Prepared in Cooperation with: the Houston Galveston Area Council and the Texas Commission on Environmental Quality. By Lee Bodkin and Jeannette Oden

Transcription

1 Surrogate Relationship Development of Suspended Sediment and Total Suspended Solids Utilizing Turbidity and Streamflow Data in the West Fork San Jacinto River, near Conroe, Texas, July 2008 August 2009 By Lee Bodkin and Jeannette Oden Prepared in Cooperation with: the Houston Galveston Area Council and the Texas Commission on Environmental Quality 06/21/2011

2 Outline Introduction Study Area Methods Development of Regression Models Conclusions 2

3 Introduction The San Jacinto River Basin is a primary source of water for a large portion of the Houston area. Water-quality concerns include bacteria and sediment. Urbanization and surface mining can contribute to suspended sediment in streams and contribute to sedimentation in reservoirs. PURPOSE: document the relation between streamflow and sediment/tss concentration from July August 2009 PURPOSE: evaluate correlations between sediment/tss and monitored parameters 3

4 Study Area San Jacinto River (SJR) Basin is located in south eastern Texas and includes the East and West Fork SJR, tributaries, and coastal Bayous West Fork San Jacinto includes Lake Conroe (417,900 acre-feet) and Lake Houston (133,900 acrefeet) Focused reach West Fork SJR between HWY 105 and I-45 Major Tributary is Lake Creek Land use is primarily woody wetlands, with some developed open space and high intensity development. 4

5 Study Area 5

6 Approach Conduct initial reconnaissance using recently developed land-use maps to identify potential sources of suspended sediment loads along the West Fork San Jacinto River. Install and operate five parameter (water temperature, specific conductance, ph, dissolved oxygen, and turbidity), continuous waterquality monitoring stations at two existing USGS streamflow stations. Collect field parameters and suspended sediment samples from the two continuous monitoring stations approximately two times per month and during storm events. At the two continuous monitoring stations, relate in-situ water quality data and suspended sediment sampling results to develop surrogate relations to establish suspended sediment estimated values. From the estimated suspended sediment values, calculate suspended sediment load estimations. 6

7 Deployments 5-parameter water quality data sondes were deployed at each station providing real-time water quality data in 15 minute intervals. Parameters monitored included; water temperature, specific conductance, ph, dissolved oxygen concentration, and turbidity. Water quality monitor sondes were operated in accordance with the Texas Commission on Environmental Quality (TCEQ) protocols. Data was validated in accordance with TCEQ protocols. 7

8 West Fork San Jacinto at SH-105 8

9 Deployments 9

10 Deployments 10

11 West Fork at I-45 11

12 Deployments 12

13 Deployments 13

14 West Fork San Jacinto River at SH

15 West For San Jacinto River at I-45 15

16 Sample Collection Methods TSS samples were collected in accordance with TCEQ methods and procedures. SSC samples were collected in accordance with USGS methods and procedures. 16

17 Methods Sample collection occurred at both sites twice a month regardless of streamflow conditions. Sampling also occurred during streamflow events at both locations throughout the study period. The 5 auxilliary sampling locations were sampled up to 5 times during the study period during low-flow conditions. The 5 auxilliary sampling locations were also sampled up to 5 times during the study period during 17

18 West Fork San Jacinto River at SH

19 West Fork San Jacinto River at SH

20 West Fork San Jacinto River at SH

21 West For San Jacinto River at I-45 21

22 West For San Jacinto River at I-45 22

23 West For San Jacinto River at I-45 23

24 West For San Jacinto River at I-45 24

25 West For San Jacinto River at I-45 25

26 West For San Jacinto River at I-45 26

27 West For San Jacinto River at I-45 27

28 Sample Comparison 28

29 Sample Collection Data Station name USGS Site ID TCEQ Site ID Date Time Sample Type Discharge (cfs) Water Temperatu re (degrees celcius) Specific Conductance (µs/cm at 25 degrees Celcius) ph (standar d units) Dissolved Oxygen (milligrams per liter) Turbidity (formazin nephlomet ric units) Total Suspended Solids (milligrams per liter) Suspended Sediment Concentration (milligrams per liter) Sand/Fine Break (percent >.062mm) West Fork San Jacinto River below Lake Conroe near Conroe, Texas /5/ ER /16/ ER /18/ ER /19/ EE /23/ EE /6/ ER /29/ ER

30 Data Summary Using the S-Plus statistical package various surrogate relations were evaluated. The strongest surrogate relations were determined to exist between SSC and Turbidity and Streamflow data. The strongest surrogate relations were determined to exist between TSS and Turbidity and Streamflow data. All data was base-10 logarithmic transformed. 30

31 Regression Equations for West Fork at SH-105 Location West Fork San Jacinto River below Lake Conre, near Conroe, Texas (West Fork at SH-105), July 2008 August log 10 (SSC) = *log 10 (Turbidity) *log 10 (Streamflow) log 10 (TSS) = *log 10 (Turbidity) *log 10 (Streamflow)

32 Sediment Load Estimations For the study period 15 minute estimated SSC and TSS values were calculated using real-time turbidity and stream flow data. Those 15 minute estimated values were summed to give daily values, monthly totals, and study period totals. 32

33 Monthly Suspended Sediment Load Estimates for the West Fork at SH- 105 location Total TSS (Tons/15 minutes) Total SSC (Tons/15 minutes) July August September October November December January February March April ,047 1,793 May June July August Total (July August 2009) 1,895 3,538 33

34 Monthly Suspended Sediment Load Estimates for the West Fork at I-45 location Total TSS (Tons/15 minutes) Total SSC (Tons/15 minutes) July August ,475 September ,461 27,091 October ,680 2,860 November ,188 53,850 December January February March ,809 3,106 April ,218 60,390 May ,866 6,055 June July August Total (July August 2009) 72, ,064 34

35 Precipitation (inches) Important Climate Consideration More than 80 percent of all samples collected during a period of average to below average streamflow. Little variation in stream flow occurred during the study period Streamflow at HWY105 ranged from 0.30 cfs to 2,230 cfs (period of record range is 0 to 56,000 cfs) Streamflow at I-45 ranged from 16.0 cfs to 7,300 cfs (period of record range is 11 cfs to 115,000 cfs) Total Monthly Precipitation (inches) Normal Precipitation ( ) (inches) Month 35

36 Summary It is estimated that more suspended sediment is occurring at the West Fork at I-45 location than the upstream site. The equations generated during this study are site specific. A less than ideal sample set was collected during this time period due to the limited amount of variation in hydrologic conditions. More data points will be required to maintain these equations or improve their certainty at mid to high flows at both locations. 36

37 Questions Further Information Please Contact: Lee Bodkin 37