GLobal HYdrogeology MaPS (GLHYMPS) of permeability and porosity

The lack of robust, spatially distributed subsurface data is the key obstacle limiting the implementation of complex and realistic groundwater dynamics into global land surface, hydrologic, and climate models. We map and analyze permeability and porosity globally and at high resolution for the first time. The new permeability and porosity maps are based on a recently completed high-resolution global lithology map that differentiates fine and coarse-grained sediments and sedimentary rocks, which is important since these have different permeabilities. The average polygon size in the new map is ~100 km2, which is a more than hundredfold increase in resolution compared to the previous map which has an average polygon size of ~14,000 km2. We also significantly improve the representation in regions of weathered tropical soils and permafrost. The spatially distributed mean global permeability ~10-15m2 with permafrost or ~1014m2 without permafrost. The spatially distributed mean porosity of the globe is 14%. The maps will enable further integration of groundwater dynamics into land surface, hydrologic, and climate models.

缺乏可靠的空间分布式地下数据，是制约将复杂且贴合实际的地下水动力学过程纳入全球陆面、水文及气候模型的核心障碍。本研究首次在全球范围内以高分辨率完成了渗透率（permeability）与孔隙度（porosity）的全域绘图与分析。本次构建的渗透率与孔隙度分布图，基于新近完成的高分辨率全球岩性（lithology）图：该图可区分细粒与粗粒沉积物及沉积岩（sedimentary rocks），而不同类型地质体的渗透率存在显著差异，这一分类依据至关重要。新分布图的平均多边形面积约为100平方千米，相较此前平均多边形面积约14000平方千米的旧版图谱，分辨率提升了百倍以上。本研究还显著优化了风化热带土壤与多年冻土（permafrost）区域的参数刻画精度。全域空间分布的平均渗透率，在存在多年冻土时约为10⁻¹⁵平方米，无多年冻土时约为10¹⁴平方米。全球全域空间分布的平均孔隙度为14%。本次发布的分布图将推动地下水动力学过程进一步融入陆面、水文及气候模型体系。