What are the consequences of increasing drought?

Water supply from rivers is unavailable in many elevated parts of the Netherlands. Consumers fully depend on precipitation and groundwater. Consequently, such areas are more prone to water shortages, resulting in drought stress. Drought stress occurs when the soil dehydrates to a point that inhibits plant evaporation. Drought stress may cause part of the plant or the entire plant to die. In agriculture, drought stress can reduce crop yield. Drought-intolerant crops include, e.g., vegetables, potatoes, and beetroots. Drought stress also has a severe impact on the natural environment: local extinction of species, a higher risk of wildfire, pools and brooks running dry. Furthermore, a severely dehydrated soil will hamper water infiltration. During torrential rain, this may lead to waterlogging.

Low-lying parts of the Netherlands can be supplied with water from rivers and other freshwater sources, such as Lake IJsselmeer. However, this supply also has its limitations. This is one of the conclusions from the stress test conducted in the IJsselmeer region. In dry summers, water requirements will increase, whilst river discharges will be low. Water shortages will cause an additional problem in the coastal provinces: salinisation. Salinisation – the accumulation of salts in groundwater and surface water – occurs when saline sea water travels further inland in times of drought and low river discharges. Salinisation poses problems for various functions that depend on fresh water, such as the drinking water supply, but also for bulb growing, agricultural areas, and the industry. In addition, fish and plant species habitats will shift, whilst salinisation can also be harmful to certain types of nature. Salinisation also occurs in the major rivers, such as the Rhine and the Meuse. Consequently, the problem extends beyond the coastal areas.

Drought can add to soil subsidence. As a result of less water in the soil, the soil will compact. This process is referred to as “shrinkage”. Once more rain starts to fall, part of the soil may expand again, but a part will remain compacted. The latter is referred to as “settling”. The compaction will cause the soil to subside. An additional process is peat oxidation. When groundwater levels fall, peat will be exposed to oxygen. Peat that comes into contact with oxygen will decay and disappear. As a result, the soil will subside even more. Furthermore, this process will release a great deal of greenhouse gases. Soil subsidence due to drought may also cause subsidence and cracks in buildings, roads, and dykes. In addition, drought can cause problems in wooden foundations. Many older houses in clay and peat areas are founded on wooden poles. These poles must remain submerged in water to prevent rotting and mould through exposure to oxygen. Drought may result in such foundations running dry. This will cause pole rot and subsidence. The Foundations Risk Maps map narrative of the Climate Impact Atlas shows the areas that are at risk of foundation damage.

During a period of drought, insufficient water will be available for farming. In the event of water shortages, irrigation bans may be imposed. This can cause damage. Agricultural areas on the elevated sandy soils in the south and east of the Netherlands are particularly prone to drought damage. The Climate Damage Atlas estimates the costs of drought-related damage over the period 2018 – 2050. For the agriculture sector, the data is based on lower crop yields and crop damage. Taking the current climate as our point of departure, agricultural drought damage in the Netherlands will run to between 24 and 47 billion euros up to 2050. The lower limit factors in irrigation and the upper limit considers the situation without irrigation. In the event of sharp changes in the climate, drought damage will amount to between 23 and 51 billion euros. Changing land use has been taken into account in this scenario.

During a period of drought, insufficient water will be available for farming. In the event of water shortages, irrigation bans may be imposed. This can cause damage. Agricultural areas on the elevated sandy soils in the south and east of the Netherlands are particularly prone to drought damage. The Climate Damage Atlas estimates the costs of drought-related damage over the period 2018 – 2050. For the agriculture sector, the data is based on lower crop yields and crop damage. Taking the current climate as our point of departure, agricultural drought damage in the Netherlands will run to between 24 and 47 billion euros up to 2050. The lower limit factors in irrigation and the upper limit considers the situation without irrigation. In the event of sharp changes in the climate, drought damage will amount to between 23 and 51 billion euros. Changing land use has been taken into account in this scenario.

Many municipalities are working on greening their urban areas. Greenery boosts the climate resilience of the environment and promotes public health. Expanding greenery in the built environment can help to reduce drought, because more water will be able to seep into the soil. However, drought also constitutes a threat to the greenery. Water shortages in the built environment may lead to drought damage to public greenery. Thus, drought will push up public greenery management and maintenance costs. For each type of landscape, the Urban Areas Climate and Water Requirements study report features a fact sheet with the main conclusions on the future trend in urban water requirements.

Drought can have negative health effects. Some examples:

• Without the washout effects of rainfall, drought increases the amount of particulate matter suspended in the air. Particulate matter is released into the air by strong pollutants such as car traffic, wood stoves and barbecues. Particulate matter particularly affects people with lung problems.
• Heavy showers after a dry period can cause infectious diseases in people and animals. This can happen if sewer overflows occur, which is more likely to happen in drought because water is less able to infiltrate into dry soil. Sewer overflows can cause contaminated water to enter surface and groundwater, as well as the streets.
• During dry periods, water evaporates faster, causing higher concentrations of pollutants in surface water. It is then more difficult to purify the water into clean drinking water.