Terrain Drainage Research Articles

Terrain drainage in the landslide area on the Danube slope in Novi Sad

Terrain drainage in the landslide area on the Danube slope in Novi Sad

CFD model simulation of dispersion from chlorine railcar releases in industrial and urban areas

To assist in emergency response decisions and planning in case of releases of pressurized liquefied chlorine from railroad tank cars in industrial sites and cities, the FLACS Computational Fluid Dynamics (CFD) model has been used to simulate the transport and dispersion of the dense chlorine cloud. Two accident locations are studied: an actual railcar accident at an industrial site in Festus, MO, and a hypothetical railcar accident at a rail junction in the Chicago urban area. The results show that transport of a large dense gas release at ground level in an industrial site or large city could initially extend a hundred meters or more in the upwind and crosswind directions. The dense cloud may follow terrain drainage, such as river channels. Near the source, the obstacles tend to slow down the dense gas cloud and may constrain it and cause increased concentrations. Farther downwind, the obstacles may cause enhanced mixing and dilution once the cloud has grown larger. In some cases, significant amounts of cloud mass may become “trapped” in obstacle wakes for many minutes after the main cloud has passed. Although the CFD model can account for the details of the flow and dispersion much better than standard widely-used simple dense gas models, many similarities are found among the various models in their simulated variations with downwind distance of the maximum cloud centerline concentration.

The extraction of ordered vector drainage networks from elevation data

A data structure is presented for efficiently encoding the ordered vector representation of terrain drainage networks. A method is outlined for producing drainage networks from terrain elevation data using this data structure. The crucial elements in this method are the processes of converting raster drainage data into vector form, linking discontinuous data, and structuring the vector data to reflect the ordering of the drainage branches. Experimental results are presented using the method on actual elevation data produced automatically by machine and from maps (DMA DTED level one data).