2. It begins with a storm …
They were rolls, waves that finished in a puff: known noises,
village things. Everything that we have here is animated, lively,
maybe because the distances are short and fixed as in a theatre.
The downpours were onto the courtyards here around, the
thunder up here above the roofs; I could recognize by ear, a
little further up, the place of the usual God that made storms
when we were children, He too a village character. Here all is
as if intensified, a matter of scale probably, of inner
relationships. The shape of the noises and of these thoughts
(which were, after all, the same thing) seemed to me for a
moment truer than true, but it cannot be recreated with words
3. Objectives
“To explain what hydrology is and what it
deals with..”
•
•
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The elements of the water cycle
The spatial and temporal scales involved
The mass and energy balance at a global scale
4. The Water Cycle
The water on Earth flows from the atmosphere to the
ground. And then from the rivers to the sea, from where
it returns to the atmosphere:
“Hydrology is the science
that studies these flows,
which make up
the water cycle.”
5. The flows from the atmosphere to the surface of the
Earth are called Precipitations. The water that
reaches the ground can infiltrate and flow within
the soil or it can run off on the surface - these are
referred to as “Horizontal Flows”.
At the same time, there is evaporation from the soil
and water surfaces, and transpiration from plants
and animals (in a word, evapotranspiration) Infiltration and evaporation constitute the “Vertical
Flows.”
6.
7. During the first seconds after the Big Bang, Hydrogen
and Helium were created. According to the Theories,
oxygen was formed a little later. However, it is the third
element more diffuse in the
universe.
8. If you consider that Helium is not very much reactive, it
couldn’t be a real surprise that an element built on
Hydrogen and Oxygen is abundant on the Earth.
9.
For a given catchment, in an interval of time ∆t, the
continuity equation for water in its various phases
can be given as:
Mass inflow – Mass outflow = Change In Mass Storage
If the density of the inflow, outflow and storage
volumes are the same:
Vi – Vo= ∆S
Vi - Inflow volume in to the catchment, Vo - Outflow volume
from the catchment and ∆S - change in the water volume
10. Therefore, the water budget of a catchment for a
time interval ∆t is written as:
P – R – G – E – T = ∆S
P = Precipitation
R = Surface runoff
G = net ground water flow out of the catchment,
E = Evaporation
T = Transpiration
∆S = change in storage
The above equation is called the WATER
BUDGET EQUATION for a catchment.
11. Total quantity of water in the world is
estimated as 1386 M km3
1337.5 M km3 of water is contained in
oceans as saline water
The rest 48.5 M km3 is land water
13.8 M km3 is again saline
34.7 M km3 is fresh water
10.6 M km3 is both liquid and fresh
24.1 M km3 is a frozen ice and glaciers in the
polar regions and mountain tops
12. Estimated World Water Quantitites
96%
2%
1%
1%
Ocean-saline
Land - saline
Fresh - Liquid
Fresh - Frozen
13.
14.
15. •
The variation of water production from catchments
can be calculated and described by hydrology.
•
It is used to find out maximum portable flood at
proposed sites. e.g. dam ..
•
Used in prediction of flood over a spillway, at
highway culvert or in urban storm drainage.
•
Used to assess the reservoir capacity required to
assure enough water for irrigation or municipal
water supply during drought.
16. •
•
Engineering hydrology enables us to find out
the relationship between a catchments' surface
water and groundwater resources.
Used in connection with design and operations
of hydraulic structure.
