Environmentally-displaced peoples and the cascade effect: lessons from Tanzania
Charnley, S.
Human Ecology 25(4): 593-618
1997
ISSN/ISBN: 0046-8169 PMID: 12293626 DOI: 10.1023/a:1021885924512Document Number: 273780
This article presents a case study of the environmentally displaced population of Nyakyusa and Sukuma of the Usangu Plains in southwestern Tanzania. The study illustrates the "cascade effect" whereby environmental problems are transferred to other rural areas and become increasingly more complex. This analysis examined the processes of ecological change and migration and the ecological consequences of settlement by migrants in new locations. The ecological changes in the Usangu Plains were due to social patterns and the spread of cash crop production. Most migrants benefited from resettlement. The Nyakyusa were pushed out due to land shortages, increasing land values, and an ineffective means of gaining access to land for young men. Young men moved and began rice production via irrigation. The consequence was loss of woodlands to agriculture, dry riverbeds, and greater marshy lands due to lack of drainage canals. These changes were due to the settlement pattern of migrants, weak social institutions for managing water, a lack of knowledge and technical skills for irrigation, and land tenure arrangements. Cash crop production also pushed migration among the Sukuma. Mobility was a part of a resource management strategy for livestock raising. Lack of land rights made sustainable resource practices less likely. Ecological changes included loss of grasslands, increases in bush/scrub, and greater tick-borne livestock disease. The multiethnic character of migration made it more difficult to cooperate in resource use and management. This case study reveals that migration was not a "safety valve" for dispersing marginalized people to other locations.