Geographical Information System (GIS) proves to be an important tool in the study of Hydrology. In the era of climate change, we cannot depend on conventional methods of survey, hence we need some exclusive techniques and GIS is one of them. Watershed is to be analyzed and decision-makers can make better choices when it is done in a well-equipped manner.
GIS in Hydrogeological Survey
GIS in surface water
It is important to manage available surface water wisely as the glaciers are melting and we are completely dependent on surface water, only ¼ on groundwater for all the household, commercial and industrial activities.
GIS can be used to monitor the catchment area, runoff and stream direction. Historical data and Real-time Stream flow data is readily available on different websites or in previous journals which can be directly linked to GIS software online. This data is available in a tabular manner which can be represented spatially in GIS and different layers can be created. GIS is much more capable of displaying it spatially than temporally. Various geomorphic parameters like infiltration rate, stream length, elongation ratio, etc. can be calculated mathematically than, by using DRM(District resource map) or with available data different maps can be generated. Initially one has to delineate the watershed, geology and geomorphology maps to be created, DEM and Slope maps are to be produced.
After a complete analysis of all the aspects of sub-watersheds, it is being prioritized. This prioritization helps hydrologist and watershed managers in understanding the run-off direction in case of precipitation and snow melt. It helps in making further decisions.
Another important application is in Land use, land cover management. The precipitation maps of the area can be generated, which will benefit farmers in crop management. Also, runoff or stream flow direction can be monitored in the region with dense forests. Sometimes forestation reduces the stream flow speed, which can be monitored and decision-makers can make their move at very low cost as compared to conventional methods.
Flood risk management is another major application of GIS. Flood risk management involves modeling of watershed hydrology, river hydrodynamics and mapping of flood inundation. Historical data available and by literature review rainfall data, topography, land use, soil and stream flow data can be used for modeling and mapping of floods. Hydrologic and hydraulic models can be produced for better understanding and stimulating water resources of the region.
GIS in Ground Water
Excluding glacial and polar ice, 98% of the freshwater used in human and environmental activities comes from groundwater. In India, Bangalore is already in the red zone and facing water scarcity. This situation occurred due to the mismanagement of water resources and is being tapped severely. Over pumping for irrigation is another major problem in a country where many depend on agriculture. Depicting groundwater flow is a complex task as compared to tracking the surface water flow but with smart work and proper data collection, this can be done with the help of GIS software, which is analyzed by scientists and natural resource managers. The aquifer is the sub surface water-bearing permeable layer. Waterlog and pumping test data is collected from existing wells to depict the groundwater flow direction in the aquifer. New wells and bore-hole planning is done accordingly. This GIS could be the front end to a groundwater modeling simulation devised to fully capture the contaminant and valuable in planning remediation measures.
Another problem that can be resolved with sub surface mapping is the land subsidence or saline water intrusion in the coastal regions. Pumping can be prevented and land parameters can be thoroughly studied before any construction activity.
A cautious study and management of groundwater within GIS and with modeled GIS data can forestall the risk or alleviate the problem.
- S. MANJARE, V.S. Nathani, P. Malgave, 2017. Drainage Morphometric analysis of Nand River, using Geographical Information System techniques. INDIAN JOURNAL OF GEOMORPHOLOGY Volume 22(2), July-Dec., 2017, pp.169-181