Water Harvesting in Eastern Coastal Plains (Orissa, AP, TN)

1
Water Harvesting in Eastern Coastal Plains
(Orissa, AP, TN)

• Sangati CPR Working group

2
Area of focus

• Between Eastern ghats and Bay of Bengal
• Rainfall range 1000-3000mm
• Subdivisions
• Mahanadi delta
• Southern AP plains
• Krishna and Godavari deltas
• Kanyakumari coast
• Sandy littorals
• Madras/Coromandel coast

3
Role of Water Harvesting

• Study by an organization known as PROGRESS
• Area of focus drainage basin of a few
  tributaries of Krishna river
• Elevation difference between mouth of basin and
  topmost point 290m
• Heavy runoff
• Main rainfall July and August
• Rainfall in 1988-90 900mm per year
• Yet soil was moisture-deficient (drought
  conditions)

4
Role of Water Harvesting

• Study over two years with
• Water-absorbing cropping techniques
• Intercropping, organic farming, etc.
• Water harvesting
• Runoff conserved through interconnected water
  structures, so that overflow in one gets
  collected in another
• 170 structures, covering 4 of the basin area
• Harvested 25 of total rainfall
• Conclusions of study
• Drought is not because of lack of rainfall but
  because of mismanagement of existing rainfall
• Traditional water structures if revitalized can
  harvest 75 of the runoff
• Worst-affected by lack of over-reliance on
  individual wells (as opposed to tanks) are the
  small farmers. Leads to the usual cycle of
  indebtedness

5
Orissa, AP

• Area Mahanadi delta, Palar basin
• Tanks, percolations tanks, etc.

6
Tamil Nadu

• Drought-prone state
• Artificial irrigation imperative
• Classic example Tanjore
• For the most part, the soil is naturally poor,
  and it is irrigation alone which makes the
  province such a scene of fertility (British
  irrigation authority)
• Annual Rainfall 750-1000mm NE monsoon, 250mm
  SW monsoon

7
Anicuts

• Small to medium size dams
• Length 329m, width 12-18m, depth 4.5m
• Mainly around the Cauvery delta to channel water
• Silting/scouring of the riverbed was a problem
  (not carefully engineered to prevent this)
• Prevented by controlling the water flow into the
  Cauvery delta, by constructing centralized
  regulators or kallanais at the head of the
  Cauvery delta in Srirangam
• Serpentine structure for kallanai to resist
  floods better

8
Eris

• Ancient tanks
• Approximately one-third of the irrigated area of
  Tamil Nadu is watered by eris (tanks).
• Eris have played several important roles in
  maintaining ecological harmony as flood-control
  systems, preventing soil erosion and wastage of
  runoff during periods of heavy rainfall, and
  recharging the groundwater in the surrounding
  areas.
• The presence of eris provided an appropriate
  micro-climate for the local areas. Without eris,
  paddy cultivation would have been impossible.

9
History of Eris

• Till the British arrived, local communities
  maintained eris.
• Historical data from Chengalpattu district
  indicates that in the 18th century about 4-5 per
  cent of the gross produce of each village was
  allocated to maintain eris and other irrigation
  structures.
• The early British rule saw the enormous
  expropriation of village resources by the state
• Eris managed by centralized Public Works
  Department
• Led to the poor maintenance and degeneration of
  eris

10
Oorani

• Smaller tanks (compared to eris) containing just
  enough water to cultivate the few acres of land
  dependent on them.
• Major source of water for drinking and domestic
  use where groundwater not sufficient
• Generally excavated to depths ranging from 2-5 m
  below ground.
• In many cases, rehabilitation of neglected
  village tanks saves approximately 365 hours or 45
  working days per household
• Which is the total time spent each year to fetch
  water from neighboring villages.
• Especially applicable where groundwater is saline

11
Kudimaramath

• Voluntary labor undertaken by village communities
  traditionally to maintain the eris / ooranis
• Checking the growth of weeds on tank bunds
• Clearing away underwood from tank bunds
• Clearing out deposits/silt
• Blocking breaches through ring bunds
• Came to an end when the British forced eris under
  PWD
• Eri maintenance was contracted out, leading to
  the usual cycle of negligence, corruption, etc.

12
Decline of tank irrigation in TN

• Old records 39000 tanks in TN!
• Sharp decline, esp. in North Arcot, South Arcot
  and Chengalpattu
• Traditional Irrigation Institutions (TIIs) that
  perform maintenance have reduced in effectiveness
• Centralization of tank maintenance
• Emergence of wells and electricity, also leading
  to cuts in payments of maintenance workers
• Transfer of land / redistribution of land means
  more owners of land, more castes own land
• Caste-based factions of TIIs, more people means
  less effectiveness
• Many tanks in TN are fed by an anicut system
  Palar anicut system supplies water to 317 tanks
  in N. Arcot and Chengalpattu
• Here, the tanks close to the head have more
  effective TIIs, tail-reach tanks are less
  effective

13
Chennai

• Annual rainfall 1200mm, which is sufficient
• Lack of facilities to store this water
• Current capacity 100 million cu. M, or 2700
  million cu. Ft. or 76,356 million liters
• 124 tanks, plus 39 temple tanks (or kulams) (?)
• 5.5 of Madras Metropolitan area
• Include tanks in Cholavaram and Red Hills which
  are used only for domestic needs (28000 million
  liters)
• Rough demand 283 million liters a day, or
  100,000 million liters a year
• Clearly, the current capacity to store rain water
  needs to be fully utilized!
• RWH crucial!

14
Chennai

• However, traditional temple tanks (and other
  tanks too) have degenerated
• Storm-water courses that refill these tanks have
  disappeared
• Water runs off into the sea
• Slum resettlements on tank and lake beds
• When World Bank gave TNHB Rs. 600 crore as aid
  for slum improvement schemes, we had no land to
  implement them on. Hence, we had to think of tank
  beds (deputy planner, MMDA)
• As a result, ground-water depletion heavy
• Salt water front of the sea has advanced by 800m
  in 20 years (10-year old data, probably even
  worse now)