Why protect forests is essential to water security ?

Recent research reveal that forests are not only influencing the global carbon cycle and biodiversity but are also affecting rainfall and temperature from global to local scales. Indeed, forests’ impacts on water security are far more important than we first thought, considering their specific ability to lower the temperature ground surface, to provide a cooling effect and affect the generation of clouds.

Forests and the natural cooling effect

Some of the main non-carbon processes through which forests affect the climate include Albedo. Albedo is the reflectivity of a surface: bright surfaces reflect much of the sun's energy back into space, having then a cooling effect (high albedo). In contrast, the canopy of a forest, which is much darker than the ground it covers, absorbs the rays from the sun and can be warming (low albedo). Dark green tree cover usually absorbs more energy than snow cover, crops or bare soil, warming the air as leaves release that heat, much like the heat radiating from a blacktop road. Then, in a second phase, evapotranspiration effect comes into play. Trees release moisture into the air and produce a cooling effect. This happens when water evaporates from the surface of leaves, as well as when water pulled up through the tree’s roots is released through tiny pores in leaves. These processes function as natural air conditioning, cooling Earth’s surface and near-surface air. Surface roughness, affects wind speed and turbulence helps lift heat and moisture away from Earth’s surface, providing also a cooling effect. Finally, trees release tiny particles called aerosols. Their chemical compounds interact with the atmosphere and change ozone and nitrate concentrations affecting the color of clouds.

Together, albedo, evapotranspiration, surface roughness and aerosols affect the generation of clouds, which in turn increase albedo with a cooling effect. This process has been verified on many occasions. For example, in 1999, after a storm that devastated the Landes forest in southwest France, a decrease in cloud cover was observed.

Deforestation in one country can contribute to drought in others

Large expanses of tropical forest — such as those in the Amazon and Congo Basins — recycle moisture in the atmosphere as it passes across the continents, falls as rain, and then is released by trees through evapotranspiration. Large-scale deforestation can disrupt this cycle, exacerbating droughts in downwind areas even hundreds of miles away. For example, researchers estimate that forests in Brazil provide 13-32% of annual precipitation in the downwind countries of Bolivia, Paraguay, Uruguay and Argentina. Deforestation in Brazil can therefore be a major contributor to drought in these countries.

Groundwater begins as precipitation

Preserve forests to protect water resources seems essential, as trees highly contribute to rebalance the natural water cycle. We also know that water infiltration is depending on soil quality. Some land covers have a great impact on infiltration and rainfall runoff. Vegetation can slow the movement of runoff, allowing more time for it to seep into the ground. Impervious surfaces, such as parking lots, roads, and developments, act as a "fast lane" for rainfall - right into storm drains that drain directly into streams. Agriculture and the tillage of land also changes the infiltration patterns of a landscape. Water that, in natural conditions, infiltrated directly into soil now runs off into streams.?

At Bazanowice in Poland, on Diehl Metering site, a meadow have been created to help biodiversity and keep soil moisture.?        

At Diehl Metering, sustainability has always been at the heart of what we do. But today, we wish to go further and expand our commitments to cover every aspect of sustainability. Supporting employee initiatives is part of our DNA. For example, at our Polish production site, an entire area has been preserved and a meadow been created. Not only it contributes to preserve biodiversity, but also to keep soil moisture and to refill underground water. As meadow has longer roots than grass, it does not need to be watered and precipitation infiltrates much better. Compared to a lawn, a meadow is much more helpful to refresh soil, keep water into the ground – even in summer, and is much nicer to look at.?

Author: Delphine Wagner, Communication Manager - Customer Water Segment, Diehl Metering