Knowledge of soil hydraulic parameters for the van Genuchten function is important to characterize soil water movement for watershed management. Accurate and rapid prediction of soil water flow in heterogeneous gravel soil has become a hot topic in recent years. However, it is difficult to precisely estimate hydraulic parameters in a heterogeneous soil with rock fragments. In this study, the HY...

土壌パラメータ α は，土の粒径組成の特徴に基づいて決定され，土中の不飽和浸透挙動を数値計算等で評価・検討する場合に必要なパラメータの 1 つである。例えば，原位置透水試験のプレッシャーインフィルトロメータ法では，原位置での現場飽和透水係数の算出において土壌パラメータ の設定が必要である。しかし，各種試料の土壌パラメータ の推定方法は，現状では十分に確立されているとは言い難い。本論文では，土の粒径組成の特徴に応じて設定される土壌パラメータ をより適切に推定・設定することを目的に，土の透水係数と土壌パラメータ との関係を整理し，良好な相関関係が得られた。その結果，土の粒径組成の特徴に応じて設定される土壌パラメータ は，土の透水係数に基づいて概ね推定できると共に，水分飽和近傍の現場飽和透水係数を基に，完全な飽和状態の飽和透水係数も推定できる可能性を示した。

Extreme rainfall events are the major driver of shallow landslide occurrences in mountainous and steep terrain regions around the world. Subsurface hydrology has a dominant role on the initiation of rainfall-induced shallow landslides, since changes in the soil water content affect significantly the soil shear strength. Rainfall infiltration produces an increase of soil water potential, which i...

1 Heterogeneity and lack of sufficient site characterization render accurate and reliable predictions of subsurface flow and transport in the vadose zone notoriously elusive. It is now widely recognized that for quantitative descriptions of subsurface phenomena to be scientifically defensible, they have to be accompanied by some measure of predictive uncertainty. In other words, a major goal of...

Nutrient leaching in highly weathered tropical soils often poses a challenge for crop production. We investigated the effects of applying 20 t ha biochar (BC) to a Colombian savanna Oxisol on soil hydrology and nutrient leaching in field experiments. Measurements were made over the third and fourth years after a single BC application. Nutrient contents in the soil solution were measured under o...

This paper presents an overview of constitutive modelling of unsaturated soils and the numerical algorithms for solving the associated boundary value problems. It first discusses alternative stress and strain variables that can be used in constitutive models for unsaturated soils. The paper then discusses the key issues in unsaturated soil modelling and how these issues can be incorporated into...

Arbuscular mycorrhizal fungi (AMF) proliferate in soil pores, on the surface of soil particles and affect soil structure. Although modifications in substrate moisture retention depend on structure and could influence plant water extraction, mycorrhizal impacts on water retention and hydraulic conductivity were rarely quantified. Hence, we asked whether inoculation with AMF affects substrate wat...

The effect of different tillage practices on soil hydraulic properties was studied in a mature, drip irrigated apricot orchard with a 7% slope, in Murcia (SE Spain). The soil had a loamy texture. Three soil tillage treatments were applied between the rows of trees: 1) control treatment (non-tilled, although weeds were cut to ground level using a blade attached to a tractor following the common ...

hydraulic conductivity variations around the boreholes in uniformly graded sands for cyclic water injection pressure have been evaluated by laboratory tests. prototype laboratory devices have been designed and constructed for this research. the cell has a capability to model the well, the boundary condition and to measure the hydraulic conductivity. while increasing water injection pressure, hy...

The parameter n in the well-known expression for hydraulic conductivity K ˆ K0S e (where K0 is its value at satiation and Se the e€ective saturation) is determined as a function of the exponent in the power form of the soil±water retention relationship. The result is validated with an extensive experimental database comprising some 43 soils, collected by Mualem. Ó 2000 Elsevier Science Ltd. All...