The soil water retention model developed by Kosugi was modified to be compatible with Mualem's in order derive an analytical expression for the relative hydraulic conductivity K r . is derived applying a lognormal distribution law pore radius function. Parameters of this have physical significance on content (θ)– capillary pressure (ψ) curve and are related directly statistics distribution. accuracy resulting combined water‐retention‐hydraulic‐conductivity verified observed data sets six...

Many models for soil water retention have been proposed. However, most of these are curve‐fitting equations and do not emphasize the physical significance their empirical parameters. A new model that exhibits increased flexibility was developed by applying three‐parameter lognormal distribution laws to pore radius function ƒ( r ) capacity function, which taken be capillary pressure ƒ(ψ). This contains three parameters closely related statistics ƒ(ψ): bubbling ψ c , mode 0 ƒ(ψ) standard...

Both scaling effect and connectivity of overland flow were examined in steep hillslopes covered by (1) Japanese cypress (hinoki, Chamecyparis obtusa ) plantations with sparse understory vegetation, (2) hinoki fern (3) deciduous forests. Two sizes plots installed for monitoring flow: small (0.5 × 2 m) large hillslope scale (8 24–27 m). For all hillslopes, measurable amounts occurred during storms. Runoff coefficients (0.1–3%) consistently smaller than those (20–40%). Estimated runoff lengths...

We examined the effects of forest floor coverage on overland flow generation and soil erosion in mature Japanese cypress plantations with different conditions: sparse understory litter (uncovered plots), dense fern (covered experimental removal vegetative covered plots (removal plots). measured hydraulic properties monitored three replicated (approximately 1 × 2 m each) representing uncovered, covered, conditions. Because strong water repellency surface soil, a substantial amount occurred,...

Recent studies have suggested that bedrock groundwater can exert considerable influence on runoff generation, water chemistry, and the occurrence of landslides in headwater catchments. To clarify infiltration redistribution processes between soil shallow their effect storm base flow discharge a small catchment underlain by weathered granite, we conducted hydrometric observations using tensiometers combined with hydrochemical measurements budget analyses at three different spatial scales....

A tree can partition rainfall into throughfall and stemflow (SF), causing water to be funneled around the base, preferentially divert rainwater in soil layers, roots. To determine effects of each on dynamics, we compared dynamics a hillslope basis 2 years field observations before (SF period) after (non‐SF intercepting tree. Additionally, two sprinkling experiments were conducted using different dye tracers separately indentify infiltration pathways derived from stemflow. The observation...

It has been suggested that pipe flow and bedrock groundwater play important roles in storm runoff generation. We examined the effects of on generation rainfall‐runoff phenomena a steep headwater catchment central Japan. Measurements pore water pressures, flow, streamflow showed when total rainfall amount was <30 mm, process could be explained by Darcy's law using saturated hydraulic conductivity values core samples. When >70 dominant shifted to flow. Temperature measurements indicated...

Abstract Recent studies have suggested that soil water repellency can be one of the important factors affecting hydrological processes on headwater catchments. In Japan, is known to occur under Japanese cypress ( Chamaecyparis obtusa ) forests, a typical plantation type in however, previous not evaluated severity and its effects surface runoff generation. To quantify effects, this study combined critical tension (CST) test with new spraying experiment which infiltration rates ethanol...

Understanding a discharge hydrograph is one of the leading interests in catchment hydrology. Recent research has provided credible information on importance bedrock groundwater hydrographs from headwater catchments. However, intensive monitoring rare mountains with steep topography. Hence, how controls dispute. In this study, we conducted long‐term hydrological observations using densely located wells underlain by granitic bedrock. The topography affected diastrophic activities. Results...

Precipitation in a forest is intercepted by the canopy and partitioned into throughfall stemflow, leading to heterogeneous water inputs that affect soil dynamics. To clarify effects of tree stand on rainfall infiltration processes steep forested hillslope, we conducted detailed observations throughfall, content, pore pressure at high spatial resolution for many storm events. The results showed content increased rapidly greatly region downslope from stem, especially points close stem. At...

When [6-3H,6-14C]glucose was given in glucose loads to fasted rats, the average 'H/'"C ratios glycogens deposited their livers, relative that glucoses administered, were 0.85 and 0.88.When [3-'H,3-'"C]lactate trace quantity along with unlabeled loads, 'H/14C ratio 0.08.This indicates a major fraction of carbons converted liver glycogen without first being lactate.glu~ose ' H/"C averaged 0.44.This significant amount H bound carbon 3, but not 6, is removed within conversion glycogen.This can...

Recent studies have emphasized the importance of bedrock in hydrologic processes occurring headwater catchments. To understand water flow through variously weathered bedrock, we measured saturated hydraulic conductivity, K s , and retention characteristics weakly to highly Tanakami granite Rokko core samples. On basis these core‐scale properties, along with shape situ measurements, defined two groups bedrock: C M class (weakly weathered) L D (moderately weathered). The cores had almost no...

Abstract We investigated the characteristics of nutrients (N and P) dissolved organic carbon (DOC) concentrations during high, intense typhoon storm base flow periods from three watersheds (W1, W2 W3) in central Japan. Concentrations were low relatively constant. In contrast, N, P, DOC runoff storms became highly dynamic. Particulate nitrogen (PN) particulate phosphorus (PP) 4–50 times greater than those for all events. Because PN PP significantly correlated with suspended sediment...

Abstract A chain of connected macropores, which develops nearly parallel to the impermeable subsurface layer, is commonly found in hillslopes and referred as a soil pipe. Field observations have revealed that water flow such pipe (pipe flow) has large hydrogeomorphic effects, since it contributes rapid transfer storm erosion. This study proposed simple simulation method describe dynamics piped hillslope. The applicability was examined using data obtained from bench‐scale experiment pseudo...

Unsaturated infiltration of rain and irrigation water convective chemical transport processes in the vadose zone are poorly understood. This is partly due to traditional techniques used sample unsaturated soil water. study evaluated performance a recently developed controlled‐suction period lysimeter field for more than 400 d. The consists two tensiometers porous plate connected suction system. matric pressures immediately above horizontally buried plate, at same depth natural profile,...

The formation of groundwater in the soil mantle has a dominant effect on rainwater discharge and shallow landslide occurrence headwater catchments. Here, we report two completely different responses within single well excavated into mantle. One was an ephemeral‐type response that is described by physical hydrology models based geographic information system (GIS). other semi‐perennial‐type response, rarely reported previous studies, which cannot be explained existing models. semi‐perennial...

Abstract Overland flow, which occurs when the rainfall intensity exceeds infiltration rate, is an important factor in hillslope hydrological processes. Recent studies have suggested that a cause of Hortonian overland flow on forested hillslopes water repellency surface soils. However, few addressed contribution storm runoff such catchments. The generated needs to reach stream channels order contribute from catchment. Therefore, spatial pattern rate essential for understanding runoff. To...