water budgets

• What is the water budget?

  The annual balance between precipitation, evapotranspiration, and runoff
• How is the water budget calculated?

  Using the formula $P =$$E +$$R \pm S$
• What do the variables in the water budget formula represent?

  P is precipitation, E is evapotranspiration, R is runoff, and S represents changes in storage
• At what scales can the water budget be calculated?

  From global to local scales
• What does a national or regional water budget indicate?

  The amount of water available for human use
• What is available soil water?

  The amount of water that can be stored in the soil and is available for growing crops
• How can farmers use available soil water information?

  To identify when irrigation might be required and how much
• What is a river regime?

  The annual variation in the discharge or flow of a river at a particular point
• What factors influence the character of a river's regime?

  Size of the river, precipitation, temperatures, geology, vegetation cover, and human activities
• How is river discharge usually measured?

  In cumecs
• What do storm hydrographs show?

  Discharge changes over a short period of time, often no more than a few days
• What are the main features of a hydrograph?

  Rising limb, peak discharge, lag time, falling limb, and base flow
• What is lag time in a hydrograph?

  The time interval between peak rainfall and peak discharge
• How does the shape of a storm hydrograph vary?

  It varies from one rain event to the next and from one river to another
• What are 'flashy' hydrographs characterized by?

  Short lag time, high peak discharge, and steep rising limbs
• What are 'delayed' hydrographs characterized by?

  Long lag time, low peak discharge, and gently inclined limbs
• What is the impact of urbanization on storm hydrographs?

  It increases the flood risk and changes the characteristics of the land surface
• How does construction work affect hydrological processes?

  It leads to the removal of vegetation cover, exposing soil and increasing runoff
• What happens to rainwater in urban areas?

  It is swiftly fed into drains by gutters and pipes
• How do drains and sewers affect rainwater?

  They reduce the distance and time rainwater travels before reaching a stream or river channel
• What is the effect of channelization of urban rivers?

  It guards against flooding but can lead to more devastating floods
• Why is urbanization a concern for flood risk?

  Many towns and cities are located close to rivers, increasing flood risk
• What role do planners play in managing flood risk?

  They help manage the impacts of urbanization on flood risk
• What actions are involved in flood risk management?

  Strengthening embankments, implementing flood emergency procedures, and steering development away from high-risk areas
• What are the interacting factors affecting the shape of storm hydrographs?

  • Weather/climate: Intense storms vs. steady rainfall
  • Rock type: Impermeable vs. permeable rocks
  • Soils: Low vs. high infiltration rates
  • Relief: High steep slopes vs. low gentle slopes
  • Basin size: Small basins vs. larger basins
  • Shape: Circular vs. elongated basins
  • Drainage density: High vs. low drainage density
  • Pre-existing conditions: Wet vs. dry basins
  • Vegetation: Bare/low density vs. dense vegetation
  • Human activity: Urbanization vs. reforestation
• How do impermeable rocks affect storm hydrographs?

  They restrict percolation and encourage rapid surface runoff
• How do permeable rocks affect storm hydrographs?

  They allow percolation and limit rapid surface runoff
• How does soil type influence storm hydrographs?

  Clay soils have low infiltration rates, while sandy soils have high infiltration rates
• How does relief affect storm hydrographs?

  High, steep slopes promote surface runoff, while low, gentle slopes allow infiltration
• How does basin size affect storm hydrographs?

  Small basins tend to have flashy hydrographs, while larger basins have more delayed hydrographs
• How does the shape of a basin influence storm hydrographs?

  Circular basins have shorter lag times, while elongated basins tend to have delayed hydrographs
• How does drainage density affect storm hydrographs?

  High drainage density means water moves quickly to the measuring point, while low density means slower movement
• How do antecedent conditions affect storm hydrographs?

  Wet basins lead to low infiltration, while dry basins allow high infiltration
• How does vegetation affect storm hydrographs?

  Bare or low-density vegetation leads to low interception, while dense vegetation increases interception
• How does human activity influence storm hydrographs?

  Urbanization creates impermeable surfaces, while reforestation increases interception