The interactive pedological-hydrological processes and environmental sensitivity of a tropical isolated wetland in the Brazilian Cerrado

Abstract

In seasonal flooding isolated wetlands, the degree of wetness suggests a close synergy between soil processes, landscape evolution and hydrology along space and time. Until now, that subject has received insufficient attention despite natural wetlands supply essential environmental services to society and are surrounded by intensive agriculture that uses agrochemicals and fertilizers in their management. The objectives of this study were to propose an infiltration architecture model based on local surface and subsurface water-fluxes in isolated wetland embedded in lateritic plateau covered by savanna and qualify the environmental sensitivity as an area of aquifer recharge. Grain size, soil bulk density, and hydraulic conductivity were determined in five profiles in a soil catena. Unmanned Aerial Vehicle high-resolution images were obtained to generate a digital elevation model and discriminate areas with different vegetation, water accumulation, and environmental sensitivity. Electrical tomography was performed to unveil the soil architecture and infiltration. The soils (Plinthosols) developed on aquic conditions determine the linkage between the surface–subsurface hydrodynamics with the soil's physical properties. We have identified vertical and lateral water-flows in the soil architecture. Vertical flow occurs exclusively at the center, where the wetland is characterized as a recharge zone. Lateral flow towards the borders characterizes a discharge zone. The recharge zone is a depression surrounded by crops; therefore, it is a point of high environmental sensitivity. This hydrodynamic model is essential to support studies related to the dispersion of contaminants since soybean agriculture dominates the whole area of well-drained soils in the Brazilian Cerrado.

A Review of Unoccupied Aerial Vehicle Use in Wetland Applications: Emerging Opportunities in Approach, Technology, and Data

“…The mapping and modeling of abiotic environmental features such as land cover classes [4,58,65,124,129] and water [32,45,66,127,131] are important for understanding surface dynamics and how landscapes evolve, which complements the multitude of UAV wetland vegetation studies by providing information on the structure and habitat of these species. We reviewed fifteen papers pertaining to abiotic surveys, which was the second largest number of papers in one category, following the vegetation inventory group (Figure 3).…”

“…This is a useful technique in abiotic UAV research that pertains to modeling shoreline losses and habitat destruction [4,130], floodplain connectivity [127], carbon storage estimates [129], and topobathymetry [58,128]. Real-time kinematic (RTK) GPS can greatly enhance the precision of such studies [4,5,45,58,65,124,131] and ground control points (GCPs) [4,45,58,65,66,124,129] can generate greater horizontal and vertical accuracy in landscape modeling and change detection studies. In particular, Correll and colleagues [28] rigorously employed RTK to measure elevation in a tidal marsh.…”

“…Their study reported that raw UAS data "do not" work well for predicting ground-level elevation of tidal marshes, likely because a DSM is not equivalent to a DEM [28]. Other projects in the realm of abiotic mapping involve RGB analysis of soil structure and infiltration [131], delineations of riparian zones [125], and saltmarsh shoreline deposition [126], in addition to thermal analysis of river to floodplain connectivity [127], river temperature heterogeneity in fish habitats [45], and peatland groundwater seepage detection [32].…”

“…First, UAVs provide spatiallycomprehensive coverage that enable researchers and managers to view the wetland as an entire entity. This large spatial extent differs from field surveys that capture discrete rather than continuous data at smaller spatial and temporal resolutions, although certain types of data necessarily must come from ground observations, such as soil samples [117,131]. High resolution imagery from a UAV enables a high degree of visual recognition, providing an array of opportunities from basic surveying (e.g., plant cover, vegetation types with distinct morphological properties, visual texture and color) [55,63,68,81] to mapping, modeling, and quantifying wetland characteristics.…”

“…Finally, it may be necessary to avoid site disturbance during GCP installation and upkeep; for instance, one application [5,66] deployed GCPs on metal poles by boat during the high tide to both ensure their elevation above the water and reduce the impact on marsh vegetation. As real-time positioning technologies such as RTK are becoming more accessible, the labor-intensive task of GCP placement and maintenance may become less relevant over time (e.g., [7,28,131,144]).…”