Difference between revisions of "Carmel River Watershed: Don Juan Bridge to Highway 1 Flow Duration Analysis"
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* CSUMB-CCoWS Carmel Watershed Assessment | * CSUMB-CCoWS Carmel Watershed Assessment | ||
Revision as of 08:28, 5 March 2009
Hydrologic setting
The Carmel River begins in the Santa Lucia Mountains and flows through Carmel Valley to the Pacific Ocean. The Don Juan Bridge gage lies in the Carmel valley and serves as a Carmel River midpoint. The Highway 1 Bridge gage lies at the mouth of the Carmel River, several miles downstream of the Don Juan gage. A wide floodplain with generally porous and permeable soils lies between these 2 points. This area in general is classified as a recharge area [1].
Analysis
The flow duration curve (FDC) for the Carmel River indicates that at Don Juan Bridge, the river flows about 99.9% of the time and indicates perennial flow. 50% of the time, the Carmel river flows 10 m3/s or greater. 20% of the time, the Carmel river flows 100 m3/s or greater. The general smoothness of the FDC may be indicative of an unregulated flow regime.
The FDC for the Carmel River at Highway 1 has a smooth curve with a steep drop off indicating unregulated and uncommon flows with flow roughly 50% of the time. This gage is located in the lower Carmel watershed and considering the wide floodplain path from Don Juan Bridge to Highway 1, the Carmel River may have significant loss to infiltration.
Comparing the two curves, the Don Juan Bridge flow and Highway 1 flow have nearly equal duration curves with periods of very high flow ( >100 m3/s). There is a significant separation between both curves in periods of low flow (<100 m3/s). There is also a slight seperation during anomolously high flow periods ( >3000 m3/s ). These observations in combination indicate either:
- flow across the headwater only occurs during periods with high flow
- and/or, loss of flow due to diversion or infiltration during normal flow and anomolously high flow
The lower Carmel River goes dry annually due to heavy infiltration of surface waters to replace groundwater in the Carmel aquifer which is pumped for municipal use. The continuous flow of the Carmel River at the Don Juan Bridge stays non-zero and may indicate a source of flow that is unrelated to direct storm runoff. The Los Padres Dam lies upstream of this river and annually releases storage water during the summer months. Due to the mid-Carmel location of this stream gage, any regulations upstream may not be evident.
Summary
Based on visual comparison of flow duration curves, the Carmel River from Don Juan Bridge to Highway 1 appears to exhibit watershed processes such as:
- Streambed infiltration
- Managed Streamflow Sources
References
- CSUMB-CCoWS Carmel Watershed Assessment
