Is it really true that deforestation and land use practices of the Himalayan farmers are to blame for the recurring and devastating monsoon floods in the plains of the Ganga and Brahmaputra? The validity of this paradigm has been increasingly questioned. This book presents new evidence resulting from a research project on floods in Bangladesh in the context of highland-lowland linkages.
Massive floods have occurred regularly before man’s impact on the large river basins began. There is no statistical evidence that the frequency of flooding in Bangladesh has increased during the 20th century. There is indication however, that the inter-annual variation of floods and the areal extent of big events have increased since 1950. This trend can be related to similar trends in rainfall and discharge patterns.
The hydro-meteorological processes in the Himalayas are not the main causes for floods in Bangladesh. The combination of simultaneous discharge peaks of the big rivers, high runoff from the Meghalaya Hills, heavy rainfall in Bangladesh, high groundwater tables and spring tides creates particularly favourable conditions for large-scale flooding. Lateral river embankments and the disappearance of natural water storage areas in the lowlands seem to have a significant impact on the flooding processes.
Accordingly, the myth about deforestation creating big floods and the habit of blaming mountain dwellers for the flood catastrophes must be abandoned. However, this does not relieve the mountain inhabitants of their responsibility to use and manage the environment sustainably.
Whereas politicians and engineers perceive monsoon floods as the main problem for Bangladesh, the flood affected people are more concerned – besides the devastating tropical cyclones – with lateral river erosion, landlessness and economic survival problems.
Thomas Hofer is a mountain expert in the UN Food and Agriculture Organization in Rome. Bruno Messerli is professor emeritus and former Director Institute of Geography and Rector University of Bern.