Mid‐Range Streamflow Forecasts Based on Climate Modeling – Statistical Correction and Evaluation1

Abstract: Mid‐range streamflow predictions are extremely important for managing water resources. The ability to provide mid‐range (three to six months) streamflow forecasts enables considerable improvements in water resources system operations. The skill and economic value of such forecasts are of great interest. In this research, output from a general circulation model (GCM) is used to generate hydrologic input for mid‐range streamflow forecasts. Statistical procedures including: (1) transformation, (2) correction, (3) observation of ensemble average, (4) improvement of forecast, and (5) forecast skill test are conducted to minimize the error associated with different spatial resolution between the large‐scale GCM and the finer‐scale hydrologic model and to improve forecast skills. The accuracy of a streamflow forecast generated using a hydrologic model forced with GCM output for the basin was evaluated by forecast skill scores associated with the set of streamflow forecast values in a categorical forecast. Despite the generally low forecast skill score exhibited by the climate forecasting approach, precipitation forecast skill clearly improves when a conditional forecast is performed during the East Asia summer monsoon, June through August.     

Cost-effective reduction of NOx emissions from electricity generation.

This paper analyzes the benefits and costs of policies to reduce NOx emissions from electricity generation in the United States. Because emissions of NO contribute to the high concentration of atmospheric ozone in the eastern states associated with health hazards, the U.S. Environmental Protection Agency (EPA) has called on eastern states to formulate state implementation plans (SIPs) for reducing NOx emissions. Our analysis considers three NOx reduction scenarios: a summer seasonal cap in the eastern states covered by EPA's NOx SIP Call, an annual cap in the same SIP Call region, and a national annual cap. All scenarios allow for emissions trading. Although EPA's current policy is to implement a seasonal cap in the SIP Call region, this analysis indicates that an annual cap in the SIP Call region would yield about $400 million more in net benefits (benefits less costs) than would a seasonal policy, based on particulate-related health effects only. An annual cap in the SIP Call region is also the policy that is most likely to achieve benefits in excess of costs. Consideration of omissions from this accounting, including the potential benefits from reductions in ozone concentrations, strengthens the finding that an annual program offers greater net benefits than does a seasonal program.     

Development of a decision support system for Prioritization of multimedia dischargers

In 1990 the Environmental Protection Agency (EPA) began sponsoring several pilot projects in its regional offices to examine the potential benefits of adopting a multimedia approach to facility management. This approach differs from traditional practices at EPA in that facilities (dischargers regulated under permits issued by the agency) are managed based upon their cumulative impacts to all media: air, water, and land. Currently, facilities are managed by separate programs at EPA that evaluate environmental impacts from a single-media perspective. One aspect of discharger management is the necessity to allocate limited financial resources in a way that will minimize risk to human health and the environment. A careful, risk-based prioritization of facilities is one means of providing insight to the most effective strategy of allocating monitoring, inspection, and enforcement resources. Prioritization from a multimedia perspective is particularly difficult, however, since it requires translation and integration of medium-specific facility performances, management objectives, and perceptions of risk into a cumulative rating. A computerized decision support system (DSS) designed to guide management through the prioritization process from a multimedia perspective was identified as a potentially valuable tool for use in the pilot projects. This article describes the development of such a prototype, outlines the features of the completed system, and discusses its potential for use at EPA.     

Mate choice in the face of both inbreeding and outbreeding depression in the intertidal copepod Tigriopus californicus

 In species vulnerable to both inbreeding and outbreeding depression, individuals might be expected to choose mates at intermediate levels of genetic relatedness. Previous work on the intertidal copepod Tigriopus californicus has repeatedly shown that crosses between populations result in either no effect or hybrid vigor in the first generation, and hybrid breakdown in the second generation. Previous work also shows that mating between full siblings results in inbreeding depression. The present study again found inbreeding depression, with full sibling mating causing significant fitness declines in two of the three populations assayed. In the mate choice assays, a single female was combined with two males. Despite the costs of both inbreeding and outbreeding, mate choice showed clear inbreeding avoidance but no clear pattern of outbreeding avoidance. This lack of outbreeding avoidance may be attributed either to the temporary increase in fitness in the F₁ generation or to the absence of selection for premating isolation in wholly allopatric populations with infrequent migration. If this inability to avoid unwise matings is common to other taxa, it may contribute to the problem of outbreeding depression when allopatric populations are mixed together. Received: 18 May 1999 / Accepted: 25 January 2000     

Nitrate and nitric acid concentrations at two Rocky Mountain baseline monitoring sites

A two-tiered, Teflon/nylon filterpack system was used to characterize spatial and temporal patterns of particulate nitrates and nitric acid vapors at two monitoring sites in the Rocky Mountains. Geometric means for particulate nitrates were 38.9 and 52.8 ng/m(3) for the upper and lower sites, respectively. For nitric acid, geometric means of 70.4 ng/m(3) for the upper site and 295 ng/m(3) for the lower site were observed. The relatively low concentrations found at these two sites are comparable to published values for these materials at other remote sites. Atmospheric concentrations of nitrates and nitric acid were correlated significantly at each site, and the total nitrate concentrations (NO(3)(-) plus HNO(3)) were correlated between sites. Comparisons between the two sites indicate that nitric acid concentrations were statistically greater at the lower elevation site, whereas nitrate concentrations were not significantly different. No general seasonal or annual pattern of nitrate or nitric acid concentrations were evident when comparable sampling periods were examined.     

A selection of forest condition indicators for monitoring

Regional monitoring and assessments of the health of forested ecosystems require indicators of forest conditions and environmental stresses. Indicator selections depend on objectives and the strategy for data collection and analysis. This paper recommends a set of indicators to signal changes in forest ecosystem distribution, productivity, and disturbance. Additional measurements are recommended to help ascribe those changes to climate variation, atmospheric deposition, and land use patterns. The rationale for these indicators is discussed in the context of a sequential monitoring and assessment strategy.     

Disciplined Planning,Structured Participation,and Collaborative Modeling — Applying Shared Vision Planning to Water Resources

Participatory planning applied to water resources has sparked significant interest and debate during the last decade. Recognition that models play a significant role in the formulation and implementation of design and management strategies has encouraged the profession to consider how such models can be best implemented. Shared Vision Planning (SVP) is a disciplined planning approach that combines traditional water resources planning methodologies with innovations such as structured public participation and the use of collaborative modeling, resulting in a more complete understanding and an integrative decision support tool. This study reviews these three basic components of SVP and explains how they are incorporated into a unified planning approach. The successful application of SVP is explored in three studies involving planning challenges: the National Drought Study, the Lake Ontario‐St. Lawrence River Study, and the Apalachicola‐Chattahoochee‐Flint/Alabama‐Coosa‐Tallapoosa River Basin Study. The article concludes by summarizing the advantages and limitations of this planning approach.     

Assessment of prenatal mercury exposure in a predominately Caribbean immigrant community in Brooklyn, NY

Prenatal mercury exposure and its fetotoxic effects may be of particular concern in urban immigrant communities as a result of possible contributing cultural factors. The most common source of exposure in these communities is ingestion of fish and shellfish contaminated with methylmercury. Other sources of exposure may occur in ritualistic practices associated with Hispanic and Caribbean-based religions. This study 1) assessed total mercury levels in both random urine specimens from pregnant women, and in cord blood; and 2) examined environmental sources of exposure from a convenience sample in a predominantly Caribbean immigrant population in Brooklyn, New York. A questionnaire designed in collaboration with health professionals from the Caribbean community assessed the frequency of fish consumption, ritualistic practices, occupational exposures, and use of dental amalgams and mercury-containing skin and household products. The geometric mean for total mercury in cord blood was 2.14 μg L(-1) (95%CI: 1.76-2.60) (n = 78), and 0.45 μg L(-1) (95%CI: 0.37-0.55) (n = 183) in maternal urine corrected for creatinine (μg g(-1)). Sixteen percent of cord blood mercury levels exceeded the estimated equivalent of U.S. Environmental Protection Agency's Reference Dose (5.8 μg L(-1) blood). Predictors of cord blood mercury included maternal fish consumption and foreign birth of the mother. Predictors of urine mercury included foreign birth of the mother, number of dental amalgams, and special product use. There were no reports of mercury use in ritualistic practices or in cosmetics; however some women reported use of religious medals and charms. This study characterized risk factors for mercury exposure in a sample of urban, predominantly Caribbean-born blacks. Findings may help target interventions in this population, which might include appropriate fish selection and consumption frequency during pregnancy, and safe handling of mercury-containing products in the home.     

A study of metal and metalloid contaminant availability in Antarctic marine sediments

Previous studies of impacted sites near Casey Station, Antarctica, have revealed elevated concentrations of metals and metalloids, particularly Cd, Cu, Fe, Pb, Sn and Zn in marine sediments. However, attempts to understand the availability and mobility of contaminant elements have not provided a true understanding of speciation. The current work shows, for the first time, that sediments in Brown Bay, an embayment adjacent to the Thala Valley waste disposal site, have elevated concentrations of sulfide, well in excess of that required to bind contaminant metals such as Cd, Cu, Pb and Zn. Furthermore, sediment characterisation using the BCR sequential extraction scheme has shown metal partitioning consistent with sulfides being the controlling factor in metal availability, thus explaining the low porewater concentrations of these metals. The speciation of Sn in Brown Bay, however, is still unclear with the BCR sequential extraction scheme partitioning Sn predominantly into the residual fraction despite Sn being readily extracted by dilute HCl.     

Forest Health Monitoring in the United States: First Four Years

To address the need for more effective methods for evaluating and assessing forest ecosystem health, the USDA-Forest Service and the US Environmental Protection Agency through its Environmental Monitoring and Assessment Program developed the Forest Health Monitoring program. The program was initiated in 1990 and by 1994 was present in the major areas of the United States. This paper presents an overview of the program, the indicators and methods developed for the program, and some of the results after four years of monitoring and research.