eChapters

3.1 Introduction

Different types of farm ponds with their characteristics features are discussed in this Chapter. It is observed that farm ponds can be constructed at different sites starting from the plain areas with relatively flat slopes to valley terrain having steep slopes. The choice of a particular type of pond largely depends on the kind of water supply available and on the existing topography of the site selected. In general for valleys with bottom width less than 100 m, barrage ponds may work well whereas valleys with bottom width more than 100 m, diversion ponds find suitable.

3.2 Collection of Basic Information

Basic information on different data relating to the soil, climate, plant, topography, groundwater table, catchment characteristics, and livestock populations are to be collected for the area where pond has to be constructed. Estimation of water supply from different sources and water demand form the pond for various purposes are to be done and a pond water balance study needs to be done before designing a pond in a particular place.

2.1 Introduction

Farm ponds are the most commonly used source of ex-situ water harvesting structures. It has wide adaptability in farmers’ fields and used as handy source for water supply to crop fields. It has been used since time immemorial not only as an assured source of water supply to crops but also to meet demands in other sectors. However, these ponds have wide variations in shape and size as per the method of construction and their suitability for different topographic conditions. Most of the ponds, initially constructed in fields have regular shape. However, as time progresses and because of the poor or no repair and maintenance, these ponds loose their regular shape and become irregular.

1.1 Introduction

Water is the basis of all forms of life. It supports life system not only to the plants but also to all other animals. The embryo from the conception till birth floats in the liquid medium. Cell, the basic unit of life, contains as high as 95- 98% water. Cellular metabolism is controlled by content of water. Majority of this water requirement of the crops is met from different forms of precipitation. However, when the water requirement is not fully met from precipitation, then growth of the crops is affected. This results in reduction of yield of the crops. The reduction in yield depends on the amount of scarcity of water requirement of the crops. Water requirement of crops depend on many factors. It depends on the type of crops, irrigation schedules practiced, soil texture, position of groundwater table below the effective root zone of the crop and management practice followed in crop cultivation. The pulses, oilseeds, vegetables which are also otherwise termed as dry land crops need less water compared to rice which is a water loving crops and perennial crops like sugarcane and banana.

Water requirement of crops is partly met by the upward flux of groundwater. The capillary rise of shallow water table in the form of upward flux helps in meeting the water requirement of crops to some extent. The upward flux depends on the type of the soil, effective root zone depth of the crop, depth of water table below effective root zone depth of the crop and potential gradient of soil moisture suction. The residual soil moisture helps in supporting water requirement of crops also. The heavy soil like clay has more moisture retention capacity than the light soils like sandy soil. The residual soil moisture held in clay soil is released slowly and supports soil moisture to the crops for a longer period than the sandy soil which has less soil moisture retention capacity. After meeting the water requirement of crops from all sources including different forms of precipitation, ground water contribution by capillary rise and residual soil moisture, if there is any shortage of water, then this shortage should be met from other sources which is called as irrigation.

The influence of water quality on the soil and plant growth is related to the chemical and physicalproperties of the soil, the salt tolerance of the crop, the climaticregime of the area and the method,frequencyand the amount of irrigation water applied. Irrigation water quality refers to its suitability and sustainability for use in agricultural crops. The problems thatresultfrom the use of a particular irrigation water, vary both in kind and degree, and are modified by soil, climate and crop as well as by the skill and knowledge of the water user. As a result there is no set limiton water quality, rather itssuitability for use is determined by the conditions of use which affects the accumulation of water constituents andwhichmayrestrictcrop yield.The soilproblems mostcommonlyencountered and used as a basisto evaluate water quality are those related to salinity, water infiltrationrate,toxicityanda group of other miscellaneous problems. Numerous guidelines are available for evaluation of water quality. Time to time some of theseguidelines has been updated with modification of some criteria like SAR to Adj. SAR and the Adj. R_Na and development of new concepts like water qualityIndex (WQI) whichhave increasedour predictability. Thenewguidelines are relied heavily on old ones.The modified guideline by Ayers and Westcot (1985) was foundto be themost reliabletopredict thewaterqualityforirrigation.

Irrigated agriculture is playing a major role in enhancing food and livelihood security of a country. Supply of fresh water which is an importantinput for the sustainable and economic development of agriculture are not enough to meet the requirement of all sectors of economy. Reduced water availability to agriculture from the present share of 85% of country’s water resources to about 70-75% by 2020AD wouldaffect the capacity of the country to meet the food production target, unless supplies are augmented from unconventional sources. For future agriculture there are no alternatives but to rely on non conventional sources for partial alleviation of the forecasted water scarcity. Amongthese sources extraction of marginal quality groundwater and the waste water generatedfromurban and industrial activities have thepotential to augment the water supplies. Many associatedsoil, plant and environmental problems come up when these sources of water are directly used for irrigation. For addressing theseproblems and to get more benefit from thesesourcesof water, the first step is to understand how an irrigation water source affects the soil plantsystem.Thereforeknowledge of irrigationwaterqualityiscriticaltodevelop appropriate site and crop specific comprehensive short term and long term management programs.

3.1 Concepts of Soil Sampling

Samplinginvolvesthe selection fromthe total populationof a subset ofindividuals upon which measurements will be made. The measurements made on this subset (or sample) will then be used to estimate the properties (or parameters) of the total population.Samplingisinherent toanyfield research programinsoilscience because the measurement of the total population is impossible for any realistic study.

Samplingdesign involves theselection of the mostefficient method forchoosing the samples thatwill be used to estimatethe properties of the population. The definition of the population to be sampled is central to the initial formulation of the research study. The sampling design defines how specificelementswill be selected from the population, and these sampled elements form the sample population.

Pedogenetic and soilgeomorphic studies focus on determining the processes thatformed the soilproperties or landscapes under study and the environments that controlled the rates of these processes. Pedonscale studies are closely associated with thedevelopmentof soil taxonomic systems andfocus onvertical, intrapedon processes. Soil geomorphic studies are the interface between quaternary geologyand soil science and soil geomorphologistsfocus on lateral transferprocesses and the historical landscape evolution. Hence sampling is difficult for a particular population and is differentfor differentstudy.

Advances in analyticalchemistry and instrumentalanalytical chemistry in the pastfew decades have significantlyimproved, makingelemental determinations in soil extracts and water samples easier, faster and less challenging for the analyst. For most of the elemental analysis procedures, the more traditional wet chemistryprocedures havebeenreplaced byvarious analytical instrumental procedures that employ either emission or absorption spectrophotometry. The elemental concentration in prepared soil extracts and water samples can be determined by a number of instrumentalanalyticalprocedures.

The trend today is toward greater analytical sophistication, to multielement computer controlled analytical instrumentation, resulting in a less ended understandingof the analytical principlesinvolved, and “black box” concepts of instrument calibration, maintenance, and operation. Preparation of the analyte and suitable adaptation for a method of analysis requires an understanding, by the analyst, of the principle of the method as well as its requirements and limitations. Adequate testing is usually required before putting the method to use, following procedures such as those that have been adapted by the Association of Official Analytical Chemists (AOAC).

It is not possible to cover in adequatedetail every method of analysissuitedfor the elemental concentration determination in soil extracts and water samples. Therefore, the objective here is to provide sufficient background information about the instrumentalprinciples to guide the reader.

Manychemicalreactions innature,particularlyinlivingsystems,occur inaqueous solutions. Reactions are often carried out in the laboratory in aqueoussolution becausethese aregenerallymore rapid in solutionthanwhen puresolid reactions are mixed. Analysisof substancesmaybe qualitative or quantitative in nature. A quantitative analysisis one inwhich the amountor concentrationof a particular species in a sample is determined accurately and precisely.

1.1 Volumetric Analysis

Volumetric analysis is a quantitative analysis. It involves the measurement of the volume of a known solution required to bring about the completion of the reaction witha measuredvolume of the unknown solution.

The reaction used in volumetric analysis must fulfil the followingconditions;

The world is head98ing towards a water crisis. Africa and West Asia are likely to be worst affected by water scarcity, but with increasing population, water may fall short even in the other parts of the world. According to the recent UN report, the supply of clean and fresh water is depleting at such an alarming rate in some regions, that within 30 years, about two third of population will suffer moderate to severe water stress.

In hydrogeomorphological context of social environment the water is an essential natural resource for sustaining life. The available water resources are under tremendous pressure due to increased demands. The time is not far when water, which is the free gift of nature, will become a scare commodity. Therefore, conservation and preservation of water resources are urgently required to be done at priority basis. Water management has always been practiced in our communities since ancient times. But such practices have faded away during the past few decades mainly due to lack awareness. Hydrogeologists feel that the water harvesting practices must be urgently implemented to overcome the problem of water crises. In India the Ministry of water Resources is endeavouring to make rainwater harvesting a part of every day life in villages and cities as a people’s movement. Hydrogeomorphological aspect of social environment include (a) Social - Cultural -Administrative Consideration (b) Education and Training in Hydrogeology for Professionals and Technicians (c) Education for Farmers and Women (d) Education for Masses. These are described as below:

Common groundwater investigations include necessary considerations of the system’s influx sources, flow regime, discharge points and geomorphological characteristics of the area. Often, hydrogeomorphological mapping of an area is required as to determine these characteristics. The primary data can be acquired from the survey of India toposheet map and the satellite images. The secondary data set includes the satellite imageries, the preparation of digital elevation model (DEM) and digitized precipitation maps.

The first step in the procedure of hydrogeomorphological mapping is to calculate the watershed/basin area, which serves as a mask to define the area of interest. The watershed/basin calculation relies on the digital elevation data and assumes that topographic aspect (dip direction of the cell surface) completely controls the extent to which surface flow emanating from each point in the study area can reach the low point in the valley. The calculation of the potential annual recharge of the aquifer combines techniques described above with data for recharge areas, DEM aspect, and precipitation. First, the catchment area of the recharge zones must be calculated in a process similar to the watershed analysis, returning the area associated with the catchment coded as “1”. A simple multiplication overlay with the precipitation data and the catchment areas yields a result giving the amount of precipitation for each catchment cell. Before using the precipitation data, we converted it to meters so as to keep units consistent. The precipitation amounts within the catchment area (i.e. each cell value) are to be summed, yielding the amount of water available for influx into the groundwater system. Finally precipitation per year data can be acquired.

Identifying surface areas of groundwater discharge is based on the observation that such areas provide a relatively constant source of moisture, which is readily exploited by vegetation in semi-arid region. Thus areas with year-round green vegetation are assumed to be indicators of discharge. The relative amount of vegetation in a scene can be estimated by calculating a vegetation index (Reddy et al, 1989 and Tucker 1979).

New techniques and approaches to groundwater studies are always in deep concern with the hydrogeomorphologists. The designing of new techniques or adapting existing techniques with better enhancement to solve practical problems in the study of groundwater are of central concern. One of the recent technical developments include the mathematical model of groundwater flow that has become the most widely used computer-based model in the groundwater industry. Techniques to identify and date recently recharged water that is useful in characterizing the susceptibility of hydrogeologic environments to contamination are utilized by various research groups all over the world.

Geophysical methods for determining the hydraulic properties of fractured rocks gained the importance in the hydrogeomorphic studies. Predicting the movement of water and contaminants through fractured rocks has been one of the most challenging problems in hydrogeomorphology. Besides conventional and above mentioned techniques the techniques discussed in this chapter are Remote Sensing, Geographical Informational system (GIS), Global Positioning System (GPS), Digital Elevation Model (DEM), Groundwater Information System (GWIS), Digital Surface Terrain Modelling (DSTM), Multicriteria evaluation (MCE) and Thermal Infra Red (TIR) Mapping and Microwave Data.

Water is a primary source of life and sustains all human activities such as domestic needs, agriculture, industries etc. The allocation and management of water resources is becoming a difficult task due to increasing demands, decreasing supply and diminishing quality. This calls for judicious use of water resources. The geomorphology describes the environment in which the hydrological processes operate. A strong mutual correlation exists between geomorphological variables and hydrological characteristics. Such relationship can be applied to both surface and groundwater regime. Thus the linking of geomorphological parameters with hydrological characteristics of the basin provides a simple way to understand the hydrogeomorphological behaviour of different basins and particularly of un-gauged basins.

During the last few years various applications of hydrogeomorphology with reference to the Geographic Information System (GIS) and various other techniques have emerged as an extensively effective tool for analyzing and prioritizing natural resource management alternatives. Because natural resource management problems are spatial in nature the GIS technology provides a tool for defining the extent of the problem, and facilitates the design and implementation of alternative management strategies. The GIS is used to estimate the hydrogeomorphological parameters of the watershed, which can be used in watershed planning and management at micro and macro levels. The results of the study can be utilized to infer the hydrological features like runoff potential, infiltration and groundwater recharge of the region. Some of the applications of hydrogeomorphological studies are described below:

The beginning of the 20^th century was heralded by methodological revolution in geomorphological studies brought in by Davis (1899). His classical model of geographical cycle defined by him ‘ as a period of time during which and uplifted landmass undergoes its transformation by the process of land sculpture ending into a low featureless plain (peneplain)’ dominated the geomorphological investigations all over the world throughout 1^st half of the 20^th century.

The statistical techniques by Horton (1932 and 1945) brought quantitative revolution in the field of geomorphology when he presented quantitative analysis of morphometric characteristics of fluvially originated drainage basin. Post 1950 geomorphology has undergone vast change in the methods and approaches to the study of landforms, conceptual framework, paradigm and thrust areas of study. The most outstanding contribution to the advancement of geomorphological knowledge in this period is the adoption of quantitative approach based on deductive scientific method to the study of landforms and processes at short spatial and temporal scales (Strahler, 1956 and Schumm, 1956).

Several attempts have been made in the world in past to classify large territories and landforms into morpho-units. Valuable contributions pertaining to landform analysis have been summarized below: Joerg (1914) subdivided North America into natural regions, Fenneman (1914) established physiographic boundaries and gave physiographic divisions of the United States, whereas Anderson (1941) gave physiographic divisions of Columbia plateau. Howard and Spock (1940) and Weaver (1965) presented the excellent ways of classification of the landforms while Wood and Snell (1960) applied the quantitative systems for the classification of the landforms. However, Linton (1951) and Hammond (1954 and 1965) gave techniques for mapping delineating small scale and large-scale landforms.

Geomorphometric analysis is the measurement of the threedimensional geometry of landforms and has traditionally been applied to watersheds, drainages, hill slopes, beaches, and other groupings of terrain features. In particular basin morphometric parameters have received a lot of attention from hydrologists and geomorphologists since watersheds (catchments) have been used for analysis of various physical ecosystem processes, including soil erosion, deposition, runoff, stream discharge, sediment yield, sedimentation of streams, irradiation by sunlight, evaporation, evapotranspiration, and nutrient distribution. The study of morphometric parameters, which include variables such as average basin slope, the basin elongation ratio, compactness ratio, basin relief and stream density. Some parameters, such as slope length or stream sinuosity, can be used to represent both basin and hill slope, or basin and stream channel properties.

The main task before geomorphologists is to use an ideal unit of the earth surface for the study of its landforms. The search for an ideal areal unit, within which the collection, processing, organization and interpretation of the data of the geometry of landform, particularly of erosional origin can be made has been the main aim of the geomorphologists right from Fennemen (1914), Horton (1932 and 1945), Strahler (1956 and 1957), Miller (1953), Chorley (1957), Schumm (1956), Shreve (1966), Singh (1981), Sarkar (1995), Schumm and Spitz (1996), Sharma and Amin (1996), Iqbaluddin et al (1997) and Raj et al (1999).

Application of the principal of geomorphology provides information, which will be of value in predicating the geometry of aquifers. On weathering and erosion, many geological formations develop landforms that are distinctive in respect of slope continuity of outcrops and symmetry of valley flanks. The surface topographic features of bedrocks can some times be extrapolated to reasonable depths to predict the thickness of alluvium or aeolian sands occurring as valley fill deposits, by treating slope profile as mathematical curves for which equations similar to regression equations can be found (Doornkamp and King, 1971).

The influence of tectonic movements and resultant structural features on landform is of paramount importance for hydrogeomorphologists. The control of structure on landforms and hydrogeological processes are being discussed here. The structural geology concerns with the features such as uniclinal or inclined beds, folds, faults and joints. Of these the structural features like faults, fractures, joints etc appear as linear feature.

Linear features on the surface of the earth have attracted the attention of geologists for over one hundred years. This interest has grown most rapidly since the introduction of aerial photographs into geological studies. Geologists have recently proven that various structural features perceived in remotely sensed images are reliable indicators of geologic resources (Caran et al, 1982). These structures have been used in many applications: petroleum and mineral exploration (Blanchet, 1957); nuclear energy facility siting (Seay, 1979); geothermal assessments (Woodruff et al, 1982); and water resource investigations (Lattman and Parizek, 1964). Lattman and Parizek (1964) established a relationship between the occurrence of groundwater and fracture traces for carbonate aquifers, and in particular zones of localized weathering and increased permeability and porosity underlying these structures.

Groundwater exists at many places beneath the surface of the earth. It is normally hidden from view but, on occasion, can be seen flowing from springs and wells or seeping into tunnels. Certain properties of the various geologic materials control the ability of groundwater to enter into, move through, be stored in, or be extracted from the ground. Therefore, an understanding of geology is necessary in order to gain an understanding of groundwater found within a particular area of investigation. A basic part of the study of the geology of an area includes the preparation of a map showing surfacial exposures of each rock type. Interpretation of the map facilitates the study of the underground configuration, characteristics, and physical properties of these materials. This, in turn, enables the evaluation of groundwater storage, movement, and yield, as well as the identification of areas of ground water quality problems, recharge, and extraction.

The fundamental unit of a geologic study is the geologic formation. A formation has been defined as any assemblage of rocks, which have some character in common, whether of origin, age, or composition. In this sense, the term “rock” is defined as any naturally occurring part of the earth’s crust, made up of aggregate of minerals and includes hard, dense granite, lava ash, clay, sand, and even loose-uncohesive soil.

An aquifer is a geologic formation, a part of a formation, or a group of formations that will yield water. The quantity of ground water that an aquifer will yield to wells depends partly on its thickness, extent, continuity, and homogeneity, and partly on its physical properties of permeability and porosity.

Groundwater is stored in subsurface void spaces below the water table. The geologic material that stores, transmits, and yields groundwater to wells and springs are called aquifers. The key word here is yields. To be an aquifer, it must store and transmit water at rates fast enough to supply reasonable amounts to wells and springs. Therefore, not all groundwater is stored in an aquifer. Productive aquifers can be comprised of sand and gravel, sandstone, limestone and dolomite, or basalt flows, whereas fractured igneous or metamorphic rocks are only marginal aquifers.

The classifications of aquifer are given below:

Surface Water Resources

Surface water is a general term describing any water body which is found flowing or standing on the surface, such as streams, rivers, ponds, lakes and reservoirs. Surface water originates from various combinations of sources:

1. Direct precipitation - rainfall which falls directly in the surface water body;
2. Surface runoff - rainfall which has fallen onto the surrounding land and that flows directly over the surface into the water body;
3. Interflow - excess soil moisture which is constantly draining into water body; and
4. Water table discharge - where there is an aquifer below the water body and the water table is high enough, the water will discharge directly from the aquifer into the water body.

The quality and quantity of surface water depends on a combination of climate and geological factors. The recent pattern of rainfall, for example, is important in enclosed water bodies such as lakes and reservoirs where water is collected over a long period and stored. The water storage in streams and rivers is in a constant stage of movement and depend on the weather conditions.

Present day hydrogeomorphological research is the explanation of landscape and landforms: what they are, how they function and have developed with reference to the hydrological conditions. Research is a much more complex undertaking than giving names to landforms or even the study of processes, both in terms of what we mean by process and how explanations are approached. It is worthwhile examining some reasons for this, as it shows the increasing complexity of the subject and lead to ideas of how hydrogeomorphology can be studied. Here are some of the fundamentals required for hydrogeomorphological studies:

Mechanism and Processes

‘Mechanism’ provides explanations in detail by describing physical or chemical effects. ‘Process’ signifies the integration of mechanisms in time. Thus, for example when we talk about ‘fluvial process’ or, more specifically, about the ‘mechanism of saltation’, then we have to discuss about the energy source and processes of carrying the material. A process can thus be viewed as the simultaneous operation of a set of specific mechanisms over a specific time period.

The term hydrogeomorphology can be divided into three terms hydro- means water including both surface and groundwater; geo- means the earth and morphology- is the surface expression of the features in the form of landforms. This means that the hydrogeomorphology is dealing with the aspects of water, rocks and earth’s morphological features (land). Of these water and land are most important natural resources for human beings.

Water is synonymous with life. This is a natural resource and an absolute necessity for the survival of the living beings. Human beings have an organic relationship with water. For living and livelihood, human beings solely depend upon the availability of water. They have an inalienable right on water. This is a community resource and cannot be made a tradable commodity, violating normative law of nature. Water is among the most precious gifts of nature to mankind. Most of the ancient towns of the world grew on the banks of the river, and some of the ancient civilizations are known by the names of rivers. Rivers have always been important sources of drinking water and the means of sustaining human, animal and plant life. Whenever one is dealing with water resources development and utilization, it has to be kept in mind that not only quantity of water but also quality of water is very important. The well being and development of our society is dependent on the availability of water.

Key words : Participatory GIS (P-GIS), Geo-Participatory Rural Appraisal (Geo-PRA) Social Mapping, Resource Mapping, Seasonality Maps, DGPS.

Participatory GIS

Geographical information System (GIS0 and Geographics Information Technologies (GITS) are no more restricted to the elite group of the society. Planners are busy in searching ways in merging community participation with GIS in the context of urban planning, environment equity, sustainable development etc. (Aitken and Michael, 1995, Craig and Ehwood, 1998; Talen, 2000 and Sieber, 2000). In all the cases, common thing is the linking of community participation and GIS in a diversity of social and environmental contexts. Through development, demonstration and modification of methodologies by academics and practitioners the concept of Participatory GIS (P-GIS) emerges. It is an outcome of a spontaneous fusion of participatory forms of development planning with modern information technologies. Experts gave considerable thoughts on the probing questions like whether a bottom up GIS could be successfully developed, how many community participation could be incorporated into GIS and to what context such participation would serve only to legitimize conventional top-down decision making. From these reflections only the concept of people’s participation GIS arose.