Annika Dahlberg

Diversion of water flow from a floodplain wetland stream: an analysis of geomorphological setting and hydrological and ecological consequences.

Diversion of water has been ongoing in the Mkuze Wetland for several decades. Two canals form the focus of this study; the Mpempe-Demazane Canal and the Tshanetshe Canal. The former involved an ambitious excavation over a distance of 13.5 km in the lower part of the wetland, while the latter was a minor excavation over a distance of approximately 100 m in the upper part of the wetland. Although ambitious and costly, the Mpempe-Demazane Canal resulted in little downward or headward erosion, and there was minor diversion of flow. However, the minor excavation of the Tshanetshe Canal resulted in erosion downstream of the excavation (the Tshanetshe Stream), downward and lateral erosion of the excavated section, and headward erosion that has propagated almost 4 km upstream along the Mkuze River. Most of the flow of the Mkuze River has been captured by the Tshanetshe Canal and Stream. The impact of canalisation on floodplain wetlands is thus more dependent on the location than the scale of activity. The avulsion of the Mkuze River into the Tshanetshe Canal and Stream is due to a large difference in elevation between the Mkuze River and floodplain into which it was diverted, and the fact that in this region the river typically has high discharges. This avulsion may have been inevitable as a result of natural processes of sedimentation. In contrast, the difference in elevation between the Mkuze River and the basin into which it was diverted via the Mpempe Canal was small as is discharge of the Mkuze River in this part of the wetland. Thus, the diversion was unsuccessful. The presence of hippos that create hydraulically efficient pathways that are oriented parallel to the regional hydraulic slope, may accelerate avulsion in large African wetlands. Overall, it is argued that the environmental consequences of excavation need to be viewed against the background that wetlands are dynamic features within the landscape.

The 1997 Flash Flood at Mount Fulufjället, West Central Sweden: Geomorphic and Vegetational Investigations Of Stora Göljån Valley

On 30-31 August 1997, extreme precipitation fell locally over parts of west central Sweden, causing flash floods on the eastern and southern slopes of Mount Fulufjallet. Here we report from fieldwork carried out during the first year after the event. A survey map of the Stora Goljan flash flood channel is pre-sented. The geomorphic effects are described, as well as the general status of the recolonisation of vegetation. The erosional effects of the flash floods were extensive, and included the expansion of stream channels, mass movement, and the almost complete removal of vegetation in broad strips along the water-courses. Future work is presented in a theoretical context.

Categories are all around us: Towards more porous, flexible, and negotiable boundaries in conservation-production landscapes

Dahlberg, D. 2015. Categories are all around us: Towards more porous, flexible, and negotiable boundaries in conservation-production landscapes. Norsk Geografisk Tidsskrift–Norwegian Journal of Geography Vol. 00, 00–00. ISSN 0029-1951. In order to communicate and act in the world we divide it into categories, with boundaries that define belonging and exclusion. Categories take shape through processes influenced by, for example, history, discourses, ecologies, and power relations. Although we intellectually know that categories are social constructs we tend to treat them as if they have an intrinsic reality of their own when we describe and act in any given landscape. This understanding is explored within a political ecology framework through a case study of protected areas in relation to other land uses in Sweden. The study relies primarily on interviews with actors affected by conservation efforts, and highlights that categories are not neutral phenomenon, but have ecological, material and social effects in the landscape. It discusses how the simplification of a complex and dynamic whole into static categories can result in paradoxes with unexpected and sometimes negative effects on rural development and land care arrangements. The study advocates a more flexible understanding and handling of categories – and thus of landscapes – to enhance the potential for multiple landscape values to exist in overlapping, dynamic and paradoxical ways.