tutorials 1,2,3,4

Question 1

list some typical water quality issues

Answer 1

• pathogen pollution
• pharmaceuticals and EDCs
• excess nutrients and eutrophication
• organic pollution and low DO
• salinity pollution
• chemical pollution
• microbial pollution

Question 2

affected parties of water quality issues

Answer 2

• agriculture
• aquatic life/animals
• infrastructure (dams)
• people
• nature!

Question 3

the main contributors of water quality issues

Answer 3

• industry
• agriculture
• domestic users

Question 4

sources of pollution

Answer 4

• untreated sewage
• domestic waste inputs (are growing)
• open decification
• salt intrusion
• agriculture
• industry
• insecticides
• food industry

Question 5

what are the water challenges of this century

Answer 5

• increase in water use
• changes in water availability and water quality

both of these result in an increase of water stress

Question 6

falkenmark indicator

Answer 6

calculates the volume of water available per person
waterstress = water availability/population

Question 7

water use to availability ratio

Answer 7

focuses on the amount of water that is used to available water resources. can also be used to calculate sector-specific water stress or total water stress. water use/water availability

Question 8

waterfootprint to availability ratio

Answer 8

waterfootprint/water availability

Question 9

water scarcity including water quality indicator

Answer 9

calculates the ratio of sectoral water withdrawal of acceptable water quality to the overall water availability

Question 10

why does water quality matter for water scarcity?

Answer 10

the usability of water depends on sufficient water quantity and quality

Question 11

water pollutants

Answer 11

• nutrients
• water temperature
• salinity
• pathogens
• chemicals
• EDCs
• heavy metals
• BOD
• emerging pollutants like medicines

Question 12

why is there a need for a multi pollutant approach

Answer 12

• multiple pollutants may have an impact of multiple sectors
• pollutants can interact (chemically, biologically, physically)
• pollutants can have common sources
• policies for one pollutant may affect other pollutants
• pollutants have multiple impacts on nature and society
• sensitivity to pollution may increase if more pollutants are around

Question 13

ecosystem services and ecosystem services lakes give to us

Answer 13

ecosystem services are benefits to humans gifted by the environment. the ecosystems we ‘get’ are dependent on the state of the lake. this depends again on the nutrient load, and can either be healthy or unhealthy. examples of ecosystem services are: drinking water, water buffering, flood regulation, filtration, recreation, food, biodiversity, carbon storage, hydropower, education

Question 14

stressors for lakes

Answer 14

nitrogen, phosphorus, agriculture, sewage systems, fertilizers, insecticides, domestic waste, invasive species

Question 15

sources of nutrients in lakes

Answer 15

• natural runoff
• agriculture
• urban areas
• industry
• aquaculture

Question 16

nutrient load

Answer 16

nutrient loss from different sources that ends up into the lakes

Question 17

PC lake(+)

Answer 17

models the amount of nutrients (N,P,Si) in different compartments of the model. the model includes 3 compartments: air, water and sediment. also includes different water layers, so also stratification

Question 18

PC lake model inputs

Answer 18

nutrient pollution and temperature. this is measured or other model input

Question 19

why do we use models

Answer 19

• to formulate hypotheses
• to better understand stressors on ecosystems
• to qualify indicators
• to qualify the impact of these stressors

Question 20

critical nutrient load and the relationship with temperature

Answer 20

critical nutrient load is the nutrient treshold to keep the lake in a healthy state. this can be used as an indicator for lake water quality. the critical nutrient load is affected by temperature. bc algae do better in warm conditions. higher water temp, bigger change in algae blooms. also stratification when theres a large difference in Temp. disturbs the ecosystem and increases the risk for o2 depletion and P release from the sediment (dead zooplankton sinks)

Question 21

how can we build trust in models?

Answer 21

1. compare model results with observations (validation)
2. compare modelled trends over time with observations
3. sensitivity analysis: test how sensitive the model outputs are to changes in model parameters
4. comparing model inputs with independent datasets
5. expert knowledge or local knowledge
6. compare model results with the results of similar models

Question 22

strenghts and weaknesses of model validation

Answer 22

+ easy to understand
+ easy to calculate
+ gives an indicator of how well our models represent reality
+ builds trust

• extreme values can have a large impact
• data are uncertain
• date does not always fit (e.g. global model with no observational data for a continent)
• data is not always comparable

Question 23

cycle of building trust

Answer 23

compare modelled nutrient fluxes with empirical studies –> compare modelled nutrient trends with empirical studies –> sensitivity analysis –> compare model inputs with other independent datasets –> expert knowledge –> compare model results with other modelling studies