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Sedimentology, Resource Conservation Methods and Environmental Policy of Irrigated Row Crop Agriculture in the Salinas V

Sedimentology, Resource Conservation Methods and Environmental Policy of Irrigated Row Crop Agriculture in the Salinas Valley, CA. Don Kozlowski May 2001. Background. 1972, Clean Water Act, Sect. 303(d) list & fix pollution via TMDL Salinas River listed as impacted by sediment

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Sedimentology, Resource Conservation Methods and Environmental Policy of Irrigated Row Crop Agriculture in the Salinas V

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  1. Sedimentology, Resource Conservation Methods and Environmental Policy of Irrigated Row Crop Agriculture in the Salinas Valley, CA Don Kozlowski May 2001

  2. Background • 1972, Clean Water Act, Sect. 303(d) • list & fix pollution via TMDL • Salinas River listed as impacted by • sediment • Beneficial uses & the Endangered • Species Act • 2001, still no TMDL for the Salinas • Salinas Sediment Study hired by • state for technical assistance

  3. Possible Sources • Natural processes • Recreational use • Mining • Urban/suburban • Grazing • Viticulture • Agriculture • 15% of area is row crop agriculture (165,000 ha) • 40% sediment of U.S. rivers from cultivated land • ag’s contribution to the Salinas River?

  4. Objectives Determine: • Typical sediment yields from row crop ag fieldsdue to irrigation and storm events during a season • Efficiency of a particular best management practice, the water/sediment detention basin

  5. Methods Site selection Catchment construction Filtration Recording and analysis

  6. Methods (cont’) • Create model that predicts field erosion • Determined from various event parameters • Upscale the field data to watershed scale • GIS model to get area & slope • Rainfall model • For detention basins • Compare sediment into basin to sediment out

  7. Results (15 events monitored: 9 irrigation, 6 rainfall) Erosion Analysis (example):

  8. Results (cont’) Erosion Model:

  9. Watershed Scale Erosion Estimates: Rainfall: 93 kilo-tonnes, 1.2 tonnes/ha Irrigation: 141 kilo-tonnes, 1.7 tonnes/ha Total: 234 kilo-tonnes, 2.9 tonnes/ha 60% of agricultural row cropland, slopes <2.3% Only a fraction of this made it to the Salinas River Still More Results CAUTION!! • Efficiency of Detention Basin • 100% for sand, at least 99% for silt/clay • 211mg/L max outgoing; 46,400 mg/L max incoming

  10. Discussion/Wrap-up • Agricultural land use produces a lot of erosion • Many BMP’s are in place • Detention basins appear to work well • Improvements: • Storm erosion dynamics, need more data • Slopes > 2%, need data • Rain model

  11. Acknowledgements • Farmers • SSS team (Thor, Wendi, Adrian, Alana, Bronwyn, Joel, Julie) • Mark Angelo, RWQCB • Bryan Largay, Monterey Co. RCD • NASA/EPA • Dr. Sharon Anderson • Dr. Lars Pierce • Dr. Fred Watson

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