147 



siderable decline. The rise of the flood may occur in any of 

 the succeeding months up to and including April. There is a 

 predominance of flood movement in January as compared with 

 February, there being more instances in the former month of 

 movements exceeding 3 feet and culminations of floods exceed- 

 ing 10 feet than there are in the latter. What is popularly 

 known as a " January thaw " is probably the occasion of this 

 predominance. The rise of the flood is often very rapid, as, for 

 example, in 1881, 1883, and 1895, the rise in 1883 being over 11 

 feet in 8 days. These rapid rises often occur after heavy pre- 

 cipitation in winter months when the conditions favor a very 

 rapid run-off. The initial stages of the flood are usually less 

 precipitous, as are also the final stages preceding the culmina- 

 tion, especially at overflow stages, when the flood capacity is 

 greatly increased by the impounding action of the flood-plain. 

 The flood curve is rarely an even one, such as that of 1887, since 

 fluctuations of more or less importance occur, as a rule, during 

 both the rise and fall. A well-defined culmination is, however, 

 present, except in a few instances, such as in 1890, when three 

 about equal maxima appear. 



The maximum, of the flood occurs most frequently in the 

 latter part of March or the first part of April, though it may 

 appear as early as December, as in 1895, or as late as June, as 

 in 1889. Of the twenty-one maxima six have been in April, 

 five in March, three each in January and February, two in 

 May, and one each in December and June. The highest point 

 reached at Copperas Creek in 21 years was 19.25 feet in 1885. 

 The rises in excess of 10 feet above low water in the 21 years 

 have appeared nine times in April, six in June, five in March, 

 four in January, three each in December, February, and May, 

 and but once in November, while no fiood has reached this limit 

 in the remaining four months. The decline of the flood is much 

 less rapid than its rise, and is often marked by secondary rises 

 which more or less delay the return of the low-water period. 



The "June rise," caused by the heavy rainfall of that month, 

 is masked by the averaging process in the mean hydrograph, 



