Salinisation

The impact of salinisation is becoming a bigger problem in various parts around the world. Given climate change, droughts, sea level rise and anthropogenic impacts such as rising demand for fresh water, dams and dredging, long-term effects must be considered in current and future interventions in the system. Deltares is using its system knowledge and models to contribute to monitoring, forecasting, scenario analysis, policy studies, effect analyses, testing innovations and implementing solutions. A partner to tackle salt intrusion in an integrated and future-resilient way.

Legend

Functions

Drivers

Solutions for salinisation

Salt water

Fresh water

Brackish water

Sea level rise and land subsidence

Larger ships (channel deepening and construction of large sea locks)

Sand mining (channel deepening)

Sealing subsurface and shortage of fresh water

Lower river discharges and more water demand

Overextraction and water mismanagement practices

Storms, hurricanes, typhoons and cyclones

Ecology

Drinking water supply

Industry

Agriculture

Ship traffic

A very small amount of salt in fresh water is already too salty for most fresh water users.

Drivers

Sea level rise and land subsidence

Larger ships (channel deepening and construction of large sea locks)

Sand mining (channel deepening)

Lower river discharges and more water demand

Sealing subsurface and shortage of fresh water

Overextraction and water mismanagement practices

Storms, hurricanes, typhoons and cyclones

Long-term effects

Unwanted changes in ecology

Less and more expensive drinking water

Unsuitability for certain crops

Migration

Unsuitability for industry

Health effects

Keeping sea water out of the delta

Coastal defence

Prevent the seawater to overflow the coastline or overtop the coastal defence.

Dams and discharge sluices

By closing of river mouths and estuaries, the inflow of saline water into a fresh water system can be limited. This requires hard civil engineering solutions that both block the sea water inflow as well as allow outflow of river water (for instance during ebb tide).

Accomodating to conditions

Salt-resistant crops

Some crops grow better (and even taste better too), if there is brackish groundwater in the soil.

Change of land use and functions

Adapting to the available water conditions can be a solution as well, forexample from rice farming to fish farming.

Reducing the water demand

Less water usage/spillage

Don’t use fresh water if it is not necessary; e.g., use brackish or salt groundwater in swimming pools or for flushing toilets.

Waste water (re)usage & circulation of water flows

Use recycled (waste) water to flush your toilet and car washing. Don’t make fresh water go to waste.

Changing your water usage mindset

Utilities can be changed but consumers also need to be aware of spillage and consumption. How much fresh water is used to produce certain crops, meat or clothes?

Water pricing

Once water is priced, water use will drop over a short time.

Desalinisation

Desalinise with new technologies

Desalinisation techniques are getting cleaner and energy efficient. Desalinisation is a key asset in the coastal zone.

Brackish water as fresh water resource

In the coastal zone, fresh groundwater 'floats' on heavier saline groundwater with a brackish transition zone. This brackish groundwater is easier to desalinate (and cheaper too).

Storing fresh water

Rainwater harvesting

With improved understanding of the subsurface you can store excess (rain)water underground and use it during dryer times.

Managed Aquifer Recharge

Refill the aquifers that are used for irrigation whenever there is a surplus of fresh rain in the wet season, or fresh river water.

Partial blockage of a stratified system

Obstacles in the bed

This forms a blockage to salt water intrusion via the deeper parts of rivers and canals but allows for flow of the fresh surface layer over the obstacle.

Selective withdrawal

Selective withdrawal can be a way to more efficiently flush salt water out of a canal.

Optimising locks

Lock operation

Optimising the lock operation can reduce the salt intrusion for example by reducing the time that the doors are open for ships sailing in and out or flushing the locking chamber with fresh water.

Lock design

We test and model innovative solutions such as salt barriers and bubble screens.

Redirecting surface water supply

By allocating and distribution scarce fresh water, salt intrusion can be managed at crictical locations. This requires dams and sluices to manage water flow through various parts of the system.