🔹 1. Introduction

Inundation is one of the most dangerous mine hazards, capable of flooding workings within minutes.
Mining operations face water danger from:

• Surface sources
  
• Underground sources
  
• Geological disturbances
  
• Old waterlogged workings
  

A sudden inrush of water can cause:

• Loss of life
  
• Destruction of machinery
  
• Airblast
  
• Roof falls
  
• Production stoppage
  

DGMS mandates strict precautions to prevent inundation.

🔹 2. Sources of Water in Mines

Water enters a mine from two broad categories:

⭐ A. Surface Sources of Water

Surface water can enter the mine during:

• Rainfall
  
• Floods
  
• Overflow of rivers, tanks, lakes
  
• Breach of nallas or dams
  
• Monsoon runoff
  

Major surface sources:

Danger from water and Inundatio…

• Rivers
  
• Nallas and streams
  
• Dams
  
• Tanks
  
• Lakes and ponds
  
• Surface depressions collecting rainwater
  
• Flood water from nearby areas
  

Mechanisms of entry:

• Percolation through strata
  
• Through shaft collar
  
• Through open quarry highwalls
  
• Through cracks & fissures
  
• Through abandoned pits
  

⭐ B. Underground Sources of Water

The following underground conditions create heavy inflow:Danger from water and Inundation…

1. Old Waterlogged Workings

The most dangerous source.Old workings may contain:

• Stagnant water
  
• Accumulated water from years
  
• Unmapped galleries
  

Accidental breakthrough can cause fatal inundation.
2. AquifersPorous and permeable water-bearing strata:

• Sandstone
  
• Shale
  
• Limestone caverns
  
• Weathered zones
  

Mining below an aquifer without precautions leads to roof collapse and inrush.
3. Faults, Fissures & DykesGeological weaknesses may intersect water-rich zones.
Sudden failure leads to unexpected water inrush.
4. Surface ConnectionsThrough:

• Cracks
  
• Potholes
  
• Subsidence areas
  
• Open pits
  

5. Adjacent MinesParticularly dangerous when:

• The adjacent mine is abandoned
  
• The barrier is thin
  
• No water danger plan exists
  

⭐ C. Additional Causes of Inundation

Based on DGMS investigations:Danger from water and Inundatio…

✓ Heavy rainfall

✓ Poor surface drainage

✓ Breach of embankments

✓ Mining below river beds without proper drilling

✓ Failure to dewater old workings

✓ Neglecting check surveys

✓ Faulty plans leading to improper barrier estimation
🔹 3. Mechanisms of Inrush of Water

Water can enter through:
1. Collapse of Walls / BarriersThin barrier ➝ sudden failure ➝ violent inrush.
2. Roof Fall into Waterlogged AreaWeak strata collapse, releasing trapped water.
3. Direct PercolationCommon in mines under lakes and rivers.
4. Breach of Surface Structures

• Dam failures
  
• Tank breaches
  
• Floodwater overtopping bunds
  

🔹 4. How Inundation Causes Accidents

• Workers trapped due to rapid flooding
  
• Men engulfed by water-pressure blast
  
• Machinery destroyed
  
• Power failure and ventilation stoppage
  
• Secondary disasters like fire or roof fall
  

Major disasters (covered in Blog 5) include:

• Chasnalla 1975
  
• Ledo
  
• Damua
  
• Newton-Chikli
  
• SCCL inundations
  

(All referenced from your document.)Danger from water and Inundation…
🔹 5. Important DGMS DefinitionsWater-logged Area:

Any working that is full of water or likely to contain water.Mine Inundation:Sudden inrush of water into the working.Old Workings:Abandoned workings not shown on updated plans.Barrier:Width of solid strata left to protect from water.
🔹 6. Text Diagram: Sources of Water
SURFACE SOURCES ------------------------- | Rain / Flood Water | | Rivers / Tanks / Lakes | | Dam failures | -------------------------
UNDERGROUND SOURCES ---------------------------------- | Old Workings | Aquifers | Faults | | Fissures | Adjacent Mines | ----------------------------------
🔥 25 MCQs (DGMS Pattern) with Solutions
1) The most dangerous source of water in mines is —

a) Rainwater
b) Tanks
c) Dams
d) Old waterlogged workings
e) Streams
Answer: d
2) Inundation means —

a) Fire in mines
b) Dust explosion
c) Sudden inrush of water
d) Roof fall
e) None
Answer: c
3) Surface sources include —

a) Aquifers
b) Rivers, tanks, lakes
c) Fault zones
d) Goaf areas
e) None
Answer: b
4) Aquifers are —

a) Impermeable rocks
b) Water-bearing permeable strata
c) Mineral veins
d) Igneous rocks
e) None
Answer: b
5) Mining below rivers is dangerous because —a) Ore loss
b) Poor visibility
c) Water percolation through strata
d) Heat stress
e) Noise
Answer: c
6) A major cause of inundation is —

a) Good ventilation
b) Hard roof
c) Breach of embankment
d) Diesel fumes
e) None
Answer: c
7) The most common geological cause of water inrush —

a) Quartz veins
b) Faults & fissures
c) Coal seams
d) Iron bands
e) Basalt
Answer: b
8) Working near old workings requires —

a) More blasting
b) Probable dip survey & probing
c) High gradient
d) Rubber tyres
e) None
Answer: b
9) Inundation accidents occur mostly —a) In summer
b) During heavy rainfall/monsoon
c) Winter
d) Dry season
e) None
Answer: b
10) Large waterlogged area is detected using —a) Colour coding
b) Paint marks
c) Drilling and probing
d) Wooden stick
e) None
Answer: c
11) Sudden breakthrough of water causes —

a) Improved visibility
b) Air blast
c) Low humidity
d) High oxygen
e) None
Answer: b
12) Underground source includes —

a) Lakes
b) Aquifers
c) Rivers
d) Dam water
e) All
Answer: b
13) Percolation is high in —

a) Granite
b) Basalt
c) Sandstone
d) Shale
e) Coal
Answer: c
14) Direct connection to surface happens via —a) Timber sets
b) Cracks & fissures
c) Brattice cloth
d) Coal dust
e) None
Answer: b
15) Inundation from adjacent mines occurs if —a) Good plan
b) Enough barriers
c) Barrier left is insufficient
d) No drilling
e) None
Answer: c
16) Water danger increases in —a) Dry sandstone

b) Highly jointed rock
c) Limestone caverns
d) Both b & c
e) None
Answer: d
17) Flash flooding in opencast mines occurs due to —

a) Controlled blasting
b) Cloudburst / sudden rainfall
c) Ventilation fan trip
d) Coal dust
e) None
Answer: b
18) Old workings should be treated as —

a) No danger
b) Soft ground
c) Water danger zone
d) Safe zone
e) None
Answer: c
19) Dams near quarries must be —

a) Weak
b) Watertight and inspected
c) Plastic-lined
d) Wooden
e) None
Answer: b
20) Underground water inflow is high in —

a) Igneous rocks
b) Permeable strata
c) Roof bolts
d) Support pillars
e) None
Answer: b
21) Water dangers increase with —

a) Proper drainage
b) Bunds
c) Improper surface control
d) High-grade ore
e) None
Answer: c
22) Inundation leads to —

a) Good ventilation
b) Loss of machinery
c) Less coal dust
d) Better temperature
e) None
Answer: b
23) Geological surprises occur due to —

a) Good mapping
b) Unidentified faults
c) Water drains
d) Straight crosscuts
e) None
Answer: b
24) Sudden water inflow causes —

a) Smooth traffic
b) Roof falls
c) Less humidity
d) Good blasting
e) None
Answer: b
25) Mine inundation is prevented by —

a) Ignoring warnings
b) High explosives
c) Understanding water sources & geological features
d) Weak pumps
e) None
Answer: c
                           🔚 Conclusion

Understanding all sources of water—surface, underground, geological, and adjacent workings—is essential to prevent inundation.
Most disasters occur due to inadequate knowledge of waterlogged zones.

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