Evaluation of Surface Evaporation Considering the Effect of Soil Water Gradient

Abstract. A physics-based methodology is applied to estimate global land-surface evaporation from multi-satellite observations. GLEAM (Global Land-surface Evaporation: the Amsterdam Methodology) combines a wide range of remotely sensed observations within a Priestley and Taylor-based framework. Daily actual evaporation is derived at quarter degree resolution over the world's land surface. A running water balance of the vertical profile of soil moisture in the root zone is used to estimate the effect of soil water stress on transpiration. Forest rainfall interception, evaporation from bare soil, transpiration and snow sublimation are calculated independently. The inclusion of soil moisture deficit and forest rainfall interception – by means of the Gash analytical model – leads to an improved representation of the magnitude and distribution of the latent heat flux over semiarid and forested regions. Analyses of the global results show that interception loss plays an important role in the partition of the precipitation into evaporation and water available for runoff at a continental scale. The global distribution of evaporation and its different components is analysed to understand the relative magnitude of each component over different ecosystems. This study gives new insights into the relative importance of precipitation and net radiation in driving evaporation, and how the seasonal influence of these controls varies over the different regions of the world. Precipitation is recognised as an important factor driving evaporation, not only in areas that have limited soil water availability, but also in areas of high rainfall interception and low available energy.

Download Full-text

Root studies on grass species in a semi-arid South Africa along a soil-water gradient

Agriculture Ecosystems & Environment ◽

10.1016/j.agee.2009.01.023 ◽

2009 ◽

Vol 131 (3-4) ◽

pp. 247-254 ◽

Cited By ~ 8

Author(s):

Hennie A. Snyman

Keyword(s):

South Africa ◽

Soil Water ◽

Grass Species ◽

Water Gradient ◽

Semi Arid

Download Full-text

Reasons of Blooming on Light Clinker Paving Bricks

Materials Science Forum ◽

10.4028/www.scientific.net/msf.974.75 ◽

2019 ◽

Vol 974 ◽

pp. 75-82

Author(s):

V.D. Kotlyar ◽

Yurii V. Popov ◽

Anton V. Kotlyar ◽

Yulia V. Terekhina ◽

Roman A. Yashchenko

Keyword(s):

Soil Water ◽

Sulfur Content ◽

Mineralogical Composition ◽

Iron Hydroxides ◽

Surface Evaporation ◽

Base Materials ◽

Clinker Brick ◽

Iron Sulphates ◽

Permeable Sand ◽

Crystalline Hydrates

The paper presents the results of the research for the reasons of the formation of a brownish bloom on a light clinker brick during its operation. In the work course, the clinker bricks, their mineralogical composition, the nature of the secondary brick coloring and the base materials were tested during bricklaying. It was established that 2 factors caused incrustation. Firstly, the site on which the clinker brick was laid was characterized by a level of alkali soil water close to the surface, and the surface evaporation prevailed over the soil absorption in the warm period of the year. That is all soil water-dissolved salts migrated to the surface of the brick along well-permeable sand joints between the bricks. Secondly, ferrous minerals, including hematite, which was subjected to hydration with the formation of iron hydroxides, and also reacted with sulphates of groundwater with the formation of iron sulphates, were found in the foundation under the brick. This confirms the higher sulfur content in incrustation areas and the presence of a film similar to crystalline hydrates. The analysis of the research allowed us to develop the recommendations for the performance of paving various types of sites with clinker bricks, to develop measures to eliminate an existing bloom, and also to defend the “honor and dignity” of light bricks.

Download Full-text