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O'JJtl)4. 23 SPECIAL INVESTIGATIVE WORK Special investigative work was undertaken to explore additional tech- niques which might be found useful' in providing basic data for present and future travel time -- transit loss studies. While it was fully realized that this work was of an experimental nature, we bel ieve it provided a great advan- tage in understanding in a practical way, the river's hydraulic properties. Because the final results and conclusions of this report would be dependent upon judgment and basic knowledge of the rIver, it was necessary to have first- hand field experience on the river. Personnel from this office walked, floated, and observed the Arkansas River more than a dozen times during the summer of 1970. The most intensive field work was conducted for the May 2, 1970, release from Twin lakes when six people from this office documented that release. In the course of the experimental work and general surveys of the river, visits were made to the various gaging stations along the river, both those of the State of Colorado and those of the United States Geological Survey. In the reach of the Arkansas River from Turquoise lake to the Nepesta gage downstream of the Colorado Canal, there are a total of 13 gage stations. Of these gages, five are maIntained by the State and eight by the U.S.G.S. In all of these stations, Stevens A-36 recorders are used, which are able to maintain records for periods up to one year. In the field, the State hydro- graphers check their stations once every two weeks and the U.S.G.S. hydro- graphers check every month. Of these 13 gage stations On the river, all are float operated, with the exception of three U.S.G.S. stations which have "bubblers", which are, in e8sence, airl ines subtrerged beneath the stream, pressurized by nitrogen bottles and which drive the recorder through a mercury manometer. Several times during the course of our investIgation, various gaging stations, both float and bubbler type, were found to be Inoperative due to icing or other mechanical problems. In most instances, we observed that the clocks maintained the records at a plus or minus one-half hour accuracy. However, in some instances a two and one-hal f to three-hour error was noted. Considering overall station installations and better than plus or minus five percent, and sometimes ten percent accuracy would be all that could be expected. Some of the State gages are checked once or twice daily to verify their operation. Some observations and conclusions reached are described beiow. One experiment involved dyeing the first slug of water released from Twin Lakes on May 2. These dye tests proved useful in demonstrating the translatory wave action at the front edge of the release hydrographi that is, it showed that the wave travels faster than the physical water released. It also demonstrated the rapid fill ing of side pools found occasionally along the river and some of the many I imitations of the use of the dye because of tur- bid water. Calculations based on wave travel time ~ersus dye travel time indicate that the wave travels approximately It times tiaster than the dye. It was observed before the reservoir release that the upper Arkansas had a comparatively clear water whereas the lower Arkansas, below Canon City, was turbid and had a high suspended sol ids content. In the clear reach of the river, it was poss ible to follow the advancing wave front by not ing where turbid water was encountered as the Increased stage in the river caused an increase in suspended sol ids. It took from two to three days for the river