Streamflow Prediction in Highly Regulated, Transboundary Watersheds Using Multi-Basin Modeling and Remote Sensing Imagery.

Despite the potential of remote sensing for monitoring reservoir operation, few studies have investigated the extent to which reservoir releases can be inferred across different spatial and temporal scales. Through evaluating 21 reservoirs in the highly regulated Greater Mekong region, remote sensing imagery was found to be useful in estimating daily storage volumes for within-year and over-year reservoirs (correlation coefficients [CC] ≥ 0.9, normalized root mean squared error [NRMSE] ≤ 31%), but not for run-of-river reservoirs (CC < 0.4, 40% ≤ NRMSE ≤ 270%). Given a large gap in the number of reservoirs between global and local databases, the proposed framework can improve representation of existing reservoirs in the global reservoir database and thus human impacts in hydrological models. Adopting an Integrated Reservoir Operation Scheme within a multi-basin model was found to overcome the limitations of remote sensing and improve streamflow prediction at ungauged cascade reservoir systems where previous modeling approaches were unsuccessful. As a result, daily regulated streamflow was predicted competently across all types of reservoirs (median values of CC = 0.65, NRMSE = 8%, and Kling-Gupta efficiency [KGE] = 0.55) and downstream hydrological stations (median values of CC = 0.94, NRMSE = 8%, and KGE = 0.81). The findings are valuable for helping to understand the impacts of reservoirs and dams on streamflow and for developing more useful adaptation measures to extreme events in data sparse river basins.

Barriers and Solutions to Smart Water Grid Development.

This limited review of smart water grid (SWG) development, challenges, and solutions provides an initial assessment of early attempts at operating SWGs. Though the cost and adoption issues are critical, potential benefits of SWGs such as efficient water conservation and distribution sustain the development of SWGs around the world. The review finds that the keys to success are the new regulations concerning data access and ownership to solve problems of security and privacy; consumer literacy to accept and use SWGs; active private sector involvement to coordinate SWG development; government-funded pilot projects and trial centers; and integration with sustainable water management.

A novel marine algal toxicity bioassay based on sporulation inhibition in the green macroalga Ulva pertusa (Chlorophyta).

A 5-day aquatic toxicity test based on sporulation inhibition of the green macroalga Ulva pertusa Kjellman has been developed. Optimal test conditions determined for photon irradiance, salinity and temperature were 60-200 micromol photons m(-2)s(-1), 25-35 per thousand and 15-20 degrees C, respectively. Tests were conducted by exposing U. pertusa thallus disks to a reference toxicant (sodium dodecyl sulfate; SDS), metals (Cd2+, Cu2+, Zn2+, Pb2+) and elutriates of sludge collected from nine different locations. The EC(50) values for SDS was 5.35 mg L(-1). When four heavy metals were assayed, the NOECs were highest for lead (0.625 mg L(-1)) and lowest for copper (0.031 mg L(-1)). The EC50 values showed the following toxicity rankings: Cu(2+) (0.061 mg L(-1))>Cd2+ (0.326 mg L(-1))>Zn2+ (0.738 mg L(-1))>Pb2+ (0.877 mg L(-1)). The bioassay indicated also that the sporulation endpoint could be a sensitive indicator of toxicity effects of elutriates of sludge as reflected from the NOEC values equal to or lower than the lowest concentration employed (6.25%). Sporulation was significantly inhibitied in all elutriates with the greatest and least effects observed in elutriates of sludge from industrial waste (EC50 6.78%) and filtration bed (EC50 15.0%), respectively. The results of the Spearman rank correlation analysis for EC50 data versus the concentrations of toxicants in the sludge presented a significant correlation between toxicity and four heavy metals (Cd2+, Cu2+, Pb2+, Zn2+). Introduction of the concept of toxicity unit (TU) showed that these metals were the main cause of toxicity in elutriates of at least four out of nine sludge samples. Members of the order Ulvales show a wide geographic distribution and have similar reproductive characteristics, thus making it possible to apply the present test method to other algae of this taxa, elsewhere. This novel method will be a useful tool for assessing the aquatic toxicity of a wide range of toxicants, once the respective sensitivities are demonstrated.