Simulation of land use impacts on sediment and nutrient transfer in coastal areas of Western Cape, South Africa

Gebel, Micha; Bürger, Stephan; Wallace, Michael G.; Malherbe, Hanlie; Vogt, Hannah; Lorz, Carsten

doi:10.1515/cass-2017-0001

Cited by 4 publications

(13 citation statements)

References 14 publications

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“…The study region supports nationally important water-and soil-related ecosystem services, including water flow regulation and soil retention [20,21]. The WCP indicates a particularly high potential risk of soil erosion [29] and soil erosion occurs in areas of this region [30]. Water sources in the region are also documented to be in a poor state [31].…”

Section: Generating Ecosystem Service and Risk Mapsmentioning

confidence: 65%

“…Gebel et al [30] Malherbe et al [35] Foley et al [39] Burkhard et al [14] Foley et al [39] Gebel et al [30] Malherbe et al [35] Foley et al [39] Matson et al [40] FAO et al [41] Mills and Fey [37] Matson et al [40] Burkhard et al [3] Scholes and Biggs [38] Matson et al [40] Irrigated orchards Gebel et al [30] Malherbe et al [35] O'Farrell et al [36] Burkhard et al [14] Gebel et al [30] Malherbe et al [35] O'Farrell et al [36] FAO et al [41] Mills and Fey [37] Burkhard et al [3] Scholes and Biggs [38] Irrigated wine grapes Gebel et al [30] Malherbe et al [35] Burkhard et al [14] Gebel et al [30] Malherbe et al [35] O'Farrell et al [36] FAO et al [41] Mills and Fey [37] Burkhard et al [3] Scholes and Biggs [38] Forest plantations Malherbe et al [35] O'Farrell et al [36] Malherbe et al [35] O'Farrell et al [36] Mills and Fey [37] Scholes and Biggs [38] Urban formal Malherbe et al [35] O'Farrell et al…”

Section: Dryland Crop Cultivationmentioning

confidence: 99%

“…The literature on ecosystem services and related criteria specific to the study region and similar regions of South Africa is somewhat limited, but received the most consideration in value assignment [28,30,[35][36][37][38]. For example, Gebel et al [30] identified the land use activities that mostly contribute to sediment and nutrients reaching river networks in the same study region. For the same study region, Malherbe et al [35] assigned the LULC classes with impact scores to indicate the nutrient, sediment, and chemical inputs from LULC.…”

Section: Relating Lulc and Landscape Properties To Ecosystem Servicesmentioning

confidence: 99%

“…Gebel et al [30] Malherbe et al [35] O'Farrell et al [36] Foley et al [39] Foley et al [39] Gebel et al [30] Malherbe et al [35] O'Farrell et al [36] Foley et al [39] Matson et al [40] FAO et al [41] Mills and Fey [37] Matson et al [40] Burkhard et al [3] Scholes and Biggs [38] Matson et al [40]…”

Section: Irrigated Crop Cultivationmentioning

confidence: 99%

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Mapping the Loss of Ecosystem Services in a Region Under Intensive Land Use Along the Southern Coast of South Africa

Malherbe

Pauleit

Lorz

2019

Land

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Intensive land use activities worldwide have caused considerable loss to many ecosystem services. The dynamics of these threats must be quickly investigated to ensure timely update of management strategies and policies. Compared with complex models, mapping approaches that use scoring matrices to link land use/land cover and landscape properties with ecosystem services are relatively efficient and easier to apply. In this study, scoring matrices are developed and spatially explicit assessments of five ecosystem services, such as erosion control, water flow regulation, water quality maintenance, soil quality maintenance, and biodiversity maintenance, are conducted for a region under intense land use along the southern coast of South Africa. The complex interaction of land use/land cover and ecosystem services within a particular landscape is further elucidated by performing a spatial overview of the high-risk areas that contribute to the loss of ecosystem services. Results indicate that both agricultural activities and urban development contribute to the loss of ecosystem services. This study reveals that with sufficient knowledge from previous literature and inputs from experts, the use of scoring matrices can be adapted to different regional characteristics. This approach can be improved by adding additional landscape properties and/or adapting the matrix values as new data become available.

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Section: Generating Ecosystem Service and Risk Mapsmentioning

confidence: 65%

Section: Dryland Crop Cultivationmentioning

confidence: 99%

Section: Relating Lulc and Landscape Properties To Ecosystem Servicesmentioning

confidence: 99%

Section: Irrigated Crop Cultivationmentioning

confidence: 99%

See 2 more Smart Citations

Mapping the Loss of Ecosystem Services in a Region Under Intensive Land Use Along the Southern Coast of South Africa

Malherbe

Pauleit

Lorz

2019

Land

Self Cite

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“…For setup of the hydrological model we applied the WebGIS based software STOFFBILANZ [49][50][51]. The hydrological model aimed at providing estimates of groundwater recharge and surface water runoff rates for the model area and the AOI catchment [51][52][53][54]. The input data include daily rainfall, daily temperature, daily reference evapotranspiration, soil hydraulic properties, land cover and the growing state of crops.…”

Section: Validation Of the Rmb Results Using Hydrogeological And Hydrmentioning

confidence: 99%

Improved Approach for the Investigation of Submarine Groundwater Discharge by Means of Radon Mapping and Radon Mass Balancing

Schubert

Petermann

Stollberg

et al. 2019

Water

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The paper presents an improved approach for investigating submarine groundwater discharge (SGD) based on radon mapping and radon mass balancing in the coastal sea. While the use of radon as an environmental tracer in SGD studies is well-established, we identified based on our longstanding experience six methodical shortcomings of the conventional approach and suggest corresponding developments. The shortcomings include: (1 and 2) inadequate consideration of both detection equipment response delay and influence of tidal stage; (3 and 4) incorrect quantification of radon losses, due to offshore mixing and degassing resulting in a potentially incorrect radon mass balance; (5) inaccurate determination of the terrestrial groundwater endmember, due to inhomogeneous radon distribution in the coastal aquifer; and (6) difficulties in distinguishing between discharged fresh groundwater and recirculated seawater. The improved approach is practically demonstrated in a step by step manner in a large-scale field study, which was carried out in False Bay (South Africa) and which consisted of two parts, namely (i) qualitative SGD localization along the entire False Bay coastline based on coastal radon distribution patterns and (ii) quantitative SGD investigation within a defined coastal area of interest (AOI) based on a radon mass balance (RMB). The plausibility of the AOI related results was evaluated by a hydrogeological model, used for qualitative SGD localization, and a hydrological model, applied for estimating groundwater recharge within the AOI catchment.

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Coupling End‐Member Mixing Analysis and Isotope Mass Balancing (222‐Rn) for Differentiation of Fresh and Recirculated Submarine Groundwater Discharge Into Knysna Estuary, South Africa

et al. 2018

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Quantification of submarine groundwater discharge (SGD) is essential for evaluating the vulnerability of coastal water bodies to groundwater pollution and for understanding water body material cycles response due to potential discharge of nutrients, organic compounds, or heavy metals. Here we present an environmental tracer‐based methodology for quantifying SGD into Knysna Estuary, South Africa. Both components of SGD, (1) fresh, terrestrial (FSGD) and (2) saline, recirculated (RSGD), were differentiated. We conducted an end‐member mixing analysis for radon (222Rn) and salinity time series of estuary water over two tidal cycles to determine fractions of seawater, riverwater, FSGD, and RSGD. The mixing analysis was treated as a constrained optimization problem for finding the end‐member mixing ratio that is producing the best fit to observations at every time step. Results revealed highest FSGD and RSGD fractions in the estuary during peak low tide. Over a 24 h time series, the portions of FSGD and RSGD in the estuary water were 0.2% and 0.8% near the estuary mouth and the FSGD/RSGD ratio was 1:3.3. We determined a median FSGD of 41,000 m³ d−1 (1.4 m³ d−1 per m shoreline) and a median RSGD of 135,000 m³ d−1 (4.5 m³ d−1 per m shoreline) which suggests that SGD exceeds river discharge by a factor of 1.0–2.1. By comparison to other sources, this implies that SGD is responsible for 28–73% of total DIN fluxes into Knysna Estuary.

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Simulation of land use impacts on sediment and nutrient transfer in coastal areas of Western Cape, South Africa

Cited by 4 publications

References 14 publications

Mapping the Loss of Ecosystem Services in a Region Under Intensive Land Use Along the Southern Coast of South Africa

Mapping the Loss of Ecosystem Services in a Region Under Intensive Land Use Along the Southern Coast of South Africa

Improved Approach for the Investigation of Submarine Groundwater Discharge by Means of Radon Mapping and Radon Mass Balancing

Coupling End‐Member Mixing Analysis and Isotope Mass Balancing (222‐Rn) for Differentiation of Fresh and Recirculated Submarine Groundwater Discharge Into Knysna Estuary, South Africa

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