[MUSIC] [MUSIC] Hello. So in the next three sequences, I am going to talk to you about groundwater. The first sequence will examine the challenges of groundwater regulation. I have identified two challenges. The first challenge is actually the knowledge about groundwater And the second challenge, well, it concerns borders. Problems can arise when groundwater crosses boarders. Before discussing these challenges, I want to give you a quick introduction to groundwater, to show you how important groundwater is for both the planet and for humanity. Groundwater is so important for the planet's fresh water supply. Fresh water, as you may already know, only represents 2.53% of the earth's water. The majority of the planet's water is salt water. And groundwater represents 30% of the mass of fresh water and therefore it is a really large mass. We have about 2.5 billion people on the planet who depend entirely on groundwater for their domestic water needs. In some countries this can be 100%, like Libya in the arid zone or the Arabian peninsula. But even in Europe, where the climate is more temperate, 70% of the population depends on groundwater for its drinking water supply. Finally, the groundwater extracted from our land, from the subsoil, and 65% of the groundwater extracted on a global scale, is intended for irrigation. The first difficulty to address when managing groundwater is that it is an invisible resource. In English, we say: out of sight, out of mind. The French translation isn't quite the same: far from the eyes, far from the heart. It is not really about the heart. It is much more about the brain. Managing groundwater involves a lot of reasoning. And it's hard to manage what you do not know. Knowledge is therefore very important. And because it is an invisible resource, developing this knowledge is much more complicated than for any other infrastructure. We need to know the amount of water available and know its quality. We then need to anticipate the demand for uses and quantities of water. And for that, we need to consider more than the water. We need to consider the geological formation, the layer which houses this groundwater as it behaves differently depending on the nature of the soil. Some soils are very permeable and rain will infiltrate these quickly and the level will be quickly recharged. On the other hand, when soils are permeable, pollution will infiltrate just as quickly. So all this, all these elements are unknown and knowledge needs to be developed. I spoke a little about the nature of the soil, and in addition to managing water and its use, soil management and land use planning needs to be considered. Let me give you some examples. In the case of an uncontrolled landfill, pollution will infiltrate, depending on the nature of the soil. If the soil is very permeable, the pollution will infiltrate quickly. Or take the case of a regulated activity such as agriculture. It is true that agriculture uses groundwater for irrigation, but agriculture also uses pesticides which infiltrates the soil and will affect the aquifers. In France, in the region of Brittany, there are aquifers that have been polluted by agricultural activities. There are some activities which affect groundwater which are unrelated to the use of water but linked to the management of an activity which takes place on the land. This is also linked to land use planning. Sometimes there are motorways or airports or other infrastructures constructed close to an aquifer. This makes refilling the aquifer much harder and this will have an impact. This all needs to be taken into consideration. And before any work can begin, it is important to develop knowledge of the aquifer and the nature of the soil in order to avoid any impact. So groundwater (in addition to all the complexities I've mentioned) just like fresh water, pays no attention to borders. Groundwater can flow under the territory of two or more States, and can create rather large aquifers. In these cases, groundwater must obey political, legal and administrative matters which makes its management more complex. The transboundary aspect is also linked to knowledge, because in the case of groundwater, the perimeter of an aquifer is not always known. For example, in South America, there was a UNESCO-initiated project which allowed States sharing an aquifer to identify it. Moreover, in each of the States, the aquifer had a different name and the two names were kept when we understood that it was shared between the States. So here again we see the importance of knowledge. Next, knowledge is also important in a transboundary context. An activity in State A may have an impact in State B and vice versa of course. And it is important for States to work together, to cooperate to develop knowledge. So when cooperation is established, knowledge is shared and the technical teams of the countries can agree on the actions to be taken. At the beginning, this is how it happens. Each State has its own network. Even if the network is weak, each State monitors the aquifer and States begin to exchange information which helps them to know where they are and how the water table reacts. So our big challenge in terms of groundwater management is knowledge and this enables how the aquifer is managed. And whilst we wait for this knowledge to develop, it is important to adopt precautionary principles. In the field of law, there are all kinds of tools, impact studies, precautionary approaches and more. And at the cross border level, whilst it is certainly more complicated, it is still possible.