Groundwater Hydrology - Water Resources Engineering - Lecture Slides | CWR 4542, Study notes of Civil Engineering

Download Groundwater Hydrology - Water Resources Engineering - Lecture Slides | CWR 4542 and more Study notes Civil Engineering in PDF only on Docsity! CWR 4542 – Water Resources Engineering Department of Civil & Coastal Engineering 1 CWR 4542 – Water Resources Engineering Lecture Packet 6: Groundwater Hydrology Course website: http://www.ce.ufl.edu/~markn/CWR4542 Topics covered in this lecture packet Groundwater formations Unconfined vs. Confined Subsurface geology Darcy Equation Three-dimensional flow in porous media Flow to a well in a confined aquifer This material is covered in Chapter 6 of the text book. Groundwater Hydrology CWR 4542 – Water Resources Engineering Department of Civil & Coastal Engineering 2 Groundwater is predominant source of fresh water in Florida The study of groundwater is focused on the flow of fluids within a porous medium. Subsurface environment consists of porous medium in which the void spaces have varying degrees of saturation. (for this class we will focus on confined, saturated conditions) Groundwater Hydrology Groundwater Geologic Formations Aquifer – a geologic formation containing water that can be withdrawn in significant quantities. Aquiclude – a geologic formation that contains water but is incapable of transmitting water in significant quantities (e.g. clay layer: Hawthorn Formation). Aquifuge – a geologic formation that neither contains nor transmits water (e.g. solid rock: granite). CWR 4542 – Water Resources Engineering Department of Civil & Coastal Engineering 5 Unconfined Aquifer (water table) Figure 1: Generalized cross-section of an unconfined aquifer (Chin, 2006). Vadose zone p < 0 p = 0 p > 0 Unconfined (Saturated and Unsaturated) Conditions zone of saturation – The void spaces within this zone are completely filled (saturated) with water. capillary zone – Soil “suction” draws water above the saturated zone. The exten of capillary rise is dependent upon the pore size of the soil (The capillary rise can vary from cm to meters depending on the soil). The water level in a well intersecting an unconfined aquifer will typically correspond closely with the water table (p = 0 or atmospheric) CWR 4542 – Water Resources Engineering Department of Civil & Coastal Engineering 6 Confined Aquifer Figure 2: Generalized cross-section of a confined aquifer (Chin, 2006). Surficial aquifer (sand) Hawthorn formation (clay) Floridan aquifer (limestone) Flowing Artesian well Confined (Saturated and Unsaturated) Conditions The water level in a confined well rises to match the piezometric head at the well opening (well screen). artesian – an aquifer that produces flowing water when the upper confining unit is penetrated. springs – locations where artesian aquifers intersect land surface. recharge zone – land surface areas that supply water to a confined aquifer (recharges the aquifer). CWR 4542 – Water Resources Engineering Department of Civil & Coastal Engineering 7 Well Construction and Subsurface Geology Figure 3: Florida stratigraphy, lithology, and hydrostratigraphy (Chin, 2006). Well Construction and Subsurface Geology Stratigraphy – layering of deposits. Lithology – description of rocks (soil) with depth. Hydrostratigraphy – description of geologic layering (formations) that have distinct hydrologic properties . CWR 4542 – Water Resources Engineering Department of Civil & Coastal Engineering 10 Flow to a well in a confined aquifer Figure 6: Fully penetrating well in a confined aquifer (Chin, 2006). Superposition Figure 7: Drawdown at P is sum of drawdowns from PW1, PW2, RW1, and RW2. r1 r2 r4 r3 CWR 4542 – Water Resources Engineering Department of Civil & Coastal Engineering 11 Side note: karst dissolution channels The term "karst" refers to a type of topography that is formed over limestone, dolomite or gypsum by solution of the rock and is characterized by closed depressions or sinkholes, caves and underground drainage. Limestone caves CWR 4542 – Water Resources Engineering Department of Civil & Coastal Engineering 12 Limestone caves References Chin D.A. Water Resources Engineering. Pearson Education, Inc., Upper Saddle River, NJ. 2006 (Second Edition). Charbeneau. 2000. Groundwater Hydraulics and Pollutant Transport. Prentice Hall. Upper Saddle River, NJ.