Problem 9-1

Using a spreadsheet, calculate the regression constants, correlation coefficient, and standard error of estimate for the following paired low-flow series (annual minima):

Stream X		Stream Y
Flow		Flow
(m3/s)		(m3/s)
51		67
23		33
75		89
99		76
34		64
50		55
23		50
43		35
88		99
78		54
39		49
66		56
81		92
78		67
20		25

Problem 9-2

Program EH700B (Appendix D) solves the two-predictor-variable nonlinear regression problem (Eq. 7-45). Use this program (or put this equation in a spreadsheet) to determine the regression constants for the following data set:

Y			X1			X2
Time of Concentration			Hydraulic Length			Catchment Slope
(min)			(m)			(m/m)
65			2980			0.007
55			2567			0.009
76			2835			0.011
90			3391			0.008
29			1105			0.018
68			3003			0.009
105			5929			0.005
78			2920			0.011
45			2245			0.015
10			490			0.021
88			3305			0.008
33			1234			0.014

Problem 9-3

Calculate the regression constants a and b (Eq. 7-52) and correlation coefficient (Eq. 7-32) for the following 25-y frequency rainfall data:

Duration (min)			5			10			15			30			60			120			180
Intensity (mm/h)			17.5			10.5			7.5			5.5			4.5			3.5			2.5