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.
FACTS AND FIGURES
Drinking-water sources
Consumption
Data shows a growing trend in water consumption:
Pressures on the coast
Population density is signifi- cantly higher in coastal areas
Lower river discharges
In the future due to climate change
Ongoing trend of coastal migration
This is associated with global demographic changes. Most of the world megacities are also situated at the coast.
Sea level rise
Projected sea level rise, in meters
More and larger ships
Fleet capacity, prognose , in TEU
Costs of salinisation of agricultural land
Salinisation increases due to sea level rise and lower river discharges.