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Project Overview

Ground Water & Mineral Investigation Consultancy Centre Pvt. Ltd. (GWMICC) undertook an extensive survey with the object to understand the hydrological and hydro-geological conditions and structures surrounding to the spring water catchment area and ascertain the quality and quantity of the Dolpani spring water source, Army Welfare Project Ltd. (AWPL) had taken initiative to conduct detailed Hydrological Study of Spring Water Source located at Dolpani, Dekiling Gewog, Gelephu in Sarpang Dzongkhag(Bhutan).

The spring water source is located at Dolpani, Dekiling Gewog, in Gelephu at UTM coordinate 46R N-0234200, E-2980497 and elevation is 772 MSL by GPS. It is located in hilly region with undulating terrain. Spring water is controlled by the fracture and cavities having N 19 E- S 19 W direction.

THE PROBLEM

  1. Spring water system protection needs a forewarning of imminent contamination and thus, an integrated approach of conceptual and management-related groundwater models should be developed.
  2. Empirical and analytical approaches should be used to attain an inclusive understanding of spring water hydrology and water quality.
  3. springs should be studied considering the current updated classification schemes to obtain a comprehensive understanding of them.
  4. Monitoring of data and simulation models should be developed to establish an integrated and comprehensive understanding of Dolpani Source at Village Dolpani,spring hydrogeology.

 

THE SOLUTION

 

Here, we utilized the following methods to determine the object to follow:

 

  1. GIS Studies: -The recharge area is demarcated using SRTM satellite data with the help of ArcGIS software. The satellite imagery is processed and Digital Elevation Model (DEM) was created to define the catchment of spring water source, contour map and drainage pattern. Based on these studies recharge area of spring water source was mapped.
  1. Geological Field Survey: – Field traverses were taken and all geological structures, rock types with dip, strike and visible features like joints, fractures, fault, bedding and foliation plane etc. were recorded along and across the spring water source using Sunnto compass and GPS. Based on geological studies & contour plan, geological map was prepared depicting Lithology and structural control of spring water source.
  1. Geophysical Investigation: – Under Geophysical Investigation, Geoelectric survey was done on selected spots to know about the behavior of subsurface disposition of aquifer system in the investigated area. This survey was done to workout hydrogeological characteristics of the area in a systematic pattern to generate water level contour maps and the ground water potential map. Interpretation of Geoelectric data depicts Lithology, saturation & expected quality of ground water. Based on above comprehensive studies, areas worthy of groundwater potentiality were selected along with identification of sites for drilling.
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  3. Hydro-geological Study: – In Hydro geological studies, observations were made about types of aquifers, surface water bodies, drainage pattern, yields, quality, contour map with drainage pattern & water flow direction was demarcated. Digital current flow meter was used to assess water flow of spring and streams at different points in the month of January, 2016 to have actual assessment of flow characteristics of the spring water. Lean period estimates of flow were arrived in the light of available historical data. Based on integration of all the studies, possible origin of spring water was located so that Dolpani spring water is protected from future contamination.

RESULTS

We obtained the following outcomes and project benefits by using the employed methodology:-

Under the present circumstances, the type II/III design is recommended to obtain water quality and quantity very close to the spring water source which confirms to the natural mineral water standards at comparatively low cost and less time and can be implemented immediately with support of local community. The design of the water intake method as per recommended type II/III shall consider use of natural filter media to ensure that the subterranean natural water percolation of the spring water source is not affected.

 

 

IMPACT

Socio Economic Impact of Proposed Plant: It is concluded that the proposed natural mineral water project is feasible as regards required quantity and quality is concerned. The project is expected to have positive socio economic impact in the people of nearby areas as there will be direct and indirect new employment opportunities, development of roads and Infrastructure, provision of improvement in health, education, environment and other areas as part of corporate social responsibility of the coming up project. The plant will not have any activity causing environmental pollution in terms of air pollution, noise pollution, water pollution and flora & fauna pollution. It is envisaged that there will be no adverse or negative impact on social and demographic fabric of the area around the plant

RECOMMENDATIONS

Computation of saturated zones at each Vertical Electric Sounding points (VES) reveals that sites having dolomitic aquifer and saturated thickness more than 6 m are suitable for successful water intake well. These sites are S-16, S-17 and S-19 around the source. Therefore, spring water source, itself would be potential for obtaining natural mineral water. Hence, design is recommended at spring water source to obtain water quality and quantity same as that of spring water source which confirms to the natural mineral water standards. The direct water intake from the source would be at comparatively low cost and less time and can be implemented immediately with support of local community compared to installation of water wells at site At spring water source, collection box of appropriate dimension may be constructed over the outlet of the existing spring water source. The design of collection box may be an enclosed structure with religious significance. Water from the box is tapped through a stainless steel pipe with 4-inch diameter at the bottom of the box which is further connected to underground delivery line (HDPE pipe) leading to collection tank at lower elevation. The overflow is let out to flow through a pipe at top through the current stream course as shown in Figures respectively. The natural flow from spring water source would not be disturbed / obstructed because of installation of collection box at the source as the design would envelop the source and there will not be any direct obstructing wall of the structure at source. Protection of Micro/Macro watershed The entire micro catchment of the spring water source may be suitably protected from human, animal, industrial and other activities which may contribute contamination. The probable area of this micro catchment which is to be protected is shown in Fig-33. The delineated micro watershed is upper part of the macro watershed and as such, there is no need to protect macro watershed area for any activity except large industries which may cause environmental and subsurface water pollution.

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