'Silt deposited in Tarbela has caused loss of 8,000km2 land along delta' An interview with Dr Hasan Abbas, UNESCO Water Chair at COMSATS University

Dr Abbas holds a PhD in Hydrology and Water Resources from Michigan State University, USA; and a Masters in Hydrogeology and Groundwater Management from University of Technology, Sydney. His career in hydrology has taken him across various regions such as Australia, Middle East, North America, in addition to his work on Indus River Basin domestically.
He is known for his extensive research and industry experience in water resources evaluation; hydrological field investigations; climate change; environmental instrumentation & systems modelling; hydrometery; civil engineering works; GIS applications; geophysical/spatial surveying; glacial geology; and groundwater modelling.
In 2014, he established UNESCO Chair of 'Knowledge Systems for Integrated Water Resource Management' in Pakistan. Currently he is the founding Chairman of ZiZAK (Pvt.) Ltd. - an organisation which generates 'knowledge products' for integrated environmental systems.
BR Research recently down with Dr Hassan in Islamabad to pick his brains on the ongoing debate on management of Pakistan's water resource economy, including the debate surrounding water shortage and the 'dam' question. Below are the edited excerpts of the conversation:
BR Research: Let's start with basics. Given the increasing volatility in weather systems, it is believed that mega-dams are most suited to serve the dual purpose of flood control while also generating cheap hydroelectric power. What is the reason for your opposition to mega-dams?
Dr Hassan Abbas (HA): In 1994, WAPDA published a report on Jhelum floods of 1992, which is a good case study on the futility of large dams for flood control. It noted that any flood control by mega-dams such as Tarbela and Mangla is incidental, as they have primarily been built for hydropower and storage.
At the time of 1992 floods, these dams were already full, and the floodgates had to be opened when a cloudburst took place, causing a deluge in Jhelum valley which resulted in widespread destruction.
World over, flood control dams are purpose built, as their objective is to break the peak and slowdown the velocity of the torrent. Thus, they are always kept empty so that the intensity of flood may be absorbed by the dam's lake/reservoir, and then only release water in a controlled manner.
BRR: Why not simply expand the lake capacity of existing dams?
HA: Two reasons. First, expanding dam lakes is an expensive business. It is crucial that any technical proposal is accompanied with feasibility; otherwise no matter how sophisticated and fitting any proposed solution may be, it is essentially irrelevant.
Second reason connects back to my earlier point. The stated purpose of existing mega dams in WAPDA laws is to store water for irrigation and hydropower generation. In case the dam is already full at the beginning of monsoon in July, water cannot be released simply in anticipation of more rain/flooding in following months. Because if weather systems behave against expectations and there is no rain in late monsoon, water needed for irrigation during remainder of the year would already have been released.
Dam advocates, whether in the water sector or among politicians, promise that proposed dam structures such as Diamer Bhasha would fulfill all purposes, when in fact flood control and storage for irrigation/power conflict with each other.
BRR: But the same advocates also argue that dams can help manage the seasonality of environmental flows to the sea, which is a major cause of concern for ecologists and environmental activists such as yourself?
HA: Environmental flows are a part of natural climatic systems that precede modern day dam construction. Let's consider the case of environmental flows in Indus River Basin. Indus is the second most silted river in the world after China's Yellow River. Geologically speaking, the mountains where Indus originates are very young and in a state of high erosion, which increases the suspended load of the river. And this has continued for at least 20 million years, long enough to allow native sea-species to adapt to the high level of silt flows.
As late as until 1830s, high flows in the river would deposit large sand grains into the sea, causing sea to retreat and allowing land gain along the mouth of the river. This, in effect, was reverse of sea intrusion that we see today.
Ever since storage of water in large reservoirs such as Tarbela and Mangla began, silt began to accumulate on the bed of dam lakes/reservoirs. Now, controlled environmental flows that are allowed to flow into the sea, are virtually silt-free. In addition, the wave action from the sea causes land erosion, which environmental flows are unable to counter in absence of silt.
Second, variation of low and high flows. Natural low flows bring fine clay that is deposited into the delta and replenishes the mangroves. Water storage in artificial reservoirs disturbs the seasonality of both high and low flows, which are both equally needed by the ecological system that has evolved over millions of years.
Silt that has accumulated in Tarbela over last 40 years is equivalent two million acres of land lost to sea.
BRR: If dams are not the answer, how else can Pakistan address the spectre of water scarcity?
HA: Using decline in per capita availability of water over time as an indicator of water scarcity is a flawed approach. Water is a finite, natural resource. As population increases over time, its per capita availability is bound to fall.
Instead, countries in developed world use 'water per person requirement' approach, which places per day requirement of water anywhere between 20-150 gallons per person. This also includes water used for communal and commercial purposes. Note that the conservative estimate comes from Japan, whereas the generous upper limit is used as a reference rate in some states of USA.
Even if we put our national requirement at 40 gallons per day per person - a reference rate used by WASA - it translates into just 65 cubic meters per capita per annum. Compared to absolute water scarcity levels defined at five hundred cubic metres per capita, water availability in Pakistan continues to be in great abundance. In order to serve the water requirements of 220 million people, annual national water requirement would be between 5-20 million-acre feet (MAF), depending upon whether you rely on the conservative or more generous reference daily requirement.
BRR: Does this include the requirement of agriculture sector as well?
HA: At present, up to 105MAF water is diverted to agriculture sector annually, out of the 140MAF on average received as renewable freshwater resource.
BRR: Does the estimate of 140MAF also include groundwater resources?
HA: No, it only includes water diverted by dams and barrages to feed canal irrigation system. The number reflects water flows measured at rim stations on the river where the water flows from the mountains into the system.
BRR: But the actual surface water availability estimated in official Economic Surveys places average annual surface water availability between 90 to 105MAF.
HA: Actually, that's just the water that goes to service agriculture sector's requirements. The rim stations at Kabul River, Warsak, Tarbela, Mangla, and Chenab, places average annual flows between 135 -140MAF. Interestingly, if you were to add annual precipitation below the rim stations and adds flows from Ravi and Sutlej, annual surface water availability would be 145-150MAF.
BRR: Conflicting estimates of environmental flows required to stop seawater intrusion exist, from 10-25MAF. What is your view?
HA: As I hinted before, protecting mangroves and delta from seawater intrusion is not simply a question of volume of environmental flows required. It's also a matter of maintaining the seasonality and velocity of low- and high- flows, which artificially controlled systems of dams fail to replicate. So, let me attempt to answer your question in another way.
Out of the 35-45MAF surface water available after canal diversions, it is estimated that up to 25-30MAF water is accounted for by 'system losses', a term used an obfuscation for environmental flows (but also includes surface evaporation). If 25MAF already flows into the sea and is yet unable to stop seawater intrusion, how can it be claimed that flows of 10MAF would be sufficient?
The problem with 'so called experts' is that they come up with a project proposal, and then conduct research studies accordingly to derive desired results.
BRR: Even so, excluding agriculture sector, what is your estimate of population-based consumption?
HA: Net of 105MAF diverted to agriculture sector and 25MAF environmental flows, average water availability for all other domestic, communal, commercial and industrial uses is anywhere between 15-20MAF. This is more than adequate considering daily per capita requirement of 40 gallons as explained before.
BRR: By that token, if water availability is sufficient in absence of many large reservoirs, what explains the increased noise surrounding water shortage?
HA: The noise surrounding water shortage is a reflection of tail-end farmers increasingly receiving lower quantities of water that fails to service their farming needs. Consider that the flood irrigation still in use in Pakistan was invented ten thousand years ago in Mesopotamia and ancient Egypt. Beyond the modification of 'barrages', which were conceived by the British and gave us our 'perennial' canals', no innovations have been made.
BRR: In absence of literacy in rural regions, do you believe traditional small-scale farmer is ready to embrace modern irrigation methods?
HA: Our urban biases have forced us to believe that 'illiterate' farmers are not prepared to handle innovation. In order to test whether this argument carries any weight, just check the familiarity of today's farmers with cell phones and WhatsApp-based communication.
BRR: Granted. But many progressive farmers in the country have managed to push crop yields at par with developed world. Generally held view is that inefficient growing and irrigation practices of traditional small-scale farmers are to blame for Pakistan's abysmally low average crop yields?
HA: Let me just first note that given current levels of farming output, annual water requirement of Pakistan's agriculture sector should be no more than 20MAF.
Having said that, why does the traditional farmer use water inefficiently? Because farm markets fail to offer adequate financial returns to growers.
Farm markets fail to compensate farmers adequately because they were designed by the British with the objective to target levels of output that met colonial requirements, irrespective of how those production targets were met.
Consider that the British era laws define 'water theft' as 'misappropriate use of water' instead of as a felony, liable to be punished by payment of a fine deposited into the government's treasury. While the colonial rulers were able to extract their desired production levels from this system which took a lax view on water theft, the tail-enders not only suffered loss of water but was also not compensated monetarily.
Our failure to amend colonial era laws has only exacerbated the exploitation resulting from this extractive system since independence. The problem then is of inequity in water resource distribution, and not of shortage. However, this is obfuscated in media as a challenge of resource scarcity.
This, as I have explained, could not be further from the truth.