbers of technology engaged in developing solar energy for meaningful use are aiming to achieve the following objectives-

Introduction 
Chapter 16, “Global Warming and Food Security” delves into the intricate relationship between global warming and food security. The chapter opens by defining the multifaceted concept of food security, which includes availability, access, utilization, and stability. It emphasizes the critical importance of these components in ensuring a stable and reliable food supply. The chapter then explores various challenges to food security, highlighting the impact of rapid population growth, climate change, land and water scarcity, poverty, inequality, and conflicts. It underscores how these challenges are compounded by global warming, which exacerbates environmental stressors such as rising temperatures, altered weather patterns, and extreme weather events. The implications for agriculture are profound, affecting crop yields, livestock health, and overall food production. The section on the causes and consequences of global warming outlines key phenomena such as risi ng temperatures, changing weather patterns, melting glaciers, and ocean acidification. It illustrates how these factors disrupt agricultural systems and food distribution networks, leading to increased food insecurity. To address these issues, the chapter discusses various strategies for enhancing food security in a changing climate. These include adopting climate-smart agricultural practices, diversifying crop and livestock systems, developing climateresilient crop varieties, and implementing efficient water management strategies. It also highlights the importance of policy and institutional interventions, supportive measures for smallholder farmers, and research and development initiatives. The chapter concludes with a discussion on the need for collaboration and partnerships among various stakeholders, including governments, international organizations, and the private sector, to effectively address the dual challenges of global warming and food security. Global warming, a consequence of human-induced climate change, has emerged as one of the most pressing challenges of our time. As the Earth’s average temperature continues to rise, it brings about far-reaching impacts that extend to various sectors, including food and agriculture. The intricate relationship between global warming and agriculture is of paramount importance, as agricultural systems are both vulnerable to climate change and significant contributors to greenhouse gas emissions. Understanding the impacts of global warming on

1. White alkali soils also know as

a. Acid soil                  b. Saline soil

c. Saline sodic soil    d. Sodic soil

8.1 Climate Change

Climate change is a broad term of global negative phenomena as created predominantly by burning of fossil fuels, which add heat-trapping gases to earth’s atmosphere. The over accumulation of greenhouse gases in the atmosphere lead to increased temperature and this is called as global warming. As a result, sea-level rise; ice mass loss in Greenland, Antarctica, Arctic and mountain glaciers worldwide; shifts in flowering/ plant blooming; and extreme weather events occur.

6.1 INTRODUCTION

Besides simple analysis, GIS is useful to do advanced analysis like network analysis, spatial analysis, 3D analysis and modeling. Different softwares are available to perform such analysis and the above mentioned analysis is done in separate modules of the softwares.

6.2 NETWORK ANALYSIS

Network consists of well connected linear features. Roads, railway line, water distribution system, sewer line, streams are some of the examples of networks. These networks consists of nodes and arcs with designated directions and connection with other linear features. Networks are topology based with attributes for the flow of objects like traffic. Road network will be considered for explaining network analysis.

Road map is digitised with nodes and arcs. Signals, accidents are represented as points. Road is represented as line and two or more roads intersect at nodes. Attributes are added to the nodes and lines. Dynamic segmentation model is used for network analysis. It is built on lines of network. In road network analysis, attributes for travel time, one way street, two way street, right turn, impedance are added to the nodes and arcs. A link is the line running between two nodes. Link impedance is the cost of passing through the link. Travel time is different in links in cities due to varying traffic at different locations. Time taken to pass through a known length of link may give the cost but the travel time in a link is not uniform because of varying speed designated in the link as 20 km per hour and 30 km per hour. Hence it is important to consider the length of link and also the travel time. If the speed limit is 20 miles per hour for a length of 2 miles, then the travel time is 6 minutes (2/20x60 minutes). Also tuning in the network is considered. A road may have a maximum of 12 possible turns excluding U turns. There are right turn, left turn, straight way for each road. Also U turn is possible. This turning takes different time depending on the signal. Straight way takes less time but left and right turn may require some more time. If signals is available then signal time should also be taken into account. Fig 6.1 show the possible turns in a road.

5.1 Introduction

A steam can be defined as a flow channel in to which the surface runoff flowing over the land surfaces and base flow/ground flow flowing below the ground surfaces meet. It receives the total flow from a specified basin. Streamflow representing the runoff phase of the hydrologic cycle is the most important basic data for hydrologic studies. Interestingly, stream flow is the only part of the hydrologic cycle that can be measured accurately. Stream flow is a historical data and like rainfall and runoff, it is a stochastic hydrologic variable. It is also called as discharge or rate of flow. Discharge is defined as the volume of water flowing through a cross section in a unit time.

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.

The earth's crust is made up of minerals and rocks. Minerals are inorganic substances with a definite chemical composition, whereas rocks are mixture or aggregates of minerals. Each mineral is composed of certain elements present in fixed proportion. For example, mineral quartz, SiO₂ is a compound of the elements silicon (Si) and oxygen (O) combined in the proportion of 1:2, so its chemical formula is SiO₂, whereas rock granite is a mixture of several minerals like quartz, feldspar etc. Nature has provided unique physical properties to different minerals that can be used to identify them.

4.1 Physical Properties of Minerals

Majority of minerals contain following properties that can be used to identify them in field and in laboratory: crystal habit, cleavage, hardness, density, luster, streak, color, tenacity, magnetism, and taste.

4.1.1 Crystal habit

The faces that develop on a crystal depend on the space available for the crystals to grow. If crystals grow into one another or in a restricted environment, it is possible that no well-formed crystal faces will be developed. However, crystals sometimes develop certain forms more commonly than others, although the symmetry may not be readily apparent from these common forms. The term used to describe general shape of a crystal is habit.

Some common crystal habits are as follows: