Importância da conservação da bacia hidrográfica do rio Incomáti na preservação dos serviços ecossistémicos caso de estudo: estuário do rio Incomáti

Abstract

Activities carried out in a river basin, as well as land use, influence the quantity and quality of water, as well as the health of ecosystems and the availability of their services. Currently, the preservation of ecosystems and their services has been the focus of numerous researches, due to the concern with the environment. The Incomati river estuary is an example of an ecosystem which provides services that sustain local communities as well as the marine ecosystem. The upstream activities and exploitation of ecosystem services affect the availability and quality of water and therefore the functioning of the downstream ecosystem. However, studies on the preservation of the Incomati river estuary ecosystem and its services; that analyze both the quality and quantity of water available within the Incomati river basin are limited. In this context, this study assesses how the conservation of the Incomáti river basin influences the availability of ecosystem services in the river estuary. The work was developed through a literature review as well as field research, where the physical- chemical parameters (pH, electrical conductivity, dissolved oxygen, temperature and nutrients) that influence the water quality in the estuary were evaluated. Also, a survey of the ecosystem services that exist in the basin only in the estuary was made and how these are affected by the quality and quantity of water through interviews with local communities and by physical observation. The results of this work show that the quality and quantity of fresh water in the estuary of the Incomati river is more affected during the dry season compared to the rainy season, in such a way that the availability of ecosystem services at the study site, especially the provision service (human food) is significantly affected. From the study, it was concluded that saline intrusion phenomenon assessed through successive measurements of electrical conductivity is what most affects the availability of ecosystem services. The saline intrusion has made local communities in the Hobjana and Muntanhana neighborhoods to abandon their agricultural fields near the Incomati river, due to the fact that they have become less or totally unproductive. Unfortunately, it was found through interviews with local communities that saline intrusion is advancing, which may be caused by the reduction in the river’s water flow.