Dam Design can Impede Adaptive Management of Environmental Flows: A Case Study from the Opuha Dam, New Zealand

The Opuha Dam was designed for water storage, hydropower, and to augment summer low flows. Following its commissioning in 1999, algal blooms (dominated first by Phormidium and later Didymosphenia geminata) downstream of the dam were attributed to the reduced frequency and magnitude of high-flow events. In this study, we used a 20-year monitoring dataset to quantify changes associated with the dam. We also studied the effectiveness of flushing flows to remove periphyton from the river bed. Following the completion of the dam, daily maximum flows downstream have exceeded 100 m³ s^?1 only three times; two of these floods exceeded the pre-dam mean annual flood of 203 m³ s^?1 (compared to 19 times >100 m³ s^?1 and 6 times >203 m³ s^?1 in the 8 years of record before the dam). Other changes downstream included increases in water temperature, bed armoring, frequency of algal blooms, and changes to the aquatic invertebrate community. Seven experimental flushing flows resulted in limited periphyton reductions. Flood wave attenuation, bed armoring, and a shortage of surface sand and gravel, likely limited the effectiveness of these moderate floods. Floods similar to pre-dam levels may be effective for control of periphyton downstream; however, flushing flows of that magnitude are not possible with the existing dam infrastructure. These results highlight the need for dams to be planned and built with the capacity to provide the natural range of flows for adaptive management, particularly high flows.     

DECISION PARAMETERS FOR COMBINED USE OF EFFLUENT DISCHARGES,SURFACE FLOWS,AND GROUND WATER1

ABSTRACT: Decision parameters affecting combined use of effluent discharges and surface flows and ground water available at Gillespie Dam on the Gila River in Arizona are identified and analyzed. Hydrologic, economic, legal, and institutional parameters are considered separately and in combination. The interrelationships of irrigation subsystems, water use functions, institutional involvement, economic and legal constraints are illustrated. Recent hydrologic studies indicate that the natural flow of the Gila River will increase with the discharge of Phoenix sewage effluent and then there will be a drastic decline when the Palo Verde Nuclear Generating Station commences in 1985. Competition for any increases in effluent discharges and surface flows could be ameliorated through the combined efforts of existing or reorganized entities resulting in sharing of costs and benefits. The analysis leads to recommendations concerning joint use of facilities, proration of fixed and variable costs, and creation of a mutual water company.     

Testosterone,dominance signalling and immunosuppression in the house sparrow,<Emphasis Type="Italic"> Passer domesticus</Emphasis>

The immunocompetence handicap hypothesis (ICHH) suggests that dominance signals are costly because their development is controlled by testosterone, which is immunosuppressive. Signal control therefore links an increased disease risk with a high quality signal. The chest bib of the house sparrow, Passer domesticus, is a signal known to be related to dominance and under control of testosterone levels. We experimentally manipulated testosterone in male sparrows during the breeding season and again independently during the post-breeding period to test whether variation in levels of testosterone could cause variation in levels of immunocompetence. There was no effect of testosterone manipulation on the cell-mediated response of birds to phytohaemagglutinin injection, nor did testosterone levels appear to affect either white blood cell ratios or red blood cell counts. In contrast, both breeding season and post-breeding season testosterone levels had significant effects upon the humoral response of the birds to sheep red blood cell injections. However, whilst testosterone during the breeding season appeared to act immunosuppressively, the role of post-breeding levels is less clear. In concordance with a previous study, there was an indication that corticosterone is involved in mediating the immunosuppressive effects of testosterone. The strength of the secondary humoral response and the cell-mediated response were negatively related suggesting the possibility of a trade-off between the different arms of the immune system. These results provide some support for the ICHH as a mechanism promoting the evolution of costly badges of status, although the results question whether the immunosuppressive cost can be mediated by testosterone at the time of badge development.Communicated by W.A.Searcy     

Changing places, changing emissions: The cross-scale reliability of greenhouse gas emission inventories in the US

Greenhouse gas (GHG) emission inventories, which currently inform abatement policy discussions, are developed mostly from national scale data. Nevertheless, although the policy debate tends to take place in global and national arenas, action to abate GHG emissions is inherently within the provenance of local institutions and communities. The purpose of this paper is to examine how much information is lost by not estimating GHG emissions data at scales finer than the whole US. Such information may be critical in bridging global and local policy. Differences in the composition of GHG emission sources based on GHG emission inventories at three nested spatial scales (national, state, local) for four study sites (in Kansas, North Carolina, Ohio and Pennsylvania) are analysed, drawing upon initial results of a large collaborative study known as the 'Association of American Geographers-Global Change in Local Places (GCLP)' project. The concept of spatial sovereignty of emissions is developed to test the cross-scale reliability of emission inventories. For the test year 1990, close agreement is found in the by-gas composition of GHG emissions among national, state and local inventories. Spatial sovereignty in this case is maintained. However close agreement is not found in the by-source composition of GHG emissions among national, state and local inventories. Spatial sovereignty in this case is not maintained. Regular compilation of state and local emissions source inventories may be necessary to track important spatial and temporal deviations from national trends.     

Geophysical and Hydrologic Monitoring of Air Sparging Flow Behavior: Comparison of Two Extreme Sites

The distribution of air around injection wells is an important determinant of the effectiveness, design, and cost of air sparging remediation systems. High-level air sparging field tests were conducted at two sites for the purpose of determining the pattern of airflow under widely different subsurface conditions. One site consisted of relatively homogeneous dune sand (Site A). The other consisted of highly heterogeneous glacial till (Site B). At both sites, cross-borehole electrical resistance tomography (ERT) was used to image the principal region of airflow in the saturated zone. The response of conventional monitoring data was compared with the ERT results. At Site A, the principal region of airflow was approximately symmetric about the sparge well and only 2.4 m in radius. At Site B, the pattern of airflow was much more complex and had a major horizontal component. In both site studies, conventional monitoring data provided a much more ambiguous indication of the region of airflow in the saturated zone than did ERT. The investigations at these two sites demonstrate that, while the exact distribution of injected air is not readily discernible by conventional monitoring, the character of the airflow pattern can be recognized when appropriate physical response data are collected. Such response data can be used to evaluate site suitability for air sparging and to improve the system design and operation.     

Exposure estimates in assessing helath effects of air pollution

Air pollution has been associated with adverse health effects. Difficulties in interpreting studies of health effects of exposure to air pollution arise in estimating exposure. Until recently, studies of effects of air pollution have relied on pollution exposure measurements obtained from fixed location air pollution stations monitoring outside air (to evaluate compliance with air quality standards, rather than to examine population exposure). However, recent evidence suggests that there are substantial differences between air pollution levels measured at such sites and levels to which people are actually exposed, i.e. personal exposure. The present study examines effects of ambient urban air pollution on persons suffering from asthma, healthy non-asthmatic subjects and school children (in 2 Canadian cities, Toronto and Hamilton). Air pollution exposure is being assessed by data obtained from: (1) conventional abatement oriented fixed location air pollution monitoring stations, (2) an extensive population oriented network, (3) inside and (4) outside structures (homes and schools) as well as (5) personal air pollution samplers. The data indicate variability in these different estimates of exposure which have implications on health effects assessment.     

Lessons from Developing Methods to Study the Relationship of Energy and Water Savings to Housing Conditions and Resident Health

Energy- and water-saving have been promoted as ways of saving money while there has been controversy about the effects (if any) of such measures on resident health. In public housing in the US, energy saving has taken the form of Energy Savings Performance Contracts (ESPC) that pay for renovations out of future savings. In an attempt to test feasibility and pilot research methods we conducted a study of the relationship between gas and water use, exterior heat sensor locations, and basement ventilation with indices developed from resident-reported living conditions and health symptoms in a single housing development. The data sources that we had available to us were not ideal. In particular, we were unable to obtain water use data that coincided in time with our health survey data. Also, we did not have enough surveys in buildings with high water or gas use and had to pool those buildings with other buildings for analysis. Nevertheless, we found several associations between our measures of energy use and resident reports of health symptoms. The associations that we found were generally in the direction that energy and water savings were associated with fewer symptoms and fewer environmental problems. There is a need for studies that obtain better input data but that generally follow the approach we developed.     

Integrated models to support multiobjective ecological restoration decisions

Many objectives motivate ecological restoration, including improving vegetation condition, increasing the range and abundance of threatened species, and improving species richness and diversity. Although models have been used to examine the outcomes of ecological restoration, few researchers have attempted to develop models to account for multiple, potentially competing objectives. We developed a combined state‐and‐transition, species‐distribution model to predict the effects of restoration actions on vegetation condition and extent, bird diversity, and the distribution of several bird species in southeastern Australian woodlands. The actions reflected several management objectives. We then validated the models against an independent data set and investigated how the best management decision might change when objectives were valued differently. We also used model results to identify effective restoration options for vegetation and bird species under a constrained budget. In the examples we evaluated, no one action (improving vegetation condition and extent, increasing bird diversity, or increasing the probability of occurrence for threatened species) provided the best outcome across all objectives. In agricultural lands, the optimal management actions for promoting the occurrence of the Brown Treecreeper (Climacteris picumnus), an iconic threatened species, resulted in little improvement in the extent of the vegetation and a high probability of decreased vegetation condition. This result highlights that the best management action in any situation depends on how much the different objectives are valued. In our example scenario, no management or weed control were most likely to be the best management options to satisfy multiple restoration objectives. Our approach to exploring trade‐offs in management outcomes through integrated modeling and structured decision‐support approaches has wide application for situations in which trade‐offs exist between competing conservation objectives.