eChapters

A reservoir stores water behind a dam and can reduce downstream flooding by temporarily retaining part of the incoming flood volume. Its effectiveness depends on available storage, inflow characteristics, outlet capacity, operating rules, forecasting information, and the timing of releases. Reservoirs may also serve irrigation, municipal supply, hydropower, navigation, recreation, and environmental purposes, making their planning a multipurpose undertaking. This chapter introduces reservoir terminology, classifications, storage zones, capacity determination, site selection, sedimentation, and operating principles. It explains how flood-storage space modifies peak discharge and discusses reservoir routing, release regulation, design limitations, safety considerations, and the role of coordinated reservoir systems in basin-wide flood management.

In this method, plant available sulphur (S) is extracted with 0.15% CaCl₂ and the soluble sulphate is estimated on a colorimeter.

1.1. Soil Resource Evaluation

Soil is the essence of life on the planet Earth. It has sustained humanity and human civilizations through five functions (Karlen et al. 1997) viz., i) sustaining biological activity, diversity and productivity; ii) regulating and partitioning water and solute flow; iii) filtering, buffering, degrading, immobilizing and detoxifying organic and inorganic materials, including industrial and municipal byproducts and atmospheric decomposition; iv) storing and cycling nutrients and other elements within the earth’s biosphere; and v) providing support to socioeconomic structures and protection for archaeological treasures associated with human habitation. Reeling under the pressure of increasing food, fodder, feed, fibre and fuel production, soil has been used as a medium of plant growth with considerable reliance on external supply of major nutrients, irrigation water, plant protection chemicals, etc. Although soil, a product of millions of years of weathering, has supported various forms of terrestrial life, its sustainable management holds the key for meeting the basic requirements of burgeoning population and development commitments. So intense has been the pressure of increasing food, fodder, feed, fibre and fuel production that the soil has been exploited often exceeding its carrying capacity. The soils are increasingly used for agricultural and non-agricultural uses, such as disposal of farm, urban and industrial wastes, ensuring environmental safety etc. This is possible by the judicious use of this resource.

A clear and intimate knowledge of the kinds of soils and their extent of distribution are essential prerequisites in developing rational land use plans for agriculture, forestry, irrigation, drainage, etc. soil resource inventory or mapping provides an insight about their potentials and limitations. It is therefore imperative to prepare an inventory of this resource for developing optimum land use plan and conservation plans.

The hot water soluble method is the most common method to estimate available B content in soil

Reagents

1. Azomethine-H: Dissolve 0.45 g azomethine-H and 1.0 g L-ascorbic acid in about 100 ml de-ionized or redistilled water. If solution is not clear, it should be heated gently on water bath at about 30ºC till it dissolves. A fresh solution should be prepared every week and kept in a refrigerator.
2. Buffer solution: Dissolve 250 g ammonium acetate in 500 ml de-ionized or redistilled water. Adjust the pH to about 5.5 by slowly adding approximately 100 ml glacial acetic acid, with constant stirring.
3. EDTA reagent (0.025 M): Dissolve 9.3 g EDTA in de-ionized or redistilled water and makes the volume up to 1 litre.
4. Standard Boron solution: Dissolve 0.571 g boric acid (H₃BO₃) AR grade in a small volume of deionized water and make volume to 1000 ml to obtain a stock solution of 100 mg B/L.

Principle

Pesticide residues are extracted from soil using a mixture of acetone/water in a soxhlet apparatus for 7-8 hours. This extract can be determined directly by GLC.

Scope: This method is suitable for most OPs, OCs, SPs, and herbicides residue analysis.

Biological activity or index of a soil is the function of number of organisms present in soil and their physiological efficiency. The rate of respiration can be used as an index of the biological activity of soil as it reflects the physiological efficiency of the organisms. Monitoring of dehydrogenase, which are respiratory enzymes and integral part of all soil organisms, will give a measure of biological activity of soil at a given time.

During respiration biological oxidation of reduced compounds occur which is catalyzed by dehydrogenase. In the process TTC gets reduced to a pink coloured compound Triphenyl formazan (TPF) which can be quantitatively extracted by methanol and measured colorimeterically. The soil dehydrogenase activity in the current experiment was measured as per the methods of Cassida, (1977).

Principle

Pesticide residues in milk are derived from the intake of pesticide contaminated feed and fodder.

Scope

This method is suitable for most OPs, OCs, SPs, and herbicides residue analysis.

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).

Acid and alkaline phosphatase enzymes are among the extensively studied phosphatases and classified so because of their optimum activities in acid and alkaline pH ranges, respectively. Acid phosphatase is predominant in acid soil while alkaline phosphatase is dominant in alkaline soils. The colorimetric assay of phosphatase is based on release of p-nitrophenol from hydrolysis of p-nitrophenyl phosphate byaction of phosphatase enzyme in buffered soil solution (buffer pH 6.5 for acid and 11 for alkaline phosphatase assay).

Moisture present in the atmosphere plays a significant role in weather and climate of the region. There are three major components in the atmospheric moisture.

  I. Humidity

 II. Precipitation

III. Evaporation.

Humidity: The terminology related to humidity and concerned with gaseous form of water i.e. water vapour, several expressions of the amount of water vapour in the air is used. They are as follows.