Drought in the Southern Appalachian Temperate Rainforest? Part 2


Part One of this series discussed the local impacts of drought. This week, we focus on how people’s perceptions of climate and weather influence how we designate droughts and manage their impacts. To start, we need to rethink the basic question, what is drought?

Drought is a normal, recurrent feature of climate, but the “Drought” we see in newspaper headlines is often a combination of three different definitions—meteorological, hydrological, and socioeconomic. Meteorological and hydrological droughts are designated in relation to purely physical phenomena. Meteorological drought is the degree of dryness in comparison to some average for the area in question and the length of the dry period. Hydrological drought refers to the effect of a rain shortfall on the entire hydrological system: the surface and subsurface water supply of an entire hydrological system. Meteorological drought is more about rainfall while hydrological drought is more about water supply. Since it takes time for rainfall to show up in surface streams, lakes and subsurface deposits, the onset of these two types of drought sometimes takes longer to come about.

The third type of drought is socioeconomic drought, which reflects how a society uses water and how sensitive people are to meteorological and hydrological droughts. An example from the US–Mexico border shows why it is important to consider rainfall and society together. During the early 2000s a multi-year meteorological and hydrological drought hit the Sonoran desert. When US citizens were asked about the impact of the drought on their daily lives, many responded: “What drought?” People on the other side of the border, however, experienced drought in their daily lives: crops were lost, animals sold off, and municipal water supplies dried up. Economic losses were large. The two sides of the border had the same amount of rainfall and have similar agricultural economies, but the sensitivity to drought on the Mexico side of the border was much higher than on the US side because people have varying access to irrigation and water rights in the US compared to Mexico and they manage and use water differently.

The structure of our local and regional economies and the way we use land directly affect our sensitivity to drought. They change the amount of water we need to sustain our lifestyles — for example, intensive agriculture and industry require large amounts of water. They also change the amount of water that can be stored in the local landscape — for example, forest vs. row crops account for very different amounts of water evaporating, running off the land, or percolating into the soil. From the perspective of water management, this is good news and bad news. It means that historical land uses shape today’s water supply, but it also means that what we do today can affect water supply in the future.

Coweeta LTER researchers have studied how forest management affects streamflow and water supply, demonstrating that forest cover contributes to increased “low flow” levels, which means that forests help maintain water supply during the dry season. Land cover and land use changes in forests, housing developments and roads decrease the amount of water that trickles into the ground by compacting or paving over soils, and this can reduce low flow. This is particularly relevant for Franklin water users because the water they drink comes directly from Cartoogechaye Creek.

Because water resources move across political boundaries, managing water resources requires careful study of what is happening upstream and downstream. Over the coming years, as water demand increases throughout the Southeast, it will be important to think carefully about the wide range of factors affecting Western North Carolina’s water resources including land use, forest conversion, water demand, water quality and watershed health.

Whichever definition we follow, drought becomes relevant for most of us when it begins to affect our daily lives. This may occur through water restrictions or increased prices. However, as we have seen, drought is not just a natural phenomenon. Water scarcity, prices, and restrictions result from the amount of water we use in relation to the available supply. Demand and supply are both factors that we can influence as individuals and as a community.

If you are concerned about the long term availability of clean water for humans and the environment, we encourage you to look for additional resources about what you can do on your land, at your business, and as a community to maintain a healthy watershed long into the future. Organizations like Trout Unlimited and the Land Trust for the Little Tennessee, and government agencies like North Carolina Cooperative Extension and the Soil and Water Conservation District all provide valuable information and assistance.

Do you have memories of a particular drought year or impact on your home or environment? We would like to hear your thoughts. Please send them to the email or postal address below.

 

This column is produced by members of the Coweeta Listening Project (CLP), a branch of the Coweeta Long Term Ecological Research Program. Views expressed here are not representative of the USDA Forest Service or the Coweeta Hydrologic Lab. Please share questions, comments, or suggestions for future topics at cwtlistn@uga.edu or Coweeta Listening Project, UGA, 210 Field St., Room 204, Athens, Georgia 30602.

 

Original Citation: The Coweeta Listening Project. Franklin Press. Column on "Science, Public Policy, Community." Page B4. Oct 19, 2012.