This slides are based on the hydrology of urban and agricultural areas. It also focuses on urban flood which is one of the most disastrous issues, due to poor and unsustainable hydrology management in urban areas. Furthermore, it shows the water stability in an agricultural system in comparison to urban areas.

1. Hydrology of urban areas and
agricultural lands
-Nilisha Thapa
Prakriti Bastola
Drishti Shrestha
Bsc 4th year

2. So romantic right..???

4. Hydrology
• Movement, distribution
and management of
water on Earth and
other planets, including
the water cycle, water
resources and
environmental
watershed
sustainability.

5. Urban Hydrology
• Urban hydrology is an applied science that will have
an increasing role to play in the sustainability of
human societies.
• Part of land hydrology investigating the hydrological
cycle, water regime and quality in urbanized
territory.
• Also, link in a number of sciences dealing with the
problems of ecology, environmental protection,
conservation and rational use of the Earth’s water
resources

7. Urbanized Landscape
• Presents a territory transformed by human
activities, occupied by a city with suburbs,
industrial, economic facilities and communication
lines
• Formation and evolution result from a natural
historical process of development of the human
society with its larger portion concentrating in
cities.

8. • Urban population growth = poverty ( of clean
drinking water) ??
•  Growth of urban areas brings significant
changes in physical properties of land surface
increasing integrated vulnerability of inhabitants,
agricultural land and rural ecological life supporting
systems.

9. Growth of Urban Population and
Urbanized Territories
In 1880,only 3% of the
Earth’s population lived
in cities with 5 thousand
inhabitant
30%population lived in
cities in 1950

10. •

11. Current and
emerging
challenges
recycling of
wastewater
nutrients,
water for
sanitation
versus
sanitation
without water,
delivery of
drinking water
supply for
growing cities,
water to feed
depleted
aquifers,
urban
agriculture
wastewater
irrigation,

12. The main changes of the physical pathways of the
water cycles due to urbanization include:
• Removal of natural vegetation drainage
patterns;
• Loss of natural depressions which
temporarily store surface water;
• Loss of rainfall absorbing capacity of soil;
• Creation of impervious areas (e.g., rooftops,
roads, parking lots, sidewalks, driveways)
• Provision of man-made drainage systems
(e.g., storm sewers, channels, detention
ponds).

13. Hydrological cycle of urbanized
landscapes
• Use of large water volumes(basins and other
non renewable ground water) to cover the
domestic, industrial and economic needs of
the population.

15. Source: Nepal Water Supply Corporation (NWSC)

16. Contd.
• Water withdrawal is comprised of the water losses
due to evaporation at leaks from the water pipeline
or sewer networks, watering of green plantations,
streets, recreation zones, farmlands, etc.
The greatest portion of the
water intake in the urban
water supply with the efficient
sewer system is returned after
the use (after treatment or
without it) to the hydrographic
network as sewage water

17. Transmission of surface and water
bodies
• There are drastic transformations in the soil-ground layer.
• City planning, Roofs of buildings, asphalted streets and roads
create large areas of water impermeable or little impermeable
surfaces occupying half and more of urban territories
• With the formation and development of urbanized landscapes,
hydrographic network is transformed.
• this transformation results in a large-scale transition from a
water-penetrable (pervious) surface to water-impenetrable
(impervous) cover.
• In the process of urban construction, drastic relief changes
occur, namely, the depressions and runoff bands are covered
up.

19. Reclamation of the build-on territory, channeling, filling up or
creation of new water bodies and water courses and bog
reclamation is undertaken resulting in the disturbance of the
natural relation between surface and underground waters.

20. • Therefore, although the hydrological cycle consists of
the same elements, their proportions in urban area are
significantly different:
• Interception of rainfall is reduced due to removal of
trees;
• Precipitation is usually higher than in rural areas;
• evapotranspiration is much lower;
• Surface run-off is much larger;
• ground-water run-off, infiltration and recharge is
small;
• Water storage is much lower;
• runoff volumes and peak flows in rivers are higher;
• Frequency of surface runoff is increased.

21. Ways for Sustainable hydrology in urban
areas
• Urban development significantly increases the amount of
storm water and the frequency of extreme hydrological
events experienced by the City's catchments. The increased
runoff causes more intense local flooding, while droughts
during dry weather are deeper and longer.
• Runoff amount from the average annual rainfall.
Rural areas Urban areas
10-20% 60-70%

22. • Development of green areas in cities mitigate the
negative impact on the hydrological cycle improve
the quality of the environment and quality of life in
cities
• Increased water retentiveness of catchments
improves flood protection, quality of water,
environment and aquatic ecosystems.
• Open water spaces and green areas improves
microclimate providing better environment for
people, increasing population health, providing
recreational spaces.

23. Contd..
• Construction of permeable pavement for
improved water infiltration
• Stream restoration, stream bank erosion control
• Retrofitting previous development,
• Dredging and rehabilitation of lakes
• Construction and routine maintenance of city
sewer system and stormwater infrastructure

26. Hydrology of Agricultural lands

27. • Agricultural hydrology is the study of water balance
components intervening in agricultural water
management, especially in irrigation and drainage.
•

28. • Agro hydrology can be regarded as the study of
hydrological processes and the collection of hydrological
data, aimed at increasing the efficiency of crop
production, largely by providing beneficial soil moisture
conditions.
• Rainfall amount and its spatial and temporal distributions
determine quantity of water that reaches Land’s surface.
• Vegetation, soil conditions and topography determine
how much water infiltrates into the soil and how much
run offs the land’s surface and where it goes.
• Land uses that impact water resources include
agriculture, forestry, urbanization, recreation, and
industrialization.

29. • Agriculture, the clearing of forests, and draining of
wetlands have caused significant modifications to
the surface of the earth.
• Tillage of the land and clear cutting of forests
change infiltration and runoff characteristics which
affect groundwater recharge, sediment and water
yield, and evapotranspiration.
• Irrigation of land changes the use and distribution
of water. The removal of surface water and
groundwater for irrigation changes the water’s
natural disrtibution and impacts the ecosystem
that depend upon it.

30. • Demand for water to irrigate crops usually
occurs when there is insufficient precipitation
during the growing season, potentially causing
streams and groundwater levels to be reduced.
• Irrigation water that return to the either
groundwater or surface water can contain salts,
pesticides or have elevated levels of nutrients
such as nitrates and phosphorous.
• These contaminants in turn can cause harm to
plant and animal life that depend on returned
water.

31. Source; Wikipedia
Fig; Hydrology of agricultural land