Rice farmers occupy a potentially important intersection between economics and hydrology in Northern California. While drought makes water an increasingly precious commodity across California, the monetary worth of wa...Rice farmers occupy a potentially important intersection between economics and hydrology in Northern California. While drought makes water an increasingly precious commodity across California, the monetary worth of water is not uniform across different localities and uses. As a result, circumstances have given many Sacramento Valley rice farmers the option to sell their water to users elsewhere, in lieu of using it themselves. Because the sold water is typically surface water that would normally help recharge local aquifers when applied to a field;it is reasonable to suspect that transferring that water elsewhere could adversely affect local aquifers since that recharge would be reduced. This study performs numerical experiments using the United States Geological Survey’s Central Valley Hydrologic Model (CVHM) to better understand the temporal effects of a set of land idling scenarios. CVHM is capable of modeling the entire Central Valley, which encompasses the Sacramento and San Joaquin Valleys, and of representing rice field idling on a large scale. These experiments were executed using historical data to contrast recently typical amounts of rice field idling with scenarios reflecting varying degrees of hypothetical, increased idling. In doing so, this study aims to characterize the nature and potential magnitude of idling rice fields on groundwater storage in the Sacramento Valley. The impact of these scenarios on groundwater storage was quantified relative to an unaltered baseline model scenario. The results of this research show rice field idling will reduce recharge and groundwater storage levels;these results may provide useful information for future policy decisions and provide a basis for future study.展开更多
Sponge plant is an emerging threat that has spread throughout California including the Sacramento-San Joaquin Delta, which is an important water resource for agriculture as well as critical habitat for a variety of th...Sponge plant is an emerging threat that has spread throughout California including the Sacramento-San Joaquin Delta, which is an important water resource for agriculture as well as critical habitat for a variety of threatened and endangered species. More data are needed on effective control methods for this spreading invader, as current management practices are not preventing proliferation. The overall objectives of this research were to evaluate imazamox, penoxsulam, topramezone, florpyrauxifen-benzyl, and carfentrazone-ethyl for control of sponge plant using three testing scales, as well as compare image analysis software to traditional biomass response for measuring herbicide performance. Overall, 280 g imazamox ha−1 (with one-percent methylated seed oil surfactant) was found as a potent solution for all different growth stages of sponge plant, and 70 g penoxsulam ha−1 as an alternative for control of sponge plant in the seedling and rosette growth stage. The image analysis software yielded similar measurement of herbicide effects as traditional biomass measure. Mesocosm testing indicated imazamox treatment sites should be inspected at four week intervals to identify plants missed by prior applications. This research provides water resource managers critical information for identification of an aquatic invasive species, and selecting an effective rapid management program.展开更多
文摘Rice farmers occupy a potentially important intersection between economics and hydrology in Northern California. While drought makes water an increasingly precious commodity across California, the monetary worth of water is not uniform across different localities and uses. As a result, circumstances have given many Sacramento Valley rice farmers the option to sell their water to users elsewhere, in lieu of using it themselves. Because the sold water is typically surface water that would normally help recharge local aquifers when applied to a field;it is reasonable to suspect that transferring that water elsewhere could adversely affect local aquifers since that recharge would be reduced. This study performs numerical experiments using the United States Geological Survey’s Central Valley Hydrologic Model (CVHM) to better understand the temporal effects of a set of land idling scenarios. CVHM is capable of modeling the entire Central Valley, which encompasses the Sacramento and San Joaquin Valleys, and of representing rice field idling on a large scale. These experiments were executed using historical data to contrast recently typical amounts of rice field idling with scenarios reflecting varying degrees of hypothetical, increased idling. In doing so, this study aims to characterize the nature and potential magnitude of idling rice fields on groundwater storage in the Sacramento Valley. The impact of these scenarios on groundwater storage was quantified relative to an unaltered baseline model scenario. The results of this research show rice field idling will reduce recharge and groundwater storage levels;these results may provide useful information for future policy decisions and provide a basis for future study.
文摘Sponge plant is an emerging threat that has spread throughout California including the Sacramento-San Joaquin Delta, which is an important water resource for agriculture as well as critical habitat for a variety of threatened and endangered species. More data are needed on effective control methods for this spreading invader, as current management practices are not preventing proliferation. The overall objectives of this research were to evaluate imazamox, penoxsulam, topramezone, florpyrauxifen-benzyl, and carfentrazone-ethyl for control of sponge plant using three testing scales, as well as compare image analysis software to traditional biomass response for measuring herbicide performance. Overall, 280 g imazamox ha−1 (with one-percent methylated seed oil surfactant) was found as a potent solution for all different growth stages of sponge plant, and 70 g penoxsulam ha−1 as an alternative for control of sponge plant in the seedling and rosette growth stage. The image analysis software yielded similar measurement of herbicide effects as traditional biomass measure. Mesocosm testing indicated imazamox treatment sites should be inspected at four week intervals to identify plants missed by prior applications. This research provides water resource managers critical information for identification of an aquatic invasive species, and selecting an effective rapid management program.
