ANALYSIS OF GRACE SATELLITE GRAVITY FIELD DATA FOR NORTH INDIA

Abstract

The GRACE monthly time-variable gravity fields have wide applications in hydrology as they offer a technique to measure changes in total water storage over continental areas, representing a new source of information for hydrologists. In the Northern India, due to advancement in the urbanization, water depletion has been reported. In this thesis, total water change for North India for last 13 years has been studied in terms of Equivalent Water Height (EWH). Different gravity functional maps are obtained and filtered. Temporal and frequency EWH graphs are studied for different North Indian cities. Monsoon seasonal maps been made and EWH values are compared with rainfall data. Total water change in North India between 2003 and 2016 had been quantified. The gravity and hydrology maps from GRACE are filtered using a combination of Gaussian filter of 500 km radius and destriping filters. Different gravity functional like Earth‟s gravitational potential (V), disturbing potential (T), geoid undulations (N), gravity disturbance (δg), gravity anomaly (Δg), and equivalent water height (EWH) are obtained but EWH is mainly used for hydrological analysis. Temporal monthly variations of EWH between January 2003 and January 2016 for Delhi, Roorkee, Chandigarh, Jaipur and Lucknow give no definite trend for variation in EWH but it was observed that EWH graph has negative slope, which indicates that water content has decreased over the period of time. Monsoon seasonal EWH maps were prepared for 2003, 2009 and 2015 and it was found that Uttar Pradesh, Uttarakhand, Haryana, Delhi and Eastern Punjab depicted better water conditions as compared to Rajasthan and Western Punjab. EWH values in comparison to rainfall data of the year 2009 depicted that monsoon plays an important role in overall water content for North India. Also, a quantitative analysis for water loss in North India and adjoining region gave a water loss of 22 ± 4 km3/yr over last 13 years. If the water loss continues at this rate then it would be difficult to meet the demand for future generations and hence different water management techniques must be encouraged in this region.