Hydrologist: Heavy rains do not solve drought problem – they make it worse

Poland is not threatened with desertification in the coming decades, but the problem of drought is. Droughts occur more often, cover larger areas of the country and are more intense. The problem is not solved by heavy rains; they bring the risk of flooding, they do not end droughts - emphasized ecohydrologist Dr. Sebastian Szklarek.

The expert pointed out that droughts have a real impact on the economy, and above all on agriculture.

On the occasion of the World Day to Combat Desertification and Drought on June 17, Dr. Szklarek from the European Regional Centre for Ecohydrology of the Polish Academy of Sciences, author of the Świat Wody blog, told PAP that easily accessible water resources in Poland are not only decreasing, but are also being misused.

"When heavy rain falls, we often hear: 'oh, that's good, it will be less dry'. Meanwhile, it is precisely these most spectacular rainfalls that replenish our water resources to the least extent. Earth that has been dry for a long time does not absorb rapidly falling water. Such rainfall is similar to watering a dried-out plant, when instead of soaking in, the water runs off the surface. However, on a national scale, this effect has serious consequences," the expert noted.

He explained that terms such as "desertification" or "steppeification" describe changes in the landscape in which areas previously covered with vegetation gradually lose moisture due to loss of moisture, transforming into dry, barren spaces resembling deserts or steppes. Although such a situation does not currently concern Poland directly, the problem of changes in the structure of vegetation and decreasing soil moisture exists and deepens from year to year.

According to data from IOŚ-PIB, 45% of agricultural and forest areas in our country are at risk of agricultural drought. Regions in the center of the country, such as Wielkopolska, are particularly at risk. The effects that we can already observe are reduced yields, poorer quality of crops, their greater susceptibility to pests, and consequently higher food prices and problems in the agricultural sector.

"Contrary to popular belief, drought is not just a lack of rain. It is a disturbance of the water balance, i.e. a situation in which more water is lost from the landscape than is supplied to it. In practice, this means less rainfall and at the same time more evaporation. The latter is additionally increased by high temperatures and wind," said Dr. Szklarek.

All of these adverse processes are driven by climate change. Rainfall has been less frequent in recent years, but more intense, even torrential. As a result, although sometimes a lot of water falls, it happens in a short time, which means it has no chance to soak into the soil and instead of feeding plants or replenishing underground resources, it flows quickly over the surface, often causing flooding. Then come long periods without rain.

"You can compare it to a potted plant. If you don't water it for two weeks and then water it with a whole can at once, most of the water will overflow and dirty the windowsill, and the plant will wither anyway. Such extremes are not good for nature either," the ecohydrologist illustrated.

In addition, increasingly higher temperatures cause water to disappear from the landscape faster - it evaporates from puddles, but also from soil and plants, deepening the problem of shortages. Due to such changing water balance of entire regions, not only fields are at risk, but also forests, rivers and water reservoirs.

"Low water resources are one thing, but an equally serious problem is the too rapid drainage of rainwater, as well as concreted cities and the lack of natural forms of retention," the PAP interviewee emphasized. "For decades, we have been dominated by thinking about getting rid of water: draining fields, drying areas. Meanwhile, we should retain it where it falls - in the landscape, in the soil, in small reservoirs. Every drop matters," he added.

In his opinion, the biggest challenge is adaptation to changing climate conditions. This means, among other things, restoring wetlands, retaining water where it has fallen, using natural retention methods, and changes in agriculture, such as introducing crops that are more resistant to drought and rational water management.

The expert recalled that for decades urban development and water engineering have focused on the fastest possible drainage of rainwater, treating it as waste. Meanwhile, in current conditions it is a valuable resource that must be retained and reused. In addition to systemic actions, this means the need to implement small retention solutions, reuse sewage, introduce greenery and water reservoirs to cities, and constantly educate society.

"In Poland, access to drinking water is not at risk for now, because most of us use underground intakes, which are more stable than surface ones. In addition, large intakes, e.g. in the Vistula, often use water from the bottom of the river, so even if the water level drops, collection will still be possible. But over time, problems may start to appear here, as is already the case in some regions of Spain. We need to prepare for them appropriately," he pointed out.

Science in Poland, Katarzyna Czechowicz (PAP)

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