142 



eludes two years of unusual drouth. The fact that the earlier 

 period is in a series of wet years and the later in one of dry 

 years will, it seems, tend to obliterate whatever contrast may 

 exist in the rate of the fluctuations. Thus the extent of the 

 fluctuations is much greater in the earlier period and the dura- 

 tion of high water is longer. The river was above the six-foot 

 level during 1,028 days in the first period, as against 709 in the 

 second; and it was above ten feet, that is at a stage of overflow, 

 645 days in the earlier period, and only 297 in the later one. 

 The dam at LaGrange, completed in 1889, raises the water 2 

 feet on the lower gage at Copperas Creek at the low-water 

 stage. Its effect at the stages above cited is not, however, 

 according to Cooley, perceptible at the upper end of the pool. 



The results of the tabulation do not reveal any alarming 

 changes in the flood habits of the river. There is, however, a 

 well-defined increase in the rate of movement in the later period 

 as compared with the earlier. The average daily movement 

 (above .25 foot) is in the first period .416 foot, in the second 

 period .492 foot,^ — an increase of 18%. The difference is still 

 more marked when the comparison is made in the rate of rise 

 alone. In the earlier period the rate of movement ( in excess 

 of .25 foot) was .4848 foot per day; in the later period it was 

 .592 foot; an increase of 22%. The distribution of this increase 

 through the year is somewhat irregular, and, owing to the in- 

 sufficiency of the original data, is probably of slight significance. 

 The greatest increase occurs, however, in the months of May, 

 December, September, and March, all months in which floods 

 prevail, or at least occur occasionally. 



As shown on previous pages the conformation of the valley 

 is such as to induce a prolongation of the floods. The records 

 and the hydrographs show that the decline from a rise is in 

 most cases much less rapid than the approach of the flood. We 

 find accordingly in the above table that the number of days of 

 decline (at a rate exceeding .25 foot per day) is considerably 

 less than those of rising waters, and that the rate of fall is also 

 less than the rate of rise, being only .3185 and .337 foot, respec- 

 tively, per day, in the two periods. The increase in the rate of 



