1. 2.1 Basic hydrology

2. Small rivers are important they are lifelines..

3. Hydrology
Hydrology is defined as the study of the movement, distribution, and quality of water throughout the earth, and addresses both the hydrologic cycle and water resources.

4. Hydrological cycle
The hydrological cycle describes the continuous movement of water on, above, and below the surface of the earth. Since the water cycle is truly a "cycle," there is no beginning or end.

5. Hydrological Cycle

6. Water balance
Water balance is defined as the balance between the inflows, outflows and change of storage in any water body over a period of time.
A water balance can be used to help manage water supply and predict where there may be water shortages
The following slides wil show more on water balance

7. Water Balance - incoming water
Rain, rivers, groundwater…

8. Water Balance – outgoing water
Evapotranspiration (ET), outflowing rivers, groundwater flows…

9. Stream flows peak also, but..

10. Water balance formula In = out (+ change in storage)
In: Rain, rivers, groundwater flows
Out: drainage, runoff, groundwater flows, ET
Storage: groundwater change

11. Sustainable vs unsustainable situation
In a sustainable situation the inflow equals the outflow.
What happens in an unsustainable situation when too much water is pumped?

12. Rainfall comes in peaks

13. Overdraft
Groundwater table drops, pump can not reach it, aquifer depletes, crops die…

14. Eventually…
You can make deeper bore holes, but water table keeps dropping…

15. Overdraft
When groundwater is pumped faster than the recharge, water levels drop
Porous media lose water, pores are filled with air
Porous media could consolidate, resulting in land subsidence, sink holes, loss of water storage capacity