Appendix B. Computation of Suspended-Sediment Concentration at North Santiam, November 6–7, 2006

The Mount Jefferson debris flow resulted in extremely elevated turbidity and suspended-sediment concentration (SSC) at North Santiam on November 6–7, 2006. When the recorded turbidity remained constant at the upper limit of the sensor range (about 1,600 FNU), the samples collected at the monitoring station provided the SSC data needed to estimate the suspended‑sediment load. The continuous SSC record was completed during these 2 days using a combination of sample SSC, turbidity-estimated SSC, and interpolation.

Table B1.Computations of suspended-sediment concentration at North Santiam (14178000), North Santiam River basin, Oregon, November 6-7, 2006.

[Station reference: Complete station name is in table 1 and location is in figure 1. SSC, suspended-sediment concentration; SSQ, suspended-sediment discharge; ft³/s, cubic foot per second; FNU, Formazin Nephelometric Unit; mg/L, milligrams per liter; min, minute]

Dateand Time	Streamflow(ft3/s)	Turbidity(FNU)	SSC(mg/L)	Method of SSC estimation or computation	SSQ(tons/30min)
11/6/2006 0:00	1,650	23	31	Point sample	2.9
11/6/2006 0:30	1,630	27	24	Meltwater-driven regression	2.2
11/6/2006 1:00	1,610	92	71	Meltwater-driven regression	6.5
11/6/2006 1:30	1,640	940	575	Meltwater-driven regression	53
11/6/2006 2:00	1,600	4,970	2,510	Point sample	225.7
11/6/2006 2:30	1,580	5,980	3,000	Point sample	266.4
11/6/2006 3:00	1,570	5,630	3,080	Point sample	271.8
11/6/2006 3:30	1,550	5,220	2,860	Interpolation	249.1
11/6/2006 4:00	1,550	4,820	2,640	Interpolation	230
11/6/2006 4:30	1,550	4,410	2,430	Interpolation	211.7
11/6/2006 5:00	1,540	4,000	2,210	Interpolation	191.3
11/6/2006 5:30	1,530	3,590	1,990	Interpolation	171.1
11/6/2006 6:00	1,510	3,180	1,780	Interpolation	151.1
11/6/2006 6:30	1,520	2,770	1,560	Interpolation	133.3
11/6/2006 7:00	1,520	2,370	1,340	Interpolation	114.5
11/6/2006 7:30	1,510	1,960	1,120	Interpolation	95
11/6/2006 8:00	1,510	1,550	901	Meltwater-driven regression	76.5
11/6/2006 8:30	1,530	1,500	875	Meltwater-driven regression	75.2
11/6/2006 9:00	1,490	1,570	912	Meltwater-driven regression	76.3
11/6/2006 9:30	1,510	8,160	4,850	Interpolation	411.6
11/6/2006 10:00	1,490	14,700	8,790	Interpolation	736.1
11/6/2006 10:30	1,470	21,300	12,700	Interpolation	1,049.2
11/6/2006 11:00	1,490	27,900	16,700	Interpolation	1,398.4
11/6/2006 11:30	1,480	34,500	20,600	Point sample, Extrapolation	1,713.4
11/6/2006 12:00	1,470	26,500	17,800	Point sample	1,470.5
11/6/2006 12:30	1,430	21,800	15,500	EWI Sample	1,245.7
11/6/2006 13:00	1,400	18,200	14,200	Point sample	1,117.3
11/6/2006 13:30	1,360	13,700	10,900	Interpolation	833.1
11/6/2006 14:00	1,350	9,160	7,640	Point sample	579.6
11/6/2006 14:30	1,320	6,920	6,140	Interpolation	455.5
11/6/2006 15:00	1,300	4,680	4,640	Point sample	339
11/6/2006 15:30	1,290	3,300	3,570	EWI Sample	258.8
11/6/2006 16:00	1,270	2,750	3,320	Point sample	237
11/6/2006 16:30	1,260	1,570	3,080	Interpolation	218.1
11/6/2006 17:00	1,250	730	2,840	Interpolation	199.5
11/6/2006 17:30	1,240	1,320	2,600	Interpolation	181.2
11/6/2006 18:00	1,230	1,090	2,360	Point sample	163.1
11/6/2006 18:30	1,240	1,040	2,270	Interpolation	158.2
11/6/2006 19:00	1,240	890	2,180	Interpolation	151.9
11/6/2006 19:30	1,250	890	2,080	Interpolation	146.1
11/6/2006 20:00	1,270	730	1,990	Point sample	142
11/6/2006 20:30	1,280	740	1,920	Interpolation	138.1
11/6/2006 21:00	1,300	650	1,840	Interpolation	134.4
11/6/2006 21:30	1,340	650	1,760	Interpolation	132.5
11/6/2006 22:00	1,390	580	1,690	Point sample	132
11/6/2006 22:30	1,460	580	1,860	Interpolation	152.6
11/6/2006 23:00	1,520	680	2,040	Interpolation	174.3
11/6/2006 23:30	1,570	760	2,220	Interpolation	195.9
11/7/2006 0:00	1,640	710	2,390	Point sample	220.3
11/7/2006 0:30	1,680	800	2,750	Interpolation	259.6
11/7/2006 1:00	1,750	910	3,100	Interpolation	304.9
11/7/2006 1:30	1,830	1,240	3,460	Interpolation	355.8
11/7/2006 2:00	1,960	1,530	3,820	Point sample	420.8
11/7/2006 2:30	2,100	1,290	3,980	Interpolation	469.7
11/7/2006 3:00	2,280	1,080	4,140	Point sample	530.5
11/7/2006 3:30	2,550	1,560	4,540	Interpolation	650.6
11/7/2006 4:00	2,790	1,170	4,940	Point sample	774.6
11/7/2006 4:30	3,000	1,610	5,530	Interpolation	932.4
11/7/2006 5:00	3,150	3,190	6,120	Point sample	1,083.4
11/7/2006 5:30	3,280	1,620	5,180	Interpolation	954.9
11/7/2006 6:00	3,400	1,380	4,250	Point sample	812.1
11/7/2006 6:30	3,570	1,210	4,120	Interpolation	826.6
11/7/2006 7:00	3,780	1,110	4,000	Point sample	849.7
11/7/2006 7:30	3,930	980	3,820	Interpolation	843.7
11/7/2006 8:00	4,180	890	3,630	Point sample	852.7
11/7/2006 8:30	4,350	1,080	3,460	EWI Sample	845.9
11/7/2006 9:00	4,590	1,400	3,520	Point sample	908
11/7/2006 9:30	4,860	920	3,881	Precipitation-driven regression	1,060.1
11/7/2006 10:00	5,090	880	3,693	Precipitation-driven regression	1,056.3
11/7/2006 10:30	5,310	910	3,834	Precipitation-driven regression	1,144.1
11/7/2006 11:00	5,570	1,100	4,741	Precipitation-driven regression	1,484.1
11/7/2006 11:30	5,850	1,410	6,261	Precipitation-driven regression	2,058.4
11/7/2006 12:00	6,040	1,540	6,911	Precipitation-driven regression	2,345.9
11/7/2006 12:30	6,300	1,150	4,983	Precipitation-driven regression	1,764.3
11/7/2006 13:00	6,450	1,070	4,596	Precipitation-driven regression	1,666.2
11/7/2006 13:30	6,590	990	4,213	Precipitation-driven regression	1,560.4
11/7/2006 14:00	6,720	910	3,834	Precipitation-driven regression	1,447.9
11/7/2006 14:30	6,800	880	3,693	Precipitation-driven regression	1,411.2
11/7/2006 15:00	6,870	940	3,976	Precipitation-driven regression	1,535
11/7/2006 15:30	6,820	760	3,133	Precipitation-driven regression	1,201
11/7/2006 16:00	6,770	690	2,812	Precipitation-driven regression	1,069.9
11/7/2006 16:30	6,670	640	2,585	Precipitation-driven regression	968.9
11/7/2006 17:00	6,620	600	2,405	Precipitation-driven regression	894.6
11/7/2006 17:30	6,520	510	2,004	Precipitation-driven regression	734.5
11/7/2006 18:00	6,450	420	1,613	Precipitation-driven regression	584.6
11/7/2006 18:30	6,350	360	1,357	Precipitation-driven regression	484.3
11/7/2006 19:00	6,300	370	1,399	Precipitation-driven regression	495.4
11/7/2006 19:30	6,300	380	1,442	Precipitation-driven regression	510.4
11/7/2006 20:00	6,200	310	1,148	Precipitation-driven regression	399.9
11/7/2006 20:30	6,080	340	1,273	Precipitation-driven regression	434.9
11/7/2006 21:00	5,970	340	1,273	Precipitation-driven regression	427.1
11/7/2006 21:30	5,900	300	1,106	Precipitation-driven regression	366.8
11/7/2006 22:00	5,730	290	1,065	Precipitation-driven regression	343
11/7/2006 22:30	5,600	280	1,024	Precipitation-driven regression	322.3
11/7/2006 23:00	5,480	300	1,106	Precipitation-driven regression	340.7
11/7/2006 23:30	5,370	290	1,065	Precipitation-driven regression	321.4
11/8/2006 0:00	5,240	220	782	Precipitation-driven regression	230.2