Water in the Landscape - climate change and dewatering

Submitted by Ase Johannessen | published 22nd Nov 2021 | last updated 5th Dec 2021
Slovak landscape

Dewatering of the landscape

This video, based on Slovak expertise, describes how increased water vapour in the air in combination with dewatering of the land, can cause climate changes and extreme events. It illustrates how it is vital to manage water in the landscape to keep it in sufficient amounts.

The text below provides a recap of the main messages in the film:

Climate change has become a reality with extreme weather patterns are becoming more and more frequent. The Climatologist advice is to reduce greenhouse gases – but even if we immediately stop, we will only begin to see the result 100 years from now. We therefore need to adapt now to the consequences of climate change.

The largest cause of climate change if the release of greenhouse gases but dewatering also plays a role. Areas are dry, and hot, more like steppes. A lack of plants for evaporation also heats up the air.

Increasing extreme events and changing climates

Meteorologists in Slovakia has analysed the weather since 1878. For 120 years only three extreme events have been recorded. The last decade 1990-2000 there has been 7 years of extreme weather fluctuations with floods and droughts. “The weather has appeared to have gone mad”.  

Most of Europe has a mild climate with four different seasons, but more and more the climate is becoming more like a steppe. France, Germany and Spain are becoming like semi-deserts.

Dewatering

Dewatering is a global phenomenon which occurs with land use change. Dewatering is the process of removing water in the landscape by changing land use, reducing vegetation, sealing the surface increasing runoff, temperature, and altering water vapour flows which create extreme downpours. This is a long-time process which has been ongoing for centuries aimed at increasing the productivity of the landscape in agriculture and forestry, and for urbanisation.

Dewatering in agriculture

Clearcutting of forests and increase of large-scale agriculture. Agricultural areas used to have more natural elements keeping water in the land. Larger fields often introduced because of larger efficiency – but the last century the landscape drying out has been accelerating due to large fields.

We have only been practicing agriculture for 10 000 years. To increase productivity, we have been draining the land, which then starts resembling a steppe. For example, farmers place drainage pipes to drain the soil, canals were straightened, or even pumped away to speed up the draining. We are starting to realise that the creation of steppe landscape can bring over time dry weather, which is the weather pattern in steppes.

To keep water in the landscape benefits nature and soil conservation. If the surface is dry this can greatly heat the atmosphere, and influence weather to change its old routes. There are no longer four seasons. In other words, the weather is as we here on earth has made it.

If we don’t change our cultivation of our soil in the future, we can expect far more dramatic change in nature.

Green areas act as cooler

Land uses influence the effect of sun energy on earth. All solar energy turns into heat, but with green areas the temperature is lower. Why are green areas cooler? Because of water evaporation. Water runs through the plats – provided it has water available, flowing through the pores into the air, it is a brilliant cooling device. It is because of water vapour that the sun energy is distributed. By eliminating vegetation from the surface, we have also removed unique capability of cooling the environment, the natural hydrocycle has been disturbed. Each vegetation has a different capability. Corn fields have a different water content than areas with trees. With changing land use we are creating difference in temperature. These differences try to balance out, which create strong winds and downpours.

By drying out areas, they destroy life in these areas. This influence water vapour flows. Dry air collides with colder more humid air. After colliding these flows are sent to great hights, water vapour condenses quickly and falls as waves of extreme downpour. Hot air warm up in the dry areas met with cool air this resulted in condensation over a relatively small area, and extreme weather.

Extreme rains occur usually after droughts. Hot air from Sahara and Europe can extend north and collide with cooler air. The resultant extreme weather does not always create by the same country that suffers its impact. Likely that the floods are connected to the drying out of the landscape.

Rivers

The dried-out areas have changed the climatic conditions. For example, in East Slovac lowlands. Further dewatering is occurring by removal of meandering, and channelization. In the past we have confined rivers in concrete channels, but this practice is increasingly abandoned.

Urban areas

Cities are often drained of water with large areas asphalted, and contributing to overheating the air, especially on hot summer days.

Pot plants cannot replace the effects of vegetation and greenery for cooling and water holding capacity.

Working cultures

Water management specialism and working cultures contribute to practices which dewater the landscape. Traditionally engineering of landscapes and the use of hard infrastructure has dominated practice in water. Professionals are needed that understand the connections between different land uses, and the importance of water in the landscape.

In summary

Vegetation acts as a natural air conditioner and can run with full power if having access to water. We assume that nature will recover, and we will be alright. But the air conditioner is out of order. One natural calamity will follow on each other if we don’t bring water back to the land. We have to create evaporating areas.

Dewatering causes several phenomena which influences the climate:

  • A change of land cover changes its water content. This is a long standing practice to increase productivity and food security. For example, cutting trees and replacing with crops, or having large areas of monocultures, and urban areas with no greenery, changes the amount of water which is circulating through the soil and plants and is available for cooling.
  • This also changes the moisture content of the soil, which reduce organic material and life, and the dry soil increases runoff and flooding.
  • Reducing vegetation of the land increases temperature, as evaporation is a process which lowers temperature of the surrounding environment.

 

 

Air Conditioner Breakdown - LEON Productions. A Film by Katarina Zackova

This film was made in 2006 based on the book Water for the Third Millennium, which was published in 2000.