Is rice a suitable crop where water is scarce? What role should government play when over-irrigation threatens to degrade an environment? How can the competing demands of conservationists, farmers, livestock owners and hydroelectricity managers in Tanzania all be satisfied?

A University of East Anglia School of Development Studies report examines rice cultivation in the Usangu wetland of southern Tanzania. This complicated hydrological environment has relevance for other river basins where scarce water supplies have to be allocated to different groups of people.

A key feature of the Usangu wetland is the expansion and contraction both of the perennial swamp and the seasonally flooded wetland. The project for the Sustainable Management of the Usangu Wetlands and its Catchment (SMUWC) operates within the framework of a World Bank river basin management initiative, which grew from concern at the impact of reduced water flows on hydropower generation.

Government policy has been shaped by non-scientific misconceptions. SMUWC has not only had to nail down the real reasons for the absence of sufficient water but also to address untenable politically-generated conclusions.

Four explanations are conventionally offered for the absence of enough water:

• The progressive expansions of upstream rice irrigation on smallholder and large scale state farms.
• Expansion of livestock herds, overgrazing and compaction of soil, accelerating runoff and spate flows.
• Deforestation.
• Sedimentation in the wetland and reduction of storage capacity.

The significant findings from the study are:

• Pressure to convert bush to rice threatens the sustainability of the delicate balance between upstream agriculture and downstream wetlands.
• Given certain conditions, the wetlands and irrigated rice cultivation could co-exist. Rice should be grown on areas where sufficient water exists taking into account downstream needs.
• Increase in animal numbers has not been as great as the anti-livestock lobby has claimed.
• Smallholders on unimproved systems plant rice when the rains arrive and do not disturb the equilibrium in the way that large state farms or ‘improved’ irrigators do by draining water from perennial rivers.
• As basin-irrigated rice needs large amounts of water it is doubtful whether under large cultivated areas, it is a suitable crop for the area. Yet from local people’s point of view, income from rain-fed maize cannot compare with higher earnings from rice.

The policy implications arising from the SMUWC and similar schemes in sub-Saharan Africa include the need to recognize that:

• Fisheries and wildlife would not only benefit from allowing more water to flow but could also produce economic benefits for local people.
• State farms, supported by powerful vested interests, are more environmentally unfriendly than small-scale farmers.
• Planners must be aware of the extreme variability of available water and not take best-year projections for granted.

Source(s):
‘The sustainable coexistence of wetlands and rice irrigation: a case study from Tanzania’ by Bruce Lankford and Tom Franks, Journal of Environment and Development, Vol. 9, No. 2, June 2000

Funded by: UK Department for International Development

id21 Research Highlight: 2 May 2001

Further Information:
Bruce Lankford
School of Development Studies
University of East Anglia
Norwich NR4 7TJ
UK

Tel: +44 (0) 1603 592807
Fax: +44 (0) 1603 451999
Contact the contributor: b.lankford@uea.ac.uk

School of Development Studies, University of East Anglia (UEA), UK

Other related links:
'Flushing away arid theories: a reality check on the water debate'

IRRI is dedicated to helping farmers produce more rice on limited land using less water

IWMI supports better management of water resources for food security and poverty eradication

CIWEM focuses on water and environmental mangement

WWC promotes awareness of critical water issues

WaterWeb’s goals are to advance water related issues

More from the International Association of Hydrological Sciences