C150033 Contract

• Contract/PO #: C150033
• Contractor Name: North Fork River Improvement Association
• Contract Type: Grant
• Water District: 0
• County: Delta
• Bill Number: HB00-1419
• Loan Projects - Doc Type: Contract Documents

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Wolman grid measurements or grab samples. as appropriate
Ill. charactenze the grain-size distnbution of the main channel bed (\Volman gnd)
IV, use existing USGS water and suspended sediment gage records to examine
discharge and suspended sediment transpon regimes along the :\'onh Fork
Gunnison. including principal tributary inputs; 12 gaging stations relevant [Q this
effort have existed for differing lengths of time within the basin

The tasks listed above will allow us to develop a conceptual model of sediment sources
and sinks. and of channel dynamics through the past few dec2des. for the ~orth Fork Gunnison
River. Among the sediment SInks to which we will glve particular attention 1$ the Paonia
Reservoir. and we WIll undenake the tasks descnbed above for reaches both upstream and
downstream from the reservoir. This information will provide a basis for a second phase of the
study in v,'hich we develop a detailed. quantitative sediment budget based on sediment sampling
conducted with the US Geological Survey.

Once the second phase of the study is completed, we will be able to: (1) evaluate the
effect of Paonia Dam on sediment tranSpoll and storage along the :\ollh Fork Gunnison. (2)
compare periods of channel behavior (air photos) to measured flow regime (discharge records) to
evaluate the effects of high. and low-flow periods on channel stability. and (3) compare channel
reaches to identified sediment SOurces to evaluate the effect of spatially differing sediment supply
on specific channel reaches.

4) RIparian vegetation analysis. Cottonwood forests wli] be analyzed wIth t\....o separate goals in
rrand.
I. We will age cottonwood establishment on particular geomorphic surfaces
identified dunng the channel mappmg. The SItes chosen will be representative of
the range of landforms where cottonwoods establish In the study area. Agmg
establishment will help identify the time penod when surfaces stabilized enough
to allow nparian vegetation colonization. We wlil also age major lateral rootS on
cottonwoods in these sites. Typically fOllov,.mg a sediment burial event
cottonwoods adventitiously root into the new sediments. Thus. a set of ages from
major lateral roots can result 10 ages for sediment accumulatIon patterns on the
floodplain. These ages will help develop a more complete geomorphic plclure of
channel evolution. bar stabilization. vegetatIOn colonization patterns. and
sediment accumulatlOn rates and patterns.
ll. We will analyze the types of surfaces and modes of reproduction for cononwood
i-:: 6 5lUC.Y :-~~'::"'es of :~e \"c~c:-: c-:'rk valley. The goal IS to detennine the pattern
0( couonwood estaollsnment relatIve to large floods and other key hydrologic
processes, and whether establishment IS sexual \'1a seed or asex.ual via root
sorouting from cottonwoods Ih::!.! are already established. We will e'(~ltmne the

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es.abltshed. \\'~ C:1O examme for :?\:lmole. whether most eS!:lbh~hmem:s on the

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abandoned channels (ox bows). These analyses w1l1 pro\'lde a funcuonal