The year 2022 was an unusual year in terms of temperature, sunshine and low rainfall. These extreme weather conditions are known to have led to persistent water shortages. Has this spring's rainfall been able to make up the shortfall in streams and aquifers?
The rainfall of this spring 2023 failed to rebalance a water deficit that had been lingering indicatively since December 2021. Overall, groundwater levels in May and June 2023 were temporarily falling within the multi-year average values. However, the scarcity of rainfall in July and August, but above all their typology (extreme events of high intensity but short duration) did not allow for an adequate recharge of the aquifers: we are still observing a trend of descending levels. The latest heavy rainfall at the end of August raised levels considerably, but whether these levels will be maintained over time depends on the frequency of rainfall in the coming months.
What weather conditions would have to occur in order to make up the shortfall? Otherwise, is it possible to imagine what the likely scenario will be between now and the end of the year?
We need to understand what the rainfall trend will be in terms of quantity but above all frequency in the coming months: to adequately recharge aquifers in the long term, we do not need intense rainfall, compressed into short periods and very localized, but frequent rainfall, even of low intensity, over extensive areas.
What repercussions might this condition of water stress have or is already having?
A failure to recharge aquifers leads first of all to serious inconveniences for those municipalities that are almost exclusively dependent on springs for their water supply: if a spring significantly decreases its flow rate or even temporarily disappears, the amount of water that can be captured will be much less. Subsequently, even prolonged water stress of alluvial aquifers leads to the need to limit water consumption to essential needs only, i.e. drinking, agricultural, and industrial. Non-essential uses are prohibited by drinking water companies to rationalize the resource, which is prioritized for potable use.
In our small way, we must increasingly realize that groundwater, although invisible, is a precious resource that cannot be taken for granted, a primary good that we must use respectfully and sparingly.
In the canton of Ticino, approximately 90% of the drinking water comes from groundwater, which may either flow from springs and be collected by special tanks or be actively pumped out of the subsoil through wells. Verifying the water status of groundwater is only possible by constantly monitoring it. The hydrogeology sector of the IST collects data and compares the measurements taken (both monthly manually and automatically via probes) with the values collected over the past 10 years. Since 2012, the Institute of Earth Sciences has been monitoring groundwater in Ticino on behalf of the Canton at more than 100 measuring points, of which 19 are currently equipped with automatic probes.