Assessment of Depressional Wetland Degradation, Spatial Distribution, and Geological Aspects in Southern Brazil

Abstract

This paper presents a procedure to study depressional wetlands in southern Brazil and focuses on the mechanisms controlling water dynamics and environmental degradation due to anthropogenic interference. The study is based on an inventory of wetlands, a digital elevation model, the geological and geotechnical characteristics of geological materials, a multitemporal analysis of satellite images, the distribution of land use types, and onsite monitoring of water level and rainfall data. One hundred and twelve depressional wetlands were identified with a total area of 902 ha and a catchment area of 5456.8 ha. These wetlands were grouped into two classes with different hydrological control mechanisms. From the water level monitoring, the wetlands were found to present different hydrological conditions. Before rainy periods, the wetlands were almost dry or had little water; after rainy periods, over half of the wetlands were still dry or had groundwater levels below the surface, and the water levels of the other wetlands increased. The multitemporal analysis showed a reduction in the wetland water surface area from 270 ha in 1991 to 60 ha in 2019, which confirms the monitoring result that the amount of stored water is decreasing because of anthropogenic activities. Anthropogenic activities affect wetland water dynamics because of changes in the landscape and soil characteristics of the catchment area, and drainage of wetland areas by ditches for agricultural water supply; more than 50% of wetlands showed a high degree of change (environmental degradation), with conditions that make restoration or remediation very difficult.

Transformation of phosphorus forms and its regulation on phosphorus availability across differently degraded marsh soils

“…Soil P forms generally exhibit evident variations owing to the differences and changes in pedogenic environments of wetlands, such as parent material, hydrothermal, and vegetation conditions (Cheesman et al, 2010, 2012; Cui, Ou, Wang, Wu, Yan, Han, & Li, 2019; Negassa et al, 2020; Qu et al, 2021). Presently, more than half of wetlands worldwide have degraded due to climate change, rodent harm, and anthropogenic disturbances, such as drainage, overgrazing, and aquaculture (Nguyen et al, 2016; Ren et al, 2019; Zuquette et al, 2020), which have completely altered the conditions of hydrology, salinity, vegetation, and soil characteristics in wetland ecosystems (Cheng et al, 2020; Li et al, 2022; Zeng et al, 2021; Zhao, Bai, et al, 2017). Therefore, these changes have further affected soil P accumulation and its forms via P transformation, such as sorption/desorption, precipitation/dissolution, immobilization/mineralization, and weathering processes (Augusto et al, 2017; Barrow, 2015; Khosa et al, 2021; Qu et al, 2021; Smith et al, 2021).…”

Suitability Zoning for Sustainable Drainage Systems (SuDSs): Application in a Basin in Southern Brazil

“…Urbanized areas have been increasing in developing countries, mainly due to population growth; population migration from smaller to larger urbanized areas; regional displacements due to social and economic conditions; and, within an urbanized area, displacement from more central to peripheral areas [1,2]. This increase in urbanized areas has led to the occupation of areas with very distinct environmental characteristics, from aquifer recharge areas to areas subject to hazardous events with different natural, quasi-natural, natural-technological, and anthropogenic sources [3][4][5][6].…”

Transformation of phosphorus forms and its regulation on phosphorus availability across differently degraded marsh soils

“…The forms of P in soils generally exhibit evident variations owing to the differences and changes in the pedogenic environments of wetlands, such as parent material, hydrothermal, and vegetation conditions (Cheesman et al, 2010(Cheesman et al, , 2012Cui et al, 2019b;Negassa et al, 2020;Qu et al, 2021;Wang et al, 2016a). Presently, climate change, rodent harm, and human disturbances such as drainage, overgrazing, and aquaculture have led to the degradation of more than half of wetlands worldwide to some degree (Huisman et al, 2017;Nguyen et al, 2016;Ren et al, 2019;Zuquette et al, 2020), which has completely altered the conditions of hydrology, salinity, vegetation, and soil characteristics in some wetland ecosystems (Cheng et al, 2020;Li et al, 2022;Zeng et al, 2021;Zhao et al, 2017a). This has further affected soil P accumulation and its forms via P transformation processes such as sorption/desorption, precipitation/dissolution, immobilisation/mineralisation, and weathering (Augusto et al, 2017;Barrow, 2015;Khosa et al, 2021;Qu et al, 2021;Smith et al, 2021).…”