From traditional uses to an integrated valorisation of sediments in the Usumacinta river basin – VAL-USES

The method employed targets the creation of an interdisciplinary and participatory project.
1. The research is carried out on pilot sites, relevant for and shared by several task groups, ensuring balanced coverage of the overall river basin. The sites are selected based on a number of parameters, including the interdisciplinary scientific value, solid contacts with local stakeholders, access and safety. Short-listed areas include Yaxchilan, Frontera-Corozal (border area), Emiliano Zapata, Pantanos de Centla (biosphere reserve) and Tenosique (local extraction of sediments).
2. A task dedicated to project management (Task 0), supported by the coordinators, contributes to developing the interdisciplinary aspects, e.g. methods workshops (on site or remote). Scientific decisions are taken jointly, prior to fieldwork and experiments. Sharing of results ensures interdisciplinary awareness and discussion.
3. The research work is carried out in the language best mastered by each researcher, given that most understand both French and Spanish. Where necessary, English is used for discussions between the research teams.
4. In the field, systematic use of any and all local contacts is made, including NGOs and non-profits, local authorities and various managers, universities, students, etc. Information from knowledgeable non-experts is used to co-construct the work of the researchers.

The main scientific risk lies in the difficulty of collecting data in the field due to local security issues. The presence and high mobility of clandestine migratory networks and of drug dealers must be taken into account. For these reasons, French teams have not been able to collect data in Chiapas. The local contacts provide the necessary security information and the decision to work on pilot sites makes it possible to react quickly and fall back on alternative, safe sites. Field work is always organised in mixed groups combining both French and Mexican researchers.

Main results and major events half way through the project :
- The activity of extraction of sediments is realized during dry season, it is more important than initially thought.
- The extraction of sediments is a recent activity, which has developed during the last 30 years.
- This activity is very organized socialy, at a local level, even though it is very informal and often pursued outside the existing legislative frame.
- The analysis of contaminants has shown heavy metals pollution (lead, mercury and cadmium), quite important in some areas.
- The use of sediments for agriculture is very frequent, but droughts have strong impacts on these activities.
- To evaluate the possible co-valorisation of sediments with local waste a palm oil plant and an 'ecoagriculture rancho' have been visited.
- Local populations have shown interest for the project, by participating to workshops organiszed locally and to the extraction of sediments from the river.

Research work in progress will be deepen.

Workshop « Comprendre le socio-écosystème du bassin versant de l’Usumacinta », 3e conférence internationale I.S. Rivers, 4 juin 2018, Lyon, direction scientifique Pierre CHARRUAU et Isabelle MICHALLET www.graie.org/ISRivers/n_prog_workshops.php
Irini DJERAN-MAIGRE, Pierre CHARRUAU, Daniel LEVACHER, Andry-Rico RAZAKAMANANTSOA, Les sédiments de l’Usumacinta : réalités du terrain et prélèvements
Pierre CHARRUAU, Pollution et réseau trophique: des sédiments jusqu'au crocodile
Victoria CHIU, La gestion des bassins versants en droit de l’eau mexicain
Claire HARPET, L’Usumacinta : un fleuve, une terre, un monde. Approche ethnologique d’un territoire
Anne RIVIÈRE HONEGGER et Ana GONZÁLEZ BESTEIRO, Passé et présent du fleuve Usumacinta à Tabasco (Mexique) : transformation d’un espace sous l’égide des protecteurs de la nature
Edith KAUFFER MICHEL, Les usages sociaux du fleuve Usumacinta entre Estapilla et les rapides de San José El Grande, état du Tabasco: la frontière de la conservation
Isabelle MICHALLET, Droit international et bassins versants d’Amérique latine
Lucile MEDINA, Réflexions sur les méthodes de terrain et la construction d'un regard partagé : les enjeux d'un programme international et pluridisciplinaire
Claudia MONZÓN ALVARADO, Les observatoires socio-environnementaux au Mexique : application à l’échelon d’un bassin versant
Jean-Philippe PIERRON, Réflexions éthiques sur la vulnérabilité du bassin versant de l’Usumacinta
Hans VAN DER WAL, Agroecology in the river basin : the case of the Usumacinta Canyon

The Usumacinta river basin, located in a tropical zone, is a highly vulnerable cross-border area that is exposed to the changes incurred by human activities and by the climate. Within this highly complex situation, very little is known about one essential component, namely the river sediment. To date, no study has been put into the physical properties, pollution levels, applicable regulations, available knowledge, perceptions and symbolism of this very discreet element. The interdisciplinary approach proposed here aims to understand the issues involved in the socio-ecological system of the Usumacinta basin and its adaptation capabilities in a context of ecological transition, through an analysis of the interactions between the environment and the activities of stakeholders. A temporal approach will link the activities of the population to the future components of the integrated management project. This research programme will be ethical in that it will be set up within an observatory designed with local stakeholders. It will be innovative in that it will propose a sustainable strategy for territorial management.