How do storm events and changes in landuse drive sediment mobilization?
The Rio Santa Maria da Vitoria is one of the primary sources of freshwater for the greater Vitoria metropolitan area, the capital city of Espírito Santo. The headwaters of the Santa Maria da Vitoria are characterized by relatively pristine forested environments, transitioning into primarily agricultural and rural land uses, and finally reaching the large urban center of Vitoria near its marine receiving waters. The watershed is heavily impacted. Sediment concentrations reach such high levels during heavy rainfall that water sanitation facilities become inoperable. When water is most abundant, local citizens have little to no access to clean freshwater because of the effect of enhanced sediment levels on water sanitation facilities. The Bay of Vitoria may eventually become inaccessible to container ships without extensive dredging.
The primary motivation for the government of Espírito Santo to explore sediment fluxes and dynamics in the Santa Maria da Vitoria watershed is to inform improved freshwater resource and sanitation management practices. In response, PCGAP seeks to address these following issues:
- How do changes in landuse and water movement effect the mobilization of sediments?
Addressing these issues requires a detailed understanding of the sources and dynamics of how sediments are generated and transported across the landscape. But information on this problem is almost none-existent. As a result the strategy adopted here is to break the problem down into asking first,
- Where are the sediments when?
The first step in addressing this question is to have an understanding about what the current levels of sediment transport are, and what the controls are on those fluxes.
- Carbon transport
How would landuse impact the potential mobilization of atmospheric carbon, and provide information on sediment sources?
- Drivers of sediment mobilization
Once a first-order description of sediments is available, it will be possible to examine these questions:
* What are the impacts of changes in the practices of agricultural activities on local and regional water quality?
* What is the effect of the increase in forest cover on the reduction in erosion potential and turbidity?
* What are the priority areas for intervention to reduce turbidity via implementation of practices friendly to use of soil?
* How has the incorrect use of land in the regions of the headwaters of the Rio Santa Maria da Vitória impacted the accumulation of sediments in the bay of Vitoria? Is it possible to measure this impact?
Peer-reviewed publications resulting from this study:
Ward, N., Tan, A., de Almeida, L.F., de Jesus, G.D., Sossai, M, Richey, J.E. (in preparation, 2016): Catchment scale assessment of suspended sediment and organic matter yield in the Santa Maria da Vitória River basin, Espírito Santo, Brazil