Let’s start thinking about water!

Cities sinking (land subsidence)

This article has been in the National and Texas press quite a bit over the last month. Ohenhen (could be a great name for a chicken farmer!) and pals investigated the extent and implications of land subsidence across the 28 most populous cities in the United States, including Austin, Dallas, El Paso, Fort Worth, Houston and San Antonio. Utilizing satellite-based interferometric synthetic aperture radar (InSAR) data from 2015 to 2021, the researchers produced high-resolution maps revealing that at least 20% of each city’s area is experiencing subsidence with Dallas, Fort Worth, and Houston experiencing the highest rates in the country at more than 5 millimeters (0.2 inches) per year. The authors attribute the subsidence to groundwater production.

I certainly expected Houston to be subsiding (right?) as well as El Paso, but Dallas and Fort Worth (and even San Antonio) caught me off guard given their perches on (relatively) firm ground. Dallas and Fort Worth shows close to uniform subsidence across the region, perhaps related to the wholesale depletion of artesian pressure of the underlying Trinity Aquifer where water levels have declined about 1,000 feet. Nationally, the study identified over 29,000 buildings situated in zones of high to very high risk for structural damage due to differential settlement. Ultimately, the study shows the need for targeted mitigation and adaptation strategies, including improved groundwater management and infrastructure resilience planning.

Lakes (and reservoirs) sedimenting

When my duties at the Texas Water Development Board expanded to include surface-water resources, I was surprised (I shouldn’t have been…) that reservoirs were not indefinite supplies of water: they slowly fill up with sediments (and them sediments is nasty). There are dams that allow for sediments to pass through the system, but (to my limited knowledge), we don’t have them. Zhu and crew developed a method to project future reservoir elevation-area-capacity (rating) curves by analyzing sedimentation patterns across 80 Texas reservoirs. They projected to 2080 (the current water planning horizon) to improve estimates of reservoir firm yields—a critical metric for water planning. Compared to traditional methods like the trapezoidal approximation, the new approach provides more conservative and elevation-specific estimates of capacity loss and yield reduction. They find that sedimentation distribution varies significantly by reservoir and elevation, and firm yield can decline disproportionately as capacity shrinks. While the method assumes constant sedimentation over each projection decade, the authors acknowledge that sedimentation rates and patterns may shift due to climatic or land use changes. The findings support more accurate and resilient regional water planning by providing simplified rating curves compatible with the water availability models.

Lower planetary albedo’ing

Temperatures in 2023 were a doozy, nearly reaching the 1.5°C above preindustrial levels that folks have been warming—I mean warning—us about. Regardless of the warning, the warming was unexpectedly early in the timeline. Why was that? Goessling and colleagues took a deep dive into answering that question. Using satellite and other data, the authors found an anomalously low planetary albedo—largely due to a sharp decline in low-level cloud cover over the northern mid-latitudes and tropics—as the primary contributor to the warming. This albedo drop led to increased absorption of solar radiation, explaining approximately +0.22 ± 0.04°C of the temperature anomaly. Other factors, such as El Niño and the solar cycle, contributed smaller amounts. The findings suggest that this albedo-driven heating may reflect an emerging feedback involving cloud dynamics and potentially reduced aerosol concentrations. If not due to internal variability, these trends could imply a higher climate sensitivity and a diminished carbon budget to stay below global temperature targets. Ironically (or tragically?), decreasing pollution via aerosols increases temperatures, and this study suggests there might also be a cloud feedback to further amplify impacts.