https://padlet.com/nizzatiak/baqe6vo4a78rqqhz Made with a creative frenzy en-us 2021-11-16 02:07:52 UTC 2024-07-17 14:56:16 UTC hello@padlet.com https://padlet.com/nizzatiak/baqe6vo4a78rqqhz/wish/1892992258

Advantages of Gravimetric Techniques:
1. It is easy to calculate
2. Use direct measurement
3. Does not depend on the soil type and salinity
4. Ensure accurate measurements
5. Calibration of all other soil moisture determination techniques.

Disadvantages of Gravimetric Techniques:
1. Time consuming
2. Inapplicable to automatic control
3. Dry bulk density is required to transform data to volume moisture content.

Measurement Parameter:
-Mass water content (%of dry and wet soil weight)
-Moisture content (%) :((wet weight - dry weight )/ (wet weight)) x100


]]> 2021-11-16 03:11:49 UTC https://padlet.com/nizzatiak/baqe6vo4a78rqqhz/wish/1892992258 https://padlet.com/nizzatiak/baqe6vo4a78rqqhz/wish/1892992740
Definition
Electromagnetic (EM) techniques use a grounded electric dipole as a source that is energized with an alternating current at a given frequency to produce time-varying electric and magnetic fields that can be measured on the earth’s surface.

Basic Principles
Electromagnetic survey methods are based on two fundamental principles: Faraday’s law of electromagnetic induction and the fact that electric currents generate magnetic fields, expressed in Ampère’s law. In its simplest form Faraday’s law states that the electromotive force (EMF) in a closed circuit is proportional to the rate of change of magnetic flux through the circuit, or in even simpler terms: a changing magnetic field will induce an EMF.

Pros
- EM technique have some characteristics including the method of coupling to the ground, the physical response to pore fluids, and the speed of data acquisition
- The bulk resistivity of geologic materials depends upon the porosity, degree of saturation, pore fluid resistivity, and clay content. This sensitivity allows EM and electrical measurements to directly estimate water quality.
-  The compact size of some EM technique makes them very portable allowing near-surface EM surveys to be conducted by one or two people.


]]> 2021-11-16 03:12:01 UTC https://padlet.com/nizzatiak/baqe6vo4a78rqqhz/wish/1892992740