Impact of rooting depth and soil hydraulic properties on the transpiration peak of an evergreen forest in northern Thailand in the late dry season

2004 ◽  
Vol 109 (D23) ◽  
Author(s):  
Katsunori Tanaka ◽  
Hideki Takizawa ◽  
Tomonori Kume ◽  
Jianqing Xu ◽  
Chatchai Tantasirin ◽  
...  
Keyword(s):  
Hydraulic Properties ◽  
Dry Season ◽  
Evergreen Forest ◽  
Rooting Depth ◽  
Soil Hydraulic Properties ◽  
Northern Thailand ◽  
Soil Hydraulic

Modeling root water uptake depth driven by climate and soil texture using a simple bucket model approach

2021 ◽  
Author(s):  
Ruth Adamczewski ◽  
Sven Westermann ◽  
Anke Hildebrandt
Keyword(s):  
Soil Water ◽  
Hydraulic Properties ◽  
Water Retention ◽  
Root Water Uptake ◽  
Rooting Depth ◽  
Soil Hydraulic Properties ◽  
Soil Water Retention ◽  
Precipitation Patterns ◽  
Biogeochemical Models ◽  
Soil Hydraulic

<p>Root water uptake (RWU) in grasslands is determined by species composition, climate and soil hydraulic properties. Generally, plant communities are adapted to their environment, showing different rooting patterns along climate gradients. Due to climate change, ecosystems are exposed to shifts in precipitation patterns and rising temperatures, causing the need to adapt rooting strategies. RWU is mainly driven by plant transpiration and soil hydraulic status in the rooting zone. Soil hydraulic properties depend strongly on soil texture, which has been observed to influence rooting depth, increasing the root length from fine to coarse soils. Secondly, precipitation patterns affect the typical soil moisture status, and subsequently the rooting depth. Global models suggest that in dry environments RWU should move deeper, to enhance the plant available soil water. However, few studies have at the same time considered the effect of climate and soil properties on RWU depth, although soil properties vary substantially and probably more than precipitation patterns due to climate change.</p><p>Biogeochemical models suffer from uncertainty in subsurface hydrological processes, RWU being an important part of it. Thus, ecohydrological models are needed for an integration in larger context biogeochemical models. The trend of ecological models is towards high parameterized models, implying high uncertainty and challenging calibration for those parameters. Especially in the subsurface, parameters are often unknown and are usually impossible to derive from direct measurements. In this project, a simple, parsimonious bucket model was implemented, solving the water balance equation for a multi-layer soil profile. The objective of this work is to predict maximum required RWU depth required to satisfy potential evapotranspiration across established experimental grassland sites with different climate and soil water retention properties. For this we use soil moisture measurements, textures and hydraulic properties determined in three grassland sites of the Nutrient-Network (NutNet) across a climate gradient. We test the sensitivity of the model towards climate and soil hydraulic parameters. First model results show a high sensitivity of RWU depth besides to dynamics to climate, also to soil water retention determined by texture and organic matter content in the soils.</p>

scholarly journals Land surface scheme conceptualisation and parameter values for three sites with contrasting soils and climate

2000 ◽  
Vol 4 (2) ◽  
pp. 283-294 ◽  
Author(s):  
M. Soet ◽  
R. J. Ronda ◽  
J. N. M. Stricker ◽  
A. J. Dolman
Keyword(s):  
Land Surface ◽  
Hydraulic Properties ◽  
Bare Soil ◽  
Soil Evaporation ◽  
Rooting Depth ◽  
Surface Model ◽  
Soil Hydraulic Properties ◽  
Bare Soil Evaporation ◽  
Soil Hydraulic ◽  
Parameter Values

Abstract. The objective of the present study is to test the performance of the ECMWF land surface module (LSM) developed by Viterbo and Beljaars (1995) and to identify primary future adjustments, focusing on the hydrological components. This was achieved by comparing off-line simulations against observations and a detailed state-of-the-art model over a range of experimental conditions. Results showed that the standard LSM, which uses fixed vegetation and soil parameter values, systematically underestimated evapotranspiration, partly due to underestimating bare soil evaporation, which appeared to be a conceptual problem. In dry summer conditions, transpiration was seriously underestimated. The bias in surface runoff and percolation was not of the same sign for all three locations. A sensitivity analysis, set up to explore the impact of using standard parameter values, found that implementing specific soil hydraulic properties had a significant effect on runoff and percolation at all three sites. Evapotranspiration, however affected only slightly at the temperate humid climate sites. Under semi-arid conditions, introducing site specific soil hydraulic properties plus a realistic rooting depth improved simulation results considerably. Future adjustments to the standard LSM should focus on parameter values of soil hydraulic functions and rooting depths and, conceptually, on the bare soil evaporation parameterisation and the soil bottom boundary condition. Implications of changing soil hydraulic properties for future large-simulations were explored briefly. For Europe, soil data requirements can be fulfilled partly by the recent data base HYPRES. Sandy and loamy sand soils will then cover about 65% of Europe, whereas in the present model 100% of the area is loam. Keywords: land surface model; soil hydraulic properties; water balance simulation

A modified upward infiltration method for characterizing soil hydraulic properties

2002 ◽  
Vol 66 (1) ◽  
pp. 57 ◽  
Author(s):  
M. H. Young ◽  
A. Karagunduz ◽  
J. Šimůnek ◽  
K. D. Pennell
Keyword(s):  
Hydraulic Properties ◽  
Soil Hydraulic Properties ◽  
Soil Hydraulic ◽  
Infiltration Method

scholarly journals Pinhole Multistep Centrifuge Outflow Method for Estimating Unsaturated Hydraulic Properties with Small Volume Soil Samples

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1169
Author(s):  
Long Thanh Bui ◽  
Yasushi Mori
Keyword(s):  
Hydraulic Properties ◽  
Volcanic Ash ◽  
Small Volume ◽  
Clayey Soil ◽  
Soil Hydraulic Properties ◽  
Retention Curve ◽  
Volcanic Ash Soil ◽  
Equilibrium Data ◽  
Soil Hydraulic ◽  
Water Holding

If soil hydraulic conductivity or water holding capacity could be measured with a small volume of samples, it would benefit international fields where researchers can only carry a limited amount of soils out of particular regions. We performed a pinhole multistep centrifuge outflow method on three types of soil, which included granite decomposed soil (Masa soil), volcanic ash soil (Andisol soil), and alluvial clayey soil (paddy soil). The experiment was conducted using 2 mL and 15 mL centrifuge tubes in which pinholes were created on the top and bottom for air intrusion and outflow, respectively. Water content was measured at 5, 15, and 30 min after applying the centrifuge to examine the equilibrium time. The results showed that pinhole drainage worked well for outflow, and 15 or 30 min was sufficient to obtain data for each step. Compared with equilibrium data, the retention curve was successfully optimized. Although the curve shape was similar, unsaturated hydraulic conductivities deviated largely, which implied that Ks caused convergence issues. When Ks was set as a measured constant, the unsaturated hydraulic properties converged well and gave excellent results. This method can provide soil hydraulic properties of regions where soil sampling is limited and lacks soil data.

scholarly journals The effects of long-term fertilizations on soil hydraulic properties vary with scales

2021 ◽  
Vol 593 ◽  
pp. 125890
Author(s):  
Xiaoxian Zhang ◽  
Andrew L. Neal ◽  
John W. Crawford ◽  
Aurelie Bacq-Labreuil ◽  
Elsy Akkari ◽  
...  
Keyword(s):  
Hydraulic Properties ◽  
Soil Hydraulic Properties ◽  
Soil Hydraulic
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