So far I have obtained the NHD data for the Trinity Basin. Below is a picture of the basin with locations of USGS stream gages obtained from the Trinity Basin River Authority.

I have attempted to use the Append_NHD Aml provided by the National Hydrography Dataset. The Append Aml is a program written in the ArcInfo Macro language. Its purpose is to link CUs  together so that they become one unit. The reasons for doing this is to eliminate any overlapping information that might be present in two adjoining CUs and to link the flow network of the units. The united units present a realistic view of the HydroNetwork. 

A problem was encountered because all information needed to process the Append Aml was not available. Most of the HUC units in the Trinity Basin were missing the Landmark Feature in their NHD datasets. The Append Aml needs all of the basic feature datasets to run. It was then discovered that the wrong decompression programs were used to unzip the files downloaded from the NHD. Only certain decompression programs open files that contain 0 bites of information. The Landmark Feature is a 0 bite file for most of the CUs of the Trinity Basin.

The next step now is to re-decompress the NHD datasets. Then the Append Aml will be run using two adjacent CUs. The network created using the appended CU will be compared to the network created by the unappended CUs. Once, a definite comparison is made the next step will be to determine a way in which to accurately determine the river locations.