SINCE Pakistan is located in a region prone to severe climate change impacts, the entire water sector management regime should be revisited in the light of the emerging phenomenon.

Climate change will have significant impacts on water resources in the region, requiring a review of all water engineering projects. Projects like large dams on the Indus River system must be based on a thorough understanding and research on climate change impacts.

This may call for searching more viable options for water conservation. Another dimension may be added to the conflicts on water distribution among the stake holders, if the right option is not exercised by policy makers.

Over the past three decades, the construction of new dams on the Indus River system has particularly been a major source of conflict between the upper and lower riparian. Sindh, the lower riparian, has been strongly opposing new dams on the Indus. It has argued against big dams because of their socio-environmental impacts on the province especially on flood plains and delta.

Sindh maintains that the Indus River system does not have enough water flows to divert for storage and that may ruin economy and livelihood of people in the province. Environmentalists in Sindh specially refer to massive degradation of riverine forest and mangroves eco system in the Indus delta.

Likewise riverine kutchha (flood plain) of Sindh has lost its prosperity due to depleting flows in the Indus. Forest, fisheries, agriculture and livestock, traditionally supporting rural economy of Sindh, has been ruined. Fresh water lakes in Sindh, which provide livelihood to hundreds of thousands of people, have been degraded and the situation is bound to aggravate further with the climate change.

Climate patterns take centuries to set in agriculture planning particularly dependent on the degree of accuracy of weather prediction. Frequency and quantity of precipitation define the water resource planning and management.

The Indus River is well known for its erratic flows and if climatic change makes it more unpredictable, the whole water engineering and management would merit cautious revision. The Water Vision 2025 of Wapda does not take climate change into consideration.

Wapda is planning to add 10,000 Mega Watt hydro-power through five mega projects by 2016. These include Bhasha, Kalabagh and Akhori. While Tarbela and Mangla dams are already loosing their capacity owing to heavy silting, newly envisaged dams are bound to meet the same fate as climate change has to result in generating even greater amounts of silt from the Himalayas in the coming years.

Most of the flows of the Ganges, the Indus and Kabul rivers are generated by snow melting from the Himalayas during the summer. The lifecycle of people and their livelihood in the region is dependent on the flow pattern of these rivers.

Agriculture, the major source of livelihood and the economy suffer in case of variations in the flow patterns. Unpredictability resulting from climate change on the Himalayas` snow buildup or melting have profound impact on these basins. According to “The Melting Himalayas”, a research report issued by the International Centre for Integrated Mountain Development (ICIMOD), “the Himalayas region, including Tibetan Plateau, has shown consistent trends in overall warming during the past hundred years.

Various studies suggest that warming in the Himalayas has been much greater than the global average of 0.74 degree Celsius over the last hundred years. Many Himalayan glaciers are retreating faster than the world average and are thinning by 0.3-1.0 m/year. The rate of retreat for the Gangotri over the last three decades was more than three times the rate during the preceding 200 years. Most glaciers studied in Nepal are undergoing rapid de-glaciations.

This trend of glacial retreat clearly indicates that the rivers will experience higher flows for initial period followed by continued decline. According to the same report, various climate change scenarios will have varied impacts on flow pattern. “One concludes

that with a two degree Celsius increase by 2050, 35 per cent of the present glaciers will disappear.”

The flow patterns in major rivers fed by the Himalayan melting would become more erratic in the years to follow. Typically designing of dam takes into account historical flow data and assumes that almost the same will be maintained in the subsequent years. This assumption will no more be valid due to climate change thus questioning the basic equations of dam feasibility.

A report of ICIMOD mentions that the temperatures on the subcontinent are likely to rise between 3.5 and 5.5 degree Celsius by 2100. Extreme weathers are likely to occur due to climate change. In case of unpredictably higher floods, the dam safety would be the biggest challenge. In exceptionally high floods, the dams can either burst or their backwaters may inundate areas outside its water boundaries. In both cases, loss of life and property can attain horrible proportions.

Defrost and heavy flows will bring more debris and can reduce the dam life by accelerated silting. The Himalayas are young mountains and their rate of erosion is very high. Changes in precipitation pattern will have impact on silt flows in rivers. The Warsak dam was completely silted and the Tarbela and Mangla are said to have lost almost one third of their capacity.

Technical Paper VI “Climate Change and Water” of the Intergovernmental Panel on Climate Change also highlights this fact. It reads “Generally the frequency of occurrence of more intense rainfall events in many parts of Asia has increased, causing severe floods, landslides and debris and mud flows.”

Similarly, low flows and droughts will also question the justification of investment of billions of dollars if the dams remain underperformed. Construction of new dams promises to bring more land under plough which requires additional investment in extension of irrigation network and land development. If the dams could not deliver what they promised, the whole investment will end up in generating new conflicts.