can anybody explain what is waterlogging and salinity. what are its cause and how to address this issue

The rise of water table to the surface level is called water logging and the appearance of salty patches is called salinity.
It is mainly the outcome of canal irrigation in Pakistan. with the introduction of perennial canal water was available through out the year, resulting in the rise of water table. salt in the soil also rise to the surface with water table.(water evaporate and salt deposited on the surface )
It effect 3.5 million hectares of agricultural land.
Solution
1) lining canal to control seepage of water
2) Canal closure on temporary basis so water can be use in the time of need only
3) Installing tube-wells to lower water tables
4) Planting Eucalyptus tress which roots absorb more water go deep down

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WATER-LOGGING:
In our country the problem of water logging is of great concern,as large tracts in the indo-genetic plain suffer from waterlogging.the problem of water logging has been reported even in several recent project such as Chambal project in Rajasthan and madhya pradesh. As indicated in the report of irrigation commission 1972the total area of the land affected by water logging in different states of our country is estimated to be affected by water logging. However, several measures area taken under command area development programmed to control water logging.
EFFECTS OF WATER-LOGGING:
Water logging causes infertility of land and hence results in reduction of crop yield. a study of the effect of water logging on crop production was made at a small farm at Rauni near Patiala. This study showed that the yield per hectares for cotton which was about 7.32kn or 746kg O(f)in 1951-52dropped to 0098kn or 10kg (f)in 1959-60and the fields had become unfit for the cultivation of cotton. The drop in yield of wheat was from 13.18kn or 1344kg (f) per 1951-52 to about 8.79kn or 896kg (fs) per hectares in 1958-59.the main factors for the infertility of the waterlogged lands are as follows.
CAUSES OF WATERLOGGING:
The main factors causing waterloging are as given below:
SEEPAGE FROM CANALS
OVER IRRIGATION OF FIELDS
INADEQUATE SURFACE DRAINAGE
OBSTRUCTON OF NATURAL DRAINAGE
OBSRUCTION OF SUBSOIL DRAINAGE
NATURE OF SOIL
CONTRUCTION OF RESERVOIR