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Water Resources – Lecture 2:

Water Resources – Lecture 2:. The river environment: River Geomorphology and Chemistry. River Morphology: The Long Profile of a river. Steep Slope, low deposition: mostly suspended load Gentle Slope, higher deposition, mixed: suspended and bed-load. Mostly Bed-load.

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Water Resources – Lecture 2:

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  1. Water Resources – Lecture 2: The river environment: River Geomorphology and Chemistry

  2. River Morphology: The Long Profile of a river

  3. Steep Slope, low deposition: mostly suspended load Gentle Slope, higher deposition, mixed: suspended and bed-load. Mostly Bed-load. Two or more channels with large stable island: Suspended load. River Morphology:Channel Pattern From Morisawa, 1998

  4. River Morphology: Channel Profile Riparian Zone Channel Bank River Channel Bedload Streamflow

  5. Dynamic Equilibrium • A river is a system is in a state of equilibrium, and is continuously adjusting to changes in that system. • What changes: • longitudinal profile, • channel profile, • river bed, • pattern (straight or sinuous), • depth, • velocity • How does it change: Erosion and Deposition (aggradation, degradation).

  6. Physical Characteristics of river zones:Upper Reaches (Characterisation from Dallas and Day, 1993)

  7. Upper Reaches

  8. Physical Characteristics of river zones:Middle Reaches

  9. Middle Reaches

  10. Physical Characteristics of river zones:Lower Reaches

  11. Lower Reaches

  12. Basics of Water Chemistry in Hydrology • Important Physical Attributes of water: • Temperature (°C) • Suspended Solids (TSS mg/l) • Turbidity (function of TSS NTU) • Light Penetration

  13. Basics of Water Chemistry in Hydrology • Important Chemical Properties: • [O2] mg/l • pH • Salinity [ions, in mmol/l] (Na, Ca, K, Mg, Cl, HCO3 SO4) • Nutrients [mol/l] (Nitrates, Nitrites, Phosphates) • TDS (total dissolved solids) (mg/l, essentially from bedrock) • Natural Organics • Minor Organics • Heavy Metals

  14. Basics of Water Chemistry in Hydrology • Particulate Inorganic Matter • Silts and Clays: highly charged, and therefore remain in suspension. • Particulate Organic Matter • Shredded Leaves (Generally Coarse Particulate Organic Material {CPOM}) • Dead organic material (Fine Particulate Organic Material{FPOM}) • Bacterioplankton, Plankton.

  15. Chemical Characteristics of River Zones:Upper Reaches

  16. Chemical Characteristics of River Zones:Middle Reaches

  17. Chemical Characteristics of River Zones:Lower Reaches

  18. Photo: Kate Rowntree

  19. Mhlatuzi Case Study • Strategic Environmental Assessment • SEA is a systematic process of addressing the environmental considerations and consequences of proposed policy, programme or plan initiative, where: • Policy refers to the framework which guides any subsequent decision making. • Plan refers to the strategy for implementing the policy. • Programme refers to the schedule of proposals, commitments instruments and activities.

  20. Questions Regarding Mhlatuzi Case Study • To make a strategic assessment of water needs and allocations, what type of information do you need? • How is water valued in this catchment in economic terms, in social terms, in environmental terms, and in political terms. • The SEA team argue that the greatest biological diversity in the catchment is to be found in the undeveloped rural areas. Allocating water for the development of this region could lead to the loss of that biodiversity. How can this issue be resolved? • If water is allocated to sectors where it will be used most economically, will this also be socially and environmentally optimal?

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