14 Geospatial Techniques for Sustainable Water Resource Management

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Objectives

  • To discuss applicability of various Geomatics tools like GPS, Remote sensing and GIS techniques fo watershed mapping and management.
  • Watershed Assessment through thematic maps and Geomorsis techniques.
  • To identify the need of an integrated view of the spatial and non-spatial data in a watershed.
  • T o Understand Watershed Decision Support System in watershed management
     Keywords
     Watershed, Geospatial Techniques, Mapping, Characterization, Remote sensing,GIS, GPS,Thematic Maps

 

  Introduction

 

The rampant growth of population and advancements in life style have tremendously increased the demands for natural resources. These growing demands are putting the resilience of the natural resource base under threat. India being a developing nation lacks the presence of an effective system for the built environment. There is inefficiency in the resource management sector and lack of proper planning has resulted in misuse of resources on a very large scale, therefore the conservation, planning and management of natural resources is very crucial. Watershed management is the study of the relevant characteristics of a watershed, aimed at the sustainable distribution of its resources and the process of creating and implementing plans, programmes and projects to sustain and enhance watershed functions that affect the plant, animal and human communities within a watershed boundary. To ensure the resource conservation, the vertical and horizontal expansion of production.

 

Development through watershed approach is very effective. The study of water resources at the watershed scale is widely adopted as an approach to manage, assess and simulate these important natural resources. Watershed studies conducted using a GIS platform have demonstrated that the spatial analysis capabilities of GIS hold the key to improved watershed modeling techniques. The analytical muscle of GIS, combined with readily available digital elevation data, can be used to automate the watershed modeling process and provide a visual representation of the watershed’s response to existing conditions and proposed improvement scenarios.

 

Watershed Management

 

A watershed is a geographic area in which all sources of water drain to a common surface water body, a region or area bounded peripherally by a divide and draining ultimately to a particular watercourse or body of water (Figure 1). Land and water are the two most valuable and essential resources which forms the basis of all the life and forms key resources in all economic activities ranging from agriculture to industry.

 

Watershed management is no longer the exclusive domain of soil and water conservationists, it now needs equal contribution from social scientists and researchers.

 

    Figure 1. Hillside Watershed

 

Main Objectives of Watershed Management are:

 

1.     To suggest possible exploitation of resources within the limits of tolerance.

 

2.     Conservation of Soil and Water

 

3.     Improved ability of land to hold water

 

4.     Maintaining adequate vegetative cover for controlling soil erosion

 

5.     Rain water harvesting and ground water recharging.

 

Watershed mapping gives information about the natural resources of the particular watershed and also has a great role in watershed management and planning.

 

Watershed approach is holistic, linking upstream and downstream areas.

 

Watershed   management   requires  a three-tier   management   strategy  focusing  on

 

(i)  a micro-regional planning approach, (ii) the analysis and appraisal of the biophysical and socio-economic environs and (iii) agro-ecological zoning. The necessity for a micro-regional approach to planning arises primarily because the actual conditions of watersheds vary, depending on the local, biophysical conditions, population pressure and natural resource conditions. It aims at alleviating habitat and inhabitant impoverishment through a holistic approach of conservation and sustainable exploitation of natural resources in a harmonious co-existence manner. As an integral part of area development programme, land resources development programmes are taken upon micro watershed basis as the shape of the watershed controls, the natural resources like water, soil and productivity of the land for successful implementation of agriculture, forest and other micro level development in each hectare of a watershed the micro watershed and the village becomes the most adaptable unit. For regional planning and management the micro watersheds and villages are the most workable units.

 

Using satellite data and GIS technology, maps of land use/land cover, drainage, soil, etc., will became indispensable to manage natural and human resources. The concept of development of land and water resources on watersheds basis gained importance in India since 1974. Today, India is one of the major providers of the earth observation data in the world in a variety of spatial, spectral and temporal resolutions, meeting the needs of many applications of relevance to national development. The watershed approach is increasingly being deployed in various development programmes to manage the water and land resources like soil and water conservation. Our countries first Watershed Atlas is an outcome of the project “Generation of Database and Implementation of Web enabled Water resources Information System in the Country” short named as India-WRIS, jointly executed by the Central Water Commission (CWC) and National Remote Sensing Centre (NRSC), Indian Space Research Organization (ISRO).

 

The ‘Watershed Atlas of India’, is based on the work of systematic and scientific delineation of hydrological units of the country in hierarchical manner along with analysis of various GIS layers (Figure 2), on 1:50,000 scale will be an important digital database for planning and monitoring of development programmes being implemented in the country on watershed basis. It will serve as a uniform baseline for developing hydrologic unit based data bank to be used for water resources management. Runoff, sedimentation, water balance, evapotranspiration and several other catchment characterization related studies.

 

Role of Geomatics

 

Geomatics is an applied science and a professional discipline. As an applied science it involves an integrated approach to the measurement, analysis, management, and display of geographic and other spatial data. The combination of Geomatics and Remote sensing Information includes:

  1. Integration of natural resources information in conjunction with socio-economic data.
  2. Generation of locale specific action plans for land and water resources.
  3. Analysis of demographic data to assess developmental needs of the region.
  4. Assessment of the existing infrastructure to arrive at developmental schemes.
  5. Generation of variety of derived maps.

There are three important tools of Geomatics 1. GPS 2. Remote Sensing and 3. GIS

 

1. Global Positioning Systems (GPS): A satellite-based geo location system that functions worldwide and is accessible to the public via GPS units. Three most effective GPS system are Signals Broadcast, Triangulation and End Users (Figure 3). GPS Records a location point associated with all observations, it helps with data management. Investigators can easily revisit the same site for long term research allows others to verify results.

 

Figure 3: Signals Broadcast, Triangulation and End User GPS

 

GPS provides worldwide positionally accurate coordinates, thus, useful to establish geographic location and define the context. A way to acquire recent cost-effective in-situ data, GPS is an important tool for monitoring purpose by acquiring data repetitively about earth features and phenomena. GIS helps in visualization of geospatial data, and the visualization is a convenient and effective way to communicate complex information, e.g natural resource, and increase our level of understanding about these resources.

2. Remote Sensing: The acquisition of images and information are remotely sensed, usually by satellites. All the Information stored digitally, transmitted electronically and are fully geo-referenced (Figure 4).

 

Remote sensing techniques can be applied for Watershed Mapping in the following Manner:

  1. Delineation and codification of watershed area.
  2. Watershed characterization and assessing watershed priority, evaluation of problems, potentials and management requirements of various watersheds.
  3. Erosion intensity mapping and identification of erosion prone areas.
  4. Soil, land use/land cover mapping.
  5. Drainage pattern mapping.
  6. Evolving water conservation strategies in a watershed.
  7. Selection of sites for the construction of check dams/reservoirs on streams or streamlets.
  8. Suggesting sites for rain water harvesting structures
  9. Evaluation and monitoring of the impact of the treatment

Figure 4: Remote Sensing for Watershed Attributes Information

 

Remote Sensing and GIS Techniques for Watershed Mapping

 

The induction of modern technologies of geospatial tools like Remote Sensing (RS),Geographic Information System (GIS) and Global Positioning System (GPS) have provided very powerful methods of surveying, identifying, classifying, mapping, monitoring, characterization, and to track changes in the composition, extent, and distribution of several forms of earth resources both renewable and non-renewable, living and non-living in nature.

 

The various parameters of the watershed, i.e. stream network (drainage), physiography, land use, vegetation/forest cover and snow cover can be mapped and monitored using remote sensing data. RS data in conjunction with collateral data helps in delineation of ridge line, characterization, prioritization, identification of vulnerable areas. Technology relating to the collection or processing of data that is associated with location is known as Geospatial Technologies. Remote Sensing (RS) plays a significant role in providing geo-information in a spatial format and also in determining, enhancing and monitoring the overall capacity of the earth. Remote sensing data could be used for a number of applications, such as crop inventory and forecasts; drought and flood damage assessment; land use monitoring and management, etc.

 

The main attributes in watershed management is size, shape, physiography, slope, drainage, soil and landuse, their parameters and relevance are given in the below table (Table 1). RS data in conjunction with collateral data helps in delineation of ridge line, characterization, prioritization, erosion prone areas, etc.

 

 

Table 1 Attributes in Watershed Management

 

3. Geographic Information Systems (GIS): information systems enabling the creation, organization, and presentation of data in a spatially referenced form, as well as the production of maps and charts. The system Synthesizes different types of geospatial data, reveals spatial patterns and Simplifies confirmation of observations by others (Figure and 6).

 

Figure 5. Synthesization of Different Types of Geospatial Data

 

Figure 6: Geospatial Techniques Workflow Watershed Characterization

 

The Watershed Characterization provides an overview of fundamental natural and human characteristics of a watershed. That can be develop by compiling available background information of a watershed, including natural characteristics such as topography, soils, hydrology, etc; and human characteristics such as population, land use, and water uses/systems (Figure 7).

 

The Components of watershed Characterization are following:

 

1.  Drainage and its order,

 

2.  Watershed boundary

 

3.  Area,

 

4.  Perimeter,

 

5.  Area under various drainage order,

 

6.  Length of the stream, etc.

  1. Morphometric Analysis
  1. Laws of drainage
  1. Calculation of various watershed character

 

Watershed characterization is very useful for generating environmental indicators that can be integrated with collateral data and social indicators. i. Synoptic view, Multi-resolution, multi-spectral, repetitive offers appropriate method for quick, unbiased mapping and monitoring of natural resources both in space and time domain.

 

Figure 7. Watershed Characterization

 

Delineating a Watershed with the help of Topography Maps:

 

In order to successfully delineate a watershed boundary, the evaluator will need to visualize the landscape as represented by a topographic map (Figure 8). Each contour line on a topographic map represents a ground elevation or vertical distance above a reference point such as sea level.

 

The following procedure and example will help you locate and connect all of the high points around a watershed on a topographic map.

 

1.  Draw a circle at the outlet or downstream point of the wetland

2.  Put small “X’s” at the high points along both sides of the watercourse,

3.  Starting at the circle that was made in step one, draw a line connecting the “X’s” along one side of the watercourse. This line should always cross the contours at right angles.

4.   Continue the line until it passes around the head of the watershed and down the opposite side of the watercourse. Eventually it will connect with the circle from which you started.

Figure 8. Measuring Watershed Areas

 

There are two widely available methods for measuring the area of a watershed:

 

a. Dot Grid Method- in this method we use the plastic sheet (made of acetate or mylar) having a series of dots printed on it, over the map area to be measured. We count the dots coming within the measured area and multiplies by a factor to determine the area. We can also use the hand mechanical counting device to do the procedure fast.

 

b. Planimeter- In this method we use planimeter device having a hinged mechanical arm. One end of the arm is fixed to a weighted base while the other end has an attached magnifying lens with a cross hair. We spreads the map with the delineated area on a flat surface. After placing the base of the planimeter in a convenient location we trace around the area to be measured with the pointer. A dial or other readout registers the area being measured.

 

Watershed Characterization and Assessment through GIS

 

Remote sensing, with or without GIS technology, has emerged as an indispensable scientific tool for mapping and planning of natural resources (Mahajan and Panwar, 2005). It plays a hastily escalating role in the field of hydrology and sustainable water resources development and management. Remote sensing and GIS based techniques have been extensively applicable in nearly all fields of watershed aspects, like, estimation of evapotranspiration (Bashir et al. 2008), soil erosion (Esteves et al. 2012), rainfall runoff modelling (Rawat et al. 2011), flood management (Mason et al. 2003), irrigation and water management (Saidi et al. 2009).

 

GIS has been widely used in characterization and assessment studies which require a watershed-based approach. Basic physical characteristics of a watershed such as the drainage network and flow paths can be derived from readily available Digital Elevation Models (DEMs) and USGS’s National Hydrography Dataset (NHD) program. This, in conjunction with precipitation and other water quality monitoring data from sources such asEPA’s BASINS database and USGS, enhances development of a watershed action plan and identification of existing and potential pollution problems in the watershed. Data gathered from GPS surveys and from environmental remote sensing systems can be used within a GIS for a successful characterization and assessment of watershed functions and conditions. Information obtained from characterization and assessment studies, primarily in the form of charts and maps, can be combined with other data sets to improve understanding of the complex relationships between natural and human systems as they relate to land and resource use within watersheds. GIS provides a common framework spatial location for watershed management data obtained from a variety of sources. Because watershed data and watershed biophysical processes have spatial dimensions, GIS can be a powerful tool for understanding these processes and for managing potential impacts of human activities. The modelling and visualization capabilities of modern GIS, coupled with the explosive growth of the Internet and the World Wide Web, offer fundamentally new tools to understand the processes and dynamics that shape the physical, biological and chemical environment of watersheds.

 

The linkage between GIS, the Internet, and environmental databases is especially helpful in planning studies where information exchange and feedback on a timely basis is very crucial especially when several different agencies and stakeholders involved.GIS provides a means to investigate problems by allowing modelling various phenomena and functional in examining the causes and consequences in a place-based context, meaning we can analyze complex, integrated issues from local to global scales. All of these systems are useful in addressing the assessment, however, their relevance can vary depending upon the element of continuum (Table 2). However, an integration of such spatial technologies with other analytical approaches is often desirable to produce better information thereby enhancing our understanding for better management of natural resources.

 

Table 2. Relevance of Geospatial Technologies for Assessment Continuum

 

Source: Lovelant et.al, 2000

 

In geospatial techniques the characterization and Mapping of a particular watershed can be done by thematic maps and Geomorsis techniques.

 

    A thematic map focuses in a specific idea or theme. A thematic map illustrates a particular subject and contrasts the general map, in which the variety of geological and geographical phenomena regularly appear together (Figure 9). Thematic maps also emphasize spatial variation of one or a small number of geographic distributions. These distributions may be physical phenomena such as climate or human characteristics such as population density and health issues. Thematic maps serve three primary purposes. First, they provide specific information about particular locations. Second, they provide general information about spatial patterns. Third, they can be used to compare patterns on two or more maps. A thematic map is a map that emphasizes a particular theme or special topic such as the average distribution of rainfall in an area.

 

Map Overlay in Thematic Mapping

 

Storing digital data in multiple “layers” is known as Map overlaying through GIS software, computer-aided design (CAD) packages and spreadsheets we also create layering. The process may produce a new data layer as a product of existing layers for example in the figure agricultural pollution potential of every major watershed in the Pen State have been estimated by overlaying watershed boundaries, the slope of the terrain (calculated from USGS DEMs), soil types (from U.S. Soil Conservation Service data), land use patterns (from the USGS LULC data), and animal loading (livestock wastes estimated from the U.S. Census Bureau’s Census of Agriculture). The Grid overlays combines attributes within grid cells tha align exactly. Misaligned grids must be resampled to common formats. In polygon overlays the intersection of two or more data layers produces new features as polygons. After that all attributes (in different colours) of intersecting polygons are combined (Figure 10 and 11).

Figure 10. Map overlay is a procedure for combining the attributes of intersecting features that are represented in two or more geo registered data layers

 

 

Geomorsis

 

Other than the thematic maps the watershed characterization and mapping work is also done by Geomorsis. Geomorsis is a semi-automatic geo-morphometric analysis package for quantitative analysis of watershed for watershed characterization using GIS (Figure 12). It has six Modules

 

Figure 12: Modules of Geomorsis

1. AUDRALA– In the first Module ordering of the drainage coverage and displays the drainage coverage.

 

2. WATERSHEDSELECTION-For demarcation of a particular watershed we first separate the major drainage area, principal drainage basin and sub-basin for example an area can be divided in several category according to the area. After that Watershed displaysby name or point.

 

3. STAMPARA– In this module we analyse Basin geometry (Aerial length, Maximum order, length of stream, stream frequency, length of stream, total number and length of stream, bifurcation ratio, average length, average bifurcation Ratio and average length ratio).

 

4. BASGEO– This Module is very helpful in measuring Aerial length, Stream Length and overland flow length.

 

5. BASIN GEOMETRY PARAMETERS- Main watershed geometry parameters are :

 

1.     Area and Perimeter of Watershed

 

2.     Aerial, Stream and Overland – Flow Length of Watershed

 

3.     Elongation Ratio

 

4.     Basin Circulatory Ratio

 

5.     Form Factor

 

6.     Compactness Coefficient

 

7.     Rhodentity Factor

 

8.     Drainage Density

 

9.     Stream Frequency

 

10.  Drainage Texture

 

11.  Texture Ratio

 

12.  Lamiscate Ratio

 

The watershed development planning includes strategic planning like delineation and codification of watershed, prioritisation of watersheds, detailed soil inventory of very high and high priority watersheds in the catchments, treatment, evaluation and monitoring of the impact of the treatment etc. Effective data regarding surface water availability for watershed management demands application of geospatial techniques such as remote sensing, image processing techniques and GIS. Watershed management process not only include data related to spatial and temporal attributes but also includes data related with surface water storage, ground water recharge and ground water management, hydrology climatology, agriculture, topography, environmental and socio-economic aspects. There is a need of appropriate modelling and application of modern techniques to integrate Agriculture–Water–Soil– Climate environments to optimize and allocate the land and water resources properly. Suitable measures, data, and modern geospatial techniques and soft computing tools that could be utilized to manage watersheds imply appropriate technologies at the local level and provide watershed services for upstream and downstream areas.

 

The water resource assessment process follows a continuum that involves determining the baseline rates or levels of various phenomena, establishing the trends in these measurements. Key functions that form the process needed to assess the continuum are:

 

1. Mapping: collection of thematic and quantitative baseline data (contemporary orhistorical) in geographic format.

 

2. Measuring: more rigorous mapping process by quantifying and documenting theattributes of phenomena.

 

3. Modeling: process of describing a system under study through precise and typicallymathematical relations of inputs and outputs, and to simulate the present, past orfuture behaviour.

 

4. Monitoring: regular assessment of the conditions by recording the shifts or changes innatural phenomena and human activities.

 

WatershedRestoration Studies and Decision Support System

 

The field of watershed science, particularly watershed planning, is experiencing fundamental changes that are having profound impact on the use of computer-based simulation models in resource planning and management. The dramatically increased availability of powerful, low-cost, and easy-to-use GIS software, and more extensive spatially referenced data, are making GIS an essential tool for watershed planning and management tasks. However, with this increased use has come an increased realization that GIS alone cannot serve all the needs of planning and managing watersheds. This realization has renewed resource planners’ interest in development of decision support systems that combine GIS, spatial and non-spatial data, computer-based biophysical models, knowledge-based (expert) systems, and advanced visualization techniques into integrated systems to support planning and policy analysis functions. As a component of a spatial decision support system, GIS provides very powerful visualization facilities for display and manipulation, giving immediate intuitive evaluation capabilities to which a wide range of non-technical users and decision makers can relate to.

 

GIS has been used for restoration studies ranging from relatively small rural watersheds to heavily urbanized landscapes. Coupled with hydrodynamic and spatially explicit hydrologic/water quality modeling for an example alternatives for restoring a water body or a watershed can be studied by creating digital maps that show existing conditions and comparing them to maps that represent the alternative scenarios. GIS can also provide a platform for collaboration among researchers, watershed stakeholders, and policy makers, significantly improving consensus building and offering the opportunity for collaborative work on interdisciplinary environmental policy questions.

 

Conclusion

 

The future of human being is closely attached with the proper development and conservation of natural resource like Soil and water; hence natural resources have prime importance. In this regard prioritization of watershed on the basis of quantitative analysis of morphometric parameters are crucial one in order to decide sustainable watershed development strategy. Watershed management and development process not only include data related to spatial and temporal attributes but also includes data related with surface water storage, ground water recharge and ground water management, hydrology climatology, agriculture, topography, environmental and socio-economic aspects. The challenging task for natural resources researcher is to combine all the concepts and to prepare entire spatial and non-spatial attribute database by amalgamating the leading edge technologies to form decision making analysis technique. Thus, development of entire watershed management decision support and information system is needed to integrate the Agriculture–Water–Soil–Climate constituents to accomplish the natural resources management and, in turn, sustainable development.

 

The above discussion proves that the spatial analysis capabilities of geospatial technologies holds the key to improved watershed modeling. In the present modules we have discussed the Remote sensing and GIS techniques for watershed mapping and management, applicability of various geospatial technologies like GPS, Remote Sensing and GIS, role of Geomatics in mapping, watershed characterization and its components, watershed Assessment through GIS and use of thematic maps and Geomorsis techniques. We have identified the need for an integrated view of the spatial and non-spatial data in a watershed. Various Geospatial tools holds large potential in the field of regional and micro-level spatial planning particularly in micro-watershed planning and management. These techniques can help pull together various types of disparate data such as remote sensing data, census data, records from different administrative bodies, topographical data and field observations to assist researchers, planners, project officers and decision-makers in resource management.

 

you can view video on Geospatial Techniques for Sustainable Water Resource Management

 

References

  • AISLUS. 1990. Watershed Atlas of India, All India Soil and Land Use Survey, Dept. of Agriculture and Cooperation, Ministry of Agriculture, Govt. of India, New Delhi.
  • CGWB. 2006. Watershed Atlas of India, Central Ground Water Board, Ministry of Water Resources, Govt. of India, New Delhi. India-WRIS. 2012. River Basin Atlas of India, RRSC-W, NRSC/ ISRO, Dept. of Space, Jodhpur.
  • Mahajan, S., Panwar, P. (2005) Land use changes in Ashwani Khad watershed using GIS techniques,Journal of the Indian Society of Remote Sensing, 33(2):227–232.National Water Policy of India, 2002. Ministry of Water Resources, Govt. of India.
  • SLUSI. 2012. Watershed Atlas of India, All India Soil and Land Use Survey, Dept. of Agriculture and Cooperation, Ministry of Agriculture, Govt. of India, New Delhi.
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  • Vittala S.S, Govindaiah, S., Gowda, H.H. 2008. Prioritization of sub-watersheds for sustainabledevelopment and management of natural resources: an integrated approach using RemoteSensing, GIS and Socio-economic Data, Current Science, 95(3):345–354.
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  • Guhathakurta, P. and M. Rajeevan. 2006. Trends in the rainfall pattern over India. National Climate Centre Research Report No: 2/2006. May 2006. National Climate Centre, India Meteorological Department, Pune, India.
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  • USGS. 2012. Federal standards and procedures for the national watershed boundary dataset (WBD) by the U.S. Geological Survey and the U.S. Department of Agriculture, Natural Resources Conservation Service, Techniques and Methods 11–A3.

 

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