Submitted to: Bouyoucos Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: August 3, 1995
Publication Date: N/A
Interpretive Summary: Non-point source (NPS) agricultural pollutants such as salts are pollutants of surface and subsurface soil and water which are usually present in low concentrations, but spread out over very large areas. Concern over NPS pollutants has grown due to their degradation of surface and groundwater drinking supplies and due to their impact on agricultural soils. An integrated methodology is presented for assessing soil salinity and salt loading to the groundwater over thousands of acres. The methodology integrates ground positioning systems (GPS), remote sensing instrumentation, solute transport modeling and geographic information systems (GIS) for the purpose of measuring and predicting salt accumulation and movement through soil and into the groundwater. The presented methodology is designed to asses the impact of salt upon soil and groundwater resources, thereby serving as a decision-making tool for minimizing detrimental environmental impacts of salinity on irrigated agricultural soils.
Technical Abstract: The assessment of the environmental impact of non-point source pollutants related to agricultural activities is needed to minimize environmental deterioration while maintaining agricultural productivity. An integrated methodology is presented for the real-time measurement of soil salinity, and the prediction of soil salinity and salt-loading to the groundwater. To measure real-time salinity over large land areas (i.e., thousands of acres),a mobile,automated field-salinity measurement vehicle was developed that combines both four-electrode and electromagnetic sensors to measure the soil salinity of the root zone with a global positioning system (GPS). To predict areal distributions of soil salinity and salt-loading to the groundwater, a geographic information system (i.e., ARC/INFO) has been coupled to a solute transport model(i.e., TETrans). Approximately two-thirds (2396 hectares) of the Broadview Water District located on the westside of the San Joaquin Valley of central California was used as the test site to evaluate the coupled GIS/solute transport model. Results of the TETrans calculations are presented for a single growing season (1991). Display maps show calculated destinations of salt-loading to groundwater and predictions of potentially salt-affected soils. The maps provide the visual information essential for formulating irrigation management strategies to minimize groundwater pollution, reduce water usage, lower shallow water tables, and reclaim deteriorating soils without adversely impacting crop productivity.