No abstract

Model performance evaluation for real-time flood forecasting has been conducted using various criteria. Although the coefficient of efficiency (CE) is most widely used, we demonstrate that a model achieving good model efficiency may actually be inferior to the naïve (or persistence) forecasting, if the flow series has a high lag-1 autocorrelation coefficient. We derived sample-dependent and AR model-dependent asymptotic relationships between the coefficient of efficiency and the coefficient of persistence (CP) which form the basis of a proposed CE-CP coupled model performance evaluation criterion. Considering the flow persistence and the model simplicity, the AR(2) model is suggested to be the benchmark model for performance evaluation of real-time flood forecasting models. We emphasize that performance evaluation of flood forecasting models using the proposed CE-CP coupled criterion should be carried out with respect to individual flood events. A single CE or CP value derived from a multi-event artifactual series by no means provides a multi-event overall evaluation and may actually disguise the real capability of the proposed model.

Endosymbiotic algae of the genus Symbiodinium have been divided into nine clades (A-I) following genetic classification; some clades are known to have physiological properties that enable the coral hosts to adapt to different environmental conditions. To understand the relationships of coral-alga symbioses, we focused on Symbiodinium diversity in zooxanthellate corals living under the severe environmental conditions of the temperate region (30°-35°N) of Japan. We investigated Symbiodinium clades in 346 colonies belonging to 58 coral species from six locations. We then selected three coral species-Acropora hyacinthus, Acropora japonica, and Cyphastrea chalcidicum-to investigate whether Symbiodinium clades changed during winter or summer over the course of year (May 2009-Apr 2010) in Tanabe Bay, Japan. Three Symbiodinium clades (C, D, and F) were detected in corals in the temperate region. Notably, 56 coral species contained Symbiodinium clade C. Oulastrea crispata predominantly contained clade D, but traces of clade C were also detected in all samples. The temperate-specific species Alveopora japonica contained clades C and F simultaneously. Seasonal change of symbiont clades did not occur in the three coral species during the investigation period where SSTs range on 12.5-29.2°C. However, we found Acropora (2 spp.) and Cyphastrea (1 sp.) contained different subcladal types of clade C. These results reveal that most coral species harbored Symbiodinium clade C stably throughout the year, suggesting that Symbiodinium clade C shows low-temperature tolerance, and that two hypothetical possibilities; genetic differences of subcladal types generating physiological differences or wide physiological flexibility in the clade C.

This study demonstrates the feasibility of coastal water quality mapping using satellite remote sensing images. Water quality sampling campaigns were conducted over a coastal area in northern Taiwan for measurements of three water quality variables including Secchi disk depth, turbidity, and total suspended solids. SPOT satellite images nearly concurrent with the water quality sampling campaigns were also acquired. A spectral reflectance estimation scheme proposed in this study was applied to SPOT multispectral images for estimation of the sea surface reflectance. Two models, univariate and multivariate, for water quality estimation using the sea surface reflectance derived from SPOT images were established. The multivariate model takes into consideration the wavelength-dependent combined effect of individual seawater constituents on the sea surface reflectance and is superior over the univariate model. Finally, quantitative coastal water quality mapping was accomplished by substituting the pixel-specific spectral reflectance into the multivariate water quality estimation model.