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Most of the water evaporates.
Such a situation is surprising and strange, because it is not raining this summer, but Juozas Šimkus, head of the Division of Hydrological Observations of the Lithuanian Hydrometeorological Service (LHMT), said that there is nothing very strange here.
“It just caught our eye then. Only in some areas, the rivers are really heavily polluted, although rainfall is around 30-40%. Higher than the multi-year rate.
There seems to be enough rain, but what matters is how it falls, J. Šimkus explained. – For example, on the last day of June, the natural criteria for rain were met in some places, but that amount of water flows abruptly into the rivers. However, if the same amount of rain had fallen, for example during the week, the impact on the rivers would be much greater. “
“Where does that water go if it doesn’t reach the rivers?” I asked the hydrologist.
“It just caught our eye then.
Although there is not much heat, it is true that the last days have been a little warmer, but the evaporation is quite intense.
Furthermore, all vegetation is now very tightly assembled. Therefore, vegetation in the upper soil layer, where water seeps into groundwater, strongly evaporates that moisture. Therefore, although there is enough moisture, a large part evaporates “, – J. Šimkus explained where the water disappears.
Šušvė and Nevėžis have not yet reached the limits of hydrological drought
Still, although the water level in the rivers is quite low, the head of the LHMT’s Hydrological Monitoring Division sees nothing unusual here.
“It just caught our eye then.
Every summer, the rivers are more or less depleted.
Clearly, last year and in the summer of 2018, a hydrological drought was registered and the situation was much worse. Until today, the Nemunas, the Neris, the great rivers, are very depleted precisely because the precipitation has fallen in the form of rain, instead of constant and calm rain.
Lėvuo is also very often.
Nevėžis is also more “sitting”, and the rivers of western and slightly central Lithuania are almost the norm or even more than the norm, – said J. Šimkus. – So if we look at the situation across Lithuania, it is not as bad as it was last year or the year before.
Of course, if the rest of July and early August are dry, there will be a hydrological drought across Lithuania.
As for Šušvė or Nevėžis, which rinses Kėdainiai, both rivers are currently below the norm and are approaching the critical limit when there will be a hydrological drought, but have not yet reached it.
I even specifically compared last year’s results and the same period this year, which was much worse last year. “
Just look at the rivers
The interlocutor emphasized that if precipitation were the norm and they did not fall in the form of rain, but in calm rain, such rain would be more favorable for the recovery of rivers. And if there was as much rain as in 2017, when two and even three rates fell in a month, then of course we would have a similar situation to that of 2017.
When asked if hydrological drought affects only rivers or other bodies of water, J. Šimkus said that this happens to all bodies of water. However, currently only rivers are controlled.
“Until now, we only count and look at the rivers, we do not evaluate the lakes with that criterion.
We currently have few observable lakes to make generalizations or assessments. Until now, there simply is no need to monitor the lake’s water levels, hydrologist LHMT said about why only rivers are monitored. – According to the State Environmental Monitoring Program, the quality of the water and the ecological situation are monitored and evaluated in most of the lakes. However, such measurements are not made every day. And water levels and temperatures are observed in just thirteen lakes to date. However, this is only a very small part of Lithuanian lakes and it would be really imprecise to make some generalization. ”
J.Šimkus also denied that the lakes recover faster after the water sequence and react less to hydrological drought.
“No, lakes react more slowly to these processes.
Many lakes are fed by groundwater, and processes there are even slower. As a result, the lakes are less responsive and less responsive.
If it rains and the stream pond can rise up to two or three meters, then after the rain on the lake the water can rise only two or three centimeters. So those processes are not so obvious, “said hydrologist LHMT.
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