How has the Earth's water cycle been destabilised?

‘For the first time in the history of mankind, the world water cycle has lost its balance’ was stated in The Economics of Water report prepared by an expert commission working under the OECD. In the report, the issue is analysed from a different perspective than it has been addressed so far. In addition to the conservation and efficient use of water, the report also mentions what needs to be done in order not to disrupt the continuity of the water cycle. It emphasised the protection and restoration of natural habitats and the protection of green water, one of the most important components of the water cycle.

The formation and renewal of the water resources system is the result of a natural activity called the water cycle. Some of the precipitation falling on land returns to the atmosphere through plants as a result of a biological process called evaporation or transpiration from water, soil and vegetation surfaces. Some of it forms surface and groundwater, reaches the seas and oceans, evaporates and returns to the earth as precipitation.

This continuously repeated cycle between water and soil surface, vegetation and atmosphere is called the water cycle. The water cycle provides water for all life, including humans, and maintaining this balance as a whole is crucial for the sustainable use of natural water resources.

Impact of human activities

The formation and renewal of water resources is the result of a natural activity called ‘water cycle’. The fact that some processes in nature are organised in cycles ensures the renewal of natural resources. As long as there is no or minimal human intervention, the cycles in nature generally continue in the same order. The water cycle is one of them.

The four main elements of the water cycle are precipitation, surface runoff, groundwater, evaporation and transpiration. In the calculation of our water resources, these are calculated in quantity. However, the disruption of the water cycle by human activities causes this amount to decrease.

Climate change caused by fossil fuel use and greenhouse gas emissions directly affects the water cycle. Changes occur in precipitation patterns. In addition, faulty land use planning such as destruction of forest areas, abandonment of pasture and other agricultural areas to urban and industrial settlements, and agricultural practices that do not comply with technical rules have significant impacts on the hydrological characteristics and water cycle of a water basin. For example, forests play a critical role in releasing water vapour into the atmosphere and regulating rainfall, so deforestation affects the amount and distribution of rainfall.

The way we use land determines how much precipitation causes water loss through evaporation-transpiration and the water balance between surface runoff and infiltration into the soil. The allocation of large areas of agricultural and pasture land to urban uses has negative impacts on the hydrological balance in that region. Improper land use plans lead to a reduction in water retained in the soil and in groundwater recharge, upsetting the balance.

In summary, human activities negatively affect natural processes by changing the speed, flow and quality of the water cycle. Therefore, sustainable water use and environmental protection policies are critical for the continuation of the water cycle in the balance that has been established over millions of years. Therefore, water conservation should start with the protection of our natural environment.

Impact of climate change on the water cycle

Climate change affects temperatures, precipitation regime, precipitation patterns, evaporation rates and distribution of water resources around the world, changes the water cycle by increasing forest fires, and deteriorates the quantity and quality of water resources.

For example, the melting of glaciers caused by climate change affects the directions of ocean currents and increases the tendency of rising sea water level. This deteriorates the quality of groundwater, starting with coastal aquifers.

Since the water cycle is a process that ensures the continuous circulation of water on the earth's surface, in the atmosphere and underground, it is very fragile in the face of climate change impacts. This vulnerability especially affects rainfall-dependent agricultural production, which is directly linked to stable rainfall patterns. (Green water supply). Therefore, efforts to combat and adapt to climate change are crucial for mitigating the impacts of climate change on the water cycle.

Protection of the water cycle should be a ‘shared value’

The issue that the water cycle is a common value that provides us with water and needs to be protected should be addressed more in international activities. In this context, first of all, feasible solutions should be created to reduce the activities that cause climate change. However, approximately 60-70 per cent of global carbon emissions in the atmosphere that cause climate change originated from developed countries. Currently, approximately 40 per cent of annual global greenhouse gas emissions come from developed countries.

In order for developing and underdeveloped countries to reduce carbon emissions, plan their land and take other measures to protect the water cycle, it is essential that developed countries increase economic and technological assistance to underdeveloped countries. Effective co-operation requires a common goal, common understanding and common economic benefits. The increase in inequality between the north and the south on a global scale will disrupt the world balance in many respects.

To the extent that inter-country co-operation cannot be achieved, developed countries will regulate their water resources and become more compatible with water; developing countries will struggle with water; and underdeveloped countries will try to survive as captives of water.

However, the developed countries have started to directly experience the negative consequences of not recognising the water cycle as a common value with severe floods and longer droughts. In the near future, they will be more indirectly affected by the increasing climate migration. They should therefore be more open to co-operation and provide financial support.

Sustainable water management

In the report of the Global Water Economy Commission, it is claimed that if no measures are taken, there will be an average GDP loss of 8 per cent worldwide in 25 years. It is also mentioned that more than half of the world's food production may be at risk by 2050 due to the deepening water crisis by 2050. The report also states that the pressures on water are increasing in the regions where half of the world's population lives due to improper land use, inefficient water management and climate change.

Sustainable water management takes into account the ability to meet the water needs of future generations by using existing water resources efficiently and fairly. This management aims to ensure the sustainable use of water by balancing environmental, economic and social needs.

Governments should also implement policies for the development of the most appropriate water resources and the management of water services so that all living beings have permanent access to sufficient and safe water. For this, water should be managed in an integrated manner at the river basin scale. It is also very important for this management to be participatory and transparent in order to achieve positive results.