Modelling to bridge many boundaries: the Colorado and Murray-Darling River basins

Regional Environmental Change - Increasing pressure on shared water resources has often been a driver for the development and utilisation of water resource models (WRMs) to inform planning and...     

Initial Adjustments Within a New River Channel: Interactions Between Fluvial Processes, Colonizing Vegetation, and Bank Profile Development

A conceptual model of the morphological development of the riparian margins of newly cut river channels is presented, suggesting early feedbacks between vegetation growth and bank form. To test the model, observations of long and cross profiles, bank sediment and seed deposition, and bank vegetation development were collected over the first 2 years of river flows through a reach of the River Cole, West Midlands, UK. The newly created channel had a sinuous planform and varying asymmetric trapezoidal cross section in sympathy with the planform. No imposed bedforms or bank reseeding were included in the design. Over the 2 years, development of bedforms was rapid, with bed sediment sorting and bank profile adjustment occurring more steadily and progressively. Six classes of bank profile were identified by the end of the study period, illustrating close associations with sediment aggradation, vegetation colonization, and growth patterns. Vegetation colonization of the banks was seeded predominantly from local sources during the summer and from hydrochory (transport by the river) during the winter. Colonizing vegetation on the riverbanks appeared to act as a significant propagule source by the second summer and as an increasingly important roughness element, trapping both propagules and sediment, within the second year and providing early feedback into bank evolution. As a result, the time required for riparian margin development in the conceptual model was found to be considerably longer than observed in the study river. In addition, the role of surface wash/bank failure in modifying the bank profile and transporting seeds onto the upper bank face during the first year of bank development was found to be important in initiating rapid bank vegetation colonization and surface stabilization. This set of processes had not been incorporated in the initial conceptual model. In relation to channel restoration, this research illustrates that in small temperate rivers of modest energy the provision of an initial, sinuous corridor is sufficient to induce rapid development of fluvial features and vegetation cover without the need to construct bed forms or to seed the banks.     

Sustaining local values through river basin governance: community-based initiatives in Australia's Murray–Darling basin

Australia's Murray–Darling basin (MDB) water plan is an ambitious attempt to balance ecological, social and economic benefits, where a key aspect of the reform process has been recovery of water for environmental use. This paper focuses on a set of initiatives established by a local non-governmental organisation and an Indigenous community designed to engage with local values and priorities and incorporate them into this complex river basin governance system. Contrary to expectations that local and basin-scale interests and outcomes will diverge, the case studies reveal the ability for local groups to collaboratively manage both land and water resources to achieve locally important outcomes, and contribute to basin-scale outcomes. The analysis also highlights a progressive style of community-based environmental management for water management that utilises multiple institutional arrangements and planning pathways to protect the values that are important to local communities, and to nest those values within the broader effort to sustainably manage the basin's water resources.