The environmental problems
“Our rivers are sick” is a statement often repeated in the newspapers, by fishermen, environmentalists and many local administrators regarding the region. The sickness in the rivers is nothing less than an indicator (one of many, for those who notice them) of the general “sickness” in the environment and land. It’s a bit like having fever; it’s the symptom and not the cause of the problem, which can be mild or serious. To get rid of the fever, the cause must be found and cured. The Po-Veneto Plain is unique within Europe for its wealth of resurgence rivers: rivers like Sile, Bacchiglione and many others are unique within Europe. These rivers are invaluable for agriculture and an essential element within the environment and the landscape of the plain. “The resurgences are dying” is a cry that is being heard more and more frequently. The problem of the resurgences is not to be taken lightly, it’s much more than a passing fever. The sickness within the resurgence rivers is severe and it’s going to take more than just an aspirin to be solved! Serious structural measures need to be taken. The problem has two components.
One is volume related:
there is not enough water volume; the resurgences are drying up and there is a risk that they will disappear within a decade. This has been caused by a profound change in the hydrologic balance in the highlands, the usual recharge area for the superficial aquifers which ultimately give rise to the resurgences. In the last 30 years, throughout the Veneto resurgence belt, the levels of the phreatic aquifer have been diminishing progressively and the consequence is the reduction in the overall flow of the resurgences. Many springheads have dried up completely while many others remain dry for longer and longer periods. This phenomenon has raised the alarm and in the last decade many research studies have been carried out, both on the overall situation of the aquifers (see studies from AIM – a multi-utility company of Vicenza’s municipality, CNR – National Research Council, several universities, and from the Centro Idrico di Novoledo) and on the progressive reduction in the occurrence of resurgences, (see in particular the recent studies from the Pedemontano-Brenta Land Reclamation Consortium of the city and Province of Vicenza). Take the Destra Brenta area for example, it’s made up of around ten municipalities straddling the provinces of Vicenza and Padua, where, according to research done in 1997 by the Pedemontano-Brenta Land Reclamation Consortium, in the last 30 years the main active resurgences have gone down in number from 66 to 41 and their total overall flow has gone from 15 m3/ sec in the ’60s to 3-4 m3/sec.
A second study, concluded in 2003 and carried out by the same consortium, showed that the reduction in the occurrence of resurgences is actually much more serious: their research is not only based on the knowledge of the consortium guardians (whose job it is to know all the principle resurgences that supply the substantial irrigation water courses) but also on direct interviews with farmers, enthusiasts, naturalists, etc. The study showed that over the last 30 years, in the Destra Brenta territory, all of the small points of resurgence have disappeared (small spring wells, gatoj – a word, in the Veneto dialect, used to describe a spring rising from a crevice in the land, etc.) which at one time where everywhere. In the last 30 years more than 80% of the resurgences have disappeared and the predictions are, that if no measures are taken to halt the waning levels of the phreatic aquifer, in the arc of 10-20 years most of the existing resurgences will dry out. The causes of the progressive decrease in the levels of the phreatic aquifer and the resulting reduction in the flow from the resurgences are numerous: – A deepening at the middle course of Alpine rivers (particularly the Brenta) due to gravel extraction; – Urbanisation of the region with a resulting reduction in farmland that permitted greater infiltration of water; – Increased drainage from the aquifers for agricultural, industrial and civil purposes (see in particular the concentration of wells feeding the water mains on the middle to the lower plain in areas that straddle the resurgence belt); – Changes to in the techniques of irrigation on the upper plains (substitution of surface irrigation with sprinklers; waterproofing of the irrigation ditches and water distribution); – Changes in rainfall patterns.
In terms of quality:
The quality of water from the resurgence rivers, famous for its transparency and purity, is steadily worsening. Already the water at the springheads has higher levels of nitrogen which disturbs the correct function of the fluvial ecosystems (eutrophication); agriculture is the prime contributor of this unnatural enrichment in nutrients found in the water of the aquifer. All along their course, resurgence rivers rapidly intercept discharge from civilian treatment plants that dramatically affects its quality. The upper plain with its coarse composition of soil and the presence of unconfined aquifer are of strategic importance for the protection of the deeper underground water. The development of human activity on the Vicenza upper plain in the last decades has generated several risk factors threatening the quality of the groundwater: – dispersion of pollutants from industrial activity (heavy metals; solvents; etc.) – organic contamination from farming and civilian activity (nutrients). An extensive network and treatment plants, for waste water and sewage, have been built. This, together with changes in production processes and assisted by policies which focus their attention on protecting the recharge areas on the upper plain from pollution, has greatly reduced the risk of contamination in the groundwater (the quality of which in the Vicenza area is continually and effectively monitored by the Centro Idrico of Novoledo).
In keeping with this strategy is the progressive transfer of the consortium’s treatment plants discharge points from the upper plain to a level below the resurgence belt and the adoption enhancement areas for the waste water (see the treatment plants Thiene and Schio, managed by the company Alto Vicentino Servizi of Thiene). The same cannot be said for the agriculture sector and in particular the livestock sector. In the last few years several factors have increased the negative impact coming from livestock activities on the quality of the groundwater. This is particularly serious when it effects the recharge zone of the upper plain area: – The change in the cattle feeding rations (in the upper Vicenza area its mostly dairy cattle) has seen a reduction in the quantity of hay and an increase in the use of maize silage; this has resulted in a dramatic reduction of the permanent meadow, especially in on the upper plain. The grassy turf of permanent meadows acts as a good buffer and is functional all year round, while a maize crop, especially when planted in coarse soil, is unable to prevent the seeping of nutrients into the ground, in particular the nitrates. These are the main culprit in groundwater pollution; – the changes in the techniques of animal housing has led to a progressive transformation of the excreta: from manure to slurry. Slurry is much harder to manage at an agronomic level and can easily lead to serious contamination of the water at, and deep below, the surface; – the practice of concentrating cattle livestock in single large production units has further intensified the problem of managing the excreta, which tends to lose its traditional value as fertiliser and become waste water (i.e. a problem) to be disposed of. Resurgence rivers, apart from being fatally hit by the progressive loss of flow and reduction in water quality, have also suffered from the environmental point of view; resulting from the decline in traditional maintenance of the bordering vegetation. The wooded hedgerows which are no longer valued for their firewood, obtained by coppicing and pollarding the trees, have been slowly forgotten and not replanted. In many cases they have been completely cut down to make it easier to maintain the waterways. The final result is, these islands of biodiversity that were once resurgences, have been progressively deprived of wildlife. In the worst instances, the loss of water flow and practical worth of the resurgences has brought serious consequences: the springhead and the initial part of the natural spring outlet have been covered by earth, leaving, at best, a tube to discharge the water in the rare moments that the aquifer regains its old levels. One of the most blatant examples of this is seen at the springhead of the river Tesina at Sandrigo.