Multiscale Assessment of Agricultural Consumptive Water Use in California's Central Valley.

Spatial estimates of crop evapotranspiration with high accuracy from the field to watershed scale have become increasingly important for water management, particularly over irrigated agriculture in semiarid regions. Here, we provide a comprehensive assessment on patterns of annual agricultural water use over California's Central Valley, using 30-m daily evapotranspiration estimates based on Landsat satellite data. A semiempirical Priestley-Taylor approach was locally optimized and cross-validated with available field measurements for major crops including alfalfa, almond, citrus, corn, pasture, and rice. The evapotranspiration estimates explained >70% variance in daily measurements from independent sites with an RMSE of 0.88 mm day-1. When aggregated over the Valley, we estimated an average evapotranspiration of 820 ± 290 mm yr-1 in 2014. Agricultural water use varied significantly across and within crop types, with a coefficient of variation ranging from 8% for Rice (1,110 ± 85 mm yr-1) to 59% for Pistachio (592 ± 352 mm yr-1). Total water uses in 2016 increased by 9.6%, as compared to 2014, mostly because of land-use conversion from fallow/idle land to cropland. Analysis across 134 Groundwater Sustainability Agencies (GSAs) further showed a large variation of agricultural evapotranspiration among and within GSAs, especially for tree crops, e.g., almond evapotranspiration ranging from 339 ± 80 mm yr-1 in Tracy to 1,240 ± 136 mm yr-1 in Tri-County Water Authority. Continuous monitoring and assessment of the dynamics and spatial heterogeneity of agricultural evapotranspiration provide data-driven guidance for more effective land use and water planning across scales.

Acne, isotretinoin treatment and acute depression.

The association between isotretinoin therapy and depressive symptoms in acne patients has generated much recent interest but has not been systematically explored. A 17-year-old man with acne vulgaris developed symptoms of acute depression two weeks after beginning isotretinoin therapy. The depressive symptoms improved with reduction of isotretnoin dose and treatment with sertraline. Of note, however, is that when the isotretinoin dose was again increased, the depressive symptoms recurred despite clearing of the skin, leading to an unsuccessful suicide attempt. Isotretinoin was finally discontinued and the depression rapidly resolved. Although the effects of hypervitaminosis A may be involved aetiologically, the predictive factors of drug-related depression remain unclear. Significant depressive symptoms that develop during the course of treatment need close monitoring and may necessitate both antidepressant therapy and discontinuation of the drug. Given the uncertain causal relationship between isotretinoin and depression, versus the potential psychological benefits of effective acne treatment, systematic studies exploring the impact of isotretinoin on mood are needed.