GEG1301 Physical Geography Lecture 1 PDF

GEG1301 THE PHYSICAL ENVIRONMENT Lecture 1: Introduction to Physical Geography Textbook reading: Chapter 1 Fall 2024 Prof: Roxanne Frappier Outline Definition of Physical Geography Systems Approach to Physical Geography Scientific Metho...

GEG1301 THE PHYSICAL ENVIRONMENT Lecture 1: Introduction to Physical Geography Textbook reading: Chapter 1 Fall 2024 Prof: Roxanne Frappier Outline Definition of Physical Geography Systems Approach to Physical Geography Scientific Method in Physical Geography DEFINITION OF PHYSICAL GEOGRAPHY Geography is… “a science which has as its object the description of the Earth and in particular the study of the physical, biological and human phenomena which occur on the globe” WHY IS THIS HERE? Geography is… Geography – from gē ‘earth’ + -graphia ‘writing’. Geography is a method (spatial analysis), not a body of knowledge Holistic (encompasses the whole) Eclectic (integrate a wide range of subject matter from diverse fields) Physical geography is… Physical geographers use spatial analysis to study inter-relations between the Earth’s different parts. Physical geographers use Earth systems science: interaction between a set of parts/systems Spatialcomponent Processes, features, fluxes, changes, feedbacks... and the interaction of all of these Place, Space, Time and Scale THE EARTH SYSTEM Earth’s five main systems SPHERE O LITH Source: modified from MyNASAData The Atmosphere June 2011 The Hydrosphere The Cryosphere The Lithosphere The Biosphere Systems interactions: the Earth's System Lithosphere Biosphere Atmosphere Earth System Cryosphere Hydrosphere Systems interactions: example of the water cycle Precipitation Evaporation  SYSTEMS APPROACH IN PHYSICAL GEOGRAPHY System approach in physical geography SYSTEM A system includes: V1 V3 Variables V2 V4 Relations Sub-systems © Del Canto Viterale, F. (2019) System approach in physical geography: cycles A system is defined by cycles of: Matter: mass that assumes a physical shape and occupies space Energy: capacity to change the motion of, or do some work, on Evaporation matter System approach in physical geography: forces A system is affected by: Destabilizing forces Stabilizing forces System approach in physical geography: scales Systems operate at different spatial and temporal scales CRYOSPHERE System approach in physical geography How all the physical elements and processes (variables) act together (relations) to make up the physical environment (spatial) Benefits of system approach Rational subdivision of a complex world Stresses relations between variables Increases likelihood that all relevant variables are included Encourages quantification (modeling) Assists in prediction (theory-making) Assists in decision-making for intervention  SYSTEMS APPROACH IN PHYSICAL GEOGRAPHY Characteristics of systems Characteristics of systems 1. Open vs closed systems 2. System budget 3. System feedback 4. System equilibrium 1. Open vs closed systems Open systems: inputs/outputs of energy and/or matter E.g., global energy cycle; most natural systems in terms of energy Earth is an open system in terms of energy: solar energy enters and goes back to space Solar energy powers terrestrial systems. It is transformed in: ▪ Mechanical (kinetic and potential) energy, or ▪ Chemical energy Earth eventually radiates this energy back to space as infrared (long wave) radiation. Forest: a Natural Open System Vegetation uses energy (sunlight) and matter (water, CO2) as input to the plant, and chemical energy (sugars and carbohydrates) and material (O2) is stored and released.  1. Open vs closed systems Closed systems: inputs/outputs of energy but no inputs/outputs of matter across the system boundaries (self- contained) e.g. global hydrological cycle; most natural systems in terms of physical matter and resources) Earth’ s is a closed system in terms of physical matter and resources such as air, water and material resources (recycling is thus crucial) Global Hydrological Cycle: a Natural Closed System Energy (heat) and matter (water) is exchanged. All matter is contained in the system – no loss or gain 2. System budget How much matter and/or energy enters and exists a system. Addresses the relative quantities of inputs and outputs in a system. If it gains energy/matter, it is positively balanced and the surplus goes into storage. If it loses energy/matter, it is negatively balanced and the system experiences a decrease in storage. If inputs/outputs balance, the system is in equilibrium. 3. System Feedback Ability of a system to change itself There must be a loop in the system for feedback to exist Positive feedback enhances (magnifies) the original change Result increasingly differs from the starting Colder state temperatures Tends to lead to instability/disruption in the system Less absorption More snow Negative feedback damps down of energy and ice (diminishes) original change Tends to preserve/diminish the starting state. Example: positive feedback loop Helps to stabilize and maintain the system 3. System Feedback 3. System Feedback Solar radiation reaching surface Winter snowfall Mean cloudiness The Arctic Amplification: a positive feedback loop Air + temperatures - rise More heat is Sea ice melts absorbed + + More ocean exposed (low reflectivity) Lake level changes: A negative feedback loop Lake level Streamflow from lake 4. System equilibrium Mostsystems remain balanced over time as a result of negative feedbacks. Threetypes of system equilibrium: 1. Steady-state equilibrium: values fluctuate around a steady average Example: a river adjusts its erosive power as a result of changes in precipitation, but system remains in equilibrium Time 4. System equilibrium 2. Dynamic equilibrium: values of the average may themselves gradually change as a result of positive feedbacks. Time 3. Metastable: results from an abrupt change from one state to another; a threshold is reached where it can no longer maintain equilibrium (called a tipping point) Time Coastal bluff collapse: An example of a tipping point System must adjust to new conditions  SYSTEMS APPROACH IN PHYSICAL GEOGRAPHY Approaches to the study of systems Approaches to the study of Systems Level of sophistication of the system 1. Morphological systems 2. Cascading systems 3. Process-response systems 4. Control systems and Ecosystems 1. Morphological approach Based on the physical properties of the environment (climate, exposure, slope angle, sediment type, etc) and their relationships. The relationships between these properties can be expressed by a web of correlations. A B C  Morphological system Aspect Micro-climate Soil depth Rock structure Position Slope angle on slope Ex. Rainfall and potential runoff is dependent on… 2. Cascading approach A series subsystems connected together, such that the mass or energy output from one subsystem (i) becomes the input (A) for the adjacent subsystem (ii). Knowledge about flux of energy and/or matter through the environment. i A ii  Cascading system Cliff Erosion/weathering (Potential kinetic energy) Talus slope Transport of material by gravity Become input to Floodplain Width-depth Stream channel adjust to Become input to inputs Lake/Ocean 3. Process-Response approach Combination of cascading and morphologic The morphological form of a structure is related to the process that is energized by the cascade. Chains of intersecting cascading and morphological components which mutually adjust themselves to changing input-output relationships. i A ii B C  Process-Response system Geyser 4. Control approach Process-response modified by actions of humans; Human actions intervene to produce changes in the distribution of energy and matter. Ecosystem can also be viewed as a form of control systems, where the process-response system is modified by physical, chemical and biological interactions Human i A A ii B C Control system THE SCIENTIFIC METHOD IN PHYSICAL GEOGRAPHY Scientific method Science: a way of arriving at understanding by observing, measuring, testing, and reasoning. Two widely recognized approaches: Induction: Gather data (e.g., location, dimensions, movements) and look for patterns, trends and interconnections. Deduction: Start from known scientific principles to understand through reasoning. https://i.pinimg.com/originals/2b/dc/0f/2bdc0f2dfdb532e274e1b84ef93a3fca.png Scientific method https://i.pinimg.com/originals/2b/dc/0f/2bdc0f2dfdb532e274e1b84ef93a3fca.png Scientific 1. Make observations method 2. Ask a question The application of common sense in an organized and objective 3. Research matter. 4. Hypothesize Reasoning 5. Test hypothesis Observations (Deduction) (Induction) 6. Analyze 7. Draw conclusions Example. Using the scientific process to study cottonwood forest distribution 1. Make Observations In semi-arid regions, cottonwood forests are found along rivers. What environmental factors influence their spatial distribution? 2. Ask a question Are temperatures near rivers favorable for cottonwood forest growth? Is consistent moisture needed to survive? Do tree roots in cottonwood forests grow only in river gravel or only in sediments with specific nutrients? 3. Research Cottonwood distribution is dependent on some environmental factor: Temperature, moisture, sediment type, nutrients, sunlight, etc. Cottonwood is therefore the dependent variable. Example. Using the scientific process to study cottonwood forest distribution 4. Hypothesize A possible explanation for the observed pattern of distribution is that cottonwood requires constant moisture in the root zone. We can test this hypothesis that the density of cottonwood decreases as one moves away from the river channel because the roots are above the reach of groundwater 5. Test hypothesis Collect data for a natural experiment. Establish vegetation plots (count trees within plots, measure distance to shoreline) Measure ground moisture along a transect from the shoreline and at different depth intervals. Example. Using the scientific process to study cottonwood forest distribution 6. Analyze Experiments often reveal a correlation between measured variables. Examine the data from the experiments to reveal is our hypothesis is supported. 6. Draw conclusions If the results show that cottonwood density decreases away from river channel and that soil moisture also decreases, then our hypothesis is supported. We may conclude that cottonwood distribution along a river channel is an indication of available groundwater in semi-arid regions. If results do not show a decrease in cottonwood density away from river channel, then we reject our hypothesis. We need to replace or refine our hypothesis and start the process again. Next… This Friday: Lab #1 for Group A02 Location: Morrisset library, level 3, Room 309 (Geographic, Statistic and Government Information Center) Bring: Pencil Spare sheets of paper Ruler Calculator on Planet Earth and Mapping the Earth’s for Lecture everyone