We started by studying the Tagus River: where it originates and what changes it undergoes along its route as a result of human action. Throughout our research we analyzed temperature, precipitation, river flow and satellite data. We also invited an agricultural engineer who works with farmers in the region to tell us about their use of river water.
We conclude that the river’s flow is affected by a transfer that exists in Spain and is regulated through around fifteen dams, only two of which are located in Portugal. These two countries signed an agreement, which ensures the passage of a minimum flow from Spain to Portugal. This agreement helps prevent the river from drying up in our territory, even in years with little rainfall. We also realized that, despite the existence of dams, there is a relationship between precipitation and river flow, as we expected. Satellite images made it possible to understand that when it rains little, the vegetation does not remain as healthy and we were also able to understand when agricultural fields were irrigated. From our conversation with the agricultural engineer (Dulce Rodrigues) we learned that it is no longer possible to grow melons in this region because of the salinity of the water (we are not very far from the mouth of the river) and that currently they mainly grow tomatoes, a species that has to be watered throughout the entire growing cycle. We also learned that in 2022, which we identified as the driest in recent years, farmers had to drill deeper to find the water needed to irrigate the fields.
Finally, we thought…. Maybe the river won’t dry up completely, but these changes in flow and salinity could be affecting the river as an ecosystem…