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MANAGEMENT OF HILL TORRENTS

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;

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MANAGEMENT OF HILL TORRENTS

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  1. 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

  2. D.G.Khan Hill Torrents

  3. MAP OF KAHA HILL TORRENT

  4. 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

  5. KAHA HILLTORRENT

  6. SCHEMATIC DIAGRAM FOR MANAGEMENT OF FLOWS IN BALOCHISTAN

  7. SCHEMATIC DIAGRAM FOR MANAGEMENT OF FLOWS IN PACHAD AREA- PUNJAB Cost of Schemes – RS 130 Million Potential Area – 36,253 HA

  8. MAP SHOWING MANAGEMENT WORKS ON KAHA HILL TORRENT IN PUNJAB

  9. PRE-PROJECT PROJECT IMPACTFLOOD PEAK EVENTS/INUNDATION POST-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) • 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

  10. Discharge - CFS PRE & POST-PROJECT ATTENUATION OF FLOOD PEAKSFOR KAHA HILL TORRENT

  11. CCA = 36,253 HA CROPPING PATTERN AND INTENSITIES UNDER PRE AND POST PROJECT CONDITIONS

  12. CCA = 36,253 HA PROPOSED AND ACTUALLY BENEFITED AREAS AGAINST VARIOUS PEAK FLOODS

  13. COMPARISON OF ECONOMIC INDICATORS

  14. FUTURE STRUCTURAL IMPROVEMENTS • 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 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 • 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 < 2 meter falls with glacis be adopted instead of drop falls

  15. COST OF STRUCTURAL INTERVENTIONS

  16. 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 O&M 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.

  17. 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.

  18. 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.

  19. THANKS

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