Hysteretic steady state soil water profiles

1977 ◽  
Vol 13 (3) ◽  
pp. 549-557 ◽  
Author(s):  
A. Poulovassilis ◽  
W. M. El-Ghamry
Keyword(s):  
Steady State ◽  
Soil Water ◽  
Soil Water Profiles

scholarly journals Quantify Piston and Preferential Water Flow in Deep Soil Using Cl− and Soil Water Profiles in Deforested Apple Orchards on the Loess Plateau, China

Water ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2183 ◽  
Author(s):  
Zhiqiang Zhang ◽  
Bingcheng Si ◽  
Huijie Li ◽  
Min Li
Keyword(s):  
Soil Water ◽  
Water Flow ◽  
Loess Plateau ◽  
Preferential Flow ◽  
Chloride Ions ◽  
Apple Orchards ◽  
The Loess Plateau ◽  
Deep Soil ◽  
Soil Water Profiles ◽  
Preferential Water

Piston and preferential water flow are viewed as the two dominant water transport mechanisms regulating terrestrial water and solute cycles. However, it is difficult to accurately separate the two water flow patterns because preferential flow is not easy to capture directly in field environments. In this study, we take advantage of the afforestation induced desiccated deep soil, and directly quantify piston and preferential water flow using chloride ions (Cl−) and soil water profiles, in four deforested apple orchards on the Loess Plateau. The deforestation time ranged from 3 to 15 years. In each of the four selected orchards, there was a standing orchard that was planted at the same time as the deforested one, and therefore the standing orchard was used to benchmark the initial Cl− and soil water profiles of the deforested orchard. In the deforested orchards, piston flow was detected using the migration of the Cl− front, and preferential flow was measured via soil water increase below the Cl− front. Results showed that in the desiccated zone, Cl− migrated to deeper soil after deforestation, indicating that the desiccated soil layer formed by the water absorption of deep-rooted apple trees did not completely inhibit the movement of water. Moreover, there was an evident increase in soil water below the downward Cl− front, directly demonstrating the existence of preferential flow in deep soil under field conditions. Although pore water velocity was small in the deep loess, preferential water flow still accounted for 34–65% of total infiltrated water. This study presented the mechanisms that regulate movement of soil water following deforestation through field observations and advanced our understanding of the soil hydrologic process in deep soil.

Estimation and dimulation of sheet run-off

Soil Research ◽  
1976 ◽  
Vol 14 (2) ◽  
pp. 129 ◽  
Author(s):  
JR Ive ◽  
CW Rose ◽  
BH Wall ◽  
BWR Torssell
Keyword(s):  
Soil Water ◽  
Dry Matter ◽  
Daily Rainfall ◽  
Rainfall Events ◽  
Run Off ◽  
Townsville Stylo ◽  
Experimental Values ◽  
Water Values ◽  
Soil Water Profiles ◽  
Surface Sheet

Sheet run-off was estimated for a Townsville stylo-annual grass pasture with 1% slope in the northern Australian monsoonal region by using neutron hydrometry supplemented by gravimetric soil sampling, both carefully timed with respect to the rainfall event. The technique is applicable to run-off and run-on situations. An empirical model was developed and incorporated into a water balance routine in an existing growth model. It relates surface sheet run-off to the soil antecedent water content (top 20 cm) and the standard daily rainfall total; the coefficients of the empirical functions are site specific. For the rainfall events studied, run-off was 37 � 12% of the rainfall. The soil water values simulated with the run-off model included were significantly closer to the experimental values than when run-off was assumed to be zero. This improvement in simulation of soil water profiles was consistent with an improvement in subsequent dry matter simulation.

scholarly journals A dynamic physical model for soil temperature and water in Taylor Valley, Antarctica

2010 ◽  
Vol 22 (4) ◽  
pp. 419-434 ◽  
Author(s):  
H.W. Hunt ◽  
A.G. Fountain ◽  
P.T. Doran ◽  
H. Basagic
Keyword(s):  
Steady State ◽  
Soil Temperature ◽  
Soil Water ◽  
Capillary Flow ◽  
Temporal Trends ◽  
Soil Layer ◽  
Ground Surface ◽  
Longwave Radiation ◽  
Saturated Soil ◽  
Water Vapour Concentration

AbstractWe developed a simulation model for terrestrial sites including sensible heat exchange between the atmosphere and ground surface, inter- and intra-layer heat conduction by rock and soil, and shortwave and longwave radiation. Water fluxes included snowmelt, freezing/thawing of soil water, soil capillary flow, and vapour flows among atmosphere, soil, and snow. The model accounted for 96–99% of variation in soil temperature data. No long-term temporal trends in soil temperature were apparent. Soil water vapour concentration in thawed surface soil in summer often was higher than in frozen deeper soils, leading to downward vapour fluxes. Katabatic winds caused a reversal of the usual winter pattern of upward vapour fluxes. The model exhibited a steady state depth distribution of soil water due to vapour flows and in the absence of capillary flows below the top 0.5 cm soil layer. Beginning with a completely saturated soil profile, soil water was lost rapidly, and within a few hundred years approached a steady state characterized by dry soil (< 0.5% gravimetric) down to one metre depth and saturated soil below that. In contrast, it took 42 000 years to approach steady state beginning from a completely dry initial condition.

scholarly journals New interpretation of the role of water balance in an extended Budyko hypothesis in arid regions

2015 ◽  
Vol 12 (10) ◽  
pp. 11013-11052 ◽  
Author(s):  
C. Du ◽  
F. Sun ◽  
J. Yu ◽  
X. Liu ◽  
Y. Chen
Keyword(s):  
Steady State ◽  
Water Balance ◽  
Soil Water ◽  
Arid Regions ◽  
Water Storage ◽  
Soil Water Storage ◽  
Unsteady State ◽  
Monthly Water Balance ◽  
Storage Change

Abstract. The Budyko hypothesis (BH) is an effective approach to investigating long-term water balance at large basin scale under steady state. The assumption of steady state prevents applications of the BH to basins, which is unclosed, or with significant variations in soil water storage, i.e., under unsteady state, such as in extremely arid regions. In this study, we choose the Heihe River Basin (HRB) in China, an extremely arid inland basin, as the study area. We firstly use a calibrated and then validated monthly water balance model, i.e., the abcd model to quantitatively determine annual and monthly variations of water balance for the sub-basins and the whole catchment of the HRB and find that the role of soil water storage change and that of inflow from upper sub-basins in monthly water balance are significant. With the recognition of the inflow water from other regions and the soil water storage change as additional possible water sources to evapotranspiration in unclosed basins, we further define the equivalent precipitation (Pe) to include local precipitation, inflow water and soil water storage change as the water supply in the Budyko framework. With the newly defined water supply, the Budyko curve can successfully describe the relationship between the evapotranspiration ratio and the aridity index at both annual and monthly timescales, whilst it fails when only the local precipitation being considered. Adding to that, we develop a new Fu-type Budyko equation with two non-dimensional parameters (ω and λ) based on the deviation of Fu's equation. Over the annual time scale, the new Fu-type Budyko equation developed here has more or less identical performance to Fu's original equation for the sub-basins and the whole catchment. However, over the monthly time scale, due to large seasonality of soil water storage and inflow, the new Fu-type Budyko equation generally performs better than Fu's original equation. The new Fu-type Budyko equation (ω and λ) developed here enables one to apply the BH to interpret regional water balance over extremely dry environments under unsteady state (e.g., unclosed basins or sub-annual timescales).

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