Abstract
Soil and stream salinisation is a major environmental problem because it reduces the productivity of landscapes and degrades water quality. The Berg River (South Africa) has been exhibiting a trend of increasing salinity levels, which has primarily been attributed to the manifestation of dryland salinity. Dryland salinity occurs as a result of changes in land use (indigenous vegetation to agriculture and/or pasture), which cause a change in the water and salt balance of the landscape, consequently mobilising stored salts. The quantification of salinity fluxes at the catchment scale is an initial step and integral part of developing dryland salinity mitigation measures. The objective of this study was to quantify the salinity fluxes in the Sandspruit catchment, a tributary catchment of the Berg River. This included the quantification of salt storage, salt input (rainfall) and salt output (in run-off). The results of the catchment salt balance computations indicate that the Sandspruit catchment is exporting salts, i.e. salt output exceeds salt input, which may have serious implications for downstream water users. Interpolated regolith salt storage generally exhibited increasing storage with decreasing ground elevation. A salinity hotspot was identified in the lower reaches of the catchment. It is envisaged that the data presented in this study may be used to classify the land according to the levels of salinity present; inform land management decisions; and provide a guide and framework for the prioritisation of areas for intervention and the choice and implementation of salinity management options. The data which were generated may also be used to calibrate hydrosalinity models.
Highlights
Soil and stream salinisation is a major environmental problem and occurs in many parts of the world
Human‐induced or secondary salinisation may either be a function of the direct addition of saline water to the landscape and/or water resources, e.g. through industrial effluent and/or saline irrigation water, or it may be a result of a change in the water balance of a catchment causing the mobilisation of stored salts.[3,4,5]
Dryland/non‐irrigated salinity commonly occurs as a result of changes in land use and management which cause a change in the water and salt balance of the landscape, mobilising stored salts.[1]
Summary
Soil and stream salinisation is a major environmental problem and occurs in many parts of the world. It reduces the fertility of landscapes, impacting agricultural activities, and degrades water quality, resulting in water that is unfit for domestic, recreational, agricultural and/or industrial use. These effects result in significant economic losses and water supply issues. Human‐induced or secondary salinisation may either be a function of the direct addition of saline water to the landscape and/or water resources, e.g. through industrial effluent and/or saline irrigation water, or it may be a result of a change in the water balance (quantity and dynamics) of a catchment causing the mobilisation of stored salts (dryland/non‐irrigated salinity).[3,4,5] Dryland/non‐irrigated salinity commonly occurs as a result of changes in land use (indigenous vegetation to agriculture and/or pasture) and management which cause a change in the water and salt balance of the landscape, mobilising stored salts.[1]
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