Plan for more drought

January 19, 2013

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Despite recent rains, many forecasters say that Texas may face another year of drought.

The record-setting hot and dry conditions recorded in the state over the past few years drastically reduced the flow of water (inflows) in tributaries that feed the state’s lakes and reservoirs. For example, in 2011 inflows to the Highland Lakes of Austin were the lowest of any year in recorded history.

Although 2012 began with areas of Texas receiving substantial rains, the year finished with months of drought. For instance, early rains added more than 20 inches of moisture to lakes and rivers of the Brazos Valley. But after a below normal April where only 0.5” to 0.6” of rain fell, the Brazos Valley once again began to go dry. In fact, many regions fell back into moderate to severe drought conditions. As of September 2012, more than three quarters of the state remained in drought.

In 2012, there was little change in the water reserves collected in underground aquifers, lakes and reservoirs. Legal battles developed over water rights, with everyone vying to protect his or her access to this precious resource. The Lower Colorado River Authority recently voted not to release water to downstream farmers. Lakes Travis and Buchanan, chief Central Texas reservoirs, are at 41 percent of capacity.

10- TO 15-YEAR DROUGHT?

Last September in a news report from KBTX.com, Texas State Climatologist John Nielson-Gammon said that Texas could be facing a 10- to 15-year drought.

What do other experts predict? The U.S. Drought Monitor says, “A persistently dry outlook for the southern High Plains is expected to exacerbate long-standing drought conditions in western Texas and southern New Mexico.”

A January statement from the National Weather Service’s Climate Prediction Center printed in the Waco Tribune-Herald said, “West Texas will likely be drier than usual, but Central Texas has an unremarkable 33 percent chance of drier-than-average weather. The outlook is more uncertain than usual because there is no strong El Nino or La Nina pattern this year.”

The La Nina weather pattern is credited as being the primary trigger of the 2011 Texas drought. La Nina is characterized by cooler-than-normal temperatures in the Pacific Ocean.

Since 1900, according to National Weather Service reports, every La Nina on record has resulted in below-normal rainfall for the Southwest United States. According to weather experts at Texas A&M University, there is no scientific consensus regarding whether La Nina is increasing or decreasing in frequency or intensity.

Climatologists also say that temperature is the best predictor of drought. Long-term global temperature increases were said to contribute to 2011’s record summer heat. Therefore, long-term predictions of increased drought frequency are driven by an expectation of increased temperatures rather than decreased precipitation. Higher temperatures speed evaporation in lakes and rivers.

If drought does occur, Texans will be faced with water restrictions. Gardeners are wise to prepare. Learn to recognize drought stress in trees and shrubs, replace water thirsty plants with those that are drought tolerant, collect and use rainwater and redesign landscapes and irrigation systems so that they are water efficient.

Signs of drought stress in trees is described by the Texas Forest Service as follows:

Water deficits have an adverse effect on many tree growth processes and can severely injure or kill trees. Also, stressed trees are prone to insect and disease damage. Symptoms in hardwood trees include curled, wilting or dropping leaves. Leaves may also turn brown along the edges or change colors. At night, plants may rehydrate and recover from temporary wilting. However, during prolonged drought, plants can become permanently wilted. Prolonged, permanent wilting usually kills plants.

Evergreen trees such as pines do not “wilt” from stress. In extended drought, pines may hold their needles up to two years, but the second year the needles will most likely turn yellow and begin to drop. Once the needles turn red, the tree is dead.

Stressed pines are often attacked by beetles or other insects that bore through the bark and lay eggs.

Hardwood or broadleaved trees such as oaks are not subject to attack from beetles, but drought takes its toll. Plants store food reserves in advance of the next growing season. Therefore, growth is affected by the previous year’s growing conditions.

TREE RINGS

The width of tree growth rings is greatly affected by the availability of water.

Drought-stressed trees may exhibit signs of dieback or decline. If roots are unable to supply adequate moisture and nutrients to the crown of the tree, the crown may die back.

To determine if a tree has died from drought stress or is simply dormant, try to break a few of the tree’s twigs. If they snap, break and appear dry, the tree may be dead. If the twigs bend and don’t break easily, the tree may be alive.

Next, use your fingernail to scrape bark from a small twig or branch. If the tissue under the bark is green and moist, the tree is still living. To be absolutely sure the tree has survived, wait until the next spring to see if the tree sprouts new leaves.

Resources: Texas Forest Service, AgriLife Extension, U.S. Drought Monitor, Austin American-Statesman, Waco Tribune-Herald, KBTX.com

For answers to your horticulture questions, please call the Texas AgriLife Extension, Hood County at 817-579-3280 and ask to speak to a Master Gardener or visit the website at hoodcountymastergardeners.org.

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Category: Horticulture Archived