HydrogeologyDave Watkins

BSc 3 AG, EGG, EST, CZEM

MSc Geotechnical Engineering

Hydrogeology – Lecture 1INTRODUCTION

1 Introduction1.1 Schedule for the course1.2 What is hydrogeology?1.3 Why study hydrogeology

2 The hydrological cycle and its interactions

3 Types of aquifer3.1 Confined3.2 Unconfined3.3 Leaky

Schedule for the course

What is Hydrogeology ?

• Hydrology – The study of water in the environment

• Hydrogeology – The study of underground water

What is an aquifer ?

• An aquifer is a soil or rock unit that can store and transmit significant quantities of groundwater.

• Store water– There must be porosity to provide space for storage

• Transmit– The pores must be interconnected to allow the water to

flow continuously between the pores. Permeability.

• Significant– The quantity that may be significant for one application

may not be significant for another.

• Groundwater– Is the water held and transmitted by the saturated part

of the aquifer.

A journey around the hydrological cycle

Reasons for studying Hydrogeology

Hydrogeology is an interdisciplinary subject

• Involving– Geology

– Hydrology

– Chemistry

– Mathematics

– Physics

– Computing

– Engineering

– Agriculture

• To answer questions posed by– Engineers

– Planners

– Ecologists

– Managers

– Etc.

Groundwater is:

• A precious resource – but sustainable if properly managed, in terms

of quantity and quality

• A cause of engineering problems– Ground stability, drainage and dewatering

• An active part of the environment– Linking elements of the hydrological cycle

How rivers flow video

Basic hydrogeological terms and definitions that you need to know

Related to aquifers

• Unconfined aquifer (phreatic)

• Confined aquifer (piezometric)

• Leaky aquifer (semi-confined)

• Perched aquifer

• Aquitard

• Aquiclude

Related to flow

• Hydraulic head

• Hydraulic gradient

• Hydraulic conductivity

• Specific discharge

• Aquifer flow

• Intrinsic permeability

• Transmissivity

Related to storage

• Specific retention

• Specific yield

• Elastic storativity

Related to wells

• Specific drawdown

• Specific capacity

• Well efficiency

• Source protection zones

Types of Aquifer

• Unconfined – Phreatic

• Confined – Piezometric

• Leaky – Semi-confined/unconfined

– Refer to handouts