Friday, 16 August 2019

GIS technique for delineation of groundwater potential zones

Paper review
Objective
The objective of this study is to figure out the groundwater potential zones and develop a prospective guide map for groundwater exploration/ exploitation to ensure optimum and sustainable development and management of this vital resource.

Background
Dili city is the capital of Timor Leste. The water necessities of the city are mainly dependent upon underground water resources. Groundwater accounts for more than 60 % of the total annual water supply for agriculture, domestic, and industrial purposes. The city is urbanizing rapidly so water demand is increasing. To fulfill the demand of the city it is necessary to explore more reserves and use them effectively and to the optimal level. Timore Leste as developing country is seeking various ways to increase the freshwater availability and ensure the continuous supply of water to the individual and the community.

Study area
This study was conducted in the Comoro watershed, which consists of the Dili City as the capital of Timor Leste.

Material
The existing hydrogeological and relevant data on soils, geological/lithological units, structural features, geomorphologic, and climatic conditions of the study area were collected from relevant department. The rainfall data was collected from meteorological and agriculture department.

Methodology
ArcGIS 10.1 software was used to integrate the eight thematic layers of conventional geology, soil, drainage and lineament maps, rainfall data as well as remotely sensed data of land use, slope and topography.

Development of thematic layers
using ArcMap 10.1 software the drainage density map, topography map, and slope map of the study area were generated from ASTER DEM data.
PCI Geomatica was used to extract the lineament of the study area (lineaments are structurally controlled linear or curvilinear features, which are extracted from the satellite imagery by their relative linear alignments. These articulate the surface topography of the underlying structural features. Lineaments characterize the fault and fracture zones—resulting in increased secondary porosity and permeability).
 The slope map of the study area was generated in unit (degree) from ASTER DEM data with cell size of 30 m resolution and pixel depth of 16 bit using spatial analysis tool in ArcMap 10.1. slope is of high importance areas with steeper slope were given low importance because they have high rate of run off, while the areas with low slope and flatter area were given high importance.

Results
Results showed that the most potential zones lie in northwest part of Comoro watershed which covers about 5.4 % (13.5 km2) area of the watershed. It is observed that high potential zones are in the northwestern part of the Comoro watershed and the western part of the Dili alluvial plain.

Conclusion

From the study it is concluded that the use of geospatial technology, remote sensing, and the AHP technique is demonstrated as the best tools for the identification of groundwater potential zone. The technology will also help the authorities about the suitable area for prospective exploration of groundwater wells and protect the area from contamination.

Reference
Delineation of groundwater potential zones in the Comoro watershed, Timore Leste using GIS, remote sensing and analytic hierarchy process (AHP) technique. Appl Water Sci (2017) 7:503–519.

Review by,
Ehsan Nazeer


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