Roads versus flows in the Great Western Woodlands: surface-water insights into linear infrastructure effects

These datasets and spatial files are the data underlying the analyses presented in the paper 'Linear infrastructure impacts on landscape hydrology' published in the Journal of Environmental Management in 2018 (Volume 206, pp 446-457). The extent of roads and other forms of linear infrastructure is burgeoning worldwide, but their impacts are inadequately understood and thus poorly mitigated. Previous studies have identified many potential impacts, including alterations to the hydrological functions and soil processes upon which ecosystems depend. However, these impacts have seldom been quantified at a regional level, particularly in arid and semi-arid systems where the gap in knowledge is the greatest, and impacts potentially the most severe. To explore the effects of extensive track, road, and rail networks on surface hydrology at a regional level we assessed over 1000 km of linear infrastructure, including approx. 300 locations where ephemeral streams crossed linear infrastructure, in the largely intact landscapes of Australia’s Great Western Woodlands. We found a high level of association between linear infrastructure and altered surface hydrology, with erosion and pooling 5 and 6 times as likely to occur on-road than off-road on average (1.06 erosional and 0.69 pooling features km-1 on vehicle tracks, compared with 0.22 and 0.12 km-1, off-road, respectively). Erosion severity was greater in the presence of tracks, and 98% of crossings of ephemeral streamlines showed some evidence of impact on water movement (flow impedance (62%); diversion of flows (73%); flow concentration (76%); and/or channel initiation (31%)). Infrastructure type, pastoral land use, culvert presence, soil clay content and erodibility, mean annual rainfall, rainfall erosivity, topography and bare soil cover influenced the frequency and severity of these impacts. We conclude that linear infrastructure frequently affects ephemeral stream flows and intercepts natural overland and near-surface flows, artificially changing site-scale moisture regimes, with some parts of the landscape becoming abnormally wet and other parts becoming water-starved. In addition, linear infrastructure frequently triggers or exacerbates erosion, leading to soil loss and degradation. Where linear infrastructure densities are high, their impacts on ecological processes are likely to be considerable. Linear infrastructure is widespread across much of this relatively intact region, but there remain areas with very low infrastructure densities that need to be protected from further impacts. There is substantial scope for mitigating the impacts of existing and planned infrastructure developments.本数据集与空间文件为2018年发表于《环境管理学报》（Journal of Environmental Management）第206卷第446至457页的论文《线性基础设施对景观水文的影响》中各项分析的支撑数据。全球范围内，道路及其他类型线性基础设施（linear infrastructure）的规模正快速扩张，但其产生的影响尚未得到充分认知，相应的减缓措施也极为匮乏。过往研究已识别出诸多潜在影响，包括生态系统赖以生存的水文功能与土壤过程的改变。但此类影响鲜少在区域尺度上被量化，尤其是在知识缺口最大、影响潜在强度最高的干旱与半干旱生态系统中。为在区域尺度上探究大规模步道、道路与铁路网络对地表水文的影响，我们在澳大利亚大西部林地（Great Western Woodlands）这一整体保存较为完好的区域内，评估了超1000公里的线性基础设施，其中包含约300处暂时性溪流（ephemeral streams）横穿线性基础设施的点位。研究发现，线性基础设施与地表水文改变之间存在显著关联：平均而言，道路区域内发生侵蚀与积水的概率分别是非道路区域的5倍与6倍——车辆步道上的侵蚀特征与积水特征密度分别为1.06个·km⁻¹与0.69个·km⁻¹，而非道路区域则分别为0.22个·km⁻¹与0.12个·km⁻¹。存在步道的区域内侵蚀程度更为严重；98%的暂时性溪流横穿点位均表现出对水流运动的影响证据，其中水流阻滞占比62%、水流改道占比73%、水流汇聚占比76%，以及/或河道形成占比31%。基础设施类型、牧业土地利用方式、涵洞布设情况、土壤黏粒含量与抗蚀性、年均降雨量、降雨侵蚀力、地形条件以及裸土覆盖率，均会影响此类影响的发生频率与严重程度。我们的研究结论表明，线性基础设施常会干扰暂时性溪流的水流，并截留自然地表径流与近地表水流，人为改变局地尺度的水分状况，导致部分区域出现异常积水，而另一部分区域则陷入缺水状态。此外，线性基础设施常会诱发或加剧侵蚀作用，引发土壤流失与退化。在线性基础设施密度较高的区域，其对生态过程的影响可能极为显著。该整体保存较为完好的区域内，线性基础设施分布广泛，但仍存在部分基础设施密度极低的区域，需对其加以保护以避免遭受进一步的影响。现有与规划中的基础设施项目，其影响仍存在大量可被减缓的空间。