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Combined Geo-Scientist (Main)
Examination, 2026 SNCS-O-HDG
HYDROGEOLOGY
Time Allowed : Three Hours Maximum Marks : 200
QUESTION PAPER SPECIFIC INSTRUCTIONS
Please read each of the following instructions carefully
before attempting questions
There are NINE questions divided under FIVE Sections.
Candidate has to attempt FIVE questions in all.
The ONLY question in Section—A is compulsory.
Out of the remaining EIGHT questions, the candidate has to attempt FOUR, choosing
ONE from each of the other Sections B, C, D and E.
The number of marks carried by a question/part is indicated against it.
Symbols, abbreviations and notations have their usual standard meanings.
Neat sketches are to be drawn to illustrate answers, wherever required.
Wherever required, graphs/tables are to be drawn on the Question-cum-Answer (QCA)
Booklet itself.
Attempts of questions shall be counted in sequential order. Unless struck off, attempt of a
question shall be counted even if attempted partly.
Any page or portion of the page left blank in the Question-cum-Answer (QCA) Booklet
must be clearly struck off.
Answers must be written in ENGLISH only.
SNCS-O-HDG/70 1 [.P:r:0.
1. Write short notes on the following in not more than 5 sentences each :
(a)
(b)
()
(a)
(e)
(9)
(h)
(b)
()
“(b)
(c)
(teh) tatter
; SECTION—A
( Compulsory Section )
Piezometric nests
Types of springs
Aquitard
Effective porosity
Confined aquifers
Piydraulle head
Vadose zone
Bouguer anomaly
SECTION—B
Attempt any one question.
Define specific discharge. Compute the Darcy’s velocity when groundwater
flows through an alluvial aquifer having a hydraulic conductivity of 70 m/day
and a hydraulic gradient of 0-02.
Discuss isotropic and anisotropic aquifers with special reference to hydraulic
conductivity. Illustrate your answer with suitable sketches.
Explain the zone of aeration, zone of saturation, capillary zone and perched
aquifer with neat schematic diagrams.
Define transmissivity of an aquifer and calculate the transmissivity of an
unconfined aquifer that has a hydraulic conductivity of 250 cm/day and a
saturated thickness of 18 m.
Discuss the laboratory methods for determination of hydraulic conductivity.
Elaborate groundwater flow through dispersion and diffusion, and explain
their relationship with permeability.
SNCS-O-HDG/70 2
10
15
15
10
15
15
SECTION—C
Attempt any one question.
4. (a) Compare slug test and aquifer performance test. 10
(b) What is the specific capacity of a dug well? Explain the method in brief. If the
discharge of the well is 90 cubic metres and the drawdown As is 3 metres, what
should be the well capacity of the aquifer? 15
(c) What are the different methods of groundwater level monitoring? Explain the
use of groundwater fluctuation data. 15
5. (a) Explain different types of porosity in an aquifer and calculate the porosity, if
the total pore space is 4 cubic metres and the total volume of the aquifer is
80 cubic metres. 10
(b) Describe the impact of climate change and overexploitation of groundwater
from the Indo-Gangetic alluvial plain. 15
(c) Discuss the relationship between lowering of groundwater levels and land
subsidence with suitable examples. 15
SECTION—D
Attempt any one question.
6. (a) What is the potentiality of remote sensing techniques in groundwater
investigation? In microwave remote sensing, which wavelength band is suitable
for groundwater prospecting in unconfined arid zone? 15
(b) What are the benefits and limitations of using proton precession magnetometer
for identifying groundwater in alluvium and hard rock terrains? 10
(c) Explain different types of drilling methods in hard rocks, alluvial and bouldery
geological formations. 15
7. (a) Elaborate electrical resistivity method for groundwater exploration with a
specific note on self-potential. 15
(b) What is radiation logging? Explain the potential of natural gamma logging with
gamma-gamma logging. 15
(c) What is rose diagram? Explain the potential of this structural geological
property for groundwater exploration in hard rock area. 10
SNCS-O-HDG/70 3 [ P.T.O.
SECTION—E
Attempt any one question.
8. (a) Give an account on natural chemical constituents in groundwater. Write a few
names of major cations, anions and trace elements. 15
(b) Discuss about the groundwater pollution due to urbanization with some
examples. 15
(c) Elaborate the applications of stable isotopes in groundwater studies. 10
9. (a) Describe different methods of artificial recharge for groundwater rejuvenation
in hard rock and alluvial terrains. 15
-(b) Explain the characteristics of groundwater basins of India. 15
(c) Describe the utility of trilinear diagram for representing the analysis of
groundwater quality data. 10
kkk
SNCS-O-HDG/70 4 26BS—480
