- Monday, 17 April 2017 04:43
Conducted by Aisha Khan
Q: There are conflicting views on water availability in Pakistan. On the one hand we face water scarcity but on the other hand the absolute quantity of available surface waters remains the same. Can you explain the reason for this incongruity?
A: Water scarcity can be judged by two parameters: total amount of water available from different sources and number of water users. In Pakistan’s case, water becomes available through precipitation, only whether it is solid or liquid. Precipitation regime remained more or less unchanged over the span of a century, but the number of users (population) has increased by many folds. As the divisor is getting larger and larger, the per capita share is decreasing.
Q: From a scientific perspective, do we have reliable data on hydrology (atmospheric water vapour content, precipitation patterns, snow volume, glacial mass/balance, cryosphere and permafrost behavior, surface and ground water availability, aquifer storage and recharge capacity) to make informed policy decisions on how to cope with the changing environment?
A: So many indicators are placed together, that being a climatologist, I will be choosy to pick some of them. In most of the cases, long-term data is not available especially in cryosphere region. As temperature increases, the water vapour contents will ultimately increase because of enhanced evaporation. Both solid and liquid precipitation patterns have not permanently changed, however, they have been subjected to extreme variability over time and space. Increasing precipitation intensity is resulting into heavy downpour, flash flooding and urban flooding. Glacial mass balance studies conducted by PMD in some glaciated basins indicate alarming depletion rate. Surface and ground water resources are mismanaged.
Q: Observational records and climate projections provide us with ample evidence that freshwater resources are vulnerable to climate change. How will this hydrological imbalance between growing needs and shrinking supply sources impact societies and ecosystems?
A: Nature has blessed Pakistan with rich fresh water stocks in the form of the summer and winter precipitation. Most of our summer stock goes into waste; can’t we save it intelligently? Demand will further grow to feed the increasing population under warmer climate, yet we have to cater to that demand scientifically. Also, we have to improve our water stocks from 30 days to at least one year in the next two decades, because future projections reflect increased frequency of floods and drought.
Q: What are the main causes for changes in the large-scale hydrological cycle?
A: Hydrological cycle is composed of three processes vis-à-vis evaporation, condensation and precipitation. Heat energy operates this cycle. Due to increased concentration of Green House Gases (GHGs) in lower strata of atmosphere, more heat becomes available for intense evaporation of water reaching higher heights for condensation and then resulting into precipitation in the shape of heavy downpour. At the end of 2015, the concentration of carbon dioxide was 394 parts per million by volume, which has now crossed the critical threshold of 400 parts per million. The GHGs have great warming potential and their addition to atmosphere from industry, agriculture, transportation etc, has been increasing the air temperature.
Q: By the middle of the 21st century, the average annual river-runoff and water availability is projected to increase at high latitudes and decrease at mid latitudes. How will these hydrological changes affect Pakistan?
A: These projections of river runoff are directly linked with global warming, under which polar ice will melt faster and similar effects will be visible in HKH cryosphere much earlier. For rivers emerging from Asian High Mountains, climate projections indicate that flows will first increase, and then decrease. Ultimately, Pakistan may suffer adversely from this variable pattern of inflows from the cryosphere, which contributes 60% to 70% to the country’s river flows. Pakistan is already facing a too much or too little water scenario, and this may be further enhanced.
Q: What will be the impact of shifts in the amplitude and timing of run-off in glaciers and snowmelt-fed rivers on mountain communities and downstream population centers? What actions are needed to build resilience and reduce vulnerability?
A: The increased runoff from glaciated zones in combination with monsoon may exaggerate the riverine flooding downstream, while reduced flows will result in increased frequency and intensity of drought. Due to increasing temperatures, the snow/glacier melting will be accelerated, which may enhance glacial lake formation process. Glacial Lakes Outburst Floods, debris flow, landslides and avalanches are expected to be more common disasters for the mountainous communities. A detailed survey of the region by a multidisciplinary team should be conducted to identify the disaster risks, and their solutions should be adopted by involving the vulnerable communities. Training of communities on climate resilient adaptation would be highly result oriented.
Q: What are some of the adaptation actions that are critical to ensure conservation of water resources and efficient use of water?
A: Pakistan is located in an arid region where precipitation is far less than evaporation. Therefore, sufficient water stocks are necessary to supplement the deficit to meet the requirements of crops, animals, domestic and industrial users. That could be done through construction of small, medium and large reservoirs, which will recharge the ground water resources as well. Water metering and billing should be implanted as soon as possible and legislation on ground water extraction is also the need of the hour. Climate smart agriculture must be encouraged and promoted to save water from this major consumer sector. We must emphasize water management issues to reduce the floods and drought risk.