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.

许多河谷底部湿地都具有的挖填过程对从业人员规划湿地恢复提出了重大挑战。目前尚不清楚当前切口的同步性和空间尺度是否“自然”，以及这些湿地在“填充”阶段是否无需干预即可自然恢复。这项研究的目标集中在Pri草南非占主导地位的谷底湿地是在当前集水区限制的背景下评估自然生态系统恢复的潜力。历史降雨记录，航空摄影和DGPS调查被用来关联地貌过程。通过取样沉积物剖面调查了冲积物的沉积学。分析了样品的粒度和有机含量，其中五个使用放射性碳标注日期。沉积学和放射性碳年代被用来确定沿湿地河段的切开和积聚阶段。尽管记录中表示了切口的几个阶段，但在一个以上的位置中没有一个代表，这表明侵蚀和随后的沉积阶段在空间和时间上是分开的。因此，目前整个湿地的切口同步阶段是前所未有的。对沉降速率的分析表明，随着时间的推移，沟渠的填充量呈指数下降。在自然集水条件下，在Pietersielieskloof湿地中填满一个3m深的沟渠估计需要大约5000年的时间。分析表明，上个世纪以来，湿地的复原力有所下降，流域水文学和沉积物供应的变化改变了该系统，使其超过了地貌阈值。