Quantifying Ground Deformation in the Los Angeles and Santa Ana Coastal Basins Due to Groundwater Withdrawal

We investigate complex surface deformation within the Los Angeles and Santa Ana Coastal Basins due to groundwater withdrawal and subsequent aquifer compaction/expansion. We analyze an 18 year interferometric synthetic aperture radar (InSAR) time series of 881 interferograms in conjunction with global positioning system (GPS) data within the groundwater basins. The large data set required the development of a distributed time series analysis framework able to automatically decompose both the InSAR and GPS time series into short‐term and long‐term signals. We find that short‐term, seasonal oscillations of ground elevations due to annual groundwater withdrawal and recharge are unsteady due to changes in seasonal withdrawal by major water districts. The spatial pattern of seasonal ground deformation near the center of the basin corresponds to a diffusion process with peak deformation occurring at locations with highest groundwater production. Long‐term signals occur over broader areas and are ultimately caused by long‐term changes in groundwater production. Comparison of the geodetic data with hydraulic head data from major water districts suggests that different regions of the groundwater system are responsible for different temporal components in the observed ground deformation. Short‐term, seasonal ground deformation is caused by compaction of shallower aquifers used for the majority of groundwater production whereas long‐term ground deformation is correlated with delayed compaction of deeper aquifers and potential compressible clay layers. These results demonstrate the potential for geodetic analysis to be an important tool for groundwater management to maintain sustainable pumping practices

Unconfined Aquifer Flow Theory - from Dupuit to present

Analytic and semi-analytic solution are often used by researchers and practicioners to estimate aquifer parameters from unconfined aquifer pumping tests. The non-linearities associated with unconfined (i.e., water table) aquifer tests makes their analysis more complex than confined tests. Although analytical solutions for unconfined flow began in the mid-1800s with Dupuit, Thiem was possibly the first to use them to estimate aquifer parameters from pumping tests in the early 1900s. In the 1950s, Boulton developed the first transient well test solution specialized to unconfined flow. By the 1970s Neuman had developed solutions considering both primary transient storage mechanisms (confined storage and delayed yield) without non-physical fitting parameters. In the last decade, research into developing unconfined aquifer test solutions has mostly focused on explicitly coupling the aquifer with the linearized vadose zone. Despite the many advanced solution methods available, there still exists a need for realism to accurately simulate real-world aquifer tests

Nucleo-cytoplasmic transport of proteins and RNA in plants

Merkle T. Nucleo-cytoplasmic transport of proteins and RNA in plants. Plant Cell Reports. 2011;30(2):153-176.Transport of macromolecules between the nucleus and the cytoplasm is an essential necessity in eukaryotic cells, since the nuclear envelope separates transcription from translation. In the past few years, an increasing number of components of the plant nuclear transport machinery have been characterised. This progress, although far from being completed, confirmed that the general characteristics of nuclear transport are conserved between plants and other organisms. However, plant-specific components were also identified. Interestingly, several mutants in genes encoding components of the plant nuclear transport machinery were investigated, revealing differential sensitivity of plant-specific pathways to impaired nuclear transport. These findings attracted attention towards plant-specific cargoes that are transported over the nuclear envelope, unravelling connections between nuclear transport and components of signalling and developmental pathways. The current state of research in plants is summarised in comparison to yeast and vertebrate systems, and special emphasis is given to plant nuclear transport mutants