Water Cycle and Importance

Importance of Water

• Water’s unique chemical properties and role in ecosystem services make it essential for life
• Water is required in photosynthesis
• Water helps remove pollutants from the atmosphere
• Water provides drinking water and supports agriculture

Water Cycle and Phase Changes

• Solar power heats water in oceans, lakes, and rivers leading to evaporation from liquid to gas phase
• Plants also contribute to the gas phase as they release water vapor through their leaves
• Water vapor cools, rises, and condenses into liquid, creating clouds
• Liquid water falls back to earth as rain, sleet, snow, or hail

Fates of Precipitation (Liquid Water)

• Evaporation occurs as the sun heats water, turning it into water vapor and rising back into the atmosphere
• Surface runoff is when water flows across the Earth's surface due to gravity into streams, rivers, and lakes, making its way to the ocean
• Infiltration is when water percolates through soil and rock, becoming groundwater and replenishing underground aquifers

Watersheds

• Watersheds are areas of land where precipitation drains into a common outlet like a river, lake, or ocean
• Topographic divides, such as mountain ridges, separate watersheds directing water flow

Freshwater Use Percentages

• Globally, freshwater use is 69% for agriculture, 19% for industry, and 12% for municipal purposes
• In the US, freshwater use is 41% for agriculture, 46% for industry, and 13% for municipal purposes

Consumptive vs. Non-Consumptive Water Use

• Consumptive use involves activities where water is used but not returned to its source with irrigation as an example where water evaporates or is absorbed by plants
• Industrial cooling is also an example of consumptive use as water can evaporate
• Non-consumptive use water is when water is used and then returned to its source, such as waste-water disposal where water from homes and businesses is treated and returned

Freshwater Availability and Water Stress

• Only 2.5% of the world's water is freshwater
• Saltwater cannot be consumed or be used for irrigation due to high salt levels which can dehydrate and damage crops
• Desalination can be costly and energy intensive
• Baseline water stress is the ratio of water withdrawals to available flow
• Baseline water stress is most problematic in North America, northern Mexico, southwestern U.S., Mediterranean coastal areas, Arabian Peninsula, Iran, northwest India, Pakistan, Afghanistan, and northeastern China
• High levels of water stress results in conflicts over water rights and challenges in meeting the needs of growing populations

Groundwater

• Groundwater resides in soil and rock beneath the Earth's surface and makes up a significant portion of Earth's freshwater
• Groundwater comes from rainwater that percolates into the ground, pulled down by gravity until it reaches the saturation point
• Once it reaches the water table, it enters aquifers
• Groundwater flows downhill and surfaces in discharge zones like springs, seeps, rivers, and oceans

Groundwater Usage

• 68% of groundwater is extracted for crop irrigation
• 21% of groundwater is used in industrial processes like manufacturing and cooling
• 11% of groundwater is used for domestic purposes, including drinking, cooking, and sanitation

Increased Flooding

• Urban expansion leads to more impervious surfaces, like roads and buildings, that increases surface runoff into rivers
• Deforestation reduces the natural absorption of rainwater, leading to more water flowing into rivers
• Climate change contributes through extreme weather events, which leads to heavier rainfalls and more frequent storms
• Rising sea levels exacerbate coastal flooding
• Human activities, such as building levees and canals, can fail leading to catastrophic flooding, e.g., Hurricane Katrina (2005)

Impervious Surfaces

• Impervious surfaces prevent water from infiltrating the ground
• Paved areas like roads, sidewalks, and rooftops are examples of impervious surfaces

Strategies to Increase Filtration and Limit Flooding

• Increasing vegetation through trees and green roofs
• Implementing pervious surfaces that allow water to infiltrate the ground in areas like Portland, Oregon
• Using bioswales to slow stormwater runoff such as the 25,400 square feet of stormwater planters in Indianapolis
• Restoring natural landscapes, like natural floodplains

Green Roofs

• Green roofs are multi-layered roofs designed to support plant growth and protect buildings
• Green roofs help retain rainwater, thus helping flooding efforts, and slowly release the water through evaporation
• Green roofs can filter pollutants from rainwater, improving water quality

Aral Sea Disaster

• Once the fourth largest lake, the Aral Sea has shrunk to <10% of its original size since 1960
• Diversion of water from rivers for irrigation of over 20 million acres of desert land is the primary cause
• The Aral Sea reduction has decreased fish populations and negatively impacted fishing economies
• It has increased salinity making it inhospitable for many aquatic species

Consequences of Overdrawing Aquifers

• Overdrawing aquifers can decrease the available water supply for agriculture, industry, and municipal needs
• This can cause subsidence with ground sinking or collapsing which causes infrastructure damage
• Saltwater intrusion can occur in coastal areas, increasing the water's salinity
• Depletion could dry up wetlands, springs, and rivers which causes habitat loss for plants and animals
• Pumping water will become more expensive

Ogallala Aquifer Location and Stresses

• Spans 8 states in the High Plains: Nebraska, Southeastern Wyoming, Easter Colorado, Western Kansas, the panhandle of Oklahoma, Eastern New Mexico, and the panhandle of Texas
• It experiences stress from high agricultural demand, supplying 30% of US irrigation water
• Low rainfall leads to substantial water withdrawal
• Slow recharge rates from the Rocky Mountains
• Historically overused, it has depleted 9% of its water supply since the 1930s, and some areas have experienced >50% reduction
• The Texas panhandle shows the most severe declines

Subsidence, Saltwater Intrusion, Sinkholes

• Subsidence is the gradual sinking of land above an aquifer from the over pumping of underground water
• Saltwater intrusion occurs when saltwater contaminates a freshwater aquifer in coastal areas caused when groundwater is pumped out faster than it can be replenished
• Sinkholes are ground depressions or holes from the rapid subsidence of land after an aquifer collapses suddenly

Saltwater Intrusion Process and Consequences

• Saltwater intrusion occurs when ocean saltwater migrates into a freshwater aquifer in coastal areas when groundwater is extracted too fast
• Rapid extraction creates a cone of depression
• Over pumping reduces the freshwater pressure, allowing saltwater to move into the aquifer which can contaminate the water supply making it is unsuitable for drinking and irrigation
• This creates high economic costs, as the cost of removing salt processes increases

Water Sources in Georgia

• Aquifers are the primary water source in Georgia
• Aquifers are underground layers of water-bearing rock or sediment

Daily Water Use

• The average American uses 80-100 gallons (302-378 liters) of water each day
• The WHO estimates that only 8.7 liters are needed for survival, and 20-50 liters meets basic human needs

WaterSense Program

• WaterSense was established by the EPA in 2006 to promote water efficiency
• It is a federal partnership that provides consumers with water-efficient options which are at least 20% more efficient

Ways to Reduce Water Use at Home

• Washing only full loads of dishes and laundry
• Turn off water while brushing teeth and shaving
• Limit flushing toilets
• Reduce shower time
• Install low-flow showerheads

Water Pollution and Impairment

• Water pollution is the physical, chemical, and biological characteristics of water that affect its quality
• Pathogens are the most common cause of impairment to US waterways
• Pathogens, or harmful microorganisms, come from livestock runoff, sewage discharge, and leaking septic tanks
• Other causes are nutrients from agricultural lands and feedlots, and metals from industrial sources

TMDL Definition

• TMDL or total maximum daily load represents the maximum amount of a pollutant that a body of water can support without reducing water quality below acceptable levels

Point vs. Non-Point Sources of Pollution

• Point source pollution: pollution that originates from a single, identifiable source. For example, a factory smokestack or a municipal sewage treatment plant
• Non-point source pollution: pollution that comes from multiple, diffuse sources. For example, automobiles pollution collectively or agricultural runoff

Pollution Effects

• Pollution begins in the headwaters with runoff from mining, industrial effluent, and agriculture
• Heavy metals cause cancers, skin lesions, and intestinal problems
• Pollution devastates biodiversity
• Sediments clog up gills of filter-feeding animals, which leads to the animals' decline
• Watersheds have heavy metal contamination reducing pH and harming aquatic life
• Streams carry nutrients into lakes, causing eutrophication from excess nitrogen and phosphorus, which leads to oxygen depletion, and reduced biodiversity
• Nutrients from agriculture and urban runoff cause algal blooms and dead zones
• Pollutants like heavy metals accumulate in phytoplankton and affect the entire food web
• Nutrient pollution creates dead zones hurting marine life
• Mercury in coal burns accumulates in fish, which poses health risks to humans
• Increased CO2 levels lower ocean pH, affecting the ability of marine organisms to form shells

Eutrophication

• Eutrophication is when bodies of water become enriched with excess nutrients, such as nitrogen and phosphorous
• The agricultural runoff that contains fertilizers causes eutrophication

Dead Zones

• Dead zones are ocean regions with low oxygen where few marine animals can survive
• Nutrient runoff, algal blooms, and oxygen depletion cause dead zones
• They are found near river mouths

Ocean Acidification

• Ocean acidification is a pH reduction due to atmospheric CO2 absorption
• It limits marine organisms' ability to create calcium carbonate shells, like snails and oysters
• It alters nitrogen and iron, changing growth rates and limiting factors

Pollution in Aquatic Systems

• In streams, pollution comes from heavy metals and sediments
• Streams carry nutrients from stormwater, factories, and farms to lakes, causing eutrophication

Plastic Gyres

• Five plastic gyres: North Pacific, South Pacific, North Atlantic, South Atlantic, and Indian Ocean Gyre
• These gyres are formed by circular ocean currents driven by earth's rotation, winds, and varied water temperatures

Plastic in the Ocean

• Plastics come from discarded or lost waste from ships and coastal cities
• Rivers and streams carry plastic waste from urban areas to the sea
• Plastic harms marine life as they mistake it for food or become entangled and leads to injury or death
• Plastics leach chemicals into the water and remain in the environment by breaking down into smaller pieces over time

Manipulating and Managing Water Systems

• Wetlands help mitigate flooding and storm surges by absorbing excess water
• Drip irrigation increases efficiency by delivering water directly to plant roots which reduces waste
• Reusing water can significantly reduce freshwater consumption
• Converting seawater to freshwater provides additional water sources

Value of Wetlands

• Wetlands act like sponges by soaking up large amounts of water during storms and floods
• Dense vegetation, peat, and soils in wetlands slow down water flow, help filter and clean the water by trapping sediments and pollutants
• Wetlands provide critical habitats for a diverse range of species including dish, birds, reptiles, and mammals
• Anaerobic conditions in wetlands slow down the decomposition of organic matter, which limits the availability of nitrogen and phosphorous which contain efficient root systems
• Wetlands offer various ecosystem services, such as floodwater storage, protecting water quality, and providing habitat for wildlife

Reuse Water

• Reuse water is treated wastewater repurposed for non-drinking uses
• Georgia Southern uses reuse water as part of their sustainability efforts through engaging in environmental service activities, including recycling and gardening

Desalinization

• Desalination is the process of removing salts and other chemicals from seawater to produce freshwater
• Distillation, where you boil and condense steam, and reverse osmosis, pushing water through a membrane, are common methods
• Desalinization is most common in the Middle East, where water scarcity is significant

Agriculture Definition

• Agriculture is the system of land management used to grow domesticated plants and animals for food, fiber, or energy that involves cultivating the soil, planting seeds, and raising animals to produce crops and livestock products
• Agriculture includes raising of domesticated animals

Land Use for Agriculture

• Humans have converted about one-third of Earth's ice-free land surface to agriculture, including both croplands and grazing lands

Croplands vs. Rangelands

• Croplands are used for growing crops such as grains, vegetables, and fruits.
• Croplands require intensive management practices including plowing, planting, irrigation and harvesting
• Rangelands are used for grazing livestock such as cattle, sheep and goats.

Green Revolution

• The Green Revolution refers to advancements in agricultural practices resulted in worldwide food production increases
• Its primary goal was to enhance agricultural productivity to meet global food demands to combat food shortages in developing countries
• It was successful in increasing productivity, food security, and economic growth

Function of Fertilizers

• Fertilizers provide essential nutrients to plants like N, P, and K
• Industrial fertilizer production has increased crop yields, allowing higher productivity, but shifted from crop rotation to more intensive farms
• The increased use of fertilizers led to nutrient runoff, which causes eutrophication and contributes to environmental degradation

Fertilizer and Pesticide Trade-offs

• Fertilizers boost crop yields and allow farming on previously unproductive lands
• However, excess fertilizers can wash into water which causes eutrophication which degrades soil quality and reduces biodiversity
• Pesticides manage weeds, pests, and diseases, protecting crops and ensuring high productivity but can harm non-target species and lead to pesticide resistance, causing harm to humans

Agroecosystems vs. Natural Ecosystems

• Agroecosystems and natural ecosystems rely on energy flow principles and nutrient cycling
• Agroecosystems include nitrogen fixation and water cycling
• Agroecosystems typically have low biodiversity for human needs, while natural ecosystems have high biodiversity which enhances resilience and dynamic homeostasis
• Agroecosystems are more fragile and vulnerable to environmental stresses
• Agroecosystems require more human input in order to maintain their productivity, in contrast to natural ecosystems

Harvest Index

• Harvest index is the fraction of plant production humans use
• It represents the proportion of a crop's biomass
• A low harvest index is unfavorable, showing much of the plant's growth is not contributing marketable produce

Trophic Level Efficiency

• Trophic level efficiency is the fraction of energy transformed and stored as biomass
• It is higher for domesticated animals due to selective breeding and a more easily digested diet
• Domesticated animals are usually confined, so they conserve energy

Nitrogen Cycle

• Nitrogen makes up 78% of the Earth's atmosphere, entering the biosphere through nitrogen fixation (gas to ammonia)
• Nitrogen fixation is carried out by nitrogen-fixing bacteria
• Ammonia dissolves in water to form ammonium and specialized soil bacteria convert ammounium to nitrite and then to nitrate
• Plants absorb ammonium, nitrite, and nitrate to create organic molecules
• Animals obtain nitrogen by consuming the plants
• Decomposers break down animals and recycle ammonia back into the soil
• The Nitrogen cycle can be affected by humans through: fossil fuel combustion, fertilizer production, using nitrogen-fixing crops and synthetic fertilizers, and excess nitrogen and fertilizers can infiltrate groundwater

Largest Contributor to Nitrogen in Soil

• The largest contributor to available nitrogen in the soil is human activites
• Production of chemical fertilizers and cultivation of nitrogen fixing crops

Haber-Bosch Process

• Was developed in the 20th century and allows industrial fixation of atmospheric nitrogen into ammonia, used in fertilizers
• Since 1950, this process has increased global nitrogen fixation by 200% compared to pre-agricultural rates

Nitrogen Uptake by Plants

• Nitrogen fixation converts atmospheric nitrogen into ammonia by specialized microorganisms
• The Haber-Bosch process produces fertilizers
• Nitrification transforms ammonia into nitrate then into nitrite using soil bacteria
• Decomposers free up dead plants and animals
• Lastly, symbiotic relationsips occur where nitrogen-fixing microbes live in symbiosis with legumes enhancing soil nitrogen content

Atmospheric N

• Nitrogen makes up about 78% of the molecules in Earth’s amosphere

Phosphorus (P) Cycle

• Abiotic components: Rocks and sediments (like calcium phosphate), soil water, and oceans

• Biotic components: Plants, animals, and decomposers.

• Weathering processes releases phosphates from rocks into soil, which plants absorb, then animals eat and decomposers help return organic phosphate into soil

• Phosphorus is mined from guano deposits and sedimentary rocks rich in phosphates

Agricultural Systems vs. Natural Ecosystems

• Agricultural systems needs continual inputs like fertilizers, pesticides, and irrigation to maintain productivity due to low biodiversity and high rates of nutrient loss
• Plants and animals are selectively bred for desirable traits, but this reduces genetic diversity
• Natural ecosystems maintain nutrient cycles and energy flow naturally, support wide species variety, efficiently recycle nutrients using decomposition, and contain high genetic diversity which provides adaptability
• Improving Agri. sustainibilty requires plant diversification, alternate crops, use cover drops, minimize soil disturbance, enhance irrigation, and combine biocontrol methods

Crop Growth

• Light is essential for photosynthesis
• Water, absorbed by root hairs and transported via xylem, is crucial for photosynthesis and nutrient transport
• Nutrients like nitrogen, phosphorus, and potassium are absorbed from the soil and are vital for plant growth and development

Organisms in the Success or Failure of Agriculture

• Pollinators, especially honeybees, are crucial for crop pollination
• Soil organisms, like earthworms, recycle nutrients
• Bacteria and fungi decompose crop residues
• Mycorrhizae form beneficial relationships with plant roots to help nutrient uptake
• Weeds, herbivorous insects,nematodes, and pathogens can harm crops and lead to reduceed yields

Soil

• Soil is a resource of the Earth’s uppermost crust that composes of a mixture of organic and mineral particles
• It forms through weathering of rocks and organic matters
• Soil formation involves the weathering of rocks and adding organic matter
• Soil fertility depends on the nutrient availability, the soil pH, aeration and moisture, and the soil structure and this supports plant growth

Soil Health

• Keep soil covered using mulch to protect it from erosion
• Disturb the soil as little as possible and implement no-till farming
• Keep plants growing to feed with organic matter
• Diversify crops through crop rotation

Crop Rotation

• Crop rotation is rotating different crop species in the same field
• Nitrogen fixation
• Specialty crops disrupt pests
• Different crops help with good soil heath
• Reduced environmental impact

Contour Farming and Terracing

• Plowing along contour lines is contour farming
• This is used only on hilly terrain to prevent gullies
• Terracing is creating wide, flat steps
• It prevents erosion and makes difficult terrain cultivatable

Farming Strategies Differences

• Montainous terrain requires terracing and contour farming
• Flat terrain requires the use of no-till farming and shelterbelts/windbreaks

Intercropping

• Intercropping is growing two are more species together in one growing season
• The patterns include alternating rows and mixed planting
• Intercropping suppresses weeds by maximizing space
• Diverse crops help attract beneficial predators to minimize the use of pesticides
• Legumes can fix nitrogen and enrich soil for other plants
• It reduces the risk of crop failure from adverse conditions

No-Till Farming

• No-till farming is an agricultural practice which requires the planting of crops in unplowed soil
• It preserves the soil's structure and cover

Shelterbelt Windbreak

• A shelterbelt, known as a windbreak, is a row of trees or shrubs that protect the area from wind and erosion
• This is placed among edges to reduce the impact of strong winds

Irrigation Benefits and Costs

• Increased benefits for higher crops
• Another benefit is improving efficiency through advanced irrigation and better tech
• The third is waste management
• First cost: energy consumption, the second cost is environmental impact, and the high intial investment

Water Conservation Methods in Irrigation

• Surface irrigation: water moves through canals- low energy costs
• Overhead spraying: water sprays- has more even water distribution
• Low-Pressure Sprinklers and LEPA systems: uses drop-down tuber to help the ground and reduce water evoration
• Variable rate irrigation matches the water flow to areas
• Drip Irrigation delivers water to root zones through small pipes
• Surge water is used to wet furrows
• Crop water selection required less water

CAFO's

• CAFO's or concentrated animal feeding operations are industrial agriculture facilities where animals are in facilities/ confined for 45 days in a 12-month period where no vegetation is present
• These operations are to maximize production and efficiency

CAFO Pros and Cons

• Pros consist of rapid growth because there's less waste, feed inputs and affordable foods
• Methane from the waste can generate electricity, reducing gas missions, and the energy is renewable
• Cons: Produce large amounts of waste, pollution in waters, foul gases, deforestation ( from overgrazing resulting in soil loss reduction), disease transmission ( from close confinement), antibiotic resistance ( from antibiotics)

Alternatives to CAFO's

• First alternative: free range livestock, where animals graze on naturatal pastures, which improves the health and reduces the need for the use of antibiotics, improving soil health
• Second alternative: Organic farming which eliminates the use of chemical inputs and organic farms focuses on renewing/ fixing the farms for future generation Third alternative: advanced waste management systems- captures the waste to lower emissions and generate electricity
• The last way has sustainable grazings practices where grazing animatls can control the weed, facilitating, nutrients, recycling back to the soil

Benefits of Ducks in Rice Fields

• Ducks benefit rice fields which reduces the need use for chemical pesticides because they instead eat insects
• These acts as natural fertilizers helping the health of plants during production
• The growth and yield of this crop would improve
• They help soil Aerate creating balanced ecosystems
• Reducing more Labor required

Food Waste

• The U.S has 40% of the food where it tends to never be eaten where 11% grocery, 33% restaurants, and 44% in home

Strategies to reduce food waste

• Strategies such as planning the meal to avoid buying excessive foods, storing better and using what's left help in food production

Inglorious Fruit and Vegetable Campaign

• Goal to reduce foot waste by encouraging consumers to go for fruits regardless the unperfect appearences

Ecological Eating

• Focuses on food choices that will reduce the environmental impacts and support sustainable agriculture to make the world better
• The first step is to cut down on the wasteful foods
• Second step is to eat more plants The next step is to eat what grown locally
• Lastly choose what’s most produced, food should have minimal process ( no harmful fertilizers or biocides)

World Hunger

• Sustainable Agriculture ( irrigation)
• Minimize Food waste from all levels, it needs equitable distribution
• Last long-term vision so you will have sustainable agriculture which all comes at a cost