Chapter 6.1 Freshwater

Module 6.1 Freshwater Resources: Water Wars

Core Message

  • Freshwater is a limited, essential resource.

  • Water distribution on Earth is uneven.

  • Consumption of water is unequal.

  • Wise water use is crucial for sustainability.

Case Study: Fighting over Water in the American Southwest

  • The Colorado River supplies water to over 36 million people and other living organisms.

  • Water rights related to the Colorado River have been a source of contention.

  • The river no longer reaches the Gulf of California in most years.

How Is Water Distributed on Earth, and What Are the Sources of Freshwater?

  • Only 2.5% of water on Earth is freshwater, with limited accessibility to humans.

  • Groundwater and surface water are key sources of freshwater.

How Does Water Cycle Through the Environment?

  • Water moves through the environment via the water cycle, involving evaporation, transpiration, and precipitation.

  • Evapotranspiration is the combination of evaporation and transpiration.

How Are Surface Water and Groundwater Supplies Accessed, and What Problems Do These Water Sources Face?

  • Surface waters provide freshwater to human communities, but over-extraction can lead to shortages.

  • Groundwater supplies can shrink due to over-withdrawal and saltwater intrusion.

How Does Water Use Differ Between Sectors and Income Levels, and What Problems Does Water Scarcity Cause?

  • Agriculture is the largest user of water, followed by industrial and domestic sectors.

  • Water scarcity can be physical or economic, affecting billions of people globally.

Global Water Use and the UN's Sustainable Development Goals

  • Goal 6 of the UN's Sustainable Development Goals aims to ensure access to water and sanitation for all by 2030.

  • Targets include access to safe drinking water, sanitation facilities, pollution reduction, and sustainable freshwater withdrawals.

How Is Domestic Water Regulated in the United States, and What Problems Does Our Water Supply Face?

  • The United States has a reliable purification and delivery system for tap water under the Safe Drinking Water Act.

  • Despite the Act, thousands of violations occur annually, highlighting the need for infrastructure upgrades.

Flint, Michigan Water Crisis

  • Residents noticed discolored water

  • New county admins switched water source without safety considerations

    • Water contained lead, a neurotoxin

  • Over 100,000 people exposed to high lead for over 2 years

    • Many affected individuals were children

Wastewater Treatment

High-Tech Methods

  • Decontamination using advanced filtration and chemicals

Low-Tech Methods

  • Mimic wetlands' natural water purification process

Alternatives to Traditional Wastewater Treatment

  • Arcata, California sewage treatment resembles a natural ecosystem

  • Land converted into wetlands for water purification

Technologies Addressing Water Scarcity

Dams and Reservoirs

  • Dams block water flow in rivers or streams

  • Reservoirs store freshwater for various uses

    • e.g., Hoover Dam and Lake Mead on the Colorado River

Desalination

  • Removal of salt and minerals from seawater

    • Expensive process with extra cleansing steps

Conservation to Address Water Scarcity

  • Conservation includes water-saving technologies and behavioral changes

  • Average U.S. citizen uses 140 gallons of water per day

  • Industry water use adds up to 4,200 liters per person daily

Reducing Water Footprint

  • U.S. household water use breakdown

  • Gallons of water needed per pound of food and per product

  • Water-saving technologies and actions for reducing water usage

Summary

  • Freshwater is a precious but limited resource

  • Uneven distribution of freshwater globally can lead to conflicts

  • Methods like dams, reservoirs, and desalination increase freshwater availability

  • Newer methods like water recovery and purification are promising

  • Best way to