The root cause of flood disasters
By Naseer Memon

Heavy rains in Balochistan at the end of June not only brought disaster to this province but certain districts of Sindh on its eastern border also received devastating flash floods.

Torrents from Balochistan entered Sindh through Khirthar hills and inundated vast areas in districts of Dadu and Shahdad Kot/Qambar. Thousands lost abodes and were marooned in deep ponds of water for several days.

Unprecedented gushing flood from Mula and Bolan rivers badly shattered the flood protection network and the MNV/RBOD network breached at several places bringing havoc to local communities. The floods once again exposed vulnerability of the drainage project executed by Wapda on the Right Bank of Indus.

A review of the disaster reveals that it was not a natural calamity but bad engineering and poor flood-management strategies wen e also responsible for it. The Irrigation: Department made best possible efforts but its handling of the situation was not up to the mark. . Knowing the climatic and topographic features of the area and the history of high floods, infrastructure building in the area required a more cautious approach.

Torrential floods in Sindh: Sindh province has two sources of flood. Riverine flood is more predictable and allows ample time to react whereas torrential floods leave almost no time to respond. Torrential floods have lesser frequency and duration but very high intensity and hence their impact is also severe. These floods normally occur in months of July and August when its catchment areas in Balochistan receive heavy rains. Western boundary of Sindh is connected with Balochistan through Khirthar hills.

A series of ferocious torrents including Mula, Boolan, Khanji, Mazarani, Dillan, Buri, Salari, Shole, Gaaj, Angai, Naing and Bandani bring gushing waters from high altitudes of Khirthar to ’kachhi’ plains of Sindh. This flood requires entirely different management systems, institutional capacities and infrastructure. High floods of 1942, 1944, 1948, 1956, 1973, 1975, 1976 and 1995 are reminders of this fact. The floods of 1976 and 1995 were huge in magnitude and caused greater devastation to the flood protection infrastructure and local communities.

Protection system: Before the construction of Sukkur barrage, its command area on the right bank had natural drainage channels to carry torrential floods into Indus River. A part of flow would drain through Main Nara Valley Drain (an old river bed) and would feed into the fascinating echo system of once Asia’s largest natural fresh water pond, Manchar Lake. In 1932, when the barrage was constructed, a 70 mile-long MNVD was shaped to car, a discharge of 2235 cusecs.

The MNVD banks also acted as flood protection barrier separating irrigated right bank areas of Sukkur command from hill torrents flood plain. The MNVD was later converted into RBOD by Wapda to drain effluent from four districts, which devastated Manchar Lake. At one stage Wapda was to connect RBOD with Indus River but it retreated after a lot of hue and cry by the civil society groups.

Flood protection work in the flood areas is much more vulnerable than the riverine flood protection work. In 1935, Flood Protection Bund (FP Bund) was constructed along the natural contours to facilitate North-South diversion of torrential flows towards Manchar Lake. The objective of this 172-mile long bund was to protect irrigated areas from flash floods and safe diversion of flood to natural pond at Manchar.

According to the Indus River Commission, flood protection bund has to be provided with a six feet ’free board’ above the recorded highest flood. In 1995, flood water overtopped the FP Bund at several locations and it was breached at more than 30 locations. However the restoration work just rehabilitated it to the pre-flood level and did not maintain the new free board of six feet above the 1995 flood level. Also its remodeling was completed to only 120 RDs d the remaining part of 100 RDs was not remodeled, which faced the recent flood impact. This fact was indicated in the Flood Fighting Plan for 2007 prepared by the Sindh Irrigation Department.

A Flood Diversion Bund has been provided to divert gushing flows of Gaaj Nai in Dadu district. The 6.4 miles long bund also protects FP Bund from the direct stroke of Gaj Nai. In super flood of 1995, this structure was badly damaged. This bund was later remodeled to preflood condition. However, no additional strengthening was provided if similar flood was to strike again. Luckily this year Gaaj did not bring its usual flow and the bund survived any major damage.

This year the flood came from the north-western boundary with Balochistan and hit the districts of Shahdad Kot/Qambar and later on Larkana and Dadu district. Mula and Boolan rivers brought the major flows, which breached FP Bind at RD 179,180,184 and 230. It set off a series of breaches and cuts and 34 breaches and cutes were recorded in MNV Drain. These breaches inundated several small and large villages and threatened Qambar and Shahdad Kot towns also.

A technical assessment is required to establish the role of the infrastructure and the management system responsible for this havoc. An assessment based on site visits, meetings with local communities, irrigation experts and civil society groups brought the following facts to light:

·         Effective early warning system is the key to manage flood disasters. Since torrential floods allow very limited time to respond, effectiveness of this system becomes even more important. There exists no flood warning system between Balochistan and Sindh provinces. Since Khairthar mountains receive flood from Balochistan, there should be a mechanism by which Balochistan can inform the Sindh government well on time to take necessary precautions.

·         Sindh Irrigation Department has only one gauge station at the mouth of Gaaj Nai in Dadu district. Flash flood from this point hardly takes 12 hours to reach mainstream areas. Even if the earliest warning is received, this duration is insufficient to manage any catastrophe in making. The modern weather forecast systems based on satellite information sources has made it possible to develop a fairly reliable flood warning system. It will definitely cost much less than what the government normally spends on repair of damaged infrastructure and relief and rehabilitation of devastated communities.

·         Environmental, economic and social cost of losses will further justify this much deserving investment. This can be gauged from the fact that after 1995 flood damages, strengthening of Gaj Diversion Bund at Gaj Nai and FP Bund cost about Rs700 million to public exchequer. Effective flood warning system will also help timely evacuation of vulnerable areas identified through careful mapping.

·         Infrastructure development in the flood plains is not being Tdesigned with prior understanding of natural flood routes. Irrigation experts believe that the road network in the area also obstructed the free flow of flood. Some local roads and Rato Dero-Khuzdar Motorway are aligned against the flood flows and have inadequate cross drainage provision, causing bouncing of flood water.

·         There is no mechanism whereby National Highway Authority or Provincial Highway Department seeks Irrigation Department’s advice on the road alignment in the ’kachhi’ flood plain. This lack of institutional networking is likely to cause more damage in future.

·         Wapda’s experiment of converting fresh water MNVD into a saline water channel of RBOD resulted in disaster for Manchar Lake. Now Wapda is undertaking several drainage schemes in upper reaches through RBOD-III for canalising effluent from Balochistan’s irrigated areas and drain it to the main RBOD drain.

·         A complex drainage network for Usta Mohammad areas is under construction and the EBOD is being connected to Hairdin drain and Chukhi through new drains under RBOD-III to be connected with main RBOD network.

·         However Wapda does not bother to involve Irrigation Department at local level to assess the potential threats which may stem through this drainage projects. According to officials of the Irrigation Department, such co-ordination is non-existent and if any consultation takes place, it is restricted to higher offices which have little understanding of ground realities.

·         Since Wapda executes federal government’s projects, it hardly gives any ear to the local irrigation departments, civil society groups and communities. Failure of LBOD should have been enough lesson to learn from but it does not seem happening. Local Irrigation experts believe that the designed capacity of RBOD-III is also insufficient to carry normal flows of the local drains let alone heavy storm water.

·         In recent flood Miro Khan and Shahda Kot drains experienced backflow since MNV was facing high flood. This could have inundated Shahdad Kot and Miro Khan towns. Likewise if Indus River receives heavy flood (above 700,000 cusecs), chances are high that it may choke RBOD-II at Bago Toro hills near Sehwan, which flows very dose to Indus River.

·         There is a need to address the misuse of water in head reaches of rice cultivation areas to reduce the quantity of drainage effluent. Irrigation system designed in British period did not require drainage because it was based on judicious supply in head and tail reaches; violation of which has created the problem. Addressing the root cause is more prudent rather than addressing effects, which Wapda is practicing since years.

·         Flood Control Plan for Sindh province was developed in 1978 and has not been revised since then. Whole landscape has undergone several changes over the years and living with three decades old flood management system indicates the prevalence of institutional bankruptcy. This needs to be revised based on the experiences of last 30 years and the new ground realities. Bund manual was also developed in 1978 and merits revision. 

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