Modelling Hydrological Processes and Identifying Soil Erosion Sources in a Tropical Catchment of the Great Barrier Reef Using SWAT

Abstract

Study region: North Johnstone catchment, located in the north east of Australia. The catchment has wet tropical climate conditions and is one of the major sediment contributors to the Great Barrier Reef. Study focus: The purpose of this paper was to identify soil erosion hotspots through simulating hydrological processes, soil erosion and sediment transport using the Soil and Water Assessment Tool (SWAT). In particular, we focused on predictive uncertainty in the model evaluations and presentations—a major knowledge gap for hydrology and soil erosion modelling in the context of Great Barrier Reef catchments. We carried out calibration and validation along with uncertainty analysis for streamflow and sediment at catchment and sub-catchment scales and investigated details of water balance components, the impact of slope steepness and spatio-temporal variations on soil erosion. The model performance in simulating actual evapotranspiration was compared with those of the Australian Landscape Water Balance (AWRA-L) model to increase our confidence in simulating water balance components. New hydrological insights for the region: The spatial locations of soil erosion hotspots were identified and their responses to different climatic conditions were quantified. Furthermore, a set of land use scenarios were designed to evaluate the effect of reforestation on sediment transport. We anticipate that protecting high steep slopes areas, which cover a relatively small proportion of the catchment (4–9%), can annually reduce 15–26% sediment loads to the Great Barrier Reef.

Hydrological Responses of Watershed to Historical and Future Land Use Land Cover Change Dynamics of Nashe Watershed, Ethiopia

“…Accordingly, SWAT was implemented for this study based on the criteria specified for the Nashe watershed. Generally, SWAT is physically based, a spatially semidistributed, daily time step parameter model designed to simulate all relevant parameters of a watershed-such as surface runoff, ground water, soil water, and lateral flow [27,28]. The studies conducted on the hydrological processes of watershed based on LULC change shows marked increase in rainy season flow and surface runoff potential in a given watershed that corresponds to the expansion of agricultural land and urban area at the decline of forest cover [2,29,30].…”

Pre-development denudation rates for the Great Barrier Reef catchments derived using 10Be

“…These 10 Be data could also be used to further test and 7 support hillslope erosion rates derived for the region (Teng et al, 2016) and could be used to 8 validate and constrain a range of alternative modelling platforms (e.g. Rafiei et al, 2020). 9…”

Application of SWAT Hydrological Model to Simulate Flow of Seti-Gandaki Basin

“…The model has been implemented from the catchment 0.38 km 2 of Cunha Municipality, Brazil (Lucas-borja et al, 2020), to the basin 900,480 km 2 of Upper Parana River Basin (Rafee et al, 2019). Similarly, the model has been successfully used from the low annual rainfall records of 102 mm and 179 mm at Sarbaz river basin in South Iran with arid climate characteristics (Galavi & Mirzaei, 2020) to high annual precipitation of 3600 mm at coastal areas of North Johnstone catchment (Rafiei et al, 2020). The model has also been used in different elevation range, low altitude, and high-altitude glaciered river basins and the tropical basins.…”