OPTIMIZATION MODELING OF A NEW FACILITY FOR THE CALIFORNIA STATE WATER PROJECT1

ABSTRACT: A non-linear optimization model is applied to the California State Water Project (SWP) and portions of the Central Valley Project (CVP). The model accounts for the major hydrologic, regulatory, and operational features of both projects. The model maximizes long-term SWP yields over a 70-year period, using a quarterly time step. The potential for increased yield associated with a proposed facility improvement is evaluated with the model. The proposed facility is an extension of the Folsom-South Canal, which would allow water to be conveyed from the American River below Folsom Reservoir into New Melones Reservoir on the Stanislaus River or into the California Aqueduct. Model results indicate that extension of the Folsom-South Canal has the potential to increase SWP yields by 13 percent.     

A Comparison of Campfire Impacts and Policies in Seven Protected Areas

Using resource-monitoring data from seven protected areas, the effectiveness of three campfire policies—campfire ban, designated campfires, and unregulated campfires—were assessed based on the number of fire sites and the amount of tree damage. Results indicate that unregulated campfire policies permitted substantial numbers of fire sites and tree damage in campsites, although fire bans did not eliminate or even substantially decrease these problems. A designated campfire policy was effective in decreasing number of fire sites, but little difference was found among policies regarding tree damage. Given the importance of campfires to visitor experiences, campfire prohibitions could be viewed as unnecessarily restrictive based on their limited success in preventing resource damage. Conclusions encourage protected-area managers to consider designated campfire policies and prohibitions on axes, hatchets, and saws to better meet resource protection and visitor experience mandates.     

Green roof stormwater retention: effects of roof surface, slope, and media depth

Urban areas generate considerably more stormwater runoff than natural areas of the same size due to a greater percentage of impervious surfaces that impede water infiltration. Roof surfaces account for a large portion of this impervious cover. Establishing vegetation on rooftops, known as green roofs, is one method of recovering lost green space that can aid in mitigating stormwater runoff. Two studies were performed using several roof platforms to quantify the effects of various treatments on stormwater retention. The first study used three different roof surface treatments to quantify differences in stormwater retention of a standard commercial roof with gravel ballast, an extensive green roof system without vegetation, and a typical extensive green roof with vegetation. Overall, mean percent rainfall retention ranged from 48.7% (gravel) to 82.8% (vegetated). The second study tested the influence of roof slope (2 and 6.5%) and green roof media depth (2.5, 4.0, and 6.0 cm) on stormwater retention. For all combined rain events, platforms at 2% slope with a 4-cm media depth had the greatest mean retention, 87%, although the difference from the other treatments was minimal. The combination of reduced slope and deeper media clearly reduced the total quantity of runoff. For both studies, vegetated green roof systems not only reduced the amount of stormwater runoff, they also extended its duration over a period of time beyond the actual rain event.     

Freshwater stress on small island developing states: population projections and aridity changes at 1.5 and 2 °C

Small island developing states (SIDS) face multiple threats from anthropogenic climate change, including potential changes in freshwater resource availability. Due to a mismatch in spatial scale between SIDS landforms and the horizontal resolution of global climate models (GCMs), SIDS are mostly unaccounted for in GCMs that are used to make future projections of global climate change and its regional impacts. Specific approaches are required to address this gap between broad-scale model projections and regional, policy-relevant outcomes. Here, we apply a recently developed methodology that circumvents the GCM limitation of coarse resolution in order to project future changes in aridity on small islands. These climate projections are combined with independent population projections associated with shared socioeconomic pathways (SSPs) to evaluate overall changes in freshwater stress in SIDS at warming levels of 1.5 and 2 °C above pre-industrial levels. While we find that future population growth will dominate changes in projected freshwater stress especially toward the end of the century, projected changes in aridity are found to compound freshwater stress for the vast majority of SIDS. For several SIDS, particularly across the Caribbean region, a substantial fraction (~?25%) of the large overall freshwater stress projected under 2 °C at 2030 can be avoided by limiting global warming to 1.5 °C. Our findings add to a growing body of literature on the difference in climate impacts between 1.5 and 2 °C and underscore the need for regionally specific analysis.     

发展与气候变化

气候变化不仅是一个影响世界各国的全球性问题,它还对许多中低收入国家的发展进程构成颠覆甚至倒退的威胁.在支持发展中国家经济增长重点的同时,应对减缓和适应气候变化的双重挑战,是国际社会面临的一项重大考验.     

Measuring the effectiveness of landscape approaches to conservation and development

Landscape approaches attempt to achieve balance amongst multiple goals over long time periods and to adapt to changing conditions. We review project reports and the literature on integrated landscape approaches, and found a lack of documented studies of their long-term effectiveness. The combination of multiple and potentially changing goals presents problems for the conventional measures of impact. We propose more critical use of theories of change and measures of process and progress to complement the conventional impact assessments. Theories of change make the links between project deliverables, outputs, outcomes, and impacts explicit, and allow a full exploration of the landscape context. Landscape approaches are long-term engagements, but short-term process metrics are needed to confirm that progress is being made in negotiation of goals, meaningful stakeholder engagement, existence of connections to policy processes, and effectiveness of governance. Long-term impact metrics are needed to assess progress on achieving landscapes that deliver multiple societal benefits, including conservation, production, and livelihood benefits. Generic criteria for process are proposed, but impact metrics will be highly situation specific and must be derived from an effective process and a credible theory of change.     

Vetoing the future: political constraints and renewable energy

Despite the increased importance of and attention to renewable energy, its share in the overall energy mix has varied significantly across countries and over time. There are many determinants of clean energy transitions; this study focuses on political constraints. Here it is argued that political systems that have fewer political constraints have fewer access points through which powerful status quo veto players can slow the progress of clean energy reforms. To test the theory, a hierarchical model is applied on a dataset of 125 countries over four decades. The results provide significant support for the theory. Furthermore, the effects for political constraints hold even when we distinguish between hydro and non-hydro renewable sources and control for regime type. This study builds on research that recognizes the importance of politics in understanding the challenges and opportunities of clean energy reform.     

Cadmium and lead in tissues of Mallards (Anas platyrhynchos) and Wood Ducks (Aix sponsa) using the Illinois River (USA)

Cadmium and lead concentrations were determined in the tissues of Mallards and Wood Ducks collected from two waterfowl management areas along the Illinois River, USA, during the autumn and late winter of 1997-1998. Lead concentrations in livers of Mallards were lower than previously reported, and, along with those in a small sample of Wood Duck livers, were within background levels (<2.0 microg/g wet weight). Mean concentrations of cadmium in the kidneys of Wood Ducks utilizing the Illinois River were four times greater than in after-hatch-year Mallards, and 14 times greater than in hatch-year Mallards. Concentrations of cadmium in the kidneys of Wood Ducks were comparable with those of specimens dosed with cadmium or inhabiting contaminated areas in previous studies. Wood Ducks utilizing wetlands associated with the Illinois River, and presumably other portions of the lower Great Lakes region, may be chronically exposed to cadmium.     

Retention of arsenic on hydrous ferric oxides generated by electrochemical peroxidation

Electrochemical peroxidation (ECP), an emerging remediation technology, with direct electric current applied to steel electrode and small addition of H2O2, was used to remove As(III) from contaminated aqueous solutions. Bench scale experiments were conducted to evaluate the sorption and distribution of arsenic between the soluble and solid state hydrous ferric oxides (HFO) formed as part of the ECP process. ECP was effective in removing arsenic from the aqueous solution, with >98% of the applied As(III) adsorbed on HFO. Removal was complete within 3 min of ECP treatment and apparently independent of the initial pH of the water (3.5-9.5). In the absence of H2O2 more As(III) was adsorbed by solid state iron at pH 9.5 than at 3.5 (2600 vs. 1750 microg l(-1)). Thus H2O2 was crucial to oxidize As(III) to As(V) which is more strongly retained by HFO. Removal of As was not significantly affected by the concentration of H2O2 or by current processing time. The optimal operating conditions were pH < 6.5, H2O2 concentration of 10 mg l(-1) and current process time not exceeding 3 min. X-ray diffraction (XRD), diffuse-reflectance infrared Fourier transform (DRIFT) spectroscopy and transmission electron microscopy (TEM) were applied to study the HFO deposits. The XRD data indicated the prevalence of poorly ordered Fe minerals in the suspended ECP solids with a dominance of 5 line ferrihydrite in the absence of H2O2. At pH 3.5 and with 100 mg H2O2 l(-1), akaganeite was formed, whereas an incipient hematitic phase, reflection at 0.39 nm, occurred at pH 6.5. DRIFT data indicate that both As(III) and As(V) were specifically adsorbed onto HFO at acid and neutral pH. TEM observations indicated the presence of spherical shape ferrihydrite and provided evidence for possible formation of subrounded hematite and acicular shape goethite.