Minor Irrigation & Command Area Development 3(2+1)

LESSON 27. Remote Sensing and GIS in Water Management in India

27.1 Water Resources Development: Space Technology Perspective

Remote sensing in combination with the Global positioning system (GPS) and Geographical Information System (GIS) produces the terrain maps at this location accuracy and containing detailed information of the variables under study. In India, satellite remote sensing technology is being used effectively in the areas of irrigation performance evaluation, snowmelt-runoff forecasts, reservoir sedimentation, watershed treatment, drought monitoring, flood mapping and management.

The steady flow of data from Indian Remote Sensing Satellites – IRS-1A, 1B, P2, 1C, P3, 1D and P4 (Oceansat) have facilitated operationalising many application areas under the aegis of National Natural Resources Management System (NNRMS). Space technology applications capabilities are being further enhanced by the series of new satellites with increasing spatial, spectral and temporal resolution. The more recent IRS satellites – the RESOURCESAT (IRSP6) offers multi spectral data at a resolution of better than 6 metres from LISS-IV and large area coverage with high repetitivity from AWiFS payloads and the CARTOSAT-1 has a PAN camera of 2.5 – metre resolution with stereo view. Thus, the IRS constellation has become one of the most versatile remote sensing satellite series, offering wide range of data and services to meet the variety of applications. Thus multiple satellites concurrently in operation and steer able sensor systems enable dynamic coverage of specific areas. In complement to these developments in the space segment, we are witnessing a dramatic improvement in the ground segment, paying the way for planning, execution and monitoring of water resources projects of different magnitudes.

27.2 Water Resources Management issues through Space Technology

Space-borne spectral measurements have been used for

(i) rainfall estimation,

(ii) snow and glacier studies leading to snow melt runoff forecasting,

(iii) irrigation water management and identification of potential irrigable lands,

(iv) reservoir sedimentation

(v) watershed management

(vi) disaster management

(vii) water quality assessment,

(viii) ground water assessment and prospecting,

(ix) planning and implementation of developmental activities,

(x) infrastructure development,

(xi) disaster management and environmental monitoring.

Airborne laser based terrain mapping( ALTM), in conjunction with detailed mapping through digital camera, and traditional photographic survey provide valuable information on terrain characteristics in terms of topography, association, detailed land use/ cover, geological features, etc. for water resources infrastructure projects viz. Interlinking of Rivers Project( ILR).

27.2.1 Rainfall

Rainfall is one of the most important processes in the hydrological cycle and is also one of the most difficult to monitor. Since late 1960s, many researchers have attempted to derive techniques for the estimation of rainfall from the visible and infrared imagery provided by meteorological satellites. Manual, interactive and automatic methods have been developed for the estimation of rainfall at a number of temporal and spatial scales, and these have been applied in many different areas and situations with varying degree of success. More research is needed to determine the best method of incorporating typically sparse “point” ground station measurements into homogenous and extensive satellite estimate fields. Snow and glacier investigations and snow melt runoff forecasting are yet another area where satellite remote sensing imagery is providing information on retreading glaciers as well as possible potential snow melt run-off. Seasonal and short term (weekly) forecasts of snowmelt runoff are being provided for Sutlej and Beas and Parabati basins in Western Himalayas by the National Remote Sensing Agency since1970s.

27.2.2 Irrigation management

In India, the ultimate irrigation potential has been estimated at 140 M. ha. The irrigation potential created up to 2004 is 98 Mha. While enormous irrigation potential has been created at huge cost, the gap between created potential and utilization is significantly large (around 9 Mha ).Thus, along with the thrust towards creation of higher irrigation potential, efforts are also need to be directed to optimal utilization of created potential.

Space borne multispectral measurements at regular intervals have helped evaluating the performance in many irrigation projects across the country. The anticipated increase in irrigated area, equitable distribution and crop productivity under programmes such as the centrally sponsored Command Area Development (CAD) scheme and National Water Management Project, have been studied in some of the major irrigation command projects in India (National Remote Sensing Agency,1998). The temporal and spatial analysis of satellite data has helped mapping problem pockets of poor performance. Furthermore, spatial analysis of crop sowing periods and crop condition assessment have thrown up policy issues of relevance to irrigation scheduling, canal maintenance and agricultural productivity. Apart from performance evaluation of irrigation systems, multi temporal satellite data have also been used to map current status and to monitor the spatial extent of water logging and soil salinity and/ or alkalinity through the years in most of the irrigation projects. Such exercise has also helped in evaluation of the progress and effectiveness of reclamation programmes by monitoring the extent and magnitude of the problem.

27.2.3 Reservoir capacity monitoring

The analysis of sedimentation data of Indian reservoirs show that the annual siltation rate has been generally 1.5 to 3 times more than the designed rate and the reservoirs are generally losing capacity at the rate of 0.30 to 0.92 per cent annually. Multi temporal satellite data have been used as an aid to capacity survey of many reservoirs in a cost and time effective manner in India. While this technique helps in revising capacity table between minimum and maximum draw-down level observed in satellite data, loss of dead storage capacity can be obtained only through conventional hydrographic surveys. Realistic appraisal of reservoir capacity is essential for appropriate utilization plans. A National action plan of sedimentation survey of 124 reservoirs using remote sensing technology has been taken up in India during the 10 five year plan. Inappropriate land use practices in the upstream catchment leads to accelerated soil erosion and consequent silting up of reservoirs. Watershed management is thus an integral part of any water resources project. Space borne multispectral data have been used to generate baseline information on various natural resources, namely soils, forest cover, surface water, ground water and land use/land cover and subsequent integration of such information with slope and socioeconomic data in a Geographic Information System (GIS) to generate locale-specific prescription for sustainable development of land and water resources development on a watershed basis. The study covering around 84 M. ha and spread over 175 districts has been taken up by the Department of Space, Government of India under a national level project titled “Integrated Mission for Sustainable Development (IMSD)”. Implementation of appropriate rain water harvesting structures in selected watersheds under this programme has demonstrated the significant benefits by way of increased ground water recharge and agricultural development of once barren areas. Multi-year satellite data is also used to monitor the impact of the implementation of watershed management programmes.

27.2.4 Ground water prospecting

During past one-and-half decades, it has been demonstrated that satellite imagery are highly useful in mapping and targeting ground water prospective zones. Under National Drinking Water Technology Mission, the Dept. of Space with the active co-operation of various user departments has prepared district-wise hydro-geo-morphologial maps on 1:250,000 scale covering all 447 districts in the country using satellite imagery with limited field checks and available information. These maps have been found to be very useful in narrowing down the target zones and selection of sites for drilling besides their usefulness in regional / district level planning and identifying alternate sources of drinking water for many problem villages across the country. In order to provide safe drinking water to rural masses, the Dept. of Space has taken up a project titled "Rajiv Gandhi Drinking Water Mission". The project aims at generating groundwater prospects maps at 1:50,000 scale using IRS-1C/1D LISS-III data for entire country. Ten states, namely Rajasthan, Madhya Pradesh, Chhattisgarh, Andhra Pradesh, Karnataka, Jharkhand, Orissa, Gujrat, Himachal Pradesh and Kerala have been covered so far.

27.2.5 Natural calamities

In the event of natural calamities like drought, flood and cyclones, that adversely affect the water security, space technology has made substantial contributions in different phases such as preparedness, prevention and relief. The Earth Observation satellites, which include both geostationary and polar orbiting satellites, provide comprehensive, synoptic and multi-temporal coverage of large areas in real time and at frequent intervals, thus, have become valuable tools for continuous monitoring of atmosphere as well as surface parameters related to droughts and floods. While Geo-stationary satellites provide continuous and synoptic observations over large areas on weather including cyclone tracking. Polar orbiting satellites have the advantage of providing much higher spatial resolution images that could be used for detailed monitoring, damage assessment and relief management.

Satellite images have been found to be of immense help in providing early information and monitoring accidental water resources events. Though sitcom based applications for management of water resources in the country had a modest beginning with Central Water Commission (CWC) and Snow and Avalanche Study establishment (SASE) have deployed INSAT- DRT based DCP services for real time hydro meteorological data collection, they are expected to assume greater significance in the context of proposed interlinking of rivers programme.

27.3 Future perspective

Since the modest beginning of surface water inventory the remote sensing application scenario has witnessed a phase transition from resource mapping to decision-making. Remote sensing has thus become one of the most important tools for evaluation of the physical attributes of water and land resources in the country. A number of case studies on command area development, groundwater inventory, canal alignment, irrigation performance evaluation, etc., have proved beyond doubt that integration of remote sensing and conventional approach significantly decrease the cost and time involved as well as, improve the steadfastness. The various issue related to topographical surveys, water resource assessment, Information on Command area Expansion (command area surveys), Planning of New Storage Reservoirs, stabilizing existing enroute command areas, reservoir sedimentation, geological and geomorphological surveys, etc. can be suitably addressed through satellite/aerial data. Satellite remote sensing along with appropriate collateral data enable the inventory of quantity, quality as well as the values of the resources. The repetitive nature of space-based earth observation provides the unique opportunity to do the accounting on a periodic basis.

Water is a major input in agriculture and its relative availability in different agro climatic zones calls for efficient water resource development plans. There is, close relationship between water scarcity and reduced food productivity, mainly applicable to rain fed areas of the country. The water resource development on watershed basis has shown encouraging results in mitigating the water need in water stressed agriculture. Major institutional, policy and technological initiatives are therefore, required to ensure efficient, socially equitable and environmentally sustainable management of water resources towards achieving the water security along with food security for the country.

For ensuring sustainable water security, water resource management in the country need to be planned and implemented within the framework of integrated resource management, which requires consideration of a range of impacts, sometimes extending far beyond the immediate hydrological system, and over considerable time periods. Space borne multi spectral measurements have in some cases replaced ground based observations and in others complemented at varying levels. Improved spatial, spectral and temporal resolution data from present IRS satellites together with aerial remote sensing provides unique opportunity towards comprehensive monitoring of water resources dynamics in the country.

(Ref: Indo-US Workshop on Innovative E-technologies for Distance Education and Extension/Outreach for Efficient Water Management, March 5-9, 2007, ICRISAT, Patancheru/Hyderabad, Andhra Pradesh, India Proceeding Paper - Remote Sensing and GIS - Water Management by P.S. Roy and V.V. Rao)

27.4 Application areas of Remote Sensing in Agricultural Engineering

The interpretation of remotely sensed images may provide valuable information to the Agricultural Engineer, some of which are discussed below for various fields of applications

Sl. No.	Field of application	Useful interpreted information	Helpful in
1.	Command area development & Irrigation Engineering	Crop area, Crop yield, Crop growth condition, Crop areas that are water stressed and are in need of water	Estimating the amount of irrigation water that is to be supplied to an irrigated area over different seasons Location and alignment of field channels and structures
2.	Hydrology & Watershed management	Different types of soils, rocks, forest and vegetation of a watershed, soil moisture	Estimating runoff from a watershed, where the land-cover type and soil moisture would decide the amount that would infiltrate Estimating soil loss and capacity reduction of reservoirs Identification of drought periods and planning mitigation measures
3.	Reservoir sedimentation	Plan views of reservoir extent at different times of the year and over several years	Estimating the extent of sedimentation of a reservoir by comparing the extent of reservoir surface areas for different storage heights
4.	Drainage of flooded area	Flood inundated areas	Flood plain mapping and zoning for design of drainage Planning surface/ subsurface drainage
5.	Water Resources Project Planning	Identification of wasteland, mapping of infrastructure features like existing roads, embankments, canals, etc. apart from plan view of a river	Recent information helpful in planning and designing of a water resources project based on the present conditions of the project area