1. 2.2 Hydrology and Water Resources
Good morning/afternoon. I would like, before I begin, to thank the search committee for giving me this opportunity. I have been enjoying my visit so far very well. My presentation is titled ‘observations, modeling and scaling: the three pillars of hydrology’.

2. 2.2 Hydrology and Water Resources
2.2.1 Introduction : Why we study hydrology?
surface and ground water resources =Water Resources
UNESCO-IHE IRBM online Module, 2011
Less than 3% fresh water, in ice caps and glaciers, or is in the form of groundwater
Freshwater is renewed in the hydrological cycle of evaporation and precipitation.

3. 2.2 Hydrology and Water Resources
2.2.1 Introduction cont..
global rainfall over land is about 110,000 km3 of which roughly 40,000 km3 is potentially available for use
the remainder is lost through evaporation before reaching the sea
Source: UNESCO-IHE IRBM online Module, 2011

4. 2.2 Hydrology and Water Resources
2.2.1 Introduction cont..
the actual quantity is smaller about 9,000 km3 for the human population
part of it falls on uninhabited places.
The current freshwater consumption is about 800 m3 per person per year.
For a population of about 6,000 million this would mean that there is sufficient water.
However, as rainfall is very unevenly distributed water availability is a critical factor in socio-economic development in many areas.
Sources: UNESCO-IHE IRBM online Module, 2011

5. 2.2 Hydrology and Water Resources
2.2.1 Introduction cont..
Therefore, full understanding of hydrology of the river (surface and ground) is imperative for the socio-economic development of Regions.
Because river consists of different systems. (Fig. 1)

6. Figure 1 This diagram shows some common characteristics of a river system.

7. 2.2 Hydrology and Water Resources
2.2.2 Hydrological Cycle
The annual water cycle from rainfall to runoff is a complex system where several processes are interconnected and interdependent with only one direction of flow.
Q. What are the interconnected processes?

8. 2.2 Hydrology and Water Resources
2.2.2 Hydrological Cycle
Q. What is catchment?
A catchment is one single system and more than the sum of a large number of subsystems
Q. Where is our water is embedded?
in the hydrological system
water is finite
hydrological system generates the water that we need for different purpose

9. Macro system involving water, land, and man and their relationship in the context of river basin (Petry,B. & ,Boeriu, P.2003)
Sun energy
Evaporation
Precipitation
Macro-climate
Evapotranspiration
surface Runoff
Sediments
Ground water
Alkalinity
Nutrients
Turbidity
Soil cover
Rock structure
Terrain gradient
Earthquake
Agriculture
Fishing
Wildlife
Recreation and
tourism
Energy
Manufacture
Health
Navigation
Structure of authority
Staff and line functions
Budgeting
Appropriation of funds
Legislative control
Public participation
Political power structure
Social pressure groups
Land tenancy
Ownership of assets
Social Justice
Redistribution of income
Planning legislation
Environmental Legislation
Zooplankton
Phytoplankton
Fishes
Aquatic food chain
Disease vectors
Flora and Fauna
Soil nutrients
Vegetation

10. 2.2 Hydrology and Water Resources
2.2.2 Hydrological Cycle
Water use patterns will change as a result of water demand management measures.
The hydrological cycle can be studied at different spatial scales.

11. 2.2 Hydrology and Water Resources
2.2.2 Hydrological Cycle
‘white’ water = rainfall and that part of rainfall which is intercepted and immediately evaporates back to the atmosphere
‘green’ water = soil moisture in the unsaturated soil layer, stemming directly from rainfall, that is transpired by vegetation
‘blue’ water =water involved in the runoff (sub) cycle, consisting of surface water and groundwater (below the unsaturated zone)

12. Q: Explain why classifying water in to three types?
2.2 Hydrology and Water Resources
2.2.2 Hydrological Cycle
Q: Explain why classifying water in to three types?
The processes occurring within the three ‘colours’ of water, as well as their interconnections, determine the characteristics of each natural hydrological system.

13. 2.2 Hydrology and Water Resources
2.2.2 Hydrological Cycle
The composition (quality) of river water is basically determined by the geological nature of the catchment area and by land use.
Effects of climate change on the Hydrological Cycle
Precipitation
Evaporation
Soil Moisture
Groundwater Recharge and Resources
River Flows
Trends in Observed Stream flow
Effects of Climate Change on River Flows

14. 2.2 Hydrology and Water Resources
Effects of climate change on the Hydrological Cycle
Precipitation
the main driver of variability in the water balance over space and time
has very important implications for hydrology and water resources
influences Hydrological variability over time in a catchment

15. 2.2 Hydrology and Water Resources
Effects of climate change on the Hydrological Cycle
Precipetation
Changes (temporal and spatial variability) depend on changes in the climatology of a region.
the largest percentage precipitation changes over land are found in high latitudes, some equatorial regions, and Southeast Asia, although there are large differences between climate models.

16. 2.2 Hydrology and Water Resources
Effects of climate change on the Hydrological Cycle
Precipetation
Until recently, climate models do not necessarily reproduce observed patterns of climatic variability
Recent developments, however, open up the possibility that it may be feasible to estimate changes in year-to-year variability

17. 2.2 Hydrology and Water Resources
Effects of climate change on the Hydrological Cycle
Precipetation
Potential changes in intense rainfall frequency are difficult to infer from global climate models, because of coarse spatial resolution.
However, there are indications (e.g.,Hennessy et al., 1997; McGuffie et al., 1999) that the frequency of heavy rainfall events generally is likely to increase with global warming.

18. 2.2 Hydrology and Water Resources
Effects of climate change on the Hydrological Cycle
Precipetation
Increasing temperatures mean that a smaller proportion of precipitation may fall as snow (Mc Carthy 2001).
In areas where snowfall currently is marginal, snow may cease to occur—with consequent, very significant, implications for hydrological regimes.

19. 2.2 Hydrology and Water Resources
Effects of climate change on the Hydrological Cycle
Evaporation from the land surface
includes evaporation from open water, soil, shallow groundwater, and water stored on vegetation, along with transpiration through plants
The rate of evaporation from the land surface is:
driven by meteorological controls,
mediated by the characteristics of vegetation and soils, and
constrained by the amount of water available.

20. 2.2 Hydrology and Water Resources
Effects of climate change on the Hydrological Cycle
Evaporation from the land surface
Climate change has the potential to affect all of these factors—in a combined way that is not yet clearly understood—with different components of evaporation .

21. 2.2 Hydrology and Water Resources
Effects of climate change on the Hydrological Cycle
Effects of climate change on the Hydrological Cycle
Soil Moisture
Soil moisture contents are directly simulated by global climate models, albeit over a very coarse spatial resolution, and outputs from these models give an indication of possible directions of change.

22. 2.2 Hydrology and Water Resources
Effects of climate change on the Hydrological Cycle
Effects of climate change on the Hydrological Cycle
Soil Moisture
The local effects of climate change on soil moisture will vary not only with the degree of climate change but also with soil characteristics
Climate change also may affect soil characteristics, perhaps through changes in water logging or cracking, which in turn may affect soil moisture storage properties.

23. 2.2 Hydrology and Water Resources
Effects of climate change on the Hydrological Cycle
Effects of climate change on the Hydrological Cycle
Groundwater Recharge and Resources
Groundwater is the major source of water across much of the world, particularly in rural areas in arid and semi-arid regions, but there has been very little research on the potential effects of climate change. However, there are series of hypotheses.
Aquifers generally are replenished by effective rainfall, rivers, and lakes and change of them will affect ground water recharge.

24. 2.2 Hydrology and Water Resources
Effects of climate change on the Hydrological Cycle
River Flows
Trends in Observed Stream flow
Effects of Climate Change on River Flows

25. 2.2 Hydrology and Water Resources
Effects of climate change on the Hydrological Cycle
River Flows
Trends in Observed Stream flow

26. 2.2 Hydrology and Water Resources
Effects of climate change on the Hydrological Cycle
River Flows
Effects of Climate Change on River Flows
By far the majority of studies into the effects of climate change on river flows have used GCMs to define changes in climate that are applied to observed climate input data to create perturbed data series.
These perturbed data are then fed through a hydrological model and the resulting changes in river flows assessed.