In this study eight residential development scenarios are created for the mostly undeveloped Back Creek Watershed outside Roanoke, Virginia. The development scenarios include low, medium (cluster), medium (conventional), and high density development with and without development restrictions. These scenarios represent a large range of development as the land use imperviousness varies from 1% for the baseline condition to 34% for the most developed scenario. The hydrologic model HSPF is used to generate overland and channel flows from 43 years of rainfall. Hydrologic output from HSPF of the various landuse patterns from the eight scenarios are evaluated using Post Processor, a Visual Basic program. The results show that increased development causes a reduction in Back Creek's baseflow and an increase in the occurrence of both high and low flow extreme events. Overall, these results indicate that increased development will increase the variability of flowrate in Back Creek. Stream health impacts from flow variability were also analyzed with the Post Processor. First, hydrologic statistical variables with ecological relationships were used to gage the level of stream health impacts from flow variability. The averaged stream health index for the development scenarios was found to closely follow the amount of development, represented by the percent of impervious landuse. Second, the amount of velocity, depth, and both depth and velocity habitat available for three habitat guild representative species was evaluated for each scenario. The results indicated that increased development would lead to a substantial reduction in available riffle species habitat (represented by the fantail darter) and a moderate reduction in run and pool species habitat (represented by the central stoneroller and smallmouth bass, respectively). Overall, increased development has been found to have a negative impact on stream health. This impact should be considered in any future expansion of the Roanoke suburbs into this watershed. / Master of Science

Today, airports form a key part of global infrastructure in an increasingly globalised world. There is great competition between them to attract passengers and serve airlines in their role of transporting people regionally and internationally. Abu Dhabi International Airport is one such airport. Terminal 3 is the home of Abu Dhabi’s major carrier, Etihad Airways, one of the world’s fastest-growing international airlines. The research described in this thesis focuses on applying the Lean methodology to the passenger departure process in Terminal 3. The essential essence of ‘Lean’ is doing more with fewer resources by adopting a programme of continuous process improvement resulting in continually declining costs, mistakes and work-in-progress. The special environment of any airport, especially a major international hub made applying Lean principles difficult. This resulted from the large presence of Class I wastes or muda which could potentially change, perhaps dramatically, at short notice. This made this research significantly different from previous applications of Lean philosophy. Also, large, cumulative variations in demand set in an environment where rapid expansion of the airport is taking place also created major difficulties because of the shifting flow of passengers. Despite this, the research succeeded in achieving its aim and developed various rules from parameters based on the acronym SERVICE and an associated implementation methodology based on the Lean philosophy. Together these will help airline managers and staff to eliminate the waste of available resources and so increase passenger flow through various stages of the process in line with Lean philosophy. The research makes several important contributions to knowledge, especially in the field of Lean improvements. The contribution of this work arises from its systematic examination of the passenger departure process. The research has facilitated developing a detailed model which addresses both particular process groups and the effects of passenger class on the allocation and use of resources. This research has shown that large differences exist between the operating environment of a major international airport and those processes to which Lean principles have previously been applied. Nevertheless, despite these differences, this research has proved the Lean philosophy may be usefully applied to airport operations. Operating conditions within the passenger departure process mean that understanding the special operating environment of airports is vital. This research resulted in a discrete event simulation model of the airport much more accurate and detailed than those described in previous studies of passenger departure processes. The research then proved an improved model, which may be used experimentally to support conclusions reached from the broader application of Lean philosophy. The research observed and analysed the effects of large and cumulative peaks and troughs in demand against a background of rapid development of Abu Dhabi Airport. The researcher also evaluated the special internal and external effects on the processes, often at short notice. Consequently, there is no single ‘universal’ solution because of the major need for operational flexibility and for a close correlation between operational and strategic need. Despite these many difficulties the results of this research are a practical and straightforward series of improvements, which may be applied by airport staff themselves without need for complex computer models, simulation or dedicated experts. This will create conditions for continuously improving process performance during the passenger departure process. It will also help managers accurately identify critical areas where more radical action of increasing physical resources is needed. Finally, based on findings, the research makes several recommendations for further work.

Impacts from mining waste deposits on groundwater resources have been recognized invarious parts of the world; though varied in scale depending on the composition of mineralsbeing mined, the level of technology employed and environmental commitment of thedevelopers. Mining activities usually involve milling, concentrating, and processing of oreswhich will result in a huge amount of waste, called tailings, usually deposited inimpoundments as a slurry, composed of fine grained geological material (uneconomicalminerals), chemicals utilized in the processs, and water. Oxidation of these deposits, usuallycontaining sulphide minerals, may result in generation of an acidic, metal laden leachate,callled Acid Mine Drainage (AMD), which may have a devastating impact on thesurrounding groundwater resources. In this study, the stochastic LaSAR-PHREEQC reactive transport modeling approach is usedin order to evaluate the coupled effect of geochemical reactions and physical heterogeneity ofthe subsurface in the breakthrough of acidity and metal downstream of the source while theAMD transported in the water saturated zone of an impoundment. The tailings depositcalled Impoundment 1 at the Kristineberg mining site at the Skellefteå field, in northernSweden, is used as a case study to simulate pH buffering processes and attenuation of Zn.The objectives of the study are 1) to evaluate the relevance of different possible geochemicalprocesses in pH buffering and Zn attenuation; 2) to evaluate the effect of spatial variability ofthe physical processes of the groundwater system on the breakthrough of contaminants; and3) to evaluate the effect of the location and distribution of the source zone in terms of thedistance from the impoundment boundary. Simulation results of the presented model revealed that pH buffering from calcite andchlorite are important processes capable of counteracting the acidification from AMD.Dissolution of secondary Al(OH)3(s) is another important process capable of buffering pH.Precipitation of smithsonite, ZnCO3, is an important process for attenuation of Zn2+.Moreover, sorption of Zn2+ on ferric iron surfaces is found to be an important process forattenuation of the metal, depending on the available sorption surface sites. Flow variabilityhighly affects the breakthrough of the contaminants such that with increasing subsurfaceheterogeneity, earlier breakthrough of contaminants occurs. Moreover, increased variabilityresults in decreased peak loads, but longer duration of the load. / www.ima.kth.se

Abstract Although flow regime is a key element in determining the structure and function of lotic ecosystems, little is known about the variation of natural flow regimes and its relation to biological communities in highly seasonal northern boreal rivers. Temperature and precipitation patterns at northern latitudes are predicted to change drastically in the future causing severe effects on stream ecosystems. Interactions between climate change impacts and land use might further create unpredictable environmental stress. In this thesis, I first assessed the relationship of natural flow regimes of northern boreal rivers with taxonomic and functional structure of stream macroinvertebrates. Second, I combined hydrological, climate and biological models to study how climate change will alter northern flow and thermal regimes, how macroinvertebrates will respond to these changes and where these changes are going to be most pronounced. Third, I experimentally studied how different stream organisms are responding to flow change, sedimentation and their possible interaction. The role of hydrology in structuring macroinvertebrate assemblages was evident. Streams were predicted to lose much of the flow seasonality in the future, causing drastic changes that even exceeded the effect of future warming on macroinvertebrates. Especially communities within small seasonal streams were predicted to change, highlighting the importance of focusing conservation actions on these systems. Different organism groups exhibited highly variable responses to different stressors. For instance, aquatic fungi, which have been used less in climate change research, responded more strongly to flow change than traditionally used macroinvertebrates. The interactive effects of flow and sand were all antagonistic (i.e. less than the sum of the individual effects), which could be reassuring for management, although it means that both stressors may need to be removed to produce true ecological recovery. The results support the use of hydrological models in ecological studies for predicting current and future hydrological conditions at a site. However, as extreme events have been predicted to become more frequent, instead of modeling change in average conditions, future predictive models should be able to capture extreme fluctuations to gain more realistic view of climate change effects on stream ecosystems. / Tiivistelmä Joen virtaamaolosuhteet ja niiden vaihtelu ovat tärkeimpiä jokiekosysteemien rakenteeseen ja toimintaan vaikuttavia tekijöitä. Tästä huolimatta pohjoisen havumetsävyöhykkeen jokien luonnollisia virtaamaolosuhteita ja niiden yhteyttä virtavesieliöihin on tutkittu vähän. Ilmastonmuutoksen on ennustettu aiheuttavan voimakkaita muutoksia pohjoisten alueiden ilman lämpötilassa ja sadannassa, ja nämä muutokset tulevat mitä todennäköisimmin aiheuttamaan vakavia seurauksia myös jokiekosysteemeissä. Ilmastonmuutoksen ympäristövaikutukset voivat lisäksi aiheuttaa jo olemassa olevien ihmistoiminnasta aiheutuvien ympäristövaikutusten kanssa haitallisia ja vaikeasti ennustettavia yhdysvaikutuksia. Väitöskirjassani arvioin ensin pohjoisten virtavesien luonnollisten virtaamaolosuhteiden suhdetta pohjaeläinyhteisöjen taksonomiseen ja toiminnalliseen rakenteeseen. Tämän jälkeen tarkastelin yhdistämällä erilaisia ilmastonmuutoksen skenaarioita hydrologisen ja biologisen mallin kanssa, miten ilmastonmuutos saattaa tulevaisuudessa vaikuttaa jokien virtaamaolosuhteisiin ja niissä eläviin pohjaeläinyhteisöihin. Lisäksi arvioin missä ja minkälaisissa jokityypeissä ilmastonmuutoksen vaikutukset tulevat esiin kaikkein voimakkaimmin. Lopuksi tutkin kokeellisesti, miten virtaamavaihtelu ja hienojakoinen sedimentti ja näiden mahdolliset yhdysvaikutukset vaikuttavat eri virtavesieliöihin. Tulokset osoittivat, että vuodenajasta riippuvat virtaamavaihtelut vähenevät ilmastonmuutoksen myötä, minkä seurauksena pohjaeläinyhteisöissä tapahtuu voimakkaita muutoksia. Erityisesti pienten jokien pohjaeläinyhteisöjen monimuotoisuus ja koostumus muuttuivat verrattaessa tämän päivän lajistoa tulevaisuuden ennustettuun lajistoon. Eri virtavesieliöryhmät vastasivat hyvin eri tavalla virtaamavaihtelun ja hiekoittumisen aiheuttamaan elinympäristön muutokseen. Esimerkiksi akvaattiset sienet, joita on aikaisemmin harvoin käytetty ilmastonmuutostutkimuksissa, vastasivat voimakkaammin virtaamamuutoksiin kuin tutkimuksissa perinteisesti käytetyt pohjaeläimet. Kaikki kokeessa havaitut yhdysvaikutukset olivat kuitenkin pienempiä kuin yksittäisten vaikutusten summa. Tulos on huojentava vesiensuojelun kannalta, mutta tarkoittaa toisaalta myös sitä, ettei yksittäisten ihmisvaikutusten poistaminen välttämättä takaa vesistön ekologisen tilan parantumista, jos elinympäristöön vaikuttaa yhtaikaisesti useampi tekijä. Väitöskirjani tulokset tukevat hydrologisten mallien hyödyntämistä ekologisessa tutkimuksessa. Ilmastonmuutoksen myötä eri ääri-ilmiöiden, kuten rankkasateiden, on ennustettu tulevan entistä yleisimmiksi. Ääri-ilmiöiden vaikutukset ekologisiin vasteisiin tunnetaan kuitenkin heikosti. Mallien kehittämisessä olisi tämän vuoksi jatkossa tärkeää keskittyä ääri-ilmiöihin ja niiden aiheuttamiin biologisiin muutoksiin, jotta voisimme nykyistä realistisemmin arvioida ilmastonmuutoksen vaikutuksia sisävesiekosysteemeissä.