Groundwater and Soil Subsidence
In the Netherlands every year 1.674 million m³ groundwater is pumped up. 563 million m³ is used by households, 525 million m³ by industries and 450 million m³ in agriculture. The yearly replenishment is 2.615 million m³. The amount that can be extracted is approximately 1.900 million m³. In the lower parts of the Netherlands hardly any freshwater can be extracted, because salt or brackish water will come up. The dunes, where drinking water always has been extracted, are an exception. The freshwater reservoirs in the dunes are artificially replenished with riverwater.
However, in the Netherlands 620.000 hectare of nature reserves are subject to drought. The groundwater table in the Netherlands has lowered 25 centimeters in the last forty years and in reallocation areas and drinking water extraction areas on average 35 cm. Incidentally drops of over 1 meter have been observed. The drops are for 20% caused by groundwater extraction for households and industries, 20% by drainage of cities and surface run-off, and 60% by agriculture, especially due to fast drainage and discharge.
Soil subsidence
In many parts of the Netherlands, there is a slow, natural fall in ground level. This subsidence has various causes. In the past, natural subsidence was compensated by clay and sand deposited during the flooding of the major rivers. This was no longer possible, however, after dikes were built along the rivers. Another cause of soil subsidence is the commercial extraction of peat and clay. In the west of the Netherlands, these ground types naturally contain a lot of groundwater, and when that water is drained off, the soil subsides. In the Netherlands, groundwater has been drained off and pumped away for hundreds of years in order to use the land for agriculture.
A third cause of the soil subsidence is that peat is liable to oxidise when it lies above the water table. This is an important cause of subsidence in the peat meadows of the western Netherlands. Large-scale agriculture and the spread of cities have accelerated these processes of subsidence and oxidation.
However, in the Netherlands 620.000 hectare of nature reserves are subject to drought. The groundwater table in the Netherlands has lowered 25 centimeters in the last forty years and in reallocation areas and drinking water extraction areas on average 35 cm. Incidentally drops of over 1 meter have been observed. The drops are for 20% caused by groundwater extraction for households and industries, 20% by drainage of cities and surface run-off, and 60% by agriculture, especially due to fast drainage and discharge.
Soil subsidence
In many parts of the Netherlands, there is a slow, natural fall in ground level. This subsidence has various causes. In the past, natural subsidence was compensated by clay and sand deposited during the flooding of the major rivers. This was no longer possible, however, after dikes were built along the rivers. Another cause of soil subsidence is the commercial extraction of peat and clay. In the west of the Netherlands, these ground types naturally contain a lot of groundwater, and when that water is drained off, the soil subsides. In the Netherlands, groundwater has been drained off and pumped away for hundreds of years in order to use the land for agriculture.
A third cause of the soil subsidence is that peat is liable to oxidise when it lies above the water table. This is an important cause of subsidence in the peat meadows of the western Netherlands. Large-scale agriculture and the spread of cities have accelerated these processes of subsidence and oxidation.
