Towards Ensuring Water Security

Towards Ensuring Water Security

Water is a crucial input required to enhance agricultural production, as most of the small farmers living in arid and semi arid regions are deprived of irrigation facilities. With the anticipated global warming and climate change, rainfall is expected to be erratic and the water requirement for crops is likely to increase due to a significant increase in evaporation and transpiration losses. Therefore, concrete efforts are necessary towards - sustainable use of all the available water sources, efficient harvesting and storage of rain water, improving the irrigation use efficiency, restoration of reservoir storage capacity etc.
Over the years, spatial analysis of temporal satellite data has been facilitating the performance evaluation of irrigation commands, reservoir capacity surveys, assessing gaps in potential irrigation and utilization etc.

Command Area Development

In India, 60% of total food grain production comes from the irrigated area, which is about 40% of net sown area. Management of water supplies for irrigation in command areas requires information on total demand and its distribution. Using the time series satellite data, 14 large irrigated commands in 5 States (Andhra Pradesh, Assam, Maharashtra, Rajasthan and West Bengal), covering a total culturable command area (CCA) of 3.3 mha have been assessed. The study has helped in the performance evaluation in terms of cropping pattern, cropping intensity and the efficiency of water-use in the command areas.

Enhancing Irrigation Efficiency

In India, there is a gap of 9 million hectares between the irrigation potential created and its utilization at the ground level. In this regard, high-resolution satellite data has been utilized to map the irrigation infrastructure in the command area and monitor its progress under the“Accelerated Irrigation Benefit Programme (AIBP)”, at the behest of Central Water Commission. The results indicated that the field reported Irrigation potential is about 25% (6.54 lakh hectares) more than the satellite based study in 53 selected command areas, spread across 18 states. In phase II, 50 irrigation projects with an irrigation potential (IP) of 8.5 Lakh ha. across 14 States, has been taken up and the final results are submitted to Central Water Commission.

Capacity Estimation of Reservoirs

Spatio-temporal mapping and monitoring of about 4,000 surface water bodies was carried out using an automatic feature extraction tool from satellite remote sensing data. In view of the need for frequent and near real time monitoring of water bodies from satellite data, software tools were developed for extraction of water layer from satellite data, geo-tagging the identification to the cluster of reservoirs available in satellite image and linking lookup table for capacity estimation (pre defined area – capacity curve from the field data). Demonstration of the concept enables the future extension and implementation of this model at national scale. 

The reservoirs are fast losing the storage capacity due to higher rate of siltation then their designed value. Multi-temporal satellite data has been used to aid the reservoir capacity survey of 124 reservoirs for the Central Water Commission.

Water Resources Assessment at Basin level

NRSC and Central Water Commission (CWC) have jointly executed demonstrative pilot studies in Godavari and Brahmani-Baitarani river basins to estimate basin-level mean annual water resources using space based geospatial inputs and hydrological modeling. Expert Committee for re-assessment of water availability in India, constituted by Ministry of Water Resources, reviewed the pilot studies and recommended for up scaling to all other river basins in the country, jointly by NRSC and CWC. A proposal has been generated in this regard and submitted for necessary approval. This is done as part of developing new strategies for “Reassessment of basin-wise water situation” as identified by National Water Mission. 

Ground Water Information 

In the last two decades, significant changes have taken place in India in the use of groundwater for irrigation, and currently about 60% of irrigated agriculture depends on groundwater source. Depletion of water tables, contamination (by fluoride and nitrates) and over-extraction of groundwater have become critical issues in several regions of India. In addition, close to 90% of rural domestic water supply is from groundwater and due to rapid development and increase in population the demand on groundwater for water supply has grown considerably during the last decade. 

In this regard, Satellite data is used to identify the potential ground water sources and recharge sites in the country, in a phased manner, under the “Rajiv Gandhi National Drinking Water Mission” funded by the Department of Drinking Water Supply. This project addresses the preparation and distribution of ground water prospects zone maps at 1:50,000 scale. After successful completion of Phase I, II, III A and III B of the project covering 20 States in the country, Phase-IV activities are initiated covering the remaining 13 states (Bihar, Delhi, Goa, Manipur, Meghalaya, Mizoram, Nagaland, Puducherry, Sikkim, Tamil Nadu, Tripura, part of UP and West Bengal) and 5 union territories (Andaman and Nicobar Islands, Chandigarh, Dadra and Nagar Haveli, Daman & Diu, Lakshadweep). Phase IV is scheduled to be completed by the year 2013. A sample survey of 3 lakhs wells indicated a success rate in locating well is an enviable 90-95%, as against 50% when satellite data was not available.

Water Resource Information System

On an average, India receives annual precipitation of about 4000 km3 out of which only 1123 km3 is utilizable. Besides, considerable variations exist in the distribution of rainfall and availability of water in time and space across the country. Due to increasing population, rapid all-round development and growing economy, the demand for water is increasing at a fast pace continuously, and the water will become scarce resource in the coming decades.

Recognizing the need of judicious planning of water conservation, and its distribution, a major project namely, “Web Enabled Water Resources Information System (India- WRIS)”, has been taken up in collaboration with Central Water Commission (CWC), New Delhi. As part of the project, Version 3.0 of India-WRIS web portal was launched on December 4, 2012 (www.india-wris.nrsc.gov.in). The portal has 12 major and 35 sub info systems with 80 spatial layers starting from vintage periods (~100 years). India-WRIS portal is a ’Single Window’ solution for comprehensive data on India’s water resources along with other natural resources information in a GIS framework, to help CWC in monitoring and development of Integrated Water Resources Management (IWRM).