HYDROLOGY OF NEW YORK 



171 



tory. The runoff of the Hoosic river is, without doubt, consider- 

 ably less than that of the main Hudson. The average precipitation 

 in western Massachusetts from 1887 to 1895, inclusive, was 38.98 

 inches, as against 43.29 inches in the northern plateau from 1889 

 to 1895, inclusive, a difference of 4.31 inches. Should such dif- 

 ference continue, the runoff of Hoosic river might be expected to 

 be, on an average, about 20 inches. Moreover, the Hudson river 

 above Glens Falls (catchment about 2800 square miles) is still 

 largely in forest — probably about 85 per cent — but on the catch- 

 ments of Wood creek, Battenkill and Hoosic rivers the proportion 

 of forest is very much less — as an offhand estimate, the writer 

 would say perhaps 20 to 30 per cent. The runoff of Schroon river, 

 which is perhaps 70 per cent of an equivalent to fairly dense 

 forest, is for four years 26.84 inches. There is, however, some 

 doubt whether this record is entirely reliable, and for the present 

 it is not intended to more than merely call attention to the gen- 

 eral proposition that this stream, which, issues from an imper- 

 meable catchment with 70 per cent of it in forest, has a rather 

 large runoff. The whole catchment area of the Upper Hudson of 

 about 4500 square miles, will probably not exceed 50 to 60 per 

 cent of forest. 



The following are the catchment areas of the several streams 

 here considered : Hoosic, 711 square miles ; Battenkill, 438 square 

 miles; Sacandaga, 1057 square miles, and Schroon river, 570 

 square miles. 



The Pequannock river in -New Jersey, not far from the New 

 York line, is an interesting case. This stream is characterized 

 by sharp slopes throughout its whole extent. Its headwaters are 

 at an elevation of about 1500 feet, while the mouth is only 170 

 feet above tide. The catchment is about 14 to 16 miles long by 4 

 to 7 miles wide. Mr Vermeule states that its headwaters lie in 

 the Precambrian highlands. The sharp slopes, combined with 

 small catchment area, undoubtedly account' for the relatively 

 large runoff of this stream. There is also an uncertainty of 1 or 

 2 inches in the rainfall record. The catchment is judged by the 

 writer to be 70 per cent forest. 



