Drought in Central Texas
The 2010-2011 drought is continuing and its impacts on natural and water resources, agriculture, water supplies, rivers and spring flows, ecosystems and their flora and fauna continue to be documented. Therefore, this web page will be updated on a regular basis with regard to Central Texas water resources and related drought issues.
Drought is one of those natural phenomena described in every culture over the centuries. It’s also experienced differently – for example, the drought in Texas is known through the greatly reduced rainfall over the past year, reducing available water supplies for cities and creating extreme hardships for ranchers and agriculture. The current drought in a neighboring state, Louisiana, is experienced as reduced rainfall in the same year as major flooding; both conditions are affecting crops and water supplies.
Drought can be thought of as much lower than normal rainfall over an extended period of time, resulting in damage to crops and plants. Measurements of drought as defined by the National Drought Mitigation Center (NDMC) are mathematical indices, or numbers that represents thousands of data points over time. For drought planning, states and government agencies have found that a combination of indices can be most helpful. Here are a few indices from NDMC’s website:
• Percent of normal – dividing actual precipitation by a normal precipitation mean, or arithmetic average, x 100%. Useful for a quick reference but can be confusing as the precipitation patterns are typically median-based rather than a simple mean.
• Standardized precipitation index (SPI) – an index “based on the probability of precipitation for any time scale.” As the index can be used for different time scales, this index is considered versatile and is used for drought planning.
• Palmer drought severity index – a soil moisture calculation best suited for regions that are alike; used to monitor long-term wet and dry periods. A Palmer drought severity index map from November 12:
• Crop moisture index – a short-term index used to monitor weekly crop conditions
• Surface water supply index – indicator of surface water conditions across regions that change in topography and land uses
Overall, just over 65% of Texas is categorized as being in extreme drought conditions.
Recent NOAA forecasts indicate that the drought is likely to continue into the next year. Not only do Texans need to hone our water conservation habits during the drought, we need to think about the future. Texas’ population is projected to grow by 82% over the next 50 years (TWDB, “Water for Texas 2012”, Draft). The likelihood of cycles of droughts and flash floods continuing to stretch our water supplies is fairly high. Water management is something everyone can do at their home or business. Even more importantly, understanding climatic effects on water supplies needs to go beyond the current drought. Avoid falling into the hydro-illogical cycle!
Great resources for understanding and tracking drought: