MANAGEMENT OF HILL TORRENTS

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MANAGEMENT OF HILL TORRENTS

• Management of hill torrents crossing the Kachhi
  Canal to reduce the peak flows to safeguard the
  canal and to increase the agricultural production
  in Pachad Area
• Review alternatives to
• Adopt hill torrent management to reduce the peaks
  or
• Remodel existing X-Drainage / Hill Torrent
  Structures of D.G. Khan Canal and Dajal Branch
  from RD 0 to RD 531 as per criteria to be adopted
  for Kachhi Canal
• Review various modern alternatives for hill
  torrent management

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D.G.Khan Hill Torrents
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MAP OF KAHA HILL TORRENT
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GENERAL TYPES OF STRUCTURES FOR MANAGEMENT OF
HILL TORRENT

• Storage Dams
• Delay Action Dams
• Check Dams
• Flood Distributors
• Dispersion Structures
• Diversion Dykes
• Cross Dykes
• Flood Irrigation Channels
• Flood Disposal Channels

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KAHA HILLTORRENT
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SCHEMATIC DIAGRAM FOR MANAGEMENT OF FLOWS IN
BALOCHISTAN
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SCHEMATIC DIAGRAM FOR MANAGEMENT OF FLOWS IN
PACHAD AREA- PUNJAB
Cost of Schemes RS 130 Million Potential Area
36,253 HA
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MAP SHOWING MANAGEMENT WORKS ON KAHA HILL TORRENT
IN PUNJAB
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PROJECT IMPACTFLOOD PEAK EVENTS/INUNDATION
PRE-PROJECT

• YEAR 1973
• FLOOD PEAK 56,000 CFS (1,586 CMS)
• BREACHES - DAJAL BRANCH 148 Nos.
• DISTYS. DAMAGED
• - NAUSHERA
• - ZAMZAM
• - ISLAM
• - ABE-HAYAT
• AREA INUNDATED 45,000 ACRES (18,220 HA)

POST-PROJECT

• YEAR 2003
• FIRST PEAK 2ND JULY, 2003 60,000 CFS (1,700
  CMS)
• SECOND PEAK 10TH JULY, 2003 60,000 CFS (1,700
  CMS)
• THIRD PEAK 14TH JULY, 2003 51,900 CFS (1,470
  CMS)
• BREACHES 5 No - Relief Cuts
• DISCHARGE AT CANAL CROSSINGS 9,000 CFS
• AREA INUNDATED NOMINAL

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PRE POST-PROJECT ATTENUATION OF FLOOD PEAKSFOR
KAHA HILL TORRENT
Discharge - CFS
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CROPPING PATTERN AND INTENSITIES UNDER PRE AND
POST PROJECT CONDITIONS
CCA 36,253 HA
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PROPOSED AND ACTUALLY BENEFITED AREAS
AGAINST VARIOUS PEAK FLOODS
CCA 36,253 HA
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COMPARISON OF ECONOMIC INDICATORS
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FUTURE STRUCTURAL IMPROVEMENTS

• PROP WALL CONSTRUCTED UNDER THE CREST ON D/S
  SHOULD BE PLACED UPSTREAM UPTO CREST LEVEL TO
  ENSURE
• Uniform flow
• Check washing of fines
• Safety Against Scour

• ORDER OF CONSTRUCTION
• Construction must start from Darrah to down stream

• DEGREE OF PROTECTION
• Down stream works need more protection as
  compared to the upper ones

• STRCTURAL IMPROVEMENTS
• Upper end of Salai should be semi circular
  instead of rectangular
• Terminal end should be similar to that of guide
  bund
• Off-take should be located 10 H above the cross
  structure
• For H instead of drop falls

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COST OF STRUCTURAL INTERVENTIONS
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FINDINGS CONCLUSIONS

• Efficacy of existing cross-drainage structures on
  DG Khan Dajal branch be evaluated.
• Flood peak attenuation at cross-drainage
  structures through dispersion structures is
  significant.
• Suggested improvement in the design of structural
  interventions be taken into account in future
  hill torrent projects.
• In spite of shortcoming in design, diversion of
  flood flows in Pachad area has been reasonable
  during post-project environments.
• Construction of dispersion structures in Pachad
  area is technically and socially more attractive
  than disposal of flows into Indus River.
• Ensure the availability of funds for OM at
  proper time.
• Existing future users of canal water on the
  right bank through lift pumps be duly considered
  for planning design of Kachhi Canal.

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RECOMMENDATIONS

• Dispersion Structures in Pachad Area on Sori-
  Lund, Sakhi Sarwar,Vidore, Chachar, Zangi Shori
  Janubi and Flood Carrying Channels in Command
  Area be constructed.
• Carrying Channels leading to Indus River for
  Pitock and Shori Shumali be constructed.
• Cross drainage Structures on Kachhi Canal be
  constructed as per D G Khan Dajal Canal System.
• Dispersion Structures would facilitate in the
  irrigation of additional area of about 80,000 HA.
• Provision may be made for Channelization of water
  along the right-bank through embankments
  constructed water course crossing Pipelines.

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STUDIES PLANNED TO BE CARRIED OUT BY CONSULTANTS

• Frequency analysis of flood flows of
  nallahs/rivers at darrah(s) and at canal
  drainage structures.
• Study the adequacy of existing cross draining
  structures on DG khan system in the light of
  frequency analysis.
• Remodeling of existing cross drainage structures
  if inadequate and additional structures if
  required on DG Khan canal / Dajal Branch.
• Consultants should advise for alternative
  strategies to irrigate Pachad area in lieu of
  proposed construction of 400 water course
  crossings on Kachhi Canal
• Consultants will probe that after construction of
  dispersion structures the flood peak will be
  reduced in accordance with the existing capacity
  of cross drainage structures on DG Khan system.
• Consultancy proposal for flood management of hill
  torrents originating from Suleiman Range and
  Marri Bugti hills from Taunsa Barrage to tail of
  Kachhi Canal.
• Revision of PC-I to accomodate hill torrent works
  in Punjab Balochistan Provinces.

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THANKS