![]() ![]() Historically they have been underestimated due to their. The opinions of the author are not necessarily those of Farm Futures or Farm Progress. Ephemeral streams, which are more extended than expected, entail a significant flood risk. Even though the Trump administration agencies have attempted to make WOTUS simpler, they have, I am afraid, created many lawsuits for the future.Ī version of this commentary appeared on Jin the online Farm Futures. What the new WOTUS rule attempts to be saying is that if the stream has dry channels and occasional puddles then a farmer or rancher has an ephemeral flow which would be excluded from WOTUS jurisdiction. You may remember candidate Trump made WOTUS one of his campaign themes. This act alone, as pointed out in earlier blogs, was an enormous grab of power against all landowners. Under the Obama administration’s earlier proposal, virtually any stream bed carrying water anytime of the year put that stream on your property under the jurisdiction of EPA and the Corps of Engineers. The plurality said “…a relatively permanent body of water connected to traditional interstate navigable waters.” EPA and the Corps of Engineers have attempted to clarify what is or is not a relatively permanent body of water. Supreme Court plurality attempted to describe what it believed to be a Water of the United States. Rapanos plurality decision in promulgating the three terms. Consequently, if a stream in the more arid portions of the country flows only in direct response to a rainfall then chances are this stream is ephemeral in nature and not subject to jurisdiction. The new WOTUS rule will not give government agencies jurisdiction over these brief storm events. You may have read of farmers and ranchers being subjected to lawsuits in the West because on occasion there was water in a streambed. Ephemeral flow “…may occur simply because it is raining or has very recently rained or it has recently snowed and the snow has melted.” Generally speaking, ephemeral flow is the result of precipitation. A SPA is an area upstream from a drinking water source or intake that contributes surface water flow to the drinking water intake during a 24-hour period. The last term that is not as tricky legally as intermittent is the definition of ephemeral flow. This analysis compared the stream length of intermittent, ephemeral, and headwater streams to total stream length within all mapped Source Protection Areas (SPAs) for each county. The Trump administration’s EPA even discusses melting snow as a sole or primary source of intermittent flow. Intermittent generally means a seasonal situation when the groundwater table may be elevated. The issue is trickier when a new definition of Waters of the United States (WOTUS) is examined for perennial, intermittent, or ephemeral streams.Ī perennial stream is defined “…to mean surface water flowing continuously year-round.” An intermittent stream in the WOTUS rule means “…surface water flowing continuously during certain times of the year and more than in direct response to precipitation.” This term is very tricky and may mean you have jurisdiction by EPA and/or by the Corps of Engineers or you may not. © 2019, National Ground Water Association.In an earlier blog, I discussed what is “not” a water of the United States. The observed and simulated values of the groundwater level at different river distances are consistent, and the model provides a new basis for multiyear simulations of groundwater level fluctuations in ephemeral stream systems. The results show that the improved GH-D2 model, which considers ephemeral streamflow, unsteady flow theory and the delayed response effect of groundwater level changes, performs well in simulating multiyear changes in the groundwater level in the ephemeral stream system. A follow-on case study revisits the site of a small highway bridge crossing an ephemeral stream in an arid area of Texas with little hydrologic information. To evaluate the performance of the models, the bias, mean absolute error, root mean squared error, Nash-Sutcliffe efficiency (NSE), and coefficient of determination (R 2 ) are calculated. The model is validated in the lower reaches of the Tarim River to simulate groundwater level fluctuations within the scope of influence of the river (300, 500, 750, 1050 m) over a 16-year period (2000 to 2015). In this study, an improved groundwater hydraulics (GH-D2) model is built based on the groundwater hydraulics (GH) solution of the 1-D Boussinesq equation to simulate multiyear changes in the groundwater level in ephemeral stream systems. Typically, the linearized solution of the one-dimensional (1-D) Boussinesq equation yields acceptable performance in simulating transient conditions over short recharge periods in ephemeral stream systems, but the ability of this solution to simulate multiyear changes in groundwater levels is limited. As a component of arid ecosystems, groundwater plays an important role in plant growth therefore, it is essential to use deterministic models to reconstruct the process of groundwater level change. ![]()
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