Practices in Regional Science and Sustainable Regional Development by Unknown

Author:Unknown
Language: eng
Format: epub
ISBN: 9789811622212
Publisher: Springer Singapore

The importance of vegetation for reducing sediment production is evidenced in studies in Sagrado and Tagaçaba hydrographic units. The land cover in 2005 (mainly rural roads and agricultural activities) was responsible for a 46.24% increase in annual sediment production in the Sagrado hydrographic units (Almeida and Paula 2016; Paula 2016). A study at the Tagaçaba river basin showed that the vegetation recovery in APP would represent a decrease of sediment production of 76.6% (Paz et al. 2016).

In addition to the examples aforementioned, there are several environmental services associated with the recovery of native vegetation. Aiming to encourage such actions, policies such as the Payment for Environmental Services (PSA) can be implemented. The PSAs are voluntary transactions that are acquired by a buyer from a seller who guarantees the provision of a given environmental service (Wunder 2005).

In a landscape where the PSA would be financially more interesting than the yearly agricultural production, the landowners could be paid to plant native vegetation or adapt their conventional production to a SAF. As a result, a decrease in sediment production is hoped for. This reduction will result in a smaller demand for silting works in the local rivers, as well as port dredging. The port activity, being the largest beneficiary in this process, has the potential to finance future PSA projects on the coast of Paraná. For further development, it is necessary to do in-depth studies of sediment input monitoring in the main rivers that drain into the CEP and studies that estimate the avoided sediment’s economic value.

Along with the recovery of native vegetation as observed in the José Lutzenberger Agroforestry Settlement, the coastline plains’ fluvial channels, which were straightened, can now return to their meandric pattern. The channels of the rivers Sagrado and Jacareí are examples of basins that stand out due to their estimated sediment production volumes.

Rectified rivers in the coastal plain have a greater flow speed and, as a result, higher efficiency and capacity to transport sediment. In addition, as a direct result of engineering works, the channel deepens, leading to the widening of the plain base level. Consequently, the drainage network’s erosive power is enhanced, transporting more sediment to the CEP.

Vegetation recovery can be associated with the recovery of the fluvial channel’s meandering patterns. This recovery results in a decrease in sediment production in at least two situations. Firstly, the fluvial bends decrease the flow speed, reducing the erosive power and promoting sediment deposition on the plain. Secondly, periodic floods that are characteristic of coastal plain rivers cause sediment deposition on the plain. Properties close to the rivers can become “sediment farms.”

Lastly, in the context of the high rates of sediment production observed, especially in estuarine springs in the CEP (Antonina Bay), and the high costs of dredging work in this region, it is believed that the Antonina bay port should have adequate cabotage activities, shipyard, and tourism, in other words, activities that do not rely on drafts deeper than 5 m.

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