نتایج جستجو برای: volumetric soil moisture
تعداد نتایج: 228697 فیلتر نتایج به سال:
6 [1] Soil moisture is a critical element in the hydrological cycle especially in a semiarid 7 or arid region. Point measurement to comprehend the soil moisture distribution 8 contiguously in a vast watershed is difficult because the soil moisture patterns might 9 greatly vary temporally and spatially. Space-borne radar imaging satellites have been 10 popular for they may exhibit all-weather ob...
Soil water content is the most effective factor associated with the hydrophobic and hydrophilic changes in a soil. Water repellency in soils, is not a permanent feature; it can be reached in the dry season and reduced or eliminated in the wet season It can be said that in terms of moisture, there is a critical region that is defined as the threshold moisture content, where in lower moisture, th...
Soil moisture mapping at a high spatial resolution is very important for several applications in hydrology, agriculture and risk assessment. With the arrival of the free Sentinel data at high spatial and temporal resolutions, the development of soil moisture products that can better meet the needs of users is now possible. In this context, the main objective of the present paper is to develop a...
The recently proposed polarimetric two-scale twocomponent model (PTSTCM) in principle allows us obtaining a reasonable estimation of the soil moisture even in moderately vegetated areas, where the volumetric scattering contribution is non-negligible, provided that the surface component is dominant and the double-bounce component is negligible. Here we test the PTSTCM validity range by applying ...
Measurements of soil volumetric moisture content and temperature were made at 2, 4, 7, 10, and 15 cm below the surface of a bare field soil, over a 1-week period at 20-min intervals. The conductive heat and liquid moisture fluxes were calculated for the soil layer 7–10 cm below the surface, and the water vapor flux was then determined from both the energy transfer and mass transfer equations. W...
A multilayer soil model is presented for improved estimation of soil moisture content using the first-order small perturbation method (SPM) applied to measurements of radar backscattering coefficient. The total reflection coefficient of the natural bare soil including volume scattering contribution is obtained using the multilayer model. The surface reflection terms in SPM model are replaced by...
Field-based soil moisture measurements are cumbersome. Remote sensing techniques based on active or passive microwave data have limitations. This paper presents and validates a new method based on land surface energy balances using remotely sensed optical data ~including thermal infrared!, which allows field and landscape-scale mapping of soil moisture depth-averaged through the root zone of ex...
crop models need more evaluation and study for use in deficit irrigation. the main objective of this paper was to study the efficiency and accuracy of dssat model, in estimating of moisture in the soil profile under two levels of water application¬¬¬ in silage maize field. two irrigation treatments including deficit irrigation (0.7 smd), and a full irrigation (smd) were considered for two years...
Accurate soil moisture content measurements are vital to precision irrigation management. Remote sensing using the microwave spectrum (such as GPS signals) has been used for measuring large area soil moisture contents. In our previous work, we estimated surface soil moisture contents for bare soil using a GPS Delay Mapping Receiver (DMR) developed by NASA. However, the effect of vegetation was ...
In situ measurements of soil moisture are invaluable for calibrating and validating land surface models and satellite-based soil moisture retrievals. In addition, longterm time series of in situ soil moisture measurements themselves can reveal trends in the water cycle related to climate or land cover change. Nevertheless, on a worldwide basis the number of meteorological networks and stations ...
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