MANCHAR LAKE

INTRODUCTION : Manchar Lake is the largest natural freshwater lake in Pakistan and one of the largest in South Asia1. It is located west of the Indus River, in Jamshoro District and Dadu District, Sindh - 18 km away from Sehwan. The lake collects water from numerous small streams in the Kirthar Mountains and then empties into the Indus River. The lake’s surface area fluctuates with the seasons, from as little as 36 km² to as much as 500 km² during monsoon rains.

The lake’s banks and vicinity are home to ancient archaeological sites such as Ghazi Shah, Wahi Pandhi Ali Murad Mound1. The sites of Lal Chatto, Mashak Lohri, and Lakhiyo situated along the edge of Lake Manchar are the most ancient sites, which date from the Harappan culture1. The lake was formed when a branch of the Indus River flowed from Kashmore. In 1921, it was connected to Hamal Lake via the Main Nara Valley Drain.

Manchar Lake Levels

MANCHAR LAKE Plain & Flood 2022 Maps

Kinjhar Lake

Introduction : Keenjher Lake, also known as Kalri Lake, is situated approximately 22 kilometers away from Thatta, 122 kilometers from Karachi, and 80 kilometers from Hyderabad. This lake is artificially created and is fed by the Kalri-Baghar Feeder Upper, sourced from the Right Bank of Kotri Barrage. Covering an area of 52.00 square miles at various water levels, Keenjhar Lake was formed by constructing earthen embankments with a length of 77 RD and a height of 25 feet, utilizing natural depressions like Sonheri and Keenjhar.

The main purpose of this artificial reservoir is to ensure a reliable water supply for domestic and industrial use in Karachi, accounting for approximately 80% of the city's total requirement. The Irrigation and Power Department provides 1200 cusecs of silt-free water through the Keenjhar-Gujjo canal from Keenjhar Lake, with the canal having a discharge capacity of 1382 cusecs.

LAKE TECHNICAL & OPERATION OVERVIEW

Area of Lake at R.L 54.0 52.00 Sq. miles
Gross storage capacity 0.558 MAF Before Project
0.660 MAF After Project(RL 57)
Live storage capacity 0.38 MAF
Average depth of water 20 Ft
Maximum height of embankments 34.00 Ft
Length of embankments 15.00 Miles
Deposition of silt per year 4335 Ac.ft
Original Design Life 132 Years
Reduction of life after siltation 87 Years
Life after construction of Link Canal by passing Keenjhar Lake 192 Years

Elevation (Ft) Area (Sq. Miles) Volume (MAF)
30 11.01 0.029
32 17.39 0.047
34 23.68 0.073
36 26.8 0.106
38 29.3 0.142
40 31.68 0.181
42 34.59 0.223
44 37.69 0.27
46 40.86 0.32
48 44.25 0.374
50 46.63 0.433
52 48.91 0.494
54 51.29 0.558
56 53.72 0.625
57 54.83 0.66

SALIENT FEATURES OF KALRI BAGHAR FEEDER UPPER
The main feeding source of the Lake is Kalri-Baghar Feeder (upper) which off- takes from right bank of Kotri Barrage .
Design Discharge 9100 Cusecs
Full Supply Level 67.0 Ft
Full Supply Depth 15.0 Ft
Design Bed Level 52.0 Ft
Design Bed Width 195 Ft
Nos. of Span 6.0 Nos.
Width of Span 24.0 Ft
CCA 603000 Acres
Length of Canal 38.0 Miles
Cutoff 13.80 Ft
Pavement Level 52.0 Ft
Cill level 56.0 Ft

Karachi Water & Sewerage Board (KW & SB) initiated different projects time to time in order to meet out the present and future demand.

Project Name Discharge (Cs) Cumulative Discharge (Cs)
K-I 520 520
K-II 380 900
K-III 300 1200
K-IV 1200 2400
( under process)

Computation / Analysis for Additional Water Availability Through K-III Project
A. Computation
Before the Project
I) Computation at RL 54.0 ft.
Area of water in Lake sq miles = 51.29 sq. miles - (Area Capacity Curve)
Volume of water Lake MAF = 0.558 M.A.F - (Area Capacity Curve)
= 558000 A.F
After the Project
II) Computation at RL 57.0 ft.
Area of water in Lake sq miles = 54.83 sq. miles- (Area Capacity Curve)
Volume of water Lake MAF = 0.66 M.A.F - (Area Capacity Curve)
= 660000 A.F
B. Additional Water Availability after the Project
Total Additional Water Availability for a period of year = 660000 – 558000
= 102000 Acre ft.
Additional Water Available per period for a period of one year = 102000/ (1.98* 365)
in cusecs = 141.14 ft3/sec
Thus, Quantity of Additional Water Availability for six months = 141.14*2 = 282.28 cusecs
Thus, Quantity of Additional Water Availability for four months = 141.14*3 = 423.42 cusecs
Critical period of four months i.e. from November to February in which water supplied to Keenjhar Lake from Upper K.B Feeder is reduced, during this period; a quantity of 423 cusecs will increase the supply of K.B Feeder for supply to Karachi for a period of 120 days. Presently KW&SB is drawing un-interrupted water supply of 900 cusecs daily through Keenjhar-Gujjo Canal. Therefore if additional quantity of 423 cusecs is made available then it will meet with the present demand of water supply for Karachi i.e. 1200 cusecs as envisaged by KW&SB in their K-3 project.

Inflow from Kalri Baghar Feeder Upper (KBFU) to Keenjhar = 0.94 MAF

Rainfall contributions from Hill torrents approximately 50,000 acre- ft has been estimated from the nullahs draining into the Lake = 0.05 MAF 
Direct Rainfall on Keenjhar lake having Area(33280 acres) = 0.033 MAF
Total Inflow in MAF= 0.94+0.05+0.033= 1.02 MAF

In Kharif Season
Total Outflow 825 MGD = KG Canal (600 MGD) and PQ Fall (225 MGD) = 0.554 MAF
In Rabi Season (6 Month)
Total Outflow 600 MGD = KG Canal (460 MGD) and PQ Fall (140 MGD) = 0.400 MAF
Total Losses at the Rate of 7 % = 0.0726 MAF
Total Outflow = Kharif Season + Rabi Season + Losses
=0.554 + 0.400+ 0.0726 = 1.02 MAF

ADDITIONAL DEMAND OF 260 MGD
In Kharif Season
Total Outflow/Demand 1085 MGD = KG Canal (885 MGD) and PQ Fall (225 MGD) = 0.729 MAF
In Rabi Season (6 Month)
Total Outflow/Demand 910 MGD = KG Canal (720 MGD) and PQ Fall (190 MGD) = 0.608 MAF
Total Losses at the Rate of 7 % = 0.0826 MAF
Total Outflow = Kharif Season + Rabi Season + Losses
0.729 + 0.608+ 0.0826 = 1.42 MAF
Reservoir Storage     = 0. 80 MAF
Total      = 2.22 MAF

  • Inflow from Kalri Baghar Feeder Upper (KBFU) of 6000 Cusecs to Keenjhar (with in Three Month)
    =1.07 MAF
  • Inflow from Kalri Baghar Feeder Upper (KBFU) of 2000 Cusecs to Keenjhar (with in Eight Month)
    = 0.952 MAF
  • Rainfall contributions from Hill torrents approximately 50,000 acre- ft has been estimated from the nullahs draining into the Lake
    = 0.05 MAF 
  • Direct rainfall on Keenjhar lake having Area(33280 acres)
    = 0.033 MAF 
  • Total Inflow in MAF= 1.07+0.952+0.05+0.033= 2.11 MAF

Kinjhar lake Levels

KINJHAR LaKE Maps

Nai Gaj Gauge