Surface Water Hydrology and Advanced Hydrogeology (Course Note) PDF

Surface water hydrology and advanced hydrogeology Course note Advanced hydrogeology Instructor- Sileshi Mamo (PhD) 2018 1. TYPES OF WATER IN SOILS/ROCKS 1. Bounded or retained water – Water that fix to soil particles or rock matrix due to electro...

Surface water hydrology and advanced hydrogeology Course note Advanced hydrogeology Instructor- Sileshi Mamo (PhD) 2018 1. TYPES OF WATER IN SOILS/ROCKS 1. Bounded or retained water – Water that fix to soil particles or rock matrix due to electro molecular forces – Two types: Hygroscopic water – Fills micro pores and irregularities in the particles’ surface by means of adsorption Pellicular water – Constitute thin film around the particles – This water moves as a liquid from the much more denser to films to much thinner one 2. Capillary water – Water that partially or completely fills the pores or the sub capillary channels of soils and rocks- by capillary forces due to surface tension – Two type: Isolated or perched capillary – Occur above the water table and capillary fringe – Occupies partially capillary voids – It cannot be removed by gravity – Can be classified as retained water  Continuous or sustained capillary water – Located in capillary fringe – Fills all capillary voids just above the water table – Influenced by gravity – Classified as a free water 3. Free or gravitational water – Water that is not subjected to the action of attraction forces toward the surface of soil particles and rock bodies – Moves by gravity and is subjected to hydrostatic pressure – Most active part of the groundwater 2. DISTRIBUTION OF SUBSURFACE WATER  DISTRIBUTION OF SUBSURFACE WATER Unsaturated (vadose or aeration) zone Saturated (phreatic or groundwater) zone Zone of isolated pores and chemically combined water zone  Water Content The volumetric water content θ is the fraction of space occupied by water in a given volume of material Vt: θ =Vw/Vt where Vw is the volume of water. θ is dimensionless, and can be reported as a decimal fraction or as a percent. If a material’s pores are saturated with water, θ = n; if the pores contain some air, θ