Pedosphere 27(6): 1037--1048, 2017
ISSN 1002-0160/CN 32-1315/P
©2017 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Hydrological Responses and Flow Pathways in an Acrisol on a Forested Hillslope with a Monsoonal Subtropical Climate
Lars-Erik SØRBOTTEN1, Jannes STOLTE2, WANG Yanhui3, Jan MULDER4
1Norconsult AS, N-1338 Sandvika (Norway)
2Norwegian Institute of Bioeconomy Research (NIBIO), N-1430 Aas (Norway)
3Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing 100091 (China)
4Department of Environmental Sciences, Norwegian University of Life Sciences, N-1432 Aas (Norway)
ABSTRACT
      The nature of subsurface flow depends largely on hydraulic conductivity of the vadoze zone, permeability of the underlying bedrock, existence of soil layers differing in hydraulic properties and macropore content, soil depth, and slope angle. Quantification of flow pathways on forested hillslopes is essential to understand hydrological dynamics and solute transport patterns. Acrisols, with their argic Bt horizons, are challenging in this respect. To further elucidate flow pathways of water and short-term variability of soil moisture patterns in Acrisols, a field study was conducted on a forested hillslope in a sub-catchment of the Tie Shan Ping (TSP) watershed, 25 km northeast of Chongqing City, China. This catchment is covered by a mixed secondary forest dominated by Masson pine (Pinus massoniana). Soil saturated hydraulic conductivity (Ksat) was significantly reduced at the interface between the AB and Bt horizons (2.6×10-5 vs. 1.2×10-6 m s-1), which led to that the flow volume generated in the Bt horizon was of little quantitative importance compared to that in the AB horizon. There was a marked decrease in porosity between the OA and AB horizons, with a further decrease deeper in the mineral subsoil. Especially, the content of soil pores > 300 μm was higher in the AB horizon (14.3%) than in the Bt horizon (6.5%). This explained the difference in soil Ksat values. This study showed that Bt horizon had limited water transport capability, forcing part of the infiltrated rainwater as interflow through the OA and AB horizons. Thus, the topsoil responded quickly to rainfall events, causing frequent cycles of saturation and aeration of soil pores.
Key Words:  dye tracer, hillslope hydrology, hydraulic conductivity, preferential flow, soil pores, subsurface lateral flow
Citation: Lars-Erik SØRBOTTEN, Jannes, S., Wang, Y. and Jan, M. 2017. Hydrological Responses and Flow Pathways in an Acrisol on a Forested Hillslope with a Monsoonal Subtropical Climate. Pedosphere. 27(6): 1037-1048.
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