![]() Overall, the percentage overlap of adult distributions during the baseline years and seedlings during the second year of the drawdown were 59% for Scolochloa, 22% for Phragmites, 38% for Typha, and 67% for Scirpus. This shift resulted in Phragmites australis seedlings being most abundant at 247.4 m, an elevation at which very few adult plants were found in the pre-disturbance coenocline. The net effect of this decline was that maximum seedling densities for most species were found at lower elevations during the second year of the drawdown. Seedling densities were much lower for Scirpus lacustris, Scolochloa festucacea, and Typha glauca during the second year of the drawdown ( van der Valk and Welling, 1988). No seedlings of Phragmites were found during the drawdown years (or subsequently) at the higher elevations ( Table 10.2). australis had a bimodal distribution, with maxima at 247.9 to 248.0 m and at 247.5 m. The largest discrepancy between seed and seedling distribution patterns was for Phragmites australis. The elevations at which seedlings of emergent species were most abundant during the first year of the drawdown were either higher (e.g., Scolochloa festucacea) or lower (e.g., Typha glauca) than the elevations at which their seeds were most abundant. Because the pre-disturbance distribution of their seeds was over a wider range than the post-disturbance distribution of adult plants, seed distribution per se did not affect the final distribution of the dominant emergent species along post-disturbance coenoclines. During the baseline period, adult populations were most abundant at higher elevations ( Phragmites australis and Scolochloa festucacea) or lower elevations ( Scirpus lacustris) than their seeds in the seed bank. Secondary dispersal by wind and water currents had a significant impact on the distribution of seeds of all species along the coenocline in the Delta Marsh ( Pederson and van der Valk, 1985). Seed densities were highest for most species at 247.5 m, the water's edge. Seeds of the four dominant emergents were found over a wider elevation range than adults of the same species. Only data for the cells in the normal treatment are presented for the reflooding years. The elevations with the highest relative abundances are given in bold. Thus, the presented method is a promising tool with which to estimate parameters of aquifer heterogeneity, in particular variance and horizontal correlation length of log-transmissivity fields from steady-state pumping test measurements.A Relative abundance is based on areal cover during the baseline years and relative number of seeds, seedling, or shoots per unit area during all other years. Multiple pumping tests conducted at different locations within an individual transmissivity field are analysed, making use of the effective well flow solution to show that all statistical parameters of aquifer heterogeneity can be inferred under field conditions. The effective well flow solution reproduces the drawdown for two-dimensional pumping tests in heterogeneous media in contrast to Thiem's solution for homogeneous media. Interpretation of ensemble mean drawdowns showed proof of the upscaling method. For comparison with the effective well flow solution, virtual pumping tests are performed and analysed for both cases, the ensemble mean drawdown and pumping tests at individual transmissivity fields. The analytical form of the solution allows inversely estimating the parameters of aquifer heterogeneity. The so-called effective well flow solution is derived for two cases: the ensemble mean of pumping tests and the drawdown within an individual heterogeneous transmissivity field. Based on this approach, an analytical solution for a steady-state pumping test drawdown is deduced. Such a model is provided by the upscaling procedure radial coarse graining, which describes the transition of near-well to far-field transmissivity effectively. An effective description of transmissivity is required, being a function of the radial distance to the well and including the parameters of log-transmissivity: mean, variance, and correlation length. ![]() In contrast to mean uniform flow, pumping test drawdowns in heterogeneous media cannot be described by a single effective or equivalent value of hydraulic transmissivity. A new method is presented which allows interpreting steady-state pumping tests in heterogeneous isotropic transmissivity fields.
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