GIS Specialist, Tata Infotech Ltd. India
|Collation of data about the spatial distribution of several properties of the earth’s surface in groundwater resources evaluation has always been a complicated process due to various reasons. Currently available Business GIS integrated geoscientific softwares do attempt to execute some of the areas of groundwater monitoring, targeting and exploration of groundwater resources|
Groundwater Hydrology, a specialized domain of Earth Sciences is an interdisciplinary program, linked to most of the areas of natural sciences viz. soil science, agricultural science, earth and atmospheric sciences, climatology and meteorology. Advances in remote sensing technology in pattern recognition and extraction of landscape elements and other spatial geographic and geologic features contribute to useful and voluminous data.
The uncertain flow and occurrence of groundwater is controlled by spatial inhomogeneties viz. rock type, soil type, land use, fault, fracture, lineament, drainage pattern and slope, aspect, relief of landscape. Hence, it requires identification and evaluation of groundwater potential zones based on integration and analysis of data from varied sources viz. geophysical signatures (logging, sounding and profiling) and geochemical signatures, in addition to the surface characteristics viz. topography, slope, aspect, geomorphology, lineament, fault, fracture, geology, soil and landuse. Presentation of data in the form of a cross-section, fence, or linear depth-wise plot (borehole/well log) of various geophysical and geochemical signatures provides a thorough understanding of the sub-surface characterization and help target a 3D probable potential zone. Aquifer performance tests depict sub-surface characteristics. Grain-size analysis, based on the estimation of proportion of gravel, sand, silt and clay, explain the porosity and permeability conditions to visualize the groundwater flow, contaminant accumulation and dispersion. Composite hydrograph and watertable trend with specific time series analysis explain spatio-temporal changes in the groundwater regime. Analysis of water-quality parameters in terms of standard water-quality plots and specific spatial analyses help decision makers to allocate groundwater for irrigation, domestic and industrial uses. Statistics have been in use for studying geochemical threshold, spatial geochemical associations and detection of pollution-source and its extent. Predictive modeling using tools of Bayes, Fuzzy, Dempster-shafer theory and logistic regression analysis have been found effective in handling spatial data and an integrated analysis for targeting groundwater- potential or pollution vulnerable areas.
The complex scenario demands an integrated analysis of information gathered from several sources to extract spatial and spatio-temporal characteristics in terms of association, discrimination, deviations, randomness, clustering, regularity and anisotropy of spatial process (Cliff and Ord, 1981). The tremendous capability of handling complex spatial data and analysis with a GIS provides a hydrogeologist ample opportunities for extraction and comprehension of knowledge, recognition of pattern and an explicitly reasoned evaluation of groundwater resources (Fotheringham and Rogerson, 1994).
Scenario of Water Resources
Each year, huge amount of money is spent on monitoring the environment and to providing valuable data that enables effective management of water resources. There has been lack of analyzing these valuable data.
To quote from the US EPA (Environmental Protection Agency): “Of the order of 20 per cent of the budget allocated for the monitoring programme should be reserved for data management and data analysis activities. Failure to plan for these costs can result in the loss of information due to inadequate data preservation and limited analysis of the monitoring data that are collected.”