Changes in the Course of the River Komadugu Yobe During the 20Th Century at the Border Between Niger and Nigeria

Master’s Thesis TVVR 10/5005

Changes in the Course of the River Komadugu Yobe during the 20th Century at the Border between Niger and Nigeria

______Jenny Martinsson

Division of Water Resources Engineering Department of Building and Environmental Technology

Engineering Geology Department of Measurement Technology and Industrial Electrical Engineering

Lund University

Changes in the Course of the River Komadugu Yobe during the 20th Century at the Border between Niger and Nigeria

Jenny Martinsson

Changes in the Course of the River Komadugu Yobe during the 20th Century at the Border between Niger and Nigeria

Division of Water Resources Engineering and Engineering Geology TVVR-10/5005 ISSN-1101-9824 Changes in the Course of the River Komadugu Yobe during the 20th Century at the Border between Niger and Nigeria

Title: Changes in the course of the river Komadugu Yobe during the 20th century at the border between Niger and Nigeria

Swedish title: Förändringar i floden Komadugu Yobes väg under 1900-talet vid gränsen mellan Niger och Nigeria

Author: Jenny Martinsson

Supervisors: Gerhard Barmen, Engineering Geology, Department of Measurement Technology and Industrial Electrical Engineering, Lund University, Sweden

Guillaume Favreau, Institut de Recherche pour le Développement, HydroSciences Montpellier, France and Abdou Moumouni University, Niger

Co-supervisor: Yahaya Nazoumou, Department of Geology, Abdou Moumouni University, Niger

Examiner: Rolf Larsson, Department of Building and Environmental Technology, Division of Water Resources Engineering, Lund University, Sweden

Faculty of Engineering, LTH Lund University

Division of Water Resources Engineering Department of Building and Environmental Technology http://www.tvrl.lth.se

Engineering Geology, Department of Measurement Technology and Industrial Electrical Engineering http://www.tg.lth.se/

Lund University P.O. Box 118, SE-221 00 Lund

Printed in Sweden, 2010

i Changes in the Course of the River Komadugu Yobe during the 20th Century at the Border between Niger and Nigeria Abstract

The river Komadugu Yobe in the Lake Chad basin is a seasonal river, about 370 km long and with an average highest flow of 34 m3/s during the time period of 1957 to 1976. The river is dynamic with plenty of meanders and oxbow lakes along its sides. Komadugu Yobe’s thalweg (the line defining the lowest points in a riverbed) is the natural border between Niger and Nigeria and may change position with the river.

The objective of this study is to explore if and how the course of the Komadugu Yobe has changed during the 20th century and the impact this has on local inhabitants. Another objective is to look at similar examples in the world where the problem with a pending border exists and how this problem is dealt with. The study only concerns that part of the river constituting the border.

Maps and images on different scales and resolutions from the 20th century were compared in a GIS-program to identify possible changes. Subsequently, field observations were conducted in villages along the river together with officials representing local Niger government to permit verification of the observed changes and as a mean to understand the impacts. The results show various changes along the river: a meander that has been cut off, change in the course and erosion.

It is confirmed that the river has changed its course at numerous times during the 20th century and continues to do so. The most palpable influence of this change, as concerns local populations, is erosion of the riverbanks, which destroys and threatens houses and fields.

Key words: river, Komadugu Yobe, GIS, semiarid region, international boundary, thalweg, meander, Lake Chad basin

ii Changes in the Course of the Ri