We read with interest your article 'Large Dams cause global warming - claim' (NCE 20 June).
Your story refers to the International Rivers Network (IRN) pressure group report but there is little evidence to substantiate the group's case.
During the construction of most dams the catchment is cleared of vegetation to reduce methane production as vegetation decomposes. It is also worth noting that vegetation decomposes on an annual cycle anyway with some methane generation.
The balance of methane generation between the natural conditions and the situation in different reservoirs has not been adequately researched on a scientific basis. Reports such as the IRN report are therefore misleading.
Many of the arguments against dams ignore the significant benefits to mankind that dams give, namely: water supply - both drinking water and sewage disposal and treatment; irrigation;
hydropower; and support to other industries.
We believe that dams will become ever more necessary and if many of the World Commission on Dams' recent guidelines are followed then large dams can be created to the benefit of all.
Dr Andy Hughes, chairman, and Jim Millmore, vice chairman, British Dam Society, One Great George St, London SW1P 3AA