The document discusses the causes and effects of waterlogging in Pakistan. It identifies the main causes as seepage from canals which leads to rising water tables, poor drainage, interruptions to surface runoff from infrastructure, heavy rainfall, floods, and poor water management practices. This causes oxygen deficiency in soils, reduced growth, and buildup of toxic substances. Reclamation methods proposed include installing interceptor and surface drains, lining canals to reduce seepage, and pumping groundwater.

1. CAUSES OF WATERLOGGING
1. Seepage of water from canal system
 The main cause of waterlogging in
pakistan is seepage of water from network
of canal system.40-50% water is lost from
main canals, seeps through soil and rised
the ground water.
 In some cases the water table has risen
upto root zones or even surface of soil.
WATERLOGGING
 The soil whose surface layers are saturated with
water is called as waterlogged soil.
 Or the phenomenon of rising of water table

2. CAUSES OF WATERLOGGING
2. Poor surface runoff and slow drainage.
 The soil surface of pakistan is flat so surface
runoff is poor and hence slow drainage,
result in accumulation of water on soil
surface and move to the water table under
the influence of gravity.
 The water table has risen causes water
logging
3. Interruption of surface runoff.
 Construction of irrigation networks and
housing colonies in the path of natural drains
interrupted surface runoff, resulting in
accumulation of water in rainy season
contributes to waterlogging through seepage.

3. CAUSES OF WATERLOGGING
4. Rainfall.
 After heavy rainfall rain water percolates
down the pores between soil particles under
the action of gravity.
5. Floods.
 Flood water spreads on the surface of soil in
plains. Due to inappropriate drainage system,
this water percolates in soil and raise water
table cause waterlogging.
6. Poor water management
 Sometimes farmers use their land unscientifically.
 These are major causes of waterlogging
 Excessive irrigation
 Lack of inadequate drainage system.

4. CAUSES OF WATERLOGGING
7. By breaking hardpan at a canal bed.
 During cleaning season, the digging of
canals breaks the hardpan of the soil at
canal bed. It enhances the seepage of
water.
8. Railway lines /Roads.
 The construction of railway lines and roads
in food plains interrupted the passage of
runoff water, water collected in rainy season
in the form of ponds, percolates to soil,
Result in waterlogging.

5. EFFECTS OF WATERLOGGING ON PLANT GROWTH
 Some important effects of waterlogging on plant
growth are given below;
i. The air in the soil pore is replaced by water, leading to
oxygen deficiency and hence reduce the plant growth
ii. In waterlogged soil transport of gases is reduced
disturbing normal growth.
iii. Limited exchange of gases increase amount of Co2
which affect transpiration and water absorption.
iv. In absence of oxygen, microbes produce toxic
substances such as methane and effects growth of
plants.

6. A Sequence of Reduction Reactions Occur
after Flooding a Soil

7. There are concomitant changes in the redox potential and
pH of the soils. The pH of acid soils gradually changes.
The sequential changes in the Eh are shown below
Redox Potential

9. EFFECT OF WATERLOGGING ON PLANTS
GROWTH.
v. In waterlogged soil major form of nitrogen is
ammonia which is toxic to crops
vi. Under waterlogged condition the concentration of
phosphorus, iron, manganese, silicon increases
and that of zn decreases. The increase in ferrous
ion concentration is toxic to many crops.

10. RECLAMATION OF WATERLOGGED SOIL
 Various control measures are suggested for reclamation
of warelogged soil , the most important are given below;
i. Seepage interceptor drains
 Seepage interceptor drains may be constructed
parallel to collect seepage water.
 E.g. upper Chenab canal
ii. Surface drains
 Surface drains also constructed to collect
seepage water ,and proved more effective as
compared to seepage interceptor drain.
 E.g. balloki sulemanki link.

11. RECLAMATION OF WATERLOGGED SOIL
iii. Lining of canals
 The canals bed are lined with two layers of tiles
placed above one another and joined together by
cement-sand plaster
 E.g. balloki sulemanki link.
iv. Pumping of ground water
 Pumping out ground water by tube wells is
effective to lower the water table.