Anthropogenically-driven shifts in hydroclimatic and wildfire regimes typify fire-prone regions globally, with profound implications for sediment production and transport processes. However, the nature and extent to which past climatic shifts and fire activity have influenced fluvial sediment dynamics over long timescales remains poorly understood, especially in the Mediterranean-climate region of South Africa. This study presents a ca. 2858-year record of fluvial sedimentological change and palaeoecological reconstructions of vegetation (fossil pollen), fire (charcoal) and herbivory (dung spores) from a peatland in the Cape Floristic Region to advance understanding of the linkages between climate, vegetation, fire and geomorphic processes. Analyses of grain-size distribution revealed alternating phases of organic accumulation, punctuated by clastic sediment input. The initiation of clastic sediment pulses supersedes peaks in fire activity and encompasses the period of climatic reorganisation in the region. This highlights the apparent temporal asynchronicity between fire activity and geomorphic responses, where fire may act as a precursor disturbance, with sediment transfer occurring only in response to hydroclimatic forcing. The recovery of pre-disturbance organic sedimentation patterns, especially over the past 200 cal. yr BP, following compounded disturbances, indicates the potential resilience of this wetland. This local-scale resilience likely depends on the capacity of eco-hydro-geomorphic feedbacks to re-establish sediment (dis) connectivity states post-disturbance. By integrating geomorphological and palaeoecological evidence, this study provides novel insights into historical variability in sediment connectivity dynamics in Mediterranean-type fluvial systems. This information is timely, given intensifying human influences, and has implications for catchment management strategies and interpreting wetland evolution trajectories.

Floodplain wetlands are valued for providing ecosystem services, yet these services are threatened due to land-use pressures and climate change. Further, regulating ecosystem services such as phosphorus (P) assimilation and storage are influenced by floodplain morphology and water and sediment dispersal processes, which vary over time. To investigate the influence of hydro-geomorphic processes on total sediment-associated P in surface sediment, this study evaluated the surface inundation and sedimentary characteristics of different regions of a spatially complex semi-arid floodplain in South Africa. Data collection involved stratified floodplain surface sediment sampling to characterise surface variations in geochemistry, particle size and organic matter content. This was paired with a Sentinel-2 imagery-derived frequency of inundation and a LiDAR DEM to incorporate both the influence of hydro-geomorphology and sedimentology on sediment dispersal dynamics and P sequestration on the floodplain. P in surface sediment was strongly affiliated with organic content, Fe, Al and mean particle size. PCA revealed that sample variability was associated with sediment geochemistry and particle size (component one, 63.48

Sediment trapping in wetlands is an essential ecosystem service, with implications for downstream ecosystems and water users. There is however limited empirical evidence of the contemporary rates and magnitude of sediment trapping in valley-bottom wetlands. Time-averaged suspended sediment samples from the inlets and outlets of forestry- and agriculturally-impacted valley-bottom wetlands with contrasting morphometric characteristics were compared in terms of suspended sediment and associated total phosphorous (total P) fluxes over annual scales, a dataset that was limited by Covid travel constraints. Although both wetlands were net depositional, contemporary suspended sediment mass balances for the agriculturally-impacted wetland revealed a temporal change in the amount of sediment trapped over two water years (2019/2020 and 2020/2021), with trapping efficacies of 91% and 24%, respectively. The proportion of sediment trapped in the water year of 2020/2021 within the adjacent wetland, with a small commercially forested catchment, was up to 4 times higher than the agriculturally-impacted wetland, which drained a larger catchment. Rates of total P retention showed that the agriculturally-impacted wetland was a net sink for phosphorus in 2019/2020, but shifted to a source of phosphorus in 2020/2021 as the export of suspended sediment was enhanced. However, this contrasts with the forestry-impacted wetland, which was a net sink of sediment and associated phosphorus during the one-year study period of 2020/2021. Overall, despite data constraints, this study suggests that the efficacy of valley-bottom wetlands in the delivery of sediment trapping and phosphorus removal ecosystem services varies temporally and spatially. This variability is potentially related to the interaction between annual rainfall regimes, catchment size and wetland geomorphic character. The temporary nature of sediment recycling processes could serve to balance wetland dynamics by regulating vertical growth of valley floors and longitudinal slope stability and should be considered in catchment management and wetland restoration planning strategies. Valley-bottom wetlands in dryland landscapes are dynamic fluvial landforms and play an important role in delivering a myriad of ecosystem services and supporting human well-being. Overall, results show that the efficiency of sediment trapping and phosphorus removal services in these wetlands are temporally variable and system-specific, and likely depends on the interaction between annual rainfall regimes, catchment size and local-scale wetland geomorphology. As these systems alternate between periods of net sediment trapping and short-term episodic recycling of sediment, we suggest that this could serve as a mechanism to locally regulate morphological adjustment. This study therefore highlights the importance of considering the temporary nature and spatial variability of sediment recycling processes in catchment management and wetland restoration planning strategies.image

Anthropogenic-induced acceleration of sediment and associated nutrients presents a serious challenge to water resource management across the globe. While wetlands are potential natural solutions, little is known of how well key wetland types attenuate downstream sediment fluxes and how these relate to local- and catchment-scale factors. This research aimed to develop an understanding of patterns and rates of sediment and phosphorus retention in valley-bottom wetlands in South Africa. The geomorphology, sedimentology and historical accretion rates of three wetlands which offered diversity in size, catchment position and degree of organic accumulation were compared to ascertain the impact of local- and catchment-scale factors. Estimates of sediment and associated phosphorus accumulation suggest higher rates in clastic sediment-dominated wetlands (1089-7655 g sediment m(-2) yr(-1), 0.4-1.6 g-P m(-2) yr(-1)) compared to an organic sediment-dominated system (601-1308 g-sediment m(-2) yr(-1), 0.2-0.3 g-P m(-2) yr(-1)). Sediment accretion rates generally increased longitudinally, indicating that distal wetland reaches act as sediment and phosphorus retention hotspots. Phosphorus distribution patterns were primarily attributed to variations in organic matter content and associated aluminium and iron complexing agents in fine-grained sediment deposits, while particle size distributions were less important. However, the relevance of individual complexing agents in phosphorus dynamics varied among wetlands with differing landscape conditions. Contrasts between these systems reflect variations in catchment lithology and hydroclimatic regime, which influence the relative magnitude of sediment supply and vegetation productivity. We postulate that intermediate-sized wetlands characterised by catchments around 900 ha in size, gentle longitudinal slopes (similar to 2 %), a high proportion of fine sediment deposition, limited organic matter breakdown, and a long vegetation growing season provide optimal conditions for sediment and phosphorus accumulation. This system-scale information is essential to guide management decisions to identify and prioritize within-catchment 'hotspots' of sediment and phosphorus retention.

Zones of alluviation at tributary - trunk confluences can act as sediment storage/transfer switches. Evaluating the temporal variation in tributary - trunk connectivity is key to understanding the origin, dynamics and residence time of tributary alluvial fill sequences, and determining relative and interacting effects of different drivers of landscape development. This paper evaluates processes and timescales of tributary (Prins River) - trunk (Touws River) connectivity at a site in the Little Karoo, as context for discussing sediment dispersal dynamics and implications for interpreting the landscape response to environmental change. An alluvial terrace in the tributary valley preserves a chronology (optically stimulated luminescence) of tributary valley alluviation that is regionally synchronous with valley alluviation in the upper Huis River and floodplain alluviation in the lower Touws and Groot rivers. A climatic shift within the Little Karoo at similar to 1000 years BP from relative aridity to relative humidity (and higher-energy rain-bearing circulation types) may have initiated widespread re-working of alluvial fills and the breaching of geomorphological buffers. Alternatively, there may be an intrinsic limit to sediment preservation potential associated with a regional floodplain cycling time of one to two thousand years. Longer archives are needed to contextualize fluvial responses to climatic variability in the region.

Suspended fine sediment in rivers and small streams contributes to fluvial pollution loads because of its association with anthropogenically introduced heavy metals, pesticides / herbicides, and nutrients, including phosphorous (P). By acting as sinks for suspended sediment, wetlands located along drainage lines have considerable potential in reducing downstream sediment and nutrient fluxes. The aim of this research was to document downstream sediment fluxes within a single valley-bottom wetland to establish the effectiveness of this common wetland type in retaining P attached to sediment. The study was accomplished by conducting a topographic survey (dGPS and 0.5 m Lidar-derived DEM) with surface and sub-surface sediment sampling to establish long-term (decades to centuries) processes of erosion and deposition within the wetland, as well as consider storage of P. This was paired with event-based suspended sediment sampling at eight positions within the wetland over a wet season, as well as time-averaged suspended sediment sampling at a seasonal-scale at the wetland inlet and outlet. Sediment samples were characterised in terms of organic content, total phosphorous and particle size, which were determined using loss-on-ignition, ICP-AES following aqua regia extraction, and a combination of dry sieving and settling, respectively. Over the wet season, average suspended sediment concentrations increased to a maximum value of 0.26 g center dot L-1 and then declined, potentially because of the exhaustion of locally available sediment. The total P concentration of incoming sediment was 2174 mg/kg compared to 800 mg/kg at the wetland outlet. However, when considering the seasonal flux for the single year sampled, it was found that the wetland was a net downstream contributor of sediment (11 g of sample were retained at the inlet, relative to 19 g at the outlet). Despite this, the wetland retained similar to 37 % of the total P supplied to it from upstream sources, with the remainder passing through the wetland as a result of sediment reworking in reforming channels. Thus, while wetlands may be effective at retaining some sediment and nutrients, they are not an alternative to more formal water treatment works.

Land surface geomorphology plays an important role in water and sediment dispersal processes in wetlands. For wetland practitioners and researchers to engage with these processes in time and space, they require topographic data in order to derive wetland surface gradient, cross-sectional shape and area, surface and subsurface hydrological connectivity, and hydraulic characteristics. A range of data options, with varying spatial resolutions, are available, ranging from free national and global resources (e.g. contour data and global elevation models) to project-specific high-resolution surveys (e.g. Differential Global Positioning Systems (DGPS), Photogrammetry, Light Detection And Ranging (LiDAR)). Due to the scarcity of high-resolution and high-accuracy data, especially in developing countries, data gathering and processing costs can be significant. This paper presents a commentary on a range of topographic data and processing options for a relatively small (~ 40 ha) floodplain wetland in the Eastern Cape, South Africa. It critically reviews the usefulness and shortfalls of various wetland-related applications ranging from gradient calculations to more detailed hydraulic modelling, and the data resolution required for each application. Free, low-resolution, datasets have a limited representation of geomorphology at this scale due to the relatively low-resolution and large vertical error. Field-based surveys (using survey-grade equipment such as a DGPS) have the benefit of providing accurate terrain results in areas with dense vegetation and surface water, while photogrammetry and LiDAR data are useful to represent the higher resolution morphology across the wetland, despite shortcomings regarding the penetration of dense vegetation and surface water. However, combining DGPS data with LiDAR proves to yield the best model for detailed process modelling for wetlands at the local scale.

ecological, and social-ecological features, and as a result, they require carefully tailored research and management strategies.The surface or near-surface expression of water in these otherwise dry and climatically-variable environments (e

Abstract Land surface topography plays an important role in water and sediment dispersal processes in wetlands. For wetland practitioners and researchers to engage with these processes in time and space, they require topographic data in order to derive wetland surface gradient, cross-sectional shape and area, surface and subsurface hydrological connectivity, and hydraulic characteristics. A range of data options, with varying spatial resolutions, are available, ranging from free national and global resources (e.g. contour data and global elevation models) to project-specific high-resolution surveys (e.g. Differential Global Positioning Systems (DGPS), Photogrammetry, Light Detection And Ranging (LiDAR)). Due to the scarcity of high-resolution and high accuracy data, especially in developing countries, data gathering and processing costs can be significant. This paper presents a commentary on a range of topographic data and processing options for a floodplain wetland in the Eastern Cape, South Africa. It critically reviews the usefulness and shortfalls of various wetland related applications ranging from gradient calculations to more detailed hydraulic modelling, and the data resolution required for each application. Free, low resolution, datasets have a limited representation of topography due to low resolution and large vertical error. Field-based surveys (using survey-grade equipment such as a DGPS) have the benefit of providing accurate terrain results in areas with dense vegetation and surface water, while Structure from Motion and LiDAR data are useful to represent the higher resolution morphology across the wetland, despite shortcomings with dense vegetation and surface water. However, combining DGPS data with LiDAR proves to yield the best model for detailed process modelling.

Wetlands in drylands are dynamic landforms and hotspots of ecosystem service provision, including downstream improvements in water quality by mediating fluxes of sediment, nutrients and toxicants. This review focuses on fluvially associated wetlands including valley-bottom (also called upland swamps and ciénegas) and meandering river floodplain wetlands in drylands and specifically considers the long-term resilience of ecosystem services associated with sediment trapping in these systems. We critically evaluate global rates of sediment accretion within wetlands, consider sediment trapping and erosion dynamics and the biogeochemical cycling of phosphate, and reflect on the implications of dryland environments for sediment trapping and phosphorous removal services. Reported rates of accretion in valley-bottom wetlands are variable and low when compared to floodplains. Clastic-dominated valley-bottom wetlands have lower long-term vertical sediment accretion rates compared to systems characterised by peat accumulation. While floodplain systems exhibit a wide range of vertical accretion rates, dryland floodplains have a lower and more narrow range of accumulation rates compared to humid regions, which may be attributed to seasonality and inter-annual variability in flow-sediment regimes. The periodic desiccation of wetland sediments in dryland settings will likely amplify phosphorus (P) cycling and retention due to oxidation and precipitating cationic complexes. Organic P retention is potentially less important in these systems as rapid losses and speciation will occur due to low organic matter preservation. In valley-bottom and floodplain wetlands, storage of phosphate-rich sediment cannot be considered permanent due to sediment reworking and may become sources of P-enriched legacy sediment in the future. The review indicates that complex temporal dynamics and spatial patterns of characteristic hydrogeomorphic processes in these wetlands preclude the generalisation of sediment trapping and P removal services.

South African river floodplains and their alluvial deposits reflect a diversity of geological and geographical drivers. We use a genetic geomorphic classification system originally developed for dryland wetlands to characterise geomorphic processes and potential successions of sedimentary fill for South African floodplains. Using case studies from the literature, we consider differences between alluvial rivers and mixed bedrock-alluvial rivers in the context of macro-scale geomorphic setting, and evaluate the impact of the setting on floodplain persistence and potential as a palaeo-environmental archive. Sedimentary facies associations represented in South African floodplains, including lateral and oblique accretion, channel, channel infill, levee vertical accretion, floodplain vertical accretion and debris flow deposits, are also evaluated. Floodplains of South Africa's interior are typically mixed bedrock-alluvial as channel beds are set upon or close to bedrock and sediment thickness is limited. By contrast some floodplains in tectonic basin settings have sediment deposits exceeding 30 m in thickness. The resulting rivers are alluvial, and thus able to adjust their width, depth and slope to accommodate changes in discharge and sediment supply. Similarly, coastal floodplain rivers are alluvial due to downcutting during the last glacial maximum and subsequent sedimentary infilling as sea levels rose. When considering the potential of floodplains as palaeo archives of environmental change, two considerations emerge. First, floodplain stratigraphy is not a response to a single variable due to complex process-form feedbacks. Rather, floodplain stratigraphy is an outcome of both autogenic and allogenic processes. Second, most South African floodplains are zones of sediment recycling, and as such, preservation potential is typically low. Thus, although floodplain settings of the interior may be a few million years old, the sediment within them may be only thousands to tens of thousands of years old. Our review indicates that research has historically focused on meandering river and mixed bedrock-alluvial anabranching river floodplains, while understanding of other floodplain sub-types remains limited.

Reach-scale river restoration or environmental water allocation (EWA) exercises typically address the magnitude and temporal dynamics (frequency, duration, timing, rate of change) of flows required to sustain desirable ecological conditions along a river. The role of geomorphology in this process is to broaden the gaze beyond flows to consider larger and longer-term interactions between valley lithological structure, and the feed and fate of flow-sediment mixtures. This paper proposes the integration of numerical morphodynamic modelling in evaluations of environmental water requirements for non-perennial riverscapes (channel–riparian–floodplain environments). The paper presents a methodological framework, and proof of concept case study from the Touws River, South Africa, for the application of morphodynamic modelling in EWA. The paper illustrates operational approaches to modelling the complexity of dryland mixed bedrock-alluvial (and mixed-load) riverscapes with highly variable non-perennial flow regimes, including an approach to generating initial bed conditions for numerical experiments by ‘morphodynamic spin-up’, and approaches to synthesising and presenting numerical experiment output in the form of a dynamic range of potential variability in metrics of physical habitat suitability and diversity, and disturbance/renewal regimes. Such efforts can assist in enhancing field observations and testing field-based hypotheses of flow-sediment regime–physical habitat associations, extending the timescales of analysis beyond field observation, and constraining uncertainty about the dynamic range of variability in responses to predicted future flow-sediment regime modifications. Further research is needed to develop growth models appropriate for key non-perennial river vegetation types, to support biomorphodynamic modelling of geomorphology–vegetation interactions, and to determine or predict appropriate inlet sediment concentrations for historical and future modification scenarios.

Cut-and-fill processes, characteristic of many valley-bottom wetlands, present a major challenge to practitioners planning wetland restoration. It is not clear whether the current synchronicity and spatial scale of incision is ‘natural’, and whether these wetlands will naturally recover without intervention during the ‘fill’ phase. The aim of this study, focussed on a Prionium serratum dominated valley-bottom wetland in South Africa, was to evaluate the potential for natural ecosystem recovery in the context of current catchment constraints. Historical rainfall records, aerial photography and a DGPS survey were used to contextualise geomorphic processes. The sedimentology of alluvial fill was investigated by sampling sediment profiles. Samples were analysed for particle size and organic content, five were dated using radiocarbon. Sedimentology and radiocarbon dates were used to ascertain phases of incision and aggradation along wetland reaches. While several phases of incision are represented in the record, none were represented in more than one location, suggesting phases of erosion and subsequent deposition were spatially and temporally segregated. The current synchronous phase of incision across the wetland is therefore unprecedented. Analysis of sedimentation rates indicate that infilling of the gully decreases exponentially over time. Infilling of a 3m deep gully in the Pietersielieskloof wetland under natural catchment conditions is estimated to take ~ 5000 years. Analysis suggests that there has been a reduction in wetland resilience over the last century, and that a change in catchment hydrology and sediment supply has altered this system such that it has crossed a geomorphic threshold.

Widespread invasive nitrogen-fixing plant species pose major threats to water resources, biodiversity and nutrient dynamics of river catchments around the world. However, the impacts of invasive N-2-fixing plants on in-stream sediment nutrient dynamics remain poorly understood. Here, we quantified the impacts of invasive N-2-fixing Acacia mearnsii and A. mearnsii clearing on two mountain streams in South Africa's Cape Floristic Region. Nutrients were measured in fine sediment that had infiltrated into the gravel bed and surface water in three reaches associated with natural fynbos shrubs, A. mearnsii invaded and cleared riparian ecotones. Results showed that the impacts of A. mearnsii invasions and Acacia clearing in riparian areas on in-stream sediment-associated nutrient concentrations are context-dependent. The difference in channel morphometry and sediment geochemical attributes at reach-scale contributed to the contrasting spatial patterns of sediment-adsorbed nutrients within these rivers. There was also an indication of a long-lasting effect of invasion on total phosphorus that could persist in river sediments >= 10 years after the removal of dense A. mearnsii stands in close proximity to streams. This could be a result of the complexation between phosphorus and immobile iron in sediment, resulting in the retention of 'legacy phosphorus'. This underlines the importance of fine sediments in capturing nutrients and ultimately regulating nutrient concentrations in the water column.

We investigate coastal wetland ecosystem resilience to sea level rise by modelling sea level rise trajectories and the impact on vegetation communities for a coastal wetland in South Africa. The rate of sediment accretion was modelled relative to IPCC sea level rise estimates for multiple RCP scenarios. For each scenario, inundation by neap and spring tide and the 2, 4, and 8 year recurrence interval water level was modelled over a period of 200 years. When tidal variation is considered, the rate of sediment accretion exceeds rising sea levels associated with climate change, resulting in no major changes in terms of inundation. When sea level rise scenarios were modelled in conjunction with recurrence interval water levels, flooding of the coastal wetland was much greater than current levels at 1 in 4 and 1 in 8 year events. In the long term, increases in salinity may cause a reduction in Phragmites australis cover. Very small increases in depth and frequency of inundation are likely to cause an expansion of samphire species at the expense of Juncus spp. The study suggests that for this wetland, variability in flow may be a key factor in balancing wetland resilience.

This paper resolves the origin of clay hummock micro‐topography in seasonal wetlands of the Drakensberg Foothills, providing a review and appraisal of previously‐suggested mechanisms of hummock formation in the context of new field and laboratory data. Field surveys revealed neo‐formation of clay hummocks in a river channel that had been abandoned in c .1984. Fresh earthworm castings were located atop hummocks protruding from inundated abandoned channel margins. Earthworm castings, and sediment cores taken in hummocks and adjacent hollows, were analysed for soil‐adsorbed carbon and nitrogen using an HCN analyser, and for 210 Pb activity using alpha‐geochronology. 210 Pb activity profiles suggest relative enrichment of the isotope in hummocks, and relative depletion in adjacent hollows. Earthworm castings are characterised by very high 210 Pb activity, as well as high C and N contents. Hummocks have significantly higher C and N contents than adjacent hollows. Results suggest that it is the foraging activity of earthworms in litter‐rich seasonal wetland hollows, and repeated excretion of castings atop adjacent hummocks, that is responsible for the elemental enrichment observed. The paper presents a conceptual model of hummock formation in wetlands through interactions between hydrogeomorphology and earthworm activity, and illustrates a mechanism of biogeomorphic inheritance through which ordered patterns of preferential flow can emerge in ecosystems. Further implications of hummock formation and nodal accumulation of nutrients are considered in relation to wetland resilience and regulatory ecosystem service provision.© 2018 John Wiley & Sons, Ltd.

Due to climatic constraints in dryland regions, wetlands usually occur at confluences of flow paths, whether from surface flow, inter-flow or at locations of groundwater discharge. Long-term landscape processes that shape valleys and focus the movement of water and sediment are accountable for providing a suitable template with which hydrology interacts to allow wetland formation. Current hydrogeomorphic classification systems do not address system-scale linkages of sediment and water transport across the landscape, and are therefore unable to contextualise long-term process dynamics. Misunderstanding long-term earth system processes can result in the application of inappropriate restoration strategies that isolate wetlands from longitudinal drivers of their formation. We propose a genetic classification system that focuses on the mode of wetland formation, and is based on the understanding that genetic processes impact on the outcome hydrology, sedimentology, geomorphology, ecosystem service provision, and long-term dynamics of wetlands in drylands. The classification aims to impart understanding of dynamic processes of sediment transport through wetlands, such that restoration plans can be sensitive to long-term landscape processes. The classification system, derived from a combination of international literature and published South African case studies, has four wetland macrotypes based on sediment source (colluvial, alluvial, Aeolian, and geochemical). These are subdivided into eight wetland types; hillslope seep, floodplain, valley-bottom, plain, blocked-valley, alluvial fan, aeolian depression, and geochemical depression. The classification is based on landscape location, shape, and the occurrence of geomorphic characteristics indicative of process.

Sea-level rise associated with climate change presents a major challenge to plant diversity and ecosystem service provision in coastal wetlands. In this study, we investigate the effect of sea-level rise on benthos, vegetation, and ecosystem diversity in a tidal wetland in west Wales, the UK. Present relationships between plant communities and environmental variables were investigated through 50 plots at which vegetation (species and coverage), hydrological (surface or groundwater depth, conductivity) and soil (matrix chroma, presence or absence of mottles, organic content, particle size) data were collected. Benthic communities were sampled at intervals along a continuum from saline to freshwater. To ascertain future changes to the wetlands' hydrology, a GIS-based empirical model was developed. Using a LiDAR derived land surface, the relative effect of peat accumulation and rising sea levels were modelled over 200 years to determine how frequently portions of the wetland will be inundated by mean sea level, mean high water spring and mean high water neap conditions. The model takes into account changing extents of peat accumulation as hydrological conditions alter. Model results show that changes to the wetland hydrology will initially be slow. However, changes in frequency and extent of inundation reach a tipping point 125 to 175 years from 2010 due to the extremely low slope of the wetland. From then onwards, large portions of the wetland become flooded at every flood tide and saltwater intrusion becomes more common. This will result in a reduction in marsh biodiversity with plant communities switching toward less diverse and occasionally monospecific communities that are more salt tolerant. While the loss of tidal freshwater wetland is in line with global predictions, simulations suggest that in the Teifi marshes the loss will be slow at first, but then rapid. While there will be a decrease in biodiversity, the model indicated that at least for one ecosystem service, carbon storage, there is potential for an increase in the near future.

In southern Africa, wetlands of different types are an integral part of the drainage network, yet evolve and are sensitive to different combinations of geologic, climatic, geomorphic, edaphic and hydrologic controls. Understanding of these controls can help in the interpretation of environmental and climatic records from different wetland types, given that wetland sensitivity to environmental and climatic changes may vary throughout their 'life cycle'. The chapter discusses inland wetland records from dated sites in South Africa in order to consider their significance for reconstructing late glacial and Holocene climates; and the relationship of wetlands to preservation of the Pleistocene archaeological record. Wetlands are sensitive to degradation under contemporary environmental and climatic changes, which may impact on their hydrological and ecological function as well as the integrity of associated archaeological sites.