1. Soil Physics David Zumr room: b608 david.zumr@fsv.cvut.cz Lecture (and seminar) notes will be available: - http://storm.fsv.cvut.cz/http://storm.fsv.cvut.cz/

2. Soil Science deals with soil as a natural resource on the surface of the earth including soil formation, classification and mapping; physical, chemical, biological, and fertility properties of soils ; and these properties in relation to the use and management of soils. pedology soil genesis, morphology, clasification, structure, texture,… soil chemistry soil biochemistry soil physics Deals with the physics of soil systems Soil physics studies the properties and processes of materials in the soil. - from the physical description of soil particles, soil aggregates, into the storage and transport phenomena of water, gas, heat, and solute in soil. - soil mechanics - soil hydrology (vadose zone hydrology or hydropedology) Source http://www.cartage.org.lb

3. Soil water Essential for plant growth Basic medium for transport of contaminants Necessary (natural) for soil remediation Soil water: –chemicaly retained and hygroscopic (covering the particles) –capillary (capillary forces) –gravitational (temporary water, when the source finish, water flow out– rain, snow melting, floods,…) Source: http://piru.alexandria.ucsb.edu

4. Bulk density: m s … mass of dry soil V T … total volume V s … volume of solid phase V p … pore volume V w … water volume Soild density: Porosity: Water content (volumetric): Saturation: Basic equations solid Pore space air water

5. Exercise A cylindrical soil core sample is 5 cm in diameter and 6 cm long. When taken from the ground, the weight is 253 g, after drying it weighs 226 g. The soil is sandy, with a solid density of 2.65 g/cm 3. Estimate the following: a. bulk density b. porosity c. water content d. saturation

6. Darcy’s law Henry Darcy (1856) was solving a problem of water filtering for fountains in Dijon. By many experiments, he found out, that flow rate through sand tank depends on: - hydrostatic pressure gradient (between top and bottom) - length of the column - column cross-section - coefficient which is specific for different soils q = dHdH dl -Ks-Ks q = Q A where q is bulk flow: Ks = saturated hydraulic conductivity [LT -1 ] Q = water flow [L 3 T -1 ] A = cross-section [L 2 ] q = dHdH dz -K(θ)-K(θ) Darcy-Buckingham’s law

7. Exercise 2 Data from groundwater piezometers A and B (located 500 m apart) are shown in the following table. Assume that A and B sample the same confined aquifer (K = 0.05 cm/s throughout), and that aquifer is 10 m thick, with a uniform porosity of 0.35. a. Calculate the hydraulic gradient between A and B and determine the flow direction. b. Estimate the travel time for pore water moving from A to B. Piezometer length Surface elevation Depth to water A50m120 m33m B50m110 m25 m Mean pore volocity (seepage velocity): v = q/n