course 9 hydrogeology investigation
DESCRIPTION
gwTRANSCRIPT
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Surface and
Sub-Surface
Survey of
Groundwater
Dr. Doni Prakasa Eka Putra
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Why groundwater survey?
The potential area for groundwater development
(1). Good productive aquifer
(2). The groundwater level is not too deep
(3). The water quality is good
(4). The aquifer is protected from contamination
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Objective of Groundwater Survey
The objective of groundwater survey should be
clear from the beginning, such as:
- domestic/irrigation/industrial use ?
- quantity and quality needed ?
- area of survey ?
- Prediction ?
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Groundwater Investigation
Preparation & Reconnaisance
Prefeasibility Study
Feasibility Study
Pilot Project
Development
Exploration
Exploitation and
Management
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Scheme of groundwater survey
Surface
Investigation
Sub-Surface
Investigation
Direct Indirect
Geologic
Investigation
Hydrology
Geography
Climatology
Agriculture, etc
Supplemented by:
Remote
Sensing
Surface
Geophysical
Method
Exploration
well
Geophysical
Logging
Drilling
Pumping Test
Groundwater
Quality Test
Resistivity Log
SP Log
GR Log, etc
Groundwater Survey
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Surface Investigation of
Groundwater
Geologic Investigation Methods
Remote Sensing
Geophysical Exploration
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Geologic Investigation
Enable large areas to be rapidly appraised to their potential for groundwater development.
A geologic investigation begins with
(1). Collection, analysis and hydrogeologic interpretation of existing data.
(2). Supplemented by geologic field reconnaisance.
(3). Supplemented by evaluation of hydrologic data on; streamflow and springs; well yields; groundwater recharge and discharge, levels and water quality.
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Lithostratigraphy
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Hydrostratigraphy
Sand & Gravel
Sand
Shale / Mudstone
Till
Clay
Stratigraphic Lithologic Hydrostratigraphic
Surficial Deposits Surficial Aquitard
Floral Aquifer
Floral Fm
Floral Aquitard
Empress Gp Empress Aquifer
Bearpaw Fm Bedrock Aquitard
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Contoh Kasus
Studi Hidrogeologi Sarasuta -
Saraswaka
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Remote Sensing
Surficial Features Identified on Aerial Photographs thatAid in Evaluating Groundwater Conditions:
Topography regional relief setting and local reliefsetting
Geologic Landform likely to contain relativelypermeable strata
Lakes and Streams
Moist depressions (marshy environment) and seepages
Springs (tentatively inferred from aerial photograph)
Artificial water features Wells, Reservoirs, Canals,Developed Springs
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Satellite Image
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Surface Geophysical Exploration
Electric Resistivity Method
Seismic Refraction Method
Gravity and magnetic Method
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Electric Resistivity Method
Resistivity of rocks depend on:
1. The water content (porosity)
2. The resistivity of the water
3. The clay content
4. The content in metallic mineral
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Electrical Circuit for Resistivity
Determination
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Resistivity value of sediments and rocks
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FENCE DIAGRAM OF HYDROGEOLOGY SYSTEM
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3-D MODEL OF AQUIFER SYSTEM
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Other surface geophysical survey
Seismic Refraction
the actual presence of groundwater is difficult to determinewithout supplemental information because velocities overlap insaturated and unsaturated zones.
Gravity Method
indicate subsurface geological structure, differences in watercontent in subsurface strata seldom involve measurabledifferences in specific gravity at surface, little application togroundwater prospecting
Magnetic Method
magnetic contrast is seldom associated with groundwateroccurrence, the method has little relevant to groundwater studies
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Seismic Velocity of Geologic Materials
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Subsurface Groundwater Survey
Exploration Well / Drilling
Well Logging
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Test Drilling
Test drilling of small diameter holes to ascertain
geologic and groundwater condition.
The choice of method (cable tool, hydraulic
rotary method, auger method, jetting, etc)
depends on the type of material encountered,
drilling depth and location.
Important result Geologic Log, Drilling-Time Log (Hydraulic Rotary Method), Water
Level Measurement (electric water level
sounder)
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Geologic Log, Drilling Time Log
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Geophysical Logging
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Geophysical Logging
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Geophysical Logging
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Logging Data