Summary of topic 4.1
Download as PPTX, PDF0 likes3,186 views
This document discusses water systems and the global water cycle. It describes the three main types of ecosystems - marine, freshwater, and terrestrial - and notes that most global ecosystems are water-based. It then explains the key components of the water cycle, including storages like oceans, groundwater, and glaciers, and flows like evaporation, precipitation, melting, and streams. It notes that the ocean conveyor belt and Gulf Stream play an important role in distributing heat and affecting climate. Finally, it discusses some human impacts like unsustainable water use, changes to flows and storages, and water pollution.
Summary of topic 4.1
- 1. Topic 4 Water and aquatic food production systems and societies 4.1 Introduction to water systems Summary of topic 4.1
- 2. Ecosystems • There are 3 main types of ecosystem: 1. Marine (sea, estuary, salt marsh, mangrove) 2. Freshwater (river, lake, wetland) 3. Terrestrial • Most global ecosystems are therefore water- based Aquatic ecosystems
- 5. Distribution of Earth’s Water Compared to all of the water on Earth, there is very little freshwater. Of this freshwater, very little is easily available to humans.
- 6. Water systems • Water exists within a system • All systems include inputs and outputs (flows), processes and storages, and feedbacks storage Energy or matter in (INPUT) Energy or matter out (OUTPUT) TRANSFORMATION (Feedback mechanism to control input – and maintain EQUILIBRIUM) process In this system flows consist of matter rather than energy and processes are physical rather than chemical
- 7. Water systems • Storages include: – Organisms – Soil – The atmosphere (as water vapour) – Water bodies • Oceans • Groundwater (aquifers) • Lakes • Rivers • Glaciers • Ice caps
- 8. Water systems • Flows include – Evapotranspiration (evaporation coupled with transpiration) – Sublimation (solid directly to gas at high pressures) – Evaporation – Condensation – Advection (movement by winds) – Precipitation – Melting – Freezing – Flooding – Surface runoff – Infiltration (movement of surface water into soil) – Percolation (movement of water through soil and rock pores) – Streamflow – Currents
- 9. The Water Cycle (The Hydrological Cycle) The This shows the connections between flows and storages. It occurs between the atmosphere, lithosphere and biosphere Note: All flows in the water cycle are ultimately driven by solar radiation
- 10. How does the water cycle affect global climate? • There are differences in temperature and salinity throughout the world’s oceans • This results in differences in water density (which leads to movements of huge masses of water) • The greatest of these is the Ocean Conveyor Belt • The northern part of the Conveyor is the Gulf Stream • Warmer water rises to the surface and is advected by winds • Colder water sinks and is moved by deep-water currents • The Ocean Conveyor Belt therefore distributes heat around the world and helps to control climate • There are worries that continued anthropomorphic climate change will lead to disruption of the Ocean Conveyor Belt (and therefore result in a positive feedback effect)
- 11. The Ocean Conveyor Belt The Ocean Conveyor Belt The Day After Tomorrow – Gulf Stream stops
- 12. Human impacts on the water cycle • Unsustainable water use – There are over a billion people without access to clean drinking water and more than 2.6 billion without proper sanitation (water is a replenishable but finite resource). Water demand is increasing in both MEDCs and LEDCs • Changes to flows and storages – Humans affect this on the small and large scales e.g. large- scale agricultural irrigation, abstraction of groundwater and surface water and desalination of seawater • Water pollution – Rivers and lakes become polluted when they are used for the disposal of domestic and industrial wastes
- 13. Questions 1. List possible storages of global water 2. List possible flows of global water 3. List and evaluate human impacts on the water cycle