By Gérard Le Puill
In 2019, as in 2020, more than three quarters of our metropolitan departments were confronted with water restrictions between the beginning of summer and the middle of autumn. Beyond the consequences of two dry and hot summers on agricultural yields, the management of water for the daily use of households was made difficult due to a too low rise in the level of groundwater during two autumns and two. winters in most of our regions. For 2021, the Geological and Mining Research Bureau (BGRM), which works under the supervision of several ministries, has just published an update on the state of groundwater in the 1 er January.
He tells us that “the situation in December is satisfactory over a large western part of the territory (…) The groundwater levels are thus particularly high in the Adour-Garonne basin”. We can think that they will continue to rise in this region because of the abundant rains which flooded several departments of this basin at the beginning of the year, starting with that of the Landes.
The BGRM indicates that “the situation is less favorable” for the aquifers of the Grand Est, Bourgogne-Franche-Comté, and Auvergne Rhône-Alpes regions. But “charging has started and is slowly improving. Finally, some water tables are impacted by the fall pluviometries. Thus, the levels of the Alsace water table south of Colmar and the Provence and southern Alps water tables are falling or stable, the levels are moderately low to low ”. We should add that the good snow cover of mountain ranges is also likely to favor infiltration into the soils of these regions from spring, while directly supplying the flow of rivers.
A slow migration to deep water tables
The BGRM speaks of “contrasting trends on the very inertial water tables of the tertiary formations of the Paris Basin and of the chalk of Artois-Picardie, Seine Normandy and Beauce. Charging begins in December in these sectors and trends are on the rise in many of the points monitored. Nevertheless, the inertia of the groundwater still induces a local drop in levels. The rains infiltrated since the beginning of autumn slowly cross the unsaturated zone to reach these tables ”.
As the rainy passages continue to water most of the territory since the beginning of January, the conditions seem ripe for the level of the water tables to continue to rise all over the country. However, different situations persist, sometimes within the same region, as this observation by the BGRM shows: “On the Mediterranean coast, the situation is contrasted. In the west and in Corsica, the levels are moderately low to moderately high and the December rains improve the state of the water tables. In the east (from Bouches du Rhône to Alpes Maritimes, editor’s note), the situation is less satisfactory, with moderately low to low levels, and is deteriorating due to low rainfall ”.
Let’s learn from the situation in Spain and Morocco
Water management in connection with the preservation of our food sovereignty will be one of the major challenges of the 21st century in the world. While almost all of its rivers have their source inside the country to supply rivers that join the sea on our coasts, France has the means to manage this resource rationally. This management is becoming more and more difficult in Spain. Our neighbor from beyond the Pyrenees has, since joining the European Union 35 years ago, favored irrigated crops for export. This has resulted in the establishment of thousands of square kilometers of greenhouses and orchards whose yields are boosted by irrigation. So much so that seawater is now desalinated to produce strawberries, tomatoes and many other export crops.
Without being a member of the European Union, Morocco is going through the same situation for having too specialized its agriculture in fruit and vegetables for export. Like Spain, it made use of the comparative advantages of the sun and the low costs of its labor. In the French monthly “Succeeding fruits and vegetables” for this month of January 2021, we learn that more than one million hectares are devoted to fruit production in Morocco, to which are added 280,000 hectares of market gardening. But market gardening “consume between 6,000 and 9,000 m3 of water per hectare and per year”, according to Doctor Mimouni from the regional center for agricultural research in Agadir.
The perverse effects of the theory of comparative advantages
The French monthly notes immediately that “most production areas are already suffering from a water deficit” in Morocco. He adds that “the reduction and modification of the rains, associated with an increase in temperatures and high potential evapotranspiration values will have a clear impact on the profitability of these crops” in the coming years. Because of this evapotranspiration, 30 liters of water must be used to produce a kilo of tomatoes in Moroccan greenhouses. In those of the Netherlands, whose competitiveness is favored by the low price of gas drawn from the underground to heat greenhouses, only 5 liters of water are used to produce a kilo of tomatoes.
In many countries, agricultural specializations long based on competitive advantages will turn into a fiasco at the start of the century increasingly marked by global warming. Yet two centuries after the death of David Ricardo, his theory of comparative advantage still serves as a bible to many liberal economists. However, neither the Dutch model, nor the Spanish or Moroccan model, is relevant today. The urgency is to reduce the distance between the fork and the fork if we want to reduce the carbon footprint of our plate from day to day.