Flood control failure: San Lorenzo River,California

The San Lorenzo River on the central California coast was the site of a major US Army Corps of Engineers flood control project in 1959. By excavating the channel below its natural grade and constructing levees, the capacity of the river was increased in order to contain approximately the 100 year flood. Production and transport of large volumes of sediment from the river's urbanizing watershed has filled the flood control project with sand and silt. The natural gradient has been re-established, and flood protection has been reduced to containment of perhaps the 30 year flood. In order for the City of Santa Cruz, which is situated on the flood plain, to be protected from future flooding,it must either initiate an expensive annual dredging program, or replan and rebuild the inadequately designed flood control channel. It has become clear, here and elsewhere, that the problem of flooding cannot simply be resolved by engineering. Large flood control projects provide a false sense of security and commonly produce unexpected channel changes.     

Transport of anthracene and benz(a)anthracene through iron-quartz and three aquifer materials in laboratory columns

In groundwater systems, dissolved natural organic matter (NOM) can influence the mobility of organic contaminants by altering the contaminant behavior in water and solid phases. The transport of anthracene and benz(a)anthracene (B(a)A) was studied in the presence and absence of NOM and/or soil organic matter (SOM) in column experiments. The results show that sorption are related to the properties of polycyclic aromatic hydrocarbons (PAHs), NOM and SOM. In the Fe-quartz media, the amount of NOM (20 mg/l) in solution had a little effect on increasing the apparent solubility of anthracene and countering increased anthracene sorption. In the natural (Bemidji) soil, Suwannee river fulvic acid (SRFA, 20 mg/l) and Suwannee river humic acid (SRHA) in water did not compete with SOM for anthracene, indicating that SOM has higher partition efficiency for anthracene. It was also observed that slow diffusion through an organic phase apparently caused most of the observed tailing in column breakthrough curves (BTCs). Even though the fOC of washed Bemidji sediment was very low, the transport of B(a)A was retarded significantly, however, and the transport of B(a)A was shown to be facilitated by dissolved NOM.     

The ozone formation potential of 1-bromo-propane

1-Bromo-propane (1-BP) is a replacement for high-end chlorofluorocarbon (HCFC) solvents. Its reaction rate constant with the OH radical is, on a weight basis, significantly less than that of ethane. However, the overall smog formation chemistry of 1-BP appears to be very unusual compared with typical volatile organic compounds (VOCs) and relatively complex because of the presence of bromine. In smog chamber experiments, 1-BP initially shows a faster ozone build-up than what would be expected from ethane, but the secondary products containing bromine tend to destroy ozone such that 1-BP can have a net overall negative reactivity. Alternative sets of reactions are offered to explain this unusual behavior. Follow-up studies are suggested to resolve the chemistry. Using one set of bromine-related reactions in a photochemical grid model shows that 1-BP would be less reactive toward peak ozone formation than ethane with a trend toward even lower ozone impacts in the future.     

Relationships of Human Disturbance, Bird Communities, and Plant Communities Along the Land-Water Interface of a Large Reservoir

We examined the relationships of humanactivity, bird communities, and plant communities along theland-water interface of Lake Texoma, a large human-madereservoir on the Texas-Oklahoma border. Measurements ofhuman activity, plant surveys, and bird surveys wereperformed at 40 paired transects, one with humandisturbance, the other undisturbed. Both principalcomponents and correspondence analyses of bird-survey dataseparated disturbed sites from paired undisturbed sites, andtypical disturbance-tolerant species from those lesstolerant of human activity. Compared to undisturbed sites,disturbed sites tended to have more individual birds persurvey, pavement, and mowed lawns, and less canopy,vegetation volume, and vegetation vertical diversity. Aprincipal components analysis of quantitative disturbancemeasurements revealed that most bird and plant measures werehighly correlated with the first disturbance component. However, the correlation between birds and human activitywas much stronger than that between birds and plants, orbetween plants and disturbance. Our data suggest that bird-species composition is regulated more by human activity thanby plant-community composition. Also, in this system, birdcommunities are a better choice than plant communities toindex the effect of human disturbance. To maintain regionaldiversity of both birds and plants, undisturbed areas shouldbe maintained around reservoirs.     

Researchers’ Experiences, Positive and Negative, in Integrative Landscape Projects

Integrative (interdisciplinary and transdisciplinary) landscape research projects are becoming increasingly common. As a result, researchers are spending a larger proportion of their professional careers doing integrative work, participating in shifting interdisciplinary teams, and cooperating directly with non-academic participants. Despite the growing importance of integrative research, few studies have investigated researchers’ experiences in these projects. How do researchers perceive the outcomes of integrative projects, or career effects? Do they view the projects generally as successes or failures? This study analyses researchers’ experiences in integrative landscape studies and investigates what factors shape these experiences. The data stems from 19 semi-structured qualitative interviews and a Web-based survey among 207 participants in integrative landscape research projects. It finds that researchers experience participation in integrative projects as positive, in particular discussions among participants, networking, teamwork, and gaining new insights and skills. Furthermore, most researchers perceive the projects as successful and as having a positive effect on their careers. Less positive aspects of integration relate to publications and merit points. Factors found to contribute to positive experiences include reaching a high degree of integration amongst the involved disciplines, common definitions of integrative research concepts, and projects that include a large share of fundamental research as well as projects with many project outcomes. Based on these findings, we advise future projects to plan for integration, facilitate discussions, and reach agreement on integrative concepts. We suggest that aspects of fundamental research be included in integrative projects. We also suggest that planning be done at an early stage for peer-reviewed publications, to ensure that participants gain merit points from their participation in integrative research efforts.     

Bioremediation of Stranded Oil on an Arctic Shoreline

The application of slow-release and soluble fertilizers proved to be an effective and environmentally benign way of stimulating oil biodegradation on an Arctic shoreline. Fertilizer application to the surface of the beach delivered nutrients to the oiled sediment beneath the beach surface. There was no significant run-off of this fertilizer to either the nearshore water or to unfertilized plots, and there were no adverse toxicological effects of the fertilizer application. The fertilizer application was followed by an increase in oxygen consumption and carbon dioxide evolution from the beach, increased microbial biomass, and significantly greater biodegradation of oil on the plots that had received fertilizer. The rate of oil biodegradation was approximately doubled over the course of a year by fertilizer applications in the first two months after the spill.Simple test kits proved adequate to monitor the fertilizer-application process in the field in a time frame that would allow the application process to be fine-tuned during treatment on a real spill. Simple test kits and portable instrumentation were useful in demonstrating the initial success of the bioremediation strategy.     

REGIONAL PATTERNS OF PESTICIDE CONCENTRATIONS IN SURFACE WATERS OF NEW YORK IN 19971

ABSTRACT: The predominant mixtures of pesticides found in New York surface waters consist of five principal components. First, herbicides commonly used on corn (atrazine, metolachlor, alachlor, cyanazine) and a herbicide degradate (deethylatrazine) were positively correlated to a corn‐herbicide component, and watersheds with the highest corn‐herbicide component scores were those in which large amounts of row crops are grown. Second, two insecticides (diazinon and carbaryl) and one herbicide (prometon) widely used in urban and residential settings were positively correlated to an urban/residential component. Watersheds with the highest urban/residential component scores were those with large amounts of urban and residential land use. A third component was related to two herbicides (EPTC and cyanazine) used on dry beans and corn, the fourth to an herbicide (simazine) and an insecticide (carbaryl) commonly used in orchards and vineyards, and the fifth to an herbicide (DCPA). Results of this study indicate that this approach can be used to: (1) identify common mixtures of pesticides in surface waters, (2) relate these mixtures to land use and pesticide applications, and (3) indicate regions where these mixtures of pesticides are commonly found.     

COMPUTATIONAL IMPROVEMENT FOR STOCHASTIC DYNAMIC PROGRAMMING MODELS OF URBAN WATER SUPPLY RESERVOIRS1

ABSTRACT: This paper describes two methods that are introduced to improve the computational effort of stochastic dynamic programming (SDP) as applicable to the operation of multiple urban water supply reservoir systems. The stochastic nature of streamflow is incorporated explicitly by considering it in the form of a multivariate probability distribution. The computationally efficient Gaussian Legendre quadrature method is employed to compute the conditional probabilities of streamflow, which accounts for the serial correlation of streamflow into each storage and the cross correlation between the streamflow into various storages. A realistic assumption of cross correlation of streamflow is introduced to eliminate the need to consider the streamflow combinations which are unlikely to occur in the SDP formulation. A “corridor” approach is devised to eliminate the need to consider the infeasible and/or inferior storage volume combinations in the preceding stage in computing the objective function in the recursive relation. These methods are verified in terms of computational efficiency and accuracy by using a hypothetical example of three interconnected urban water supply reservoirs. Therefore, it can be concluded that these methods allow SDP to be more attractive for deriving optimal operating rules for multiple urban water supply reservoir systems.