Sindh Chief Minister Syed Murad Ali Shah has said that the federal government constructed Left Bank Outfall Darin (LBOD) during the 1980s, but the excavation of its Spinals blocked the natural waterways. As a result, the lands of Badin, Mirpurkhas, Sanghar, and Nawabshah started submerging during floods and degraded, turning saline; the wetland ecosystem was completely damaged, and livelihood opportunities shrank.
‘Keeping in view these problems, particularly the livelihoods and the damaged wetland ecosystem, the Sindh government decided to revive the natural route of Dhoro Puran to construct a Spinal Escape regulator at RD 210 and rehabilitate Dhoro Puran up to Shakoor Lake.’
This, he said, while speaking at the mammoth gathering just after inaugurating the LBOD system. Minister Irrigation Jam Khan Shoro, Secretary Irrigation Zareef Khero, elected representatives of the area, and the notables attended the programme in large numbers.
The CM, sharing the background of the LBOD project, said that from 1984 to 1997, the LBOD Stage-I project was executed by Wapda to relieve waterlogging and salinity in 1.27 million acres of land in Shaheed Benazirabad, Mirpurkhas, Sanghar, and Badin Districts.
Mr Shah said that the LBOD spinal drain connects the drainage network to the sea through a tidal link. The LBOD spinal drain collects surplus drainage and distributes it through a weir to two branch drains – the Kadhan Pateji Outfall Drain (KPOD) and the Dhoro Puran Outfall Drain (DPOD). The spinal drain system was designed to direct the high salinity drainage into the KPOD and then to the sea. The KPOD connects to the sea via a 26-mile-long canal, called the Tidal Link.
The CM said that 204 drains from three divisions, totalling 1735 miles in length, would discharge into the LBOD. These include 108 drains from Badin, spanning 813 miles; 51 drains from Mirpurkhas, covering 454 miles; and 43 drains from Sanghar, extending over 336.6 miles.
Mr Shah recalled that the Wapda (fed govt) handed over the LBOD Spinal to the Sindh Irrigation Department in 1993, but the system could not perform and caused damage during the heavy rains of the 1994 monsoon. Therefore, the system was returned to WAPDA in 1995. WAPDA handed over the LBOD System again to the Sindh Irrigation Department in February 2002.
LBOD project: Murad Shah said that the LBOD project includes a Spinal Drain of 261.12 km, KPOD/DPOD of 99 km, Tidal Link of 43 km, Surface Drains of 1666 km, and 1673 Drainage wells. Its benefited area is spread over 1.270 million acres. The cost of the project was Rs.33.44 billion, Commencement: July 1986, and transferred to Irrigation dept on February 1, 2002.
Conceptualization and Problem: Talking about the conceptualisation and problems, Murad Shah said that on July 4, 2022, heavy rain began and the LBOD’s drainage network efficiently carried stormwater to its outfalls. He added that the drains worked effectively due to desilting and de-weeding processes.
The CM said that the LBOD system was intended to manage 125 mm of rainfall in 48 hours with a five-day evacuation period, Murad Shah said and added that the recent heavy rainfall of 2020 and 2022 caused widespread devastation and exposed the defects, shortcomings, and vulnerabilities of the existing drainage system on the left bank of the river Indus.
Mr Shah said that the people of districts Badin, Mirpurkhas, Sanghar and Nawabshah have always suffered due to flooding as their lands have been degraded and turned into saline; the wetland ecosystem is completely damaged and degraded and livelihood opportunities have shrunk.
During monsoon 2022, the spinal gauges have raised over to their ever-maximum Gauges of 2011. The spinal was designed for passing 4600 causes, whereas at present about 12000 causes water passing through it to sea
Breaches in LBOD system: Two major breaches in Puran Dhoro occurred in RD 7 and 8 on August 28, 2022. The breach of RD 8 of Puran Dhoro was closed on the very next day while the breach of RD 7 Puran Dhoro took five days to plug.
Problem: All dhoras currently flowing within the LBOD system, including Pithoro, Hakro, Naro, Digri, Puran, and Pangrio, follow their old natural routes, ultimately combining into Dhoro Puran and outfalling into Shakoor Lake. The LBOD spinal drain intersects this natural drainage route at four locations: RD 275, RD 251, RD 239, and RD 210. These intersections lead to flooding in the vicinity of all dhoras currently flowing within the LBOD system, including Pithoro, Hakro, Naro, Digri, Puran, and Pangrio, following their old natural routes, ultimately combining into Dhoro Puran and outfalling into Shakoor Lake.
Construction of Syphon: Construction of Dhoro Puran Syphon at Spinal Drain RD 275+500. Construction of Dhoro Pangrio Syphon at Spinal Drain RD 210+800 would
divert the MMD and Digri Dhoro discharge into Dhoro Puran via a siphon at RD 275, connecting to Hakro Dhoro. This will reduce the excess load on the Spinal Drain and activate Dhoro, enhancing overall drainage efficiency.
During heavy rainfall in 2022, Pangrio Dhoro posed a significant threat to the LBOD system and its vicinity. This siphon will manage the higher discharge from Pangrio Dhoro by diverting it into Dhoro Puran, which outfalls into Shakoor Lake, mitigating risks and enhancing the system’s capacity.
In 2022, the system carried a stormwater discharge of 12,000 cusecs, far exceeding its design capacity of 4,600 cusecs. This caused elevated levels in the spinal drain, leading to blockages and backflow in the main drains of the LBOD system, ultimately resulting in breaches and overtopping in Nawabshah, Sanghar, Mirpurkhas, and Badin.
LBO Spinal Drain Rehabilitation: The Irrigation department carried out the rehabilitation of the LBO Spinal Drain, and the Desilting of the Drainage system in Sanghar. Mirpurkhas and Badin.
After the revival of natural dhoras through the construction of siphons and the rehabilitation of the LBOD system, the excess load on the spinal drain will be alleviated. This will lower the spinal drain levels, providing unimpeded access to the main drains of the LBOD system, including the drainage networks of Nawabshah, Sanghar, Mirpurkhas, and Badin. The High Flood Level of the Spinal Drain recorded in 2022 was 27.53 feet. The top level has now increased by 4 feet, reaching 31.53 feet.
The CM said that several left-over areas, including Khipro, Umerkot, Dighri, Sindhri, and Tando Mohammad Khan, lack drainage systems. Consequently, these areas experience flooding during heavy rainfall.
Mr Shah said that once the dhoras are activated and rehabilitated, drainage systems for the leftover areas will be constructed and connected to the dhoras. This network will ultimately outfall Shakoor Lake, following the natural drainage route.
Social Benefits
According to Murad Shah the construction of syphons and rehabilitation of the LBOD system will mitigate the risk of flooding in surrounding areas, enhancing the safety and well-being of local communities. By addressing drainage issues, the project will protect agricultural lands from waterlogging and flooding, ensuring more stable and productive farming conditions, and supporting farmers’ livelihoods.
The CM said that enhancing drainage efficiency and reducing excess water will boost agricultural productivity, leading to higher crop yields and economic stability for farmers. Protect infrastructure by preventing blockages and breaches in the drainage system, saving costs on repairs and maintenance. The project improves natural drainage routes, lessens environmental impact, promotes healthier ecosystems through water diversion and enhanced drainage, and supports sustainable water management practices.
Those who spoke on the occasion included Irrigation Minister Jam Khan Shoro and MPA Arbab Lutuf.
Secretary Irrigation Zareef Khero played a documentary special made on LBOD, its issues and their resolution.
Earlier, the chief minister inaugurated LBOD Syphons to revive the old natural route of Dhoro Puran to Shakeer Dandha and the Spinal Escape Regulator at RD 210 and rehabilitation of Dhoro Puran up to Shakoor Lake. Minister Irrigation Jam Khan Shoro briefed the CM about the technical works carried out by the Irrigation department.