Abstract
The soil water regime is a defining ecosystem service, directly influencing vegetation and animal distribution. Therefore the understanding of hydrological processes is a vital building block in managing natural ecosystems. Soils contain morphological indicators of the water flow paths and rates in the soil profile, which are expressed as ‘conceptual hydrological soil responses’ (CHSR’s). CHSR’s can greatly aid in the understanding of hydrology within a landscape and catchment. Therefore a soil map could improve hydrological assessments by providing both the position and area of CHSR’s. Conventional soil mapping is a tedious process, which limits the application of soil maps in hydrological studies. The use of a digital soil mapping (DSM) approach to soil mapping can speed up the mapping process and thereby extend soil map use in the field of hydrology. This research uses an expert-knowledge DSM approach to create a soil map for Stevenson Hamilton Research Supersite within the Kruger National Park, South Africa. One hundred and thirteen soil observations were made in the 4 001 ha area. Fifty-four of these observations were pre-determined by smart sampling and conditioned Latin hypercube sampling. These observations were used to determine soil distribution rules, from which the soil map was created in SoLIM. The map was validated by the remaining 59 observations. The soil map achieved an overall accuracy of 73%. The soil map units were converted to conceptual hydrological soil response units (CHSRUs), providing the size and position of the CHSRUs. Such input could potentially be used in hydrological modelling of the site.Keywords: Digital soil mapping, terrain analysis, ecosystem services, conceptual hydrological soil responses, SoLIM
Highlights
Water is probably the defining element in all natural ecosystems
Topographic variables were derived from both digital elevation model (DEM) with the basic terrain analysis tool in SAGA (SAGA User Group Association, 2011)
This meant that observations of the same soil form could be included into different conceptual hydrological soil response units (CHSRUs), such as the Bonheim soil form which fits into both the Clayey Interflow and Clayey Recharge classes
Summary
Water is probably the defining element in all natural ecosystems. Hydrological processes determine the amount, seasonality and location of water, rendering ecological system services, by directly influencing soils, wetlands and rivers controlling vegetation and animal distribution. The identification, definition and quantification of the flowpaths and residence times of the different components of flow are central to the understanding of hydrological processes. Soil can be a first-order control in partitioning hydrological flow paths, residence times and distributions and water storage (Soulsby et al, 2006). Concepts developed about the soil water regime by field observations and quantification (Van Tol et al, 2011) make it possible to predict the conceptual response of different soil forms (Ticehurst et al, 2007; Van Tol et al, 2010; Kuenene et al, 2011). A soil map can be the basis to provide both the size and position of conceptual hydrological soil responses (CHSR’s). This information could potentially improve hydrological parameterisation for predictions in ungauged basins
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