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Monitoring River Flows : Cases of the Djiri River (Republic of Congo)

Author Name(s)

NGOUBOU Roch Corneille, DINGA Jean Bienvenu et NGANGA Dominique

Abstract
The objective of this work is to conceptualize and carry out a tool for monitoring river flows with a simulation of the Djiri River data; the Djiri River is located in the Djiri watershed and to date has only one installed hydrological station. The Djiri watershed has an area of 980 km2, a length of 57 km. This watershed is located between 4 and 4-52′ south latitude and 15 and 15-55′ east longitude and the altitude between 600 and 760 m, its geology is mainly composed of Batéké sands. Most of our rivers in Africa and especially in Congo Brazzaville see their water levels drop, sometimes disappearing during dry periods. These natural stretches are often accentuated by the use of the water resource at a time when it is less available: drinking water supply, irrigation, watering of public gardens, etc. In Congo Brazzaville, for example, the majority of river flows occur during low water periods. In the face of these decreases in flows, it is necessary for daily hydrometric measurements to be carried out to monitor flows in order to facilitate the prevention, detection and resolution of any problems related to the drop in the water level of each streams. This work is carried out in the Hydrology Laboratory of the Institute for Research in Exact and Natural Sciences (IRSEN) as part of the doctoral thesis project carried out at the Faculty of Science and Technology (FST) of the Marien NGOUABI University of Brazzaville (Republic of Congo); This research is generally aimed at the design and implementation of an automated information system for tracking river flows in the Republic of Congo in order to facilitate the actors of national hydrology by acquiring a detection or prevention of possible situations observed on waterways in Congo-Brazzaville. To date, no similar monitoring tools have been implemented in the Republic of Congo and this work brings great added value in terms of automating water ecosystem management processes for national hydrology. To achieve this information system, the bibliographical knowledge of data management issues at hydrological stations allowed us to describe the process of acquiring river flows and to conduct systemic modelling of MERISE type leading to a national database on hydrometric stations, the rivers on which they are installed, daily measurements performed and the scale applied to each river. The tool put in place allows to track not only the flow of the Djiri River but also those of all the rivers of the Republic of Congo. The Djiri River data were used to simulate the tool and the analysis of this data reveals a decrease in flow over the entire period of 2017 and any season. This decrease in flow, characterized by a divergence index of 0.82344, highlights a hydrological situation for which national hydrology actors will absolutely have to implement remediation mechanisms to protect this against the possible disappearance.

Keywords

Stream flow, MERISE and information system, Hydrological scale, Hydrological station.