@SGgeology

  Hydrogeology Part – 4 SPRINGS A spring is a concentrated discharge of groundwater appearing at the ground surface as a current of flowing water. Springs occur in many forms and have been classified as to cause, rock structure, discharge, temperature, and variability.  Bryan divided all springs into       those resulting from nongravitational forces and      those resulting from gravitational forces.  Under the former category are included volcanic springs, associated with volcanic rocks, and fissure springs, resulting from fractures extending to great depths in the earth's crust. Such springs are usually thermal (fig above).  Gravity springs result from water flowing under hydrostatic pressure. the following general types are recognized: 1. Depression Springs-Formed where the ground surface intersects the water table. 2. Contact Springs-Created by a permeable water-bearing formation overlying a less permeable formation that intersects the ground surface. 3. Artesian Springs-Res

Hydrogeology Part – 2   Darcy’s law and hydraulic conductivity           Water contained within the interconnected voids of soils and rocks is capable of moving, and the ability of a rock to store and transmit water constitutes its hydraulic properties.      The laws that govern the behaviour of groundwater flow in saturated material is that formulated empirically by the French municipal engineer for Dijon, Henry Darcy, in 1856.      Darcy studied the flow of water through porous material contained in a column and found that the      T otal flow - Q, is proportional - difference in water level, h1 − h2, the cross-sectional area of flow, A, and inversely proportional to the column length, L. proportionality constant - K      where dh/dl represents the hydraulic gradient, with the negative sign indicating flow in the direction of decreasing hydraulic head. Limitations:      Darcy’s law is valid for laminar flow, i.e., the Reynolds number (Re) varies from 1 to 10,  ρ = density of water µ