............ Current Research 

Current Nutrient / Sediment Research: 1992-93 Activities 
(1994, 1995 and 1996 updates to come in future) 

Research Methods 
The water quality component of the South Tobacco Creek study began in 1992 with the establishment of monitoring sites in the headwater portion of the basin (Twin Watersheds) and at the watershed outlet near Miami (Figure 1). 

Click below on the red star for more information about the Miami or Twin Watershed site.
Miami Site  - back to map
A monitoring site at the outlet of South Tobacco Creek near Miami provides a gross basin estimate of non-point sources to the Red River downstream.  Samples are collected at this site on a flow-event basis for the purpose of determining nutrient and sediment loads. 
This station monitors and records water levels in the South Tobacco Creek.
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Twin Watersheds Site - back to map 
The Twin Watersheds are adjacent catchments sharing a common divide and consisting of a West (4.24 ha. or 10.48 ac.) and an East (5.64 ha. or 13.94 ac.) drainage area.  The basins have only slight differences in topography and other physical attributes. 
Twin watershed views. 
Below is the west watershed V-notch weir looking east.
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Below is the east  watershed V-notch weir looking north.
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Detailed Twin Watershed topography.
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Both Twin Watershed basins are monitored to record and sample flow events at the outlets of the West and East weirs.  When flow (from snow melt or rain) occurs at either weir samples are collected for analysis of :
...1. nutrients
...2. major ions
...3. suspended sediments
When possible, additional samples are collected at other points within the basin to help understand the erosion and nutrient transport processes. 
 
Nutrient / sediment sampling at the west weir.
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Initially, the West and East basins underwent a calibration stage, being subject to similar management practices (conventional cultivation).  After sufficient comparative water chemistry and sediment data were gathered, conservation farming practices were established in one watershed.  The resulting water quality is now being compared with that of the unaltered watershed. 

1992-93 Results Twin Watersheds: 
Spring Runoff 

Spring snowmelt runoff samples were collected in 1992 and 1993 and charted below. 
 

Figure 2.  Dissolved and Particulate Nitrogen at West and East Weirs 
of Twin Watersheds for Snowmelt and Runoff in 1992 and 1993.
fig_tot_nitro2.gif

The portion of dissolved nitrogen levels were significantly higher in 1993 than in 1992; some samples exceeded 15 mg/L, and this may have been due to the application of Anhydrous ammonium fertilizer in the Twin Watersheds during the fall of 1992 (Figure 2). 

Total phosphorus concentrations in the 1992 and 1993 spring runoff samples were similar.  Like nitrogen in 1993, a high proportion of phosphorus was in the dissolved form (Figure 3).
 

Figure 3.  Dissolved and Particulate Phosphorus at West and East Weirs
of Twin Watersheds for Snowmelt and Runoff in 1992 and 1993.
fig_tot_phos.gif
Note: 
Nutrient analysis of data collected during a snow collection experiment during the winter of 1994 indicated that airborne matter arriving via precipitation supply an insignificant amount of nutrients as a proportion of total spring runoff loading.  It is apparent that natural soil-water interactions regulate nutrient levels in the Twin Watersheds. 

Snow sampling and analysis at the Twin Watersheds confirmed that water quality is primarily affected by soil-water interactions, not airborne matter carried via precipitation. 
 

Establishing snow monitoring course and collecting snow samples at Twin Watersheds site. 
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Summer Storms 
A rainstorm on July 24, 1993 provided the only significant rainfall in the Twin Watersheds during this research period.  Because automatic sampling apparatus failed, manual collections were conducted.  Table 1 provides a summary of those findings: 
 
Table 1: July 24, 1993 Twin Watershed Rainfall Event
Parameter West Weir East Weir  TW Confluence
Total Nitrogen 1.02 mg/L 1.14 mg/L .96 mg/L
Total Phosphorus .5 mg/L .57 mg/L .47 mg/L
Sediment 38.0 mg/L 51.0 mg/L 76.0 mg/L
pH 7.1 7.1 7.1
Total nitrogen levels were 1.02 and 1.14 mg/L at the West and East weirs respectively.  The dissolved proportion accounted for nearly half of total nitrogen in each sample.  At the confluence of the Twin Watersheds, total nitrogen was slightly less concentrated (.96 mg/L, with 53% dissolved.) 

Total phosphorus values were roughly one half of nitrogen levels (.50 and .57 mg/L respectively), with 70% of those levels being in dissolved form. 

During the July 24 rainstorm, the Twin Watersheds displayed similar aqueous chemical characteristics, and it is hoped that both the West and East sides will continue to demonstrate similar chemical output, establishing an acceptable control scenario for future research. 

Spring Runoff 
Both the 1992 and 1993 spring runoff events were monitored for sediment concentration and water chemistry at the monitoring station on South Tobacco Creek near Miami. 

Two nitrogen samples were collected during 1992, with four samples during 1993 (Figure 4).  Most Nitrogen was in particulate form during the initial year, with dissolved N being dominant in 1993. 

Figure 4.  Dissolved and Particulate Nitrogen near Miami 
for Snowmelt Runoff  in 1992 and 1993.
The 1992 and 1993 total phosphorus values were generally within similar concentrations.  Similar to N, 1992 P values were predominantly particulate, and 1993 levels were mainly dissolved forms.  
Figure 5. Dissolved and Particulate Phosphorus near Miami 
for Snowmelt Runoff in 1992 and 1993.
While 1992 pH levels remained within a relatively narrow range, 1993 spring runoff pH ranged between 7.3 and 8.0. 

Summer Storms - Three Rain Events 
Three summer rainfall runoff events were monitored in 1993 for sediment concentrations and water chemistry at the Miami Station.  Comparing nitrogen and phosphorus values to South Tobacco Creek stream flows, some insight is provided regarding the relationship between particulate and dissolved nutrient levels (Figures 6 and 7). 
 

Figure 6. Nitrogen and Flow near Miami for 1993 Rainfall Events.

 
Figure 7. Phosphorus and Stream Flow near Miami for 1993 Rainfall Events.
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For all but one Miami station runoff sample, nutrients were largely associated with suspended matter (particulate).  This contrasts significantly with the observations at the Twin Watersheds (discussed in previous section), where sediment concentrations were relatively low and nitrogen and phosphorus were mostly in the dissolved phase.  These findings may be an indication that the sediment load observed at Miami is partly the result of stream bank erosion occurring in the South Tobacco Creek during high flow events.  However, additional monitoring will be required to confirm this hypothesis. 

For the May event, both nitrogen and phosphorus exhibited a "flow-dilution" relationship where nutrient concentrations decreased over time).  The June 8-9 event did not display a flow concentration relationship for N, largely due to a suspiciously high third sample (a possible sampling error).  However, phosphorus did display a noticeable trend - with peak concentration coinciding with peak flow - indicating a flow-drive relationship.  Additional data will be required to confirm this observation.  Concentrations of N and P in  June runoff water were higher on average than for other events monitored during 1993. 

Total nitrogen, present largely in particulate form, generally followed a flow-drive relationship during the July rain event, with N concentrations changing in direct proportion to stream flow.  Dissolve nitrogen remained constant.  A flow-drive relationship was also evident for Phosphorus. 
 

More water flow, more nutrients, more sediment.
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