Large Scale Hydro-Geomorphological Mapping of Itanagar Capital Town Using Space Technology
Groundwater serves as a major contributor in meeting the demand of water in the Country. With the rapid population growth in Arunachal Pradesh, the demand of water for drinking, domestic and agricultural purposes are increasing day by day and thus the need for groundwater exploration is also increasing. Groundwater resource is mapped based on derivative techniques involving complex processes. Groundwater prospect maps generated by NRSC under National Rural Drinking Water Program (NRDWP) have their limitations and limited scope because of their scale (50k) and resolution of satellite data used for their preparation. This study aims at generating Groundwater prospect map of Itanagar township on 1:10,000 scale to locate site for high yielding groundwater wells and to achieve sustainability of groundwater sources in the town. SUPER VIEW 1 Multispectral data of 50cm resolution and CARTOSAT 1 DEM of 10m posting have been used in the study. NRDWP thematic layers, GSI geological maps, SOI topo maps, SISDP LULC layers, available soil layers, rainfall data and published literatures of GSI and CGWB were also used in the study. Spring and well data were collected from field during pre and post monsoon season of the year 2021.Thematic layers on slope, drainage network and waterbody, drainage density, lithology, lineaments, lineament density and geomorphology were generated on 1:10k scale. Groundwater prospect map was generated by integration of all the database in GIS environment. The groundwater prospects, which is in the form of type, depth and yield range of the recommended wells, have been provided as the outcome of the analysis of hydro-geomorphological characteristics of the hydro-geomorphic units. Sites for suitable recharge structures have also been provided in the maps to improve the sustainability of sources. The study area shows wide range of variation in terms of groundwater prospect. River terraces have the better prospect whereas structural hills have the least prospect. Recharge structures like contour bunding/ trenching, gully plugging, construction of recharge pit and farm pond will improve the groundwater condition of the study area. Development and management of existing springs is recommended in the study area. The study would have improved if a more significant number of well observations were there. The prospect maps form good database and these will help the department of Public Health Engineering and Water Supply (PHE&WS), Govt. of A.P. and Central Ground Water Board (CGWB), Govt. of India in finding out sites for drilling new wells. These will be also helpful for Water Resource Department (WRD), GoAP for delineating sites for construction of recharge structures. The database and maps are also helpful for academician and researchers who are working in the field of ground water. An one day workshop was organized on 20th December,2023 at Arunachal Pradesh Civil Secretariat, Block-I, Room No.106 to formally handover the final maps and report to State PHE Department and also to showcase the large scale HGM mapping methodology to the State Space/Remote Sensing Application Centres. Sri Rajarshi Saha, Scientist-"SE" of Geosciences Division, NRSC, Sri Biplab Ray, Regional Director, Central Ground Water Board (CGWB) and Sri Somorjeet Singh, Sr. Scientist of North Eastern Space Application Centre (NESAC), attended the workshop at Itanagar. Dr. I.C.Das, Group Director, Geoscience Division, NRSC, Hyderabad has attended the workshop through video conferencing. All the State Remote Sensing Centres of North East India were present in the workshop on on-line mode. Engineer and Hydrogeologist from PHE&WS department also attended the workshop.
