John H. Matthews
Director, Freshwater Climate Change at Conservation International
Water suffers from an awareness gap: many aspects of our food, energy, forestry, and health care securities intimately depend on freshwater, but these linkages are often ignored. When demand is low or water is plentiful, sloppy coordination usually has few consequences. But water resources are also among some of the most responsive aspects of the global climate system. I believe that one of the most difficult challenges for developing economies will be managing water resources in ways that do not make poor nations and communities poorer, generate international conflict, or trash freshwater and riparian ecosystems. In practice, this will mean that policymakers will have to build and operate water infrastructure to function under a much larger range of conditions than we can accurately predict today. And that also means that climate-sustainable water policy will need to be incorporated beyond the water ministry and merge into agriculture, energy, urban planning, health, and even foreign policy.
In March 2010 I visited eastern Nepal. Dirt roads followed small rivers up deep valleys, and we passed many new and under-construction hydropower plants. We got out and talked to the dam operators: are you producing as much energy as you projected? Who consumes your electricity? How is your river changing? Many new dams were producing significantly less electricity than had been predicted, and dam operators compensated by diverting more water than planned. In some cases, four kilometers of river below a diversion dam showed bone-dry stone. Since several dams were usually built back to back, once-continuous rivers alternated between small reservoirs and dry riverbeds. Why was this happening?
The primary reason is that mainstream water resource management assumes that flow and precipitation data gathered during planning stages accurately reflects past and future patterns. Climate change nullifies this assumption. Infrastructure that operated effectively for decades under this model is beginning to diverge from its intended climate. The Hoover dam in the USA’s Colorado river basin created Lake Mead in 1936, storing water for the city of Las Vegas and generating hydropower for the region. But in recent decades Lake Mead’s level has been dropping as the regional climate dries. The current level is only about 30 percent of capacity, which is maintained in part by diverting water from other rivers in the region. Hoover dam will likely become a monument for unsustainability for the many decades it will continue to stand.
While that dam took about 50 years to move out of sync with its climate, the rapid rate of climate change in Nepal means that dams there are in danger of diverging from the start of operation. Farmers told us that Nepal’s high elevations no longer accumulate enough snow in winter many years to maintain summer flows, and the rainy season has become more irregular, so bad dam design and management make everything worse. Only one permanent meteorological station exists in eastern Nepal, so historic data is mostly nonexistent. Yet pressure for development is high: the region around Kathmandu experiences 12 to 18 hours of rolling blackouts every day because of low supply. Worse, since these hydropower facilities are performing below capacity, the already-poor nation paying for this development is likely to require longer than expected. The livelihoods and ecosystems that have long coexisted in these valleys suffer as too much pressure falls on too little water.
Policymakers and operators globally need to know that precipitation patterns are changing and will continue to change for decades — probably centuries. Different ministries must communicate with each other that balance local communities with more distant energy and supply demands, using healthy ecosystems as the “scorecard” for sustainability. Lastly, we need to develop water infrastructure and operating rules that work sustainably under a much more diverse range of climate regimes. These are all achievable goals.