Summary: Water Management

Read the summary and the most important questions on Water management

• River basin management

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• What does the term River/drainage basin mean, and what role does a drainage divide/watershed have in a river/drainage basin?

  Definition river/drainage basin: Area of land to which all the precipitation ends up into one specific stream. 
  
  Definition drainage divide/watershed: Border of adjacent watersheds. (Steep mountain ridges and hills for example). Precipitation on one side can only flow into that specific basin, and precipitation on the other side flows only in that corresponding river basin.

• What does a natural cross section of a river consists of?

  1.  Active flood plain
  2. Regulatory floodplain
  3. Geologic floodplain

• What does a semi artificial cross section of a river consist of?

  1. Summer bed
  2. Flood plain
  3. Summer dike
  4. Winter dike

• What three types of flood management exist?

  1. Increase/decrease flow velocity.
  2. Increase/decrease capacity (discharge).
  3. Reduce discharge into river.
     

• River flood measures: Deepening summerbed

  • Riverbed is deepened by excavating the surface layer of the river bed.
  • Thee deepened river bed provides more room for the river. (only works for long distances)
  • Also includes dredging of rivers (getting rid of deposits at the lower course of the river)
    

• Introduction

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• What are the 4 water types and two water bodies?

  4 Types
  1.Rivers & lakes
  2.Coastal zones
  3.Urban areas
  4.Rural areas
  2 Water bodies
  1.Surface water (Fresh, brackish & salt)
  2.Groundwater (Fresh & brackish)

• What are the 3 causes of floods, droughts & ecosystem loss?

  
  1. Climate change
  2. Spatial development
  

  • Building near, or in essential waterbodies.
  • Neglecting the maintenance of water bodies.
  • Too much water use by households, industry & agriculture

  
  3. Natural disasters
  

  • Tsunamis
  • Hurricanes

• What is the difference between the wrong & right approach for risk management?

  The wrong approach waits for an event to happen and then repairs it and takes into account preventive measures. (When a calf drowns, the well is filled in.
  
  The right approach takes a critical look at possible hazards and already takes into account measures for prevention & mitigation if required. It also prepares for that the event happens and after the event respond and if necessary work on some recovery.

• What is the definition of a Risk

  Risk if a combination of the following:
  

  • The probability of an event (flood or drought). (Also known as frequency)
  • The potential adverse consequences for human health,  the environment, cultural heritage and economic activity associated with this event. (Impact intensity, duration, costs, amount of population, Infrastructure, Settlements, Ecology.

• How does a Risk matrix work

  1. Probability (y) and Potential loss (x) are the axis
  2. Each axis had four values ranging ((very) low to (very) high)
  
  Probability is quantified as follows:
  
  Very low: 1 per 1000 years
  
  Low: 1 per 100-1000 years
  medium: 1 per 10-100 years
  High: Event that occurs more frequently than once every 10 years.