Water Resources Research Act Program

Details for Project ID 2004CO99B

Salt Chemistry Effects on Indirect Field Salinity Assessment in the Arkansas River Valley, Colorado

Institute: Colorado
Year Established: 2004 Start Date: 2004-03-01 End Date: 2005-02-28
Total Federal Funds: $2,735 Total Non-Federal Funds: $5,472

Principal Investigators: Grant Cardon, Grant Cardon

Project Summary: Salinity in the Arkansas River Basin is causing decreased productivity; with potential salinity sources being, geologic, waterlogging, urban and agricultural return flows. However, there is little chemical soil data to describe accurately and specifically, the type of salinity. Field observation suggests that the primary soil salinity is calcium-based (gypsum or calcite), and this type of salinity may be a factor in the difficulty of calibrating electromagnetic induction probes for in-field salinity assessment. Soil samples will be collected in randomly selected fields associated with a larger, on-going Salinity and Waterlogging Project. These samples will be processed to analyze for primary cations (calcium, sodium, magnesium, potassium and boron) and primary anions (chloride and sulfate). Additionally, an examination of soil water extract techniques will occur, to determine if there is a significant difference between the potential electrical conductivity measured by standard laboratory methods, and the expressed electrical conductivity in the field monitoring. Due to precipitation of large quantities of calcite and gypsum in field soils, dissolution thermodynamics may influence the differences between lab and field methods of salinity measurement. Studying dissolution and precipitation thermodynamics of in-situ soil salt chemistry will lead to an understanding of the effects of soil conditions on the performance of the electromagnetic induction salinity probe. This will be critical to accurate, rapid field assessment and monitoring of changes in salinity as water management in the Arkansas Valley changes over time.