Water balance in swelling materials: some comments

Soil Research ◽  
1997 ◽  
Vol 35 (5) ◽  
pp. 1143 ◽  
Author(s):  
D. E. Smiles
Keyword(s):  
Water Balance ◽  
Water Content ◽  
Material Balance ◽  
Physical Space ◽  
Clay Soils ◽  
Acid Sulfate ◽  
Retention Ponds ◽  
Material Space ◽  
Semi Arid

Materials ranging from wet tailings in retention ponds through potentially acid sulfate sediments in humid marine environments to clay soils in semi-arid climates shrink and swell with change in water content. This paper discusses the formulation and determination of material balance in such swelling and cracking materials. Significant errors and their likely magnitudes are identified when these estimates are based in physical space, as opposed to material space. Ways in which this problem might be dealt with are discussed.

The drainage component of the water balance equation

Soil Research ◽  
1965 ◽  
Vol 3 (2) ◽  
pp. 95 ◽  
Author(s):  
CW Rose ◽  
WR Stern
Keyword(s):  
Water Balance ◽  
Water Content ◽  
Bulk Density ◽  
Balance Equation ◽  
Clay Soils ◽  
Swelling Clay ◽  
Water Balance Equation ◽  
Field Crops

A method is presented for determining the drainage term in the water balance equation, which may then be used to solve for evaporation from field crops. Questions concerning accuracy in determination of the drainage term are considered. Two special problems that arise in this context with swelling clay soils are discussed, namely, the variation of bulk density with water content, and the inference of in situ soil water suction from volumetric water content measurement.

scholarly journals Estimation of direct evaporation from groundwater by using lysimeters in the Salar de Pedernales basin, Chilean Altiplano

2020 ◽  
Vol 30 ◽  
pp. 1-14
Author(s):  
Reynaldo Payano-Almánzar ◽  
Dimitri Dionizis
Keyword(s):  
Numerical Model ◽  
Water Balance ◽  
Shallow Groundwater ◽  
Arid Zones ◽  
Salt Flats ◽  
Chilean Altiplano ◽  
Semi Arid ◽  
Model Water

In this research an estimation of the evaporation discharges from shallow groundwater in the Salar de Pedernales basin is made, using the lysimeter methodology. The analysis performed shows values between 1400 L·s-1 and 1900 L·s-1 with an uncertainty of error of 5% with respect to the average and between 11% and 47% in relation to the minimum and maximum values which can be compared by other studies where different tools have been used to calculate evaporation, such as: chamber, numerical model, water balance, Bowen relationships, Eddy correlations, and evaporation curves vs. altitude. The results confirm that lysimeters are appropriate tools for the determination of soil evapotranspiration and evaporation from shallow groundwater, whose components are key in the hydrology of endorheic basins, arid and semi-arid zones, for the management of protected natural spaces such as salt flats, waterholes, fertile plains, and bofedales.

scholarly journals The water balance of two semi-arid shrubs on abandoned land in South-Eastern Spain after cold season rainfall

2002 ◽  
Vol 6 (5) ◽  
pp. 913-926 ◽  
Author(s):  
N. Archer ◽  
T. Hess ◽  
J. Quinton
Keyword(s):  
Water Balance ◽  
Water Content ◽  
Soil Water ◽  
Water Storage ◽  
Cold Season ◽  
Soil Layers ◽  
Retama Sphaerocarpa ◽  
Runoff Change ◽  
Abandoned Land ◽  
Semi Arid

Abstract. The inland, mountainous marginal areas (land abandoned by farming and colonised by shrubs) of the Iberian Peninsular, Spain, generally receive a higher rainfall than the coastal areas (Lazaro and Rey, 1991) and may store water after cold season (autumn and winter) rainfall. By measuring runoff, change of soil water content and rainfall, this study tests the hypothesis that two shrubs on two sites on abandoned land do not use all the water available after cold season rainfall. One site was on an upper alluvial slope dominated by Anthyllis cytisoides and the other on a lower alluvial slope dominated by Retama sphaerocarpa. The root systems of A. cytisoides and R. sphaerocarpa penetrate to 3 m and 20 m, respectively. A. cytisoides senesces during the dry season and R. sphaerocarpa is evergreen. The water balance is dominated by high actual evapotranspiration (ET), which is limited by rainfall. Reference evapotranspiration was high; runoff was low and soil water storage occurred above 2 m depth. ET and water storage were highest under A. cytisoides shrubs. Runoff was lower on the ‘Anthyllis’ site. The spatial variability of soil water is high and the problems of its measurement are discussed. The quantity of rainfall infiltrated was greater under shrubs than grass-areas, suggesting that shrub roots facilitated preferential flow. The growing season of A. cytisoides began when water was available in the upper soil layers and senescence occurred when the upper soil layers dried to less than 4% water content. A. cytisoides, therefore, relies on water from these layers. The main growth of R. sphaerocarpa occurred when the upper soil layers were relatively dry, so that R. sphaerocarpa must extract water from deeper layers. Results suggest that A. cytisoides accumulates rainfall and runoff and directs water to lower layers for later use, while R. sphaerocarpa extracts water from deeper soil layers. By mid-summer both shrubs had extracted all the available water accumulated in the upper soil layers from cold season rainfall. Keywords: water balance, neutron probe, patchy vegetation, mosaic vegetation, Spain, semi arid, Anthyllis cytisoides, Retama sphaerocarpa

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