Importance of small dams in river conservation and rehabilitation

What is it about?

The study presents and evaluates an index of cumulative small dams (Small Dams Density index) for South Africa, Lesotho and Swaziland. The index is proposed for use with a national assessment of Freshwater Ecosystem Priority Areas (NFEPA) at regional or catchment level scale for rehabilitation or river conservation. Considering that the vast majority of dams globally (~99.5% of all reservoirs in the world, according to Lehner et al., 2011) could be small dams, the research highlights the need to evaluate the impacts of small dams elsewhere.

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Why is it important?

Small dams are usually associated with some form of catchment transformation such as vineyards, stock farming and exotic timber plantations (as in South Africa). Thus, they can be considered as surrogates of the impacts of catchment transformation on river functionality. Previous research in South Africa showed that high densities of small dams are correlated with reduced baseflows and increased total dissolved salts, in addition to shifts in macroinvertebrate communities to more opportunistic and slow‐current taxa (Mantel et al., 2010a, 2010b).

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