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;
i.
ii.
iii.
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
D.G.Khan Hill Torrents
MAP OF KAHA HILL TORRENT
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
KAHA HILL
TORRENT
SCHEMATIC DIAGRAM FOR
MANAGEMENT OF FLOWS IN
BALOCHISTAN
SCHEMATIC
DIAGRAM FOR
MANAGEMENT
OF FLOWS IN
PACHAD AREAPUNJAB
Cost of Schemes – RS 130 Million
Potential Area – 36,253 HA
MAP SHOWING MANAGEMENT
WORKS ON KAHA HILL TORRENT IN
PUNJAB
PROJECT IMPACT
FLOOD PEAK EVENTS/INUNDATION
PRE-PROJECT





YEAR 1973
FLOOD PEAK
BREACHES - DAJAL BRANCH
DISTYS. DAMAGED
- NAUSHERA
- ZAMZAM
- ISLAM
- ABE-HAYAT
AREA INUNDATED
56,000 CFS (1,586 CMS)
148 Nos.
45,000 ACRES (18,220 HA)
POST-PROJECT




YEAR 2003
FIRST PEAK
SECOND PEAK
THIRD PEAK
2ND JULY, 2003
10TH JULY, 2003
14TH JULY, 2003
BREACHES
DISCHARGE AT CANAL CROSSINGS
AREA INUNDATED
60,000 CFS (1,700 CMS)
60,000 CFS (1,700 CMS)
51,900 CFS (1,470 CMS)
5 No - Relief Cuts
9,000 CFS
NOMINAL
PRE & POST-PROJECT ATTENUATION OF FLOOD PEAKS
FOR KAHA HILL TORRENT
Discharge - CFS
PEAK AT DARRAH
FLOOD PEAK AT HILL TORRENT
CROSSINGS
PRE-PROJECT
POST-PROJECT
40,000
15,000
0
50,000
23,000
2,500
60,000
31,000
4,500
70,000
39,000
9,000
80,000
48,000
14,000
CROPPING PATTERN AND INTENSITIES
UNDER PRE AND POST PROJECT CONDITIONS
CCA = 36,253 HA
Crops
Pre Project
Cropped Area (HA)
Post Project
Intensity (%)
Cropped Area (HA)
Intensity (%)
Kharif
Sorghum
1,817
5.0
8,983
24.8
277
0.8
1,864
5.1
Cotton
0
0.0
1,831
5.1
K.Total
2,094
5.8
12,678
35.0
Wheat
465
1.3
1,926
5.3
Gram
141
0.4
591
1.6
Oilseed
199
0.5
6,597
18.2
R.Total
805
2.2
9,114
25.1
Annual
2,899
8.0
21,792
60.1
Bajra
Rabi
PROPOSED AND ACTUALLY BENEFITED AREAS
AGAINST VARIOUS PEAK FLOODS
CCA = 36,253 HA
Proposed at Feasibility Level
Achievement under Post Project Period
Return Periods - Years
Return Periods - Years
Crops
2.33
5
10
25
2.33
5
10
25
Jawar
9,769
18,788
23,349
23,595
7,214
13,874
17,242
17,424
Bajra
1,489
2,863
3,559
3,597
1,100
2,114
2,628
2,656
Wheat
1,760
3,386
4,209
4,699
1,300
2,501
3,108
3,470
Gram
534
1,028
1,275
1,425
394
759
942
1,053
Oilseed
753
1,446
1,800
2,011
556
1,068
1,329
1,485
14,306
27,512
34,192
35,328
10,564
20,316
25,250
26,088
Total:
COMPARISON OF ECONOMIC INDICATORS
Sr.
No.
1
Item
Unit
Pre-Project in
Feasibility Report
1990
Post-Project in
Evaluation Report
2003
Financial Project Cost
Rs. Million
190.26
- Balochistan Works
Rs. Million
60
- Punjab Works
Rs. Million
130.26
364.9
2
Economic Project Cost
Rs. Million
171.23
329.91
3
Implementation Period
Years
3
5
4
Project Annual Benefits
Rs. Million
33.8
84.03
- Agriculture Benefit
Rs. Million
14.72
25.5
- Flood Damage Saving
Rs. Million
19.08
58.53
- Economic Interval Rate of Return
Percent
17.38
19.99
- Benefit Cost Ratio at 10% Discount
Ratio
1.63:1
1.91:1
- Net Present Worth at 10% Discount
Rs. Million
108.3
263.21
5
364.9
-
Economic Parameters
FUTURE STRUCTURAL IMPROVEMENTS
A.
PROP WALL CONSTRUCTED UNDER THE CREST ON D/S SHOULD BE
PLACED UPSTREAM UPTO CREST LEVEL TO ENSURE



B.
ORDER OF CONSTRUCTION

C.
Construction must start from Darrah to down stream
DEGREE OF PROTECTION

D.
Uniform flow
Check washing of fines
Safety Against Scour
Down stream works need more protection as compared to the
upper ones
STRCTURAL IMPROVEMENTS



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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
COST OF STRUCTURAL INTERVENTIONS
RS.MILLION
PUNJAB PROVINCE
SCENARIO - 1.
WITHOUT DISPERSION STRUCTURES
•
Cost of 40 Cross-Drainage Structures on Kachhi Canal RD: 0 – 990 (Punjab)
2,184
•
Cost for increasing Flood Carrying Capacity Against 40-Year Return Period on
D.G.Khan Canal System:
(a) Excluding cost of flood carrying channels
(b) Including cost of flood carrying channels
813
1,194
Sub Total (a)
Sub Total (b)
2,997
3,378
SCENARIO - 2.
WITH DISPERSION STRUCTURES
•
Dispersion Works in Pachad Area and Flood Carrying Channels
RD: 0 – 990
•
Constructing Drainage works on Kachhi Canal Corresponding to Existing
X-Drainage Structures on D.G.Khan Canal System
1,363
Total
BALOCHISTAN PROVINCE
Cost of flood management for Nallahs Orignating from Marri Bughti Hills &
Mountainous Regions upto Gandava/Badra Nallah
1,920
3,283
750
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.
RECOMMENDATIONS





Dispersion Structures in Pachad Area on SoriLund, 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.
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.
THANKS