Natural hazards of groundwater:
Groundwater is one of the most important natural resources and can sometimes pose natural hazards.
These risks occur in different pockets, depending on local topography, rainfall, and groundwater withdrawal.
Some natural hazards, such as water freezing, soil salinity, and groundwater-induced landslides are briefly described.
Waterlogging
This is a groundwater situation when the groundwater level is shallow and reaches 2 m below ground level. The area characterized by this water level is called an aquatic area.
When the groundwater level falls below 2-5 m below ground level, this area is likely to be aquatic. Aquatic conditions can develop in a particular area for the following reasons.
Shallow groundwater level and poor groundwater Withdrawal
The groundwater level is in a dynamic process and depends on the recharge and discharge of the aquifer system.
Groundwater level becomes shallow when recharge is limited to a more or less shallow zone. Furthermore, if the withdrawal is blocked, the water level will also rise.
Canal Command Area and Unleashed Major Canals
The area near the canal and the most irrigated area of the canal are called the canal command area. When the canal is out of line, surface water leakage takes place and replenishes the aquifer at shallow depths. Long-term continuous recharge reduces groundwater levels.
Availability of granular zones at shallow depths
This is the situation when geologic lithology is characterized by granular zones at shallow depths and underlined by a layer of clay or penetration.
Such lithological configuration does not permit the proper flow of groundwater and develops a water-flowing situation.
Soil Salinity
Soil salinity can cause dangerous groundwater. There are two types of salinity, inland salinity, and coastal salinity. In both conditions, soils and aquifers become saline and rich in sodium chloride.
Inland salinity
Poor use of groundwater is caused by increased sodium chloride content in the soil. In shallow groundwater, the loss of evaporation is intensified and the concentration of sodium chloride in the groundwater increases.
This process produces a conker pan, which prevents surface water from flowing to the groundwater, and as a result, increases soil salinity. It will degrade the soil and the formation of the Reh will take place.
This is the case in many parts of UP, such as the Jaunpur and Pratapgarh districts.
Coastal salinity
The salinity of seawater enters into aquifers, and coastal salinity is developed in the groundwater.
The coastal salinity is found in areas close to the coast of Kerala, Tamil Nadu, and Andhra Pradesh.
Excessive withdrawal of groundwater from shallow aquifers causes seawater to enter freshwater when the groundwater level is deep and the shallow water level is present. This whole process develops the salinity of the coast.
Landslides and tunneling
Groundwater may act as a trigger agent for landslides under conditions of change in groundwater regimes.
The water level relationship with the ground surface height is important because the water level should never cut the ground surface.
Movement of groundwater
In hilly areas, when groundwater levels cut the ground surface, leaks can be quite harmful and can lead to landslides.
The shallow groundwater level in the area prone to landslides is detrimental because it lubricates broken pieces and accelerates them.
Shallow groundwater levels are detrimental to the tunnel because it can cut the tunnel axis.
When groundwater is below the tunnel axis or below the ground surface of the tunnel, it is most suitable for tunneling.
When the ground level cuts the tunnel axis or is above the base of the tunnel, it damages the tunnel’s strength.
Landfall
It is a phenomenon in which the layer of the earth moves gradually or suddenly. Underground soils with water in their pore place a certain amount of pressure, which keeps the soil particles intact with lining or topsoil.
Due to over-pumping, when large quantities of water are withdrawn from the lower soil, the pressure exerted by the pumping is greater than the existing pressure of the groundwater withdrawal soil.
In such a situation, the earth will collapse and the earth will crack and the earth will collapse. In the recent past, several land cracks and crashes have occurred in UP’s Hamirpur, Banda, and Sant Rivadas urban districts.
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