A Novel Low-Cost, High-Resolution Camera System for Measuring Peat Subsidence and Water Table Dynamics
A Novel Low-Cost, High-Resolution Camera System for Measuring Peat Subsidence and Water Table Dynamics
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DOI：
10.3389/fenvs.2021.630752
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发表时间：
2021-03-22
影响因子：
4.6
通讯作者：
Jovani-Sancho, A. Jonay
中科院分区：
文献类型：
--
作者：
Evans, Chris D.;Callaghan, Nathan;Jovani-Sancho, A. Jonay
泥炭地是一个高度动态的系统，在自然条件下能够积累数千年的碳，但在排水时容易迅速沉降和碳损失。短期、季节性和长期的泥炭地表面高程变化与泥炭地的关键属性（如地下水位深度和碳平衡）密切相关，可以使用卫星雷达和激光雷达方法进行远程测量。然而，泥炭高程变化的实地测量在空间和时间上是稀疏的，依赖于低分辨率的手动沉降极测量，或昂贵的传感器系统。在这里，我们描述了一种新的，简单的和低成本的基于图像的方法，测量泥炭表面运动和WTD使用市售的延时相机和图像处理方法。基于近两年的部署泥炭相机在对比森林，烧毁，农业和油棕种植园网站在印度尼西亚加里曼丹中部，我们表明，该方法可以捕捉极高的分辨率（亚毫米）和高频率（亚日常）的变化，泥炭表面海拔在较长的时间内，并在具有挑战性的环境条件下。WTD测量的质量与市售压力传感器相似。结果表明，动态泥炭高程响应个别降雨事件，WTD的变化一致。在相对严重的2019年旱季期间，深排水泥炭地的摄像机记录了超过8厘米的最大泥炭收缩，随后部分反弹，导致每年净沉降高达5厘米。地下水位较高的地点，以及采用钻孔灌溉保持土壤湿度的地点，沉降较低，这表明有可能通过改变土地管理来减少沉降。鉴于沉降和二氧化碳排放之间的联系，这些结果有直接的影响泥炭地的管理，以减少高电流温室气体（GHG）排放。基于摄像头的传感器为商业海拔、WTD和GHG通量监测系统提供了一种简单、低成本的替代方案，适用于大规模部署，以及现有方法不切实际或负担不起的地区。如果泥炭运动的地面观测可以与测量的温室气体通量和基于卫星的监测工具相联系，这种方法提供了一个大规模泥炭地监测工具的潜力，适合于确定活性碳损失的领域，针对气候变化减缓干预措施，并评估干预结果。
Peatlands are highly dynamic systems, able to accumulate carbon over millennia under natural conditions, but susceptible to rapid subsidence and carbon loss when drained. Short-term, seasonal and long-term peat surface elevation changes are closely linked to key peatland attributes such as water table depth (WTD) and carbon balance, and may be measured remotely using satellite radar and LiDAR methods. However, field measurements of peat elevation change are spatially and temporally sparse, reliant on low-resolution manual subsidence pole measurements, or expensive sensor systems. Here we describe a novel, simple and low-cost image-based method for measuring peat surface motion and WTD using commercially available time-lapse cameras and image processing methods. Based on almost two years' deployment of peat cameras across contrasting forested, burned, agricultural and oil palm plantation sites in Central Kalimantan, Indonesia, we show that the method can capture extremely high resolution (sub-mm) and high-frequency (sub-daily) changes in peat surface elevation over extended periods and under challenging environmental conditions. WTD measurements were of similar quality to commercially available pressure transducers. Results reveal dynamic peat elevation response to individual rain events, consistent with variations in WTD. Over the course of the relatively severe 2019 dry season, cameras in deep-drained peatlands recorded maximum peat shrinkage of over 8 cm, followed by partial rebound, leading to net annual subsidence of up to 5 cm. Sites with higher water tables, and where borehole irrigation was used to maintain soil moisture, had lower subsidence, suggesting potential to reduce subsidence through altered land-management. Given the established link between subsidence and CO2 emissions, these results have direct implications for the management of peatlands to reduce high current greenhouse gas (GHG) emissions. Camera-based sensors provide a simple, low-cost alternative to commercial elevation, WTD and GHG flux monitoring systems, suitable for deployment at scale, and in areas where existing approaches are impractical or unaffordable. If ground-based observations of peat motion can be linked to measured GHG fluxes and with satellite-based monitoring tools, this approach offers the potential for a large-scale peatland monitoring tool, suitable for identifying areas of active carbon loss, targeting climate change mitigation interventions, and evaluating intervention outcomes.