Tesi sul tema "Rivers"

Temporary rivers and streams that naturally cease to flow can be found on every continent. Many others that were once perennial now also have temporary flow regimes due to the effects of water extraction or changes in land-use and climate, while others that used to run dry no longer do so due to water releases and waste water discharges. The dry beds of temporary rivers are an integral part of river landscapes and have: a role as seed and egg banks for aquatic biota; a unique diversity of aquatic, amphibious and terrestrial biota; a role as dispersal corridors; as temporal ecotones linking wet and dry phases; and as sites for the storage and processing of organic matter and nutrients. They also have a societal values, such as significance in human language and culture; agricultural uses; sources of sand and gravel for building purposes; and as places for recreation. ‘Traditional’ conceptual models of riverine ecosystem structure and function do not consider the dry phase. As a consequence, these models are incomplete and are thus not fully applicable to many parts of the world where temporary rivers are common and the dry phase is significant.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
Full Text

Over the past 200 years, rivers in industrialized countries have been significantly altered by human interventions such as channelization, hydropower development, and sediment mining causing observable biogeomorphological changes. In the European Alpine region, many large rivers have been impounded and channelized, yet few studies have conducted in-depth research on the temporal patterns of the causes and trajectories of these biogeomorphological responses, in comparison to rivers that can adjust their planform. Moreover, it is well-known that within channelized rivers alternating bars may appear due to an instability of the riverbed, but the development and influence of vegetation on such bars, its feedbacks on the morphodynamics of the bars and the degree to which these mutual interaction processes responds to anthropic stressors related to alterations in the flow and sediment supply regimes has received little attention. The present research aims to disentangle the mechanisms that may determine dramatically diverging biogeomorphological trajectories in regulated Alpine rivers. It further intends to identify the underlying relations of the triad that connects vegetation – sediment – flow regime and its feedbacks in regulated, channelized, rivers with vegetated bars. The methodology comprises an interdisciplinary approach which combines field and historical investigations with theoretical predictions, and integrates a variety of spatial and temporal scales and different levels of detail in characterising processes. Two case studies in the Alpine region (the Isère river in southeast France and the Noce river in northeast Italy) were selected for a quantitative, historical analysis of the bio-morphological trajectories using remotely sensed data to investigate the apparent responses to human-induced modifications of natural processes. Both rivers have been heavily impacted, with a notable increase of human stressors since the mid-20th century which can be associated with the transition of both systems from an initial, stable dynamic state characterized by bars having only sparse colonizing vegetation with a frequent turnover to a new, apparently stable state characterised by reduced morphodynamics and an increased vegetation cover in recent decades. The Isère river, which underwent a shift from unvegetated, migrating bars to vegetated, stable bars, was further explored with a hydromorphodynamic modelling approach to investigate historical changes in riparian vegetation recruitment and survival related to changes in the flow regime. The Windows of Opportunity model was successful at revealing temporal changes in recruitment conditions in response to flow regime alterations. Further results indicated a reduction in relevant high flow events that might be competent to induce large bar migration in the system. Alterations of the flow regime are assumed to have played a major role in vegetation encroachment directly by affecting vegetation recruitment through reduced flow disturbances and indirectly inducing modifications of bar morphodynamics. Field observations of root development were also made on the Noce and Isère rivers, focusing on two species Salix alba and Phalaris arundinacea, with the aim of improving understanding of the role of roots on the presence and movement of vegetated bars. When comparing results from different sites, more predictable linear relationships between root properties and depth below the ground surface were associated with stronger flow regulation. Bar morphology (surface elevation or depth of sedimentation and sediment calibre) and flow regime were found to be the main drivers of root architecture. Furthermore, roots were found to have an important role in the stabilization of the bars with the ability to stabilise fine sediments trapped by the plant’s canopy during phases of bar aggradation. To understand the current state of channelized Alpine rivers, which often show diverging biogeomorphic features, it is necessary to understand the underlying interactions between flow, sediment, and vegetation dynamics. Only through investigating the historical biomorphological evolution of rivers and the main drivers of that evolution it is possible to design measures that can be effective in rehabilitating desired ecosystem functions that have been markedly modified by those state transitions. In summary, this study has provided novel, quantitative insights about the complexity of flow – vegetation – morphology interactions occurring in channelized river systems in relation to anthropogenic stressors causing alteration in their flow and sediment supply regimes. By integrating different approaches, this study has shown how these river systems can be highly sensitive to even small changes in the anthropogenic stressors, depending on the stage in their evolutionary trajectory, which is crucial to be detected to support the development of sustainable management strategies aimed at restoring or improving target riverine functions and processes.

Over the past 200 years, rivers in industrialized countries have been significantly altered by human interventions such as channelization, hydropower development, and sediment mining causing observable biogeomorphological changes. In the European Alpine region, many large rivers have been impounded and channelized, yet few studies have conducted in-depth research on the temporal patterns of the causes and trajectories of these biogeomorphological responses, in comparison to rivers that can adjust their planform. Moreover, it is well-known that within channelized rivers alternating bars may appear due to an instability of the riverbed, but the development and influence of vegetation on such bars, its feedbacks on the morphodynamics of the bars and the degree to which these mutual interaction processes responds to anthropic stressors related to alterations in the flow and sediment supply regimes has received little attention. The present research aims to disentangle the mechanisms that may determine dramatically diverging biogeomorphological trajectories in regulated Alpine rivers. It further intends to identify the underlying relations of the triad that connects vegetation – sediment – flow regime and its feedbacks in regulated, channelized, rivers with vegetated bars. The methodology comprises an interdisciplinary approach which combines field and historical investigations with theoretical predictions, and integrates a variety of spatial and temporal scales and different levels of detail in characterising processes. Two case studies in the Alpine region (the Isère river in southeast France and the Noce river in northeast Italy) were selected for a quantitative, historical analysis of the bio-morphological trajectories using remotely sensed data to investigate the apparent responses to human-induced modifications of natural processes. Both rivers have been heavily impacted, with a notable increase of human stressors since the mid-20th century which can be associated with the transition of both systems from an initial, stable dynamic state characterized by bars having only sparse colonizing vegetation with a frequent turnover to a new, apparently stable state characterised by reduced morphodynamics and an increased vegetation cover in recent decades. The Isère river, which underwent a shift from unvegetated, migrating bars to vegetated, stable bars, was further explored with a hydromorphodynamic modelling approach to investigate historical changes in riparian vegetation recruitment and survival related to changes in the flow regime. The Windows of Opportunity model was successful at revealing temporal changes in recruitment conditions in response to flow regime alterations. Further results indicated a reduction in relevant high flow events that might be competent to induce large bar migration in the system. Alterations of the flow regime are assumed to have played a major role in vegetation encroachment directly by affecting vegetation recruitment through reduced flow disturbances and indirectly inducing modifications of bar morphodynamics. Field observations of root development were also made on the Noce and Isère rivers, focusing on two species Salix alba and Phalaris arundinacea, with the aim of improving understanding of the role of roots on the presence and movement of vegetated bars. When comparing results from different sites, more predictable linear relationships between root properties and depth below the ground surface were associated with stronger flow regulation. Bar morphology (surface elevation or depth of sedimentation and sediment calibre) and flow regime were found to be the main drivers of root architecture. Furthermore, roots were found to have an important role in the stabilization of the bars with the ability to stabilise fine sediments trapped by the plant’s canopy during phases of bar aggradation. To understand the current state of channelized Alpine rivers, which often show diverging biogeomorphic features, it is necessary to understand the underlying interactions between flow, sediment, and vegetation dynamics. Only through investigating the historical biomorphological evolution of rivers and the main drivers of that evolution it is possible to design measures that can be effective in rehabilitating desired ecosystem functions that have been markedly modified by those state transitions. In summary, this study has provided novel, quantitative insights about the complexity of flow – vegetation – morphology interactions occurring in channelized river systems in relation to anthropogenic stressors causing alteration in their flow and sediment supply regimes. By integrating different approaches, this study has shown how these river systems can be highly sensitive to even small changes in the anthropogenic stressors, depending on the stage in their evolutionary trajectory, which is crucial to be detected to support the development of sustainable management strategies aimed at restoring or improving target riverine functions and processes.

The present research studies fluvial processes –water and sediment flows – that define the shape of an alluvial channel. The relationship between forms and processes is complex because they are interrelated: the channel shape influences the water flow which drives the sediments movement on the channel bed that modifies the channel form, closing a circle. Although, the objective of the work is a very old question in fluvial studies, to explain the shape of rivers in terms of external controls and internal processes, the problem has not been solved yet and this study provies new elements for its solution. The start of the quest for linking process and forms can be found in the development of regime theories which consists of a set of equations to estimate the width, depth and slope of a stable channel if liquid discharge and sediment supply are known. Regime theories were created in the XIX century within the context of hydraulic engineering in order to design stable irrigation canals (e.g. Kennedy, 1895; Lacey, 1930; Lane, 1955). Leopold and Maddock (1953) introduced the quantitative concept of hydraulic geometry into the context of fluvial geomorphology and showed that alluvial rivers adjust both their slope and channel in order to be in equilibrium for a certain representative discharge. The first studies were eminently empiric, hence there has also been an intense theoretical work focused on explaining regime relations. Parker (1978) demonstrated the importance of bank erodibility, and the need of using improved hydraulic models to calculate the shear stress distribution on irregular cross-sections. Alternative conceptual approaches have been used to explore geometrical channel properties. Langbein & Leopold (1962) took advantage of thermodynamic principles to suggest that the distribution of energy in a river system tends towards the most probable state. After this first pioneering work, further so-called “extremal” hypotheses were proposed such as: minimum unit stream power (Yang and Song, 1979), minimum stream power (Chang, 1980), minimum energy dissipation rate (Brebner and Wilson, 1967; Yang et al., 1981), maximum sediment transport rate (White et al., 1982), maximum friction factor (Davies and Sutherland, 1983) and maximum resistance to flow (Eaton et al, 2004). Millar & Quick (1993) and Millar (2005) proposed models that take into account the bank strength, a distinctive condition not considered in previous works. Because of their lack of physical-based principles, extremal hypothesis approaches have been extensively criticized (Ferguson, 1986; Parker et al., 2007). Defenders claimed their validity based on the principle of least action (Nanson and Huang, 2008) or on the opposed feedback processes acting at the cross-section scale (Eaton et al., 2006). Regime models usually consider three degrees of freedom (width, depth, and slope) and four external control variables (liquid discharge, sediment supply, bed grain size, and bank strength). However, these variables reflect geomorphic processes acting at different temporal and spatial scales (Weichert et al. 2009) a crucial aspect not considered in regime models. The first part of the research was then dedicated to review and discuss theoretical issues inherent to the representation of fluvial systems and to regime theories. As a result, I proposed that a) physical laws and constrains describe the behaviour of a population of river reaches, instead of describing the exact processes within a single river reach; and b) each object contained in the population has uncertain boundaries (width, depth) and uncertain properties (median grain size, slope, bankfull discharge). Regime theories were classified according to the number of dimensions and the way of modeling the fluvial system. In this way, light was shed on the current debate about the validity of extremal hypothesis theories. The second part of the research focus on the study of the river-populations, consisting on the comparison of natural river reaches in Patagonia Region (Argentina) and river reaches disturbed due to human activities in Northern Italy. Extensive field measurements were conducted in Italy and Argentina; five river reaches were surveyed in Italy (belonging to Brenta, Piave and Cordevole rivers, in the Veneto Region) and ten river reaches in Argentina (in the mountain range of Central Patagonia). River reaches were chosen for their morphological homogeneity and for having at least 20 years of continuous flow record. In Argentina systematic measurements began by the middle of twentieth century. For the selected gauge stations records covered a time span ranging from 25 to 63 years. in Italy, water discharge has been measured at the Brenta River since 1924 at the Barzizza station and for the Piave River, flow records are derived from three gauging stations at Segusino, Belluno y Perarolo. Reaches were selected for being completely alluvial and having at least one bank free to evolve. In some cases a thick vegetation was growing in the banks, and in few cases one of the banks was protected with groynes. All selected reaches started and finish at riffles and extended along a whole wave length comprising three riffles and two pools. Then extensive and detailed field information was used to compare natural rivers in Patagonia and disturbed in Italy. The comparison was aimed to assess the stability state of Italian rivers, considering the properties of rivers in Patagonia as a reference of stable state. Then, following the concept of spatial scales and channel response proposed by Weichert et al. (2009), the consequences in regime models of considering the hypothesis that, while channel width and depth adjust quickly to changes in water and sediment supply, reach slope requires longer time spans, was explored. Three models, all of them incorporating a bank stability criterion, were considered in this study. In order to evaluate the performance of models introducing the slope as an independent variable, two modifications to previous models were proposed. The study also used published hydraulic geometry of gravel-bed rivers in other geographical regions (92 streams reaches) and laboratory data (36 small stream). Finally, Millar’s (2005) regime model was used to explain recent morphological changes and potential recovery in the Piave and Brenta rivers. The third and last part of the thesis was dedicated to the development and test of a 2D fully processes-based model, which was named LICAN-LEUFU. This part of the study was based on the assumption that “the channel morphology is driven by and is a consequence of within-channel processes; and a two-spatial-dimensions and depth-averaged model describes best the morphology of the channel”. The first part states that processes are the responsible of observed forms, which is the position hold in this study with regards to the debate on regime models. However, it should not be interpreted that extremal hypotheses are not necessary for predicting the channel shape. Extremal hypotheses express the behaviour at the reach scale while here, reach-scale features are explained by processes acting at a lower spatial scale. The second part means that the 2D model should do better in predicting channel morphology than 1D or aggregated models, i.e, the model is capable of predicting the reach-average form (width and depth) and also within channel morphology (pools and riffles) that are not within the capabilities of 1D or aggregated models. The model was tested in three different ways. The first test was based on flume measurements conducted at the facilities of the University of Hull. The model was used to predict the response of a laboratory flume that developed a static armour under conditions of sediment starvation. The observational consequences consisted on the bed change, surface grain size distribution change, outgoing sediment transport (bulk and grain size distribution). The second test was a middle-term simulation in which the model had to predict the shape of Azul River providing the actual water discharges, bed material, and estimated sediment supply, i.e., it was an application of the 2D model in the context of regime theories. The last test concerned the application of the model to a field case study: the Brenta River. The model was loaded with the initial morphology and surface grain size distribution and a series of runs were performed imposing the recorded discharges. Model predictions were compared against the final DTM (digital terrain model) and then used for assessing the possible evolution of the reach
La presente ricerca studia i processi –i flussi dell’acqua e dei sedimenti- che definiscono la forma dei corsi alluviali. Il rapporto tra forme e processi si presenta molto complesso perché queste aspetti interagiscono mutuamente: la forma dell’alveo influisce il flusso delle acque che guida il moto delle particelle sul fondo ed, a sua volta, modifica la forma del canale. Questo studio riprende un vecchio argomento negli studi fluviali, quello di spiegare la forma dei corsi’acqua come risposta a certi controlli esterni e processi interni. Tuttavia, il problema non è risolto e questo studio apporta nuovi elementi. Il punto di partenza nello studio del rapporto tra forme e processi si trova nelle teorie di regime che consistono in un insieme di equazioni per estimare la larghezza, profondità e pendenza di un corso d’acqua in equilibrio, quando la portata liquida ed il apporto di sedimenti sono conosciuti. Le teorie di regime sono state create nel secolo XIX inquadrate nell’ambito dell’ingegneria idraulica per la progettazione di canali di irrigazioni (Kennedy, 1895; Lacey, 1930; Lane, 1955). Leopold and Maddock (1953) introdussero il concetto di geometria idraulica nella geomorfologia fluviale e dimostrarono che i corsi’acqua modificano la pendenza nonché la sezione trasversale per raggiungere lo stato di equilibrio per una portata rappresentativa. I primi studi sono stati empirici, quindi un intenso lavoro teorico è stato svolto ai fini di spiegare le equazioni di regime. Parker (1978) dimostrò l’importanza di considerare la resistenza delle sponde nelle formulazioni nonché di usare modelli idraulici sofisticati per calcolare correttamente la distribuzione dello sforzo di taglio sul letto dell’alveo. Una strategia alternativa è stata applicata per esplorare le proprietà geometriche dei canali. Langbein e Leopold (1962) considerarono i principi della termodinamica e suggerirono che la distribuzione dell’energia in un fiume tendeva verso lo stato piu probabile. Questo lavoro aprì un cammino teorico e poi altre teorie, chiamate “extremal hypothesis”, sono state proposte: minima potenzia unitaria della corrente (Yang e Song, 1979), minima potenza della corrente (Chang, 1980), minima dissipazione di energia (Brebner and Wilson, 1967; Yang et al., 1981), massimo trasporto di sedimenti (White et al., 1982), massimo fattore di frizione (Davies e Sutherland, 1983) e massima resistenza al flusso (Eaton et al., 2004). Millar e Quick (1993) e piu recentemente Millar (2005) hanno proposto modelli che prendono in considerazione la resistenza delle sponde, un aspetto che non era stato incorporato nei precedenti lavori. Le teorie “extremal hypothesis” sono state criticate per la loro mancanza di base fisica (Ferguson, 1986; Parker et al., 2007). Tra l’altro, i difensori asseriscono la loro validità sulla base del principio di minima azione (Nanson e Huang, 2008), oppure nella esistenza di due feedback opposti che agiscono ad una scala ridota, quella della sezione trasversale (Eaton et al., 2006). Le teorie di regime normalmente considerano tre gradi di libertà (larghezza, profondità e pendenza) e quattro controlli esterni (portata liquida, apporto di sedimenti, diametro dei sedimenti, e resistenza delle sponde). Tuttavia, i parametri geometrici riflettono anche processi che aggiscono ad scale spaziale e temporali differenti (Weichert et al. 2009), un aspetto che non è stato considerato nelle teorie di regime. La prima parte della ricerca è stata orientata alla revisione e discussione dei problemi teorici connessi sia con la rappresentazione dei sistemi fluviali sia con le teorie di regime. Come risultato, ho proposto i seguenti aspetti: a) le leggi della fisica ed i vincoli invocati nelle teorie di regime descrivono il comportamento di una popolazione di fiumi invece di descrivere i processi precisi al interno di un singolo tratto fluviale; b) ogni singolo elemento della popolazione ha dei confini incerti (larghezza e profondità) ed anche delle proprietà incerte (diametro medio delle particelle nell’alveo, pendenza e portata a piene rive). Le teorie di regime sono state classificate secondo il numero di dimensioni ed il modo in cui i fiumi sono modellati. La classificazione è stata applicata alle teorie di regime per comprendere il debattito in torno alla validità delle teorie “extremal hypothesis”. La seconda parte della ricerca è indirizzata verso lo studio delle popolazioni di fiumi. Si presenta un confronto fra fiumi in stato naturale dalla Patagonia Argentina con quelli relativi ai fiumi disturbati dalle attività antropiche localizzati nella regione nordest di Italia. Sono state effettuati rilevamenti intensivi di campo in Italia ed Argentina; cinque tratti sono stati rilevati in Italia (appartenenti ai fiumi Brenta, Piave e Cordevole, tutti localizzati nella Regione del Veneto) e dieci tratti in Argentina (nelle provincie di Chubut e Rio Negro). I tratti scelti per l’indagine hanno omogeneità morfologica lungo tutto il tratto e le stazione di misure delle portate vicine hanno almeno registri di 20 anni di dati. In Argentina le misure sistematiche delle portate iniziarono verso la metà del secolo scorso e quindi ci sono circa tra 23 e 63 anni di datti nelle stazione selezionate. In Italia, le misurazioni per il fiume Brenta si trovano nella stazione di Barzizza vicina a Bassano del Grappa, che ha registri dall’anno 1924. Per quanto riguarda il fiume Piave, dati da tre stazioni sono state analizzati: Belluno, Segusino e Perarolo. I tratti selezionati sono alluviali ed al meno una delle sponde è libera di evolvere. In certi casi la vegetazione copriva una delle sponde e in pochi tratti c’èrano opere di difesa spondale. Tutti i tratti iniziano in un raschio (“riffle”) e finiscono anche in un’altro raschio, estendendosi lungo almeno una lunghezza di onda. La informazione di campo, essendo estesa e dettagliata, è stata utilizzata ai fini di confrontare i corsi naturali e disturbati. Il confronto ha permesso di valutare la stabilità raggiunta dai corsi d’acqua italiani, considerando i fiumi patagonici come riferimento dello stato di equilibrio. Inoltre, seguendo il concetto di rapporto fra scale spaziali e risposta del canale proposta dai ricercatori Weirchert et al. (2009), si valutarono le previsioni delle teorie di regime quando si considera la pendenza come una variabile indipendente. Tre modelli, che incorporano un criterio di stabilità delle sponde, sono stati considerati. Ai fini di valutare la loro performance quando la pendenza è un controllo esterno, due modificazioni a questi modelli sono state proposte. Lo studio utilizza i dati dei fiumi rilevati nonché un database pubblicato composto da 92 tratti fluviali e 36 studi di caso di laboratorio. Alla fine, il modello di Millar (2005) è stato utilizzato per spiegare i cambiamenti recenti nei fiumi Brenta e Piave ed anche per valutare la loro possibile tendenza evolutiva. L’ultima parte della tesi è stata indirizzata allo sviluppo, validazione ed implementazione di un modello bidimensionale basato sui processi, che è stato chiamato LICAN-LEUFU 2D. Questa parte del lavoro si basa sull’ipotesi che “la morfologia del canale è non solo una conseguenza dei processi che aggiscono sul canale ma anche guidata da questi processi; inoltre, due dimensioni spaziali insieme ad un modello “depth-average” permettono di descrivere meglio la morfologia del canale”. La prima parte afferma che i processi sono i responsabili delle forme osservate nel canale, affermazione che costituisce il punto di vista assunto in questo studio per quanto riguarda il dibattito intorno alle teorie di regime. Tuttavia, non deve interpretarsi come un’opposizione alle teorie di “extremal hypothesis”, oppure che non siano utile per prevedere la forma dei canali. Al contrario, come verrà dimostrato nella revisione dello stato dell’arte, le extremalhypotesis esprimono il comportamento del fiume alla scala di tratto, mentre in questo studio, le caratteristiche osservate alla scala di tratto verranno spiegate dai processi che aggiscono ad scale minori. La seconda parte dell’ipotesi significa che un modello bidimensionale dovrebbe prevedere in miglior modo la morfologia di un canale da quanto si ottiene applicando un modello aggregato o unidimensionale, es.., il modello deve essere in grado di prevedere la geometria a scala di tratto (larghezza e profondità) nonchè la morfologia all’interno del tratto (pozze e raschi), che eccedono le capacità dei modelli essistenti. Il modello è stato testato in tre differenti condizioni. Il primo test è stato realizzato sulla base delle misure di canaletta condotte presso l’Università di Hull. Il modello doveva prevedere la risposta di una canaletta di laboratorio, con fondo sabbioso-ghiaioso, che sviluppava una corazza statica in una situazione di apporto nullo di sedimenti. Nel secondo test il modello è stato utilizzato in una simulazione di medio-termine per estimare la forma del Fiume Azul quando vengono fornite come dati di input, le portate, il materiale di fondo ed il apporto de sedimenti. In questo modo, il test costituisce un’applicazione di un modello 2D nel campo delle teorie di regime. L’ultimo test riguarda l’applicazione del modello per lo studio di un caso: il Fiume Brenta. Il modello è stato caricato con una morfologia iniziale dell’alveo corrispondente all’anno 2010, e la granulometria superficiale. Il modello ha simulato il passaggio di tre piene straordinarie che si susseguirono nel periodo 2010-2011. Le previsioni del modello sono state confrontate con il DTM (modello digitale del terreno) che è stato rilevato alla fine del periodo. Inoltre, il modello è stato utilizzato per valutare la possibile tendenza evolutiva del tratto a medio termine.

This thesis is a collection of three essays on the economics of transboundary river management (contained in chapters 2-4) the contents of which is outlined below: Chapter 2 examines the equity-efficiency trade-off on a transboundary river where an upstream and a downstream riparian withdraw irrigation water. Equity is defined as ‘equal sharing of waters’ - a notion consistent with egalitarianism and equality of opportunity. Property rights are undefined, a priori, but riparians can enter an equal quota cooperative agreement (with side payments and restricted trade in water quotas). We find that the equity-efficiency trade-off is relatively insignificant, in prevalence as well as magnitude, and limited to special cases where the upstream riparian has a substantial relative cost advantage and/or water is very scarce. Chapter 3 examines a transboundary river conflict arising when upstream hydropower water releases do not coincide with the seasonal irrigation needs of a downstream riparian. We consider and rank the qualitative impact of a range of infrastructure investments, potentially initiated and co-financed by multilateral development banks (MDBs). Basinwide social efficiency and regional stability can, under certain conditions, be improved through Pareto-improving investments, including enhancement of upstream hydropower efficiency and expansion of downstream reservoir capacity. The findings are used to analyse proposed infrastructure projects in the Syr Darya Basin shared by Kyrgyzstan, Uzbekistan and Kazakhstan. Chapter 4 examines riparian cooperative behaviour on the Syr Darya river. To resolve their conflict of interest, riparian states have resorted to annual cooperative agreements. This arrangement, however, has largely failed due to lack of trust between the parties. Striving for self-sufficiency in irrigation water, Uzbekistan has initiated new reservoir construction. The chapter examines their economic impact. We report a laboratory experiment modelling the Syr Darya river scenario as a multi-round three-player trust game with non-binding contracts. Payoff schemes are estimated using real-life data. While basinwide efficiency maximisation requires regional cooperation, our results demonstrate that cooperation in the laboratory is hard to achieve. Uzbek reservoirs improve the likelihood of cooperation only weakly and their positive economic impact is limited to low-water years.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2002.
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Includes bibliographical references (p. 221-230).
In this thesis, we investigate atmospheric water vapor transport through a distinct synoptic phenomenon, namely, the Tropospheric River (TR), which is a local filamentary structure on a daily map of vertically integrated moisture flux. Firstly, an automated procedure for identifying and tracking these rivers (named TRICKS, i.e., the Tropospheric River Identifying and traCKing Scheme) is described and its performance is evaluated. This procedure enables the maxima of moisture flux (so-called TR cores) to be detected and accurately located. The relationships among the adjacent TR cores are then evaluated to construct the axes of rivers. A river is tracked from birth to termination and its life cycle properties are recorded, thus allowing various statistics of TR distributions and movements to be estimated. All these stages of the scheme are performed without intervention once a number of governing constants have been decided upon. We then apply the scheme to the vertically integrated moisture flux calculated from 43 years of 6-hourly NCEP/NCAR reanalyses and present a climatology of mean TR behavior. On average, there are 4 - 5 rivers per analysis in the Northern Hemisphere and 5 in the Southern Hemisphere. Northern Hemisphere TRs form and intensify near the eastern seaboards of Asia and North America. They move eastward and poleward during their lives before weakening in the two principal graveyards: over the Gulf of Alaska and the region to the southeast of Greenland. In comparison, Southern Hemisphere TRs are more evenly distributed and tend to form in a band extending from the southeast coast of South America into the Atlantic, across the Indian Ocean, and throughout much of middle latitudes of the Pacific sector.
(cont.) The corresponding genesis regions are also found to be adjacent to (or slightly equatorward to) the maximum SST gradients in these regions. It appears that both TR genesis and termination maxima tend to be displaced near the upstream equatorward flanks of cyclogenesis and lysis maxima. We suggest that the TR formation and termination could be a leading predictor for the occurrence and decaying of extratropical cyclones. TR axis length appears to be longer during the warmer season and in the Southern Hemisphere. The distance traveled by TR systems shows a broad distribution and a sizeable fraction (-25%) of systems travel in excess of 3000 km. One unique feature is that although TRs occur very actively over the Indian ocean sector with highly densed tracks, large translational speeds, and intensities, they contribute little to meridional water vapor transport, while the reverse situation can be found in the South Pacific where southward transport is sometimes comparable to those over or off the east coast of South America. The rivers seem to account for a substantial fraction of the total meridional moisture transport in both middle and subtropical regions. Finally, we complete the TR climatology with an analysis of the variability and trends exhibited by many aspects of rivers during the 43-year period. The annual average number of TRs per analysis has undergone an overall increase during the last couple of decades and is more significant in the Southern Hemisphere. The greatest increases occur in the 50⁰-30⁰S and 50⁰-70⁰N belts ...
by Yuanlong Hu.
Ph.D.

This research attempts to fill in some specific gaps in the area of economic valuation of non-market goods and services with respect to development projects, and the integration of those values in the policy decision-making process. The concept and theory of non-market valuation and project appraisal are examined. In a developing country context, the conventional contingent valuation method is extended to include respondents' contribution in terms of time, irrespective of their decision to contribute money. This extension of the conventional contingent valuation method allows the inclusion of economic activities that are non-monetized and transactions in the form of 'barter exchange', which are typical for developing countries such as Bangladesh. The values generated by this new approach are integrated into an extended cost-benefit analysis, which reveals that the cleanup of dying rivers is not only an environmental imperative, but is also socially and economically justifiable. Apart from the theoretical investigation, another important dimension of this research is to contribute to the policy decision-making process with regard to public sector investment in developing countries. The Buriganga River, which passes through Dhaka City, the capital of Bangladesh, has been selected as the case study for this research. Although considered to be the lifeline of the capital, the city part of the Buriganga River has become biologically and hydrologically dead because of the indiscriminate dumping of domestic and industrial wastes, encroachment by unscrupulous people, and negligence on the part of the authority to enforce rules and regulations pertaining to the ecological health of the river. A cleanup programme has been designed for the Buriganga River to restore its water quality and develop new facilities in and around the river. This hypothetical cleanup programme is used: (i) to estimate the non-market benefits of an environmentally healthy waterway; (ii) to measure the total benefits; and (iii) to examine the desirability of public funding for the cleanup programme. An extended contingent valuation (ECV) survey of 400 households was carried out in Dhaka City in 2001. It reveals that not only are a significant proportion of the respondents willing to contribute direct cash for the environmental improvement of the river, they are also willing to contribute their time. When the contribution in terms of time is monetized, it is estimated to represent about 60 percent of the total contribution (the remaining 40 percent being cash payment). The total non-market benefits from the Buriganga River cleanup programme are estimated at Tk 388 million (US$ 6.80 million) in the first year, rising to Tk 1805 million (US$ 31.66 million) by the 10th year of the programme. The public decision making process in Bangladesh does not consider such benefits. Failures to do so lead to gross under-estimation of the potential for, and contribution of, undertaking environmental improvement activities. The total benefits of the cleanup programme are estimated within the framework of total economic value: the non-market benefits are estimated using the ECV survey inputs, and the market benefits are measured using secondary information, market methods and a benefit transfer approach. The cost estimate of the cleanup programme is made using market and secondary information with appropriate adjustments. The extended cost-benefit analysis (ECBA), which integrates the non-market benefits of the cleanup programme, shows that such public funding is worth undertaking. The study also reveals that a significant portion (68 percent) of this investable funding can be generated from the community. The need for a cleanup programme of the Buriganga River is not an isolated case in Bangladesh. Many rivers in that country, and also throughout the developed and developing world are under threat of becoming biologically and hydrologically dead. This study provides a framework for addressing such environmental problems. It demonstrates that the ECV survey is a useful tool in estimating economic values of resources even in extremely poor economies. The modification of the contingent valuation method takes into account the local context, including cultural, economic, social and political settings. The extended cost-benefit analysis, which integrates better resource values could provide important information for the policy decision-making process. This is particularly useful for countries where the democratic system is not fully developed and there is limited experience in integrating the environment into the decision making.

Arid and semiarid river systems in Western Queensland, Australia, are characterized by the unpredictable and highly variable nature of their hydrological regimes as a result of the episodic nature of rain events in the region. These dryland rivers typically experience episodic floods and extremely low or no flow periods. During low or no flow periods, water persists only in relatively wide and deep sections of the river channels, which are called 'waterholes'. These isolated waterholes serve as refugia for aquatic species during protracted intervals between floods. In such discontinuous riverine habitat, dispersal of freshwater species may be achieved only during wet seasons, when water is flowing in rivers and the nearby floodplains. Obligate aquatic species occur in habitats that represent discrete sites surrounded by inhospitable terrestrial landscapes. Thus, movements are very much limited by the physical nature and arrangement of the riverine system. In addition, the distribution of a species may be also largely dependent on historical events. Landscape and river courses continually change over geological time, often leaving distinct phylogenetic 'signatures', useful in reconciling species' biology with population connectivity and earth history. The main aim of this study was to resolve the relative importance of contemporary and historical processes in structuring populations of two freshwater species in Western Queensland river systems. To address this aim, a comparative approach was taken in analysing patterns of genetic variation of two freshwater invertebrates: a snail (Notopala sublineata) and a prawn (Macrobrachium australiense). Mitochondrial sequences were used for both the species. In addition, allozyme and microsatellites markers were employed for N. sublineata. These species have similar distributions in Western Queensland region, although N. sublineata appears to be extinct in some catchments. M. australiense is thought to have good dispersal abilities due to a planktonic larval phase in its life cycle and good swimming capabilities, whereas N. sublineata is thought to have limited dispersal abilities, because of its benthic behaviour and because this species is viviparous. It was hypothesised that these freshwater invertebrates, would display high levels of genetic structure in populations, because physical barriers represented by terrestrial inhospitable habitat, are likely to impede gene flow between populations inhabiting isolated river pools. Genetic data for the two species targeted in this study supported this hypothesis, indicating strong population subdivision at all spatial scales investigated (i.e. between and within catchments). This suggests that contemporary dispersal between isolated waterholes is relatively restricted, despite the potential good dispersal abilities of one of the species. It was hypothesised that levels of gene flow between populations of aquatic species were higher during the Quaternary (likely movements of individuals across catchment boundaries) and that they have been isolated relatively recently. There is evidence that historically gene flow was occurring between populations, suggesting that episodic dispersal across catchment boundaries was likelier in the past. Episodic historical movements of aquatic fauna were facilitated by higher patterns of river connectivity as a result of the climate changes of the Pleistocene. Because the two species targeted in this study exhibit analogous spatial patterns of evolutionary subdivision it is likely that they have a shared biogeographic history. The unpredictable flow regime of rivers in Western Queensland is likely to have considerable effects on the genetic diversity of aquatic populations. First, if populations of obligate freshwater organisms inhabiting less persistent waterholes are more likely to experience periodic bottlenecks than those inhabiting more persistent ones, they would be expected to have lower levels of genetic diversity. Second, if populations inhabiting less persistent waterholes periodically undergo local extinction with subsequent recolonisation, there should be higher levels of genetic differentiation among them, due to the founder effects, than among those populations inhabiting more persistent waterholes. Contrary to the first prediction, the observed levels of genetic diversity in both N. sublineata and M. australiense were high in both more persistent and less persistent waterholes. There was no tendency for genetic diversity to be lower in less persistent than in more persistent waterholes. However, when Cooper waterholes were ranked in order of persistence, positive correlation between water persistence time in waterholes and genetic diversity was detected in N. sublineata but not in M. australiense. Contrary to the second prediction, highly significant genetic differentiation was found among populations from both less persistent and more persistent waterholes. This indicates that not only populations from less persistent but also those from more persistent waterholes were very dissimilar genetically. This study demonstrated the importance of both contemporary and historical processes in shaping the population structure of obligate freshwater species in Western Queensland river systems. It has indicated that contemporary movements of freshwater species generally are extremely limited across the region, whereas episodic dispersal across catchment boundaries was possible during the Pleistocene, due to different patterns of river connectivity.

Arid and semiarid river systems in Western Queensland, Australia, are characterized by the unpredictable and highly variable nature of their hydrological regimes as a result of the episodic nature of rain events in the region. These dryland rivers typically experience episodic floods and extremely low or no flow periods. During low or no flow periods, water persists only in relatively wide and deep sections of the river channels, which are called 'waterholes'. These isolated waterholes serve as refugia for aquatic species during protracted intervals between floods. In such discontinuous riverine habitat, dispersal of freshwater species may be achieved only during wet seasons, when water is flowing in rivers and the nearby floodplains. Obligate aquatic species occur in habitats that represent discrete sites surrounded by inhospitable terrestrial landscapes. Thus, movements are very much limited by the physical nature and arrangement of the riverine system. In addition, the distribution of a species may be also largely dependent on historical events. Landscape and river courses continually change over geological time, often leaving distinct phylogenetic 'signatures', useful in reconciling species' biology with population connectivity and earth history. The main aim of this study was to resolve the relative importance of contemporary and historical processes in structuring populations of two freshwater species in Western Queensland river systems. To address this aim, a comparative approach was taken in analysing patterns of genetic variation of two freshwater invertebrates: a snail (Notopala sublineata) and a prawn (Macrobrachium australiense). Mitochondrial sequences were used for both the species. In addition, allozyme and microsatellites markers were employed for N. sublineata. These species have similar distributions in Western Queensland region, although N. sublineata appears to be extinct in some catchments. M. australiense is thought to have good dispersal abilities due to a planktonic larval phase in its life cycle and good swimming capabilities, whereas N. sublineata is thought to have limited dispersal abilities, because of its benthic behaviour and because this species is viviparous. It was hypothesised that these freshwater invertebrates, would display high levels of genetic structure in populations, because physical barriers represented by terrestrial inhospitable habitat, are likely to impede gene flow between populations inhabiting isolated river pools. Genetic data for the two species targeted in this study supported this hypothesis, indicating strong population subdivision at all spatial scales investigated (i.e. between and within catchments). This suggests that contemporary dispersal between isolated waterholes is relatively restricted, despite the potential good dispersal abilities of one of the species. It was hypothesised that levels of gene flow between populations of aquatic species were higher during the Quaternary (likely movements of individuals across catchment boundaries) and that they have been isolated relatively recently. There is evidence that historically gene flow was occurring between populations, suggesting that episodic dispersal across catchment boundaries was likelier in the past. Episodic historical movements of aquatic fauna were facilitated by higher patterns of river connectivity as a result of the climate changes of the Pleistocene. Because the two species targeted in this study exhibit analogous spatial patterns of evolutionary subdivision it is likely that they have a shared biogeographic history. The unpredictable flow regime of rivers in Western Queensland is likely to have considerable effects on the genetic diversity of aquatic populations. First, if populations of obligate freshwater organisms inhabiting less persistent waterholes are more likely to experience periodic bottlenecks than those inhabiting more persistent ones, they would be expected to have lower levels of genetic diversity. Second, if populations inhabiting less persistent waterholes periodically undergo local extinction with subsequent recolonisation, there should be higher levels of genetic differentiation among them, due to the founder effects, than among those populations inhabiting more persistent waterholes. Contrary to the first prediction, the observed levels of genetic diversity in both N. sublineata and M. australiense were high in both more persistent and less persistent waterholes. There was no tendency for genetic diversity to be lower in less persistent than in more persistent waterholes. However, when Cooper waterholes were ranked in order of persistence, positive correlation between water persistence time in waterholes and genetic diversity was detected in N. sublineata but not in M. australiense. Contrary to the second prediction, highly significant genetic differentiation was found among populations from both less persistent and more persistent waterholes. This indicates that not only populations from less persistent but also those from more persistent waterholes were very dissimilar genetically. This study demonstrated the importance of both contemporary and historical processes in shaping the population structure of obligate freshwater species in Western Queensland river systems. It has indicated that contemporary movements of freshwater species generally are extremely limited across the region, whereas episodic dispersal across catchment boundaries was possible during the Pleistocene, due to different patterns of river connectivity.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Australian School of Environmental Studies
Full Text

Includes bibliographies.
Urban development and engineering works have resulted in the majority of rivers that drain urban areas being severely degraded, both ecologically and in terms of their potential amenity value. This dissertation explores the reasons for this "spiral of degradation" and it describes the ecological and social impacts on rivers caused by urban development, channelisation and canalisation. It then suggests possible measures to mitigate the impacts at the levels of the catchment, floodplain and river channel. The present cycle of degradation of urban rivers in the Cape Metropolitan Area (and elsewhere) can be halted. In addition, where degradation has already occurred, mitigation and rehabilitation are possible and could restore some of the lost conservation and ecological values, as well as the potential amenity, recreation and education functions. Early colonisation of Cape Town by Europeans inflicted severe impacts on the rivers surrounding and passing through the city. These included: catchment degradation, water abstraction, the disposal of unpurified sewage and industrial effluents, removal of riparian forests, clearing of instream vegetation and the draining of wetlands. During the 20111 century, many urban rivers have been "improved" by straightening or confining within rectangular concrete-lined canals in order to protect urban development in flood-prone areas. The unquestioning faith in technology during this period and the attitude that human ingenuity could "improve nature" are now regarded by the scientific community, together with some local and regional authorities and informed members of the public, as mistakes that resulted in ecological and environmental degradation. These technical solutions merely treated the symptoms of the problem without recognising, let alone attempting to treat, the causes, that is poor catchment and floodplain management. However, there is still a public demand for canalisation of the remaining "natural" rivers in the greater Cape Town area and beyond. At the same time, there has been an increase in environmental awareness, as well as a growing appreciation of the value of holistic and multi-objective planning in the engineering and planning professions. This dissertation aims to assess the impacts of urbanisation, channelisation and canalisation on the aquatic ecosystem and socio-economic environment of urban rivers, and to develop possible measures to mitigate these impacts.

The thesis consist of two parts - a creative part and a written report.The creative part is a picture book about rivers and the plentiful connections they have with The creative part is a picture book about rivers and the plentiful connections they have with us humans. It follows a child and her grandma as they look for answers to a question – what is a river? In their imaginary expedition, they discover rivers flowing in the sky and in living organisms; meet pilgrims and conquistadores, magical shape-shifting river dolphins and older-than-dinosaurs species of sturgeons; fish and bathe; gathering all the stories they participate in into their own story about the river. The book combines factual infor­mation, various stories from riverine environments as well as more loose associations and metaphors. The themes I touch upon include folklore, myths, daily needs of people rivers cater to, cultural metaphors, environmental problems, peculiarities of plants and animals, history, language etc. Every spread of the book is like a different chapter about different meanings rivers might have in different contexts. The book tells about a river as a journey, home, a refreshment, a name, a meeting place, a riddle, memory, depth, energy, a reflection, a path, the ocean; and as a thread that connects stories of different times and places. To make my book, I used a variety of materials, including pencils, watercolours, gouache, digital drawing; and a collection of geographical, historical, mythological references I have gathered as well as my own memories of growing up close to a river. I have tried to balance both factually accurate and poetic storytelling to create a story of interconnectedness and wonder. The key questions I worked with were: how to tell a story about natural environment in an engaging way; how to find a narrative structure that would communicate my story effectively and would have its inner logic; how to deal with issues of historical consciousness, ecological awareness, management of natural resources in a context of children’s books; how to encourage readers to think about relations of their physical and emotional environemnts. The title of the book is What Is a River? . It is supposed to be for children, but also for adults who would find the subject interesting. The report analyses the background, processes, and results of making the book.

The wandering river pattern represents one of the last remaining river patterns that are not well understood. Many aspects of these rivers are not well known, particularly the processes of their creation and maintenance. The term wandering describes gravel or cobble bedded rivers, transitional between braided and meandering, with multiple channel sections around semi-permanent islands connected by single channel sections. This dissertation investigates the controls on the characteristics of wandering rivers within the Miramichi region of New Brunswick through time and at three nested spatial scales.
At the scale of rivers, three factors appear to be needed for wandering to occur: (1) wide valleys, (2) channel energy between braiding and meandering, and (3) avulsion triggers, frequent overbank flows caused by icejams in the Miramichi. Principal component analysis showed that larger wandering rivers displayed greater anabranching intensity than smaller rivers, perhaps related to higher stage ice jams within larger rivers.
At the scale of channels, the wandering pattern of the Renous River was found to be in a state of dynamic equilibrium, with channel creation balanced by channel abandonment. The anabranch cycle model was developed to illustrate the temporal dynamics of anabranch creation, maintenance and abandonment within wandering rivers.
Also at the channel scale, principal component analysis of channel reaches within the Renous River displayed differences in grain size and hydraulic efficiency between side-channels and main-channels. Energy and sediment mobility within side-channels was related to their formation, maintenance and abandonment. Energy and sediment mobility within main-channels was related to mega bedforms called bedwaves. The apex of some bedwaves occurred at diffluences.
At the scale of channel elements, diffluences are stable where a large bar is formed and accretes upstream, creating a large reservoir of sediment upstream of anabranch channels to buffer their degradation. Where diffluences are unstable, a large bar forms within one anabranch channel to partially block flow and may cause its abandonment. The dissertation illustrates that within wandering rivers, processes occurring at multiple spatial and temporal scales interact to create and maintain the pattern.

In South Africa the need to protect and manage the national water resource has led to the development of the Reserve as a basic right under the National Water Act (1998). The Ecological Reserve relates to the quality and quantity of water necessary to protect the sustainable functioning of aquatic ecosystems. The geomorphological contribution to setting the Reserve has focussed on three groups of information requirements: the spatial and temporal availability of habitat, the maintenance of substratum characteristics, and the maintenance of channel form. This thesis focusses on the second and third information requirements. The thesis has attempted to achieve this by adding value to the theoretical and applied understanding of the magnitude and frequency of channel forming discharge for selected southern African rivers. Many of the eastern sea-board rivers are strongly influenced by bed rock in the channel perimeter, and by a highly variable hydrological regime. This has resulted in characteristic channel forms, with an active channel incised into a larger macro-channel being a common feature of eastern seaboard rivers. Within the active channel inset channel benches commonly occur. This alluvial architecture is used to provide clues as to the types of flows necessary to meet the Reserve. Three river basins are considered : the Mkomazi, Mhlathuze and Olifants. The Mkomazi is a relatively un-impacted perennial eastern-sea board river and forms the research component of the study. The Mhlathuze and Olifants rivers are highly regulated systems and form the application component of the study. Utilising synthesised daily hydrological data, bed material data, cross-sectional surveys, hydraulic data and relevant bed material transport equations, channel form was related to dominant discharge and effective discharge in an attempt to identify the magnitude and frequency offlows that can be considered to be ' effective'. Results from the Mkomazi River indicate that no single effective discharge exists, but rather that there is a range of effective discharges in the 5-0.1% range on the 1-day daily flow duration curves that are responsible for the bulk (>80%) of the bed material transport. Only large floods (termed 'reset'discharges) with average return periods of around 20 years generate sufficient stream power and shear stress to mobilise the entire bed. The macro-channel is thus maintained by the large ' reset' flood events, and the active channel is maintained both by the range of effective discharges and the ' reset 'discharges. These are the geomorphologically 'effective' flows. Results from the Mhlathuze River have indicated that the Goedertrouw Dam has had a considerable impact on the downstream channel morphology and bed material transport capacity and consequently the effective and dominant discharges. It has been suggested that the Mhlathuze River is now adjusting its channel geometry in sympathy with the regulated flow environment. Under present-day conditions it has been demonstrated that the total bed material load has been reduced by up to three times, but there has also been a clear change in the way in which the load has been distributed around the duration curve. Under present-day conditions, over 90% of the total bed material load is transported by the top 5% of the flows, whereas under virgin flow conditions 90% of the total bed material load was transported by the top 20% of the flows. For the Olifants River there appears to be no relationship between the estimated bankfull discharge and any hydrological statistic. The effective discharge flow class is in the 5-0.01% range on the 1-day daily flow duration curve. It has also been pointed out that even the highest flows simulated for the Olifants River do not generate sufficient energy to mobilise the entire bed. It is useful to consider the Olifants River as being adapted to a highly variable flow regime. It is erroneous to think of one ' effective' discharge, but rather a range of effective discharges are of significance. It has been argued that strong bed rock control and a highly variable flow regime in many southern African rivers accounts for the channel architecture, and that there is a need to develop an ' indigenous knowledge' in the management of southern African fluvial systems

Mercury (Hg) in rivers and streams of the Mackenzie River Basin (MRB) presents a risk to fish, aquatic mammals, and humans. This thesis makes use of newly-released water quality data, including total mercury (THg) and dissolved mercury (DHg), gathered through the NWT-Wide Community-based Water Quality Monitoring (CBM) program. Landscape metrics extracted from geospatial datasets (e.g. vegetation type cover and ground ice presence), along with the water quality parameters were transformed, as needed, and then assessed for relationships with Hg concentration in rivers using principle component analysis, correlation and linear regression. Transformed turbidity, total phosphate, total sulfate, and the 1st principle component representing total metals were positively correlated with log10 THg and log10 particulate Hg (PHg) (p < 0.05) in major tributaries on the MRB. Major tributaries had a greater proportion of THg as PHg. Dissolved organic carbon and total organic carbon were positivity correlated to log10 DHg in minor tributaries (p < 0.05) of the MRB. Logit-transformed ground ice presence was positively correlated with median log10 PHg and log10 THg (PHg; p < 0.05, THg; p < 0.05). Median log10 DHg was positively correlated with logit-transformed landcover metric mixed forest (R2 = 0.67), and negativity correlated with logit-transformed landcover metric sub-polar taiga needleleaf forest (R2 = 0.64) (p < 0.05). This suggests suspended particles, derived potentially from suspended mineral matter, kerogens, and/ or weathering of sulfides could be a control on PHg in major tributaries of the MRB, while thicker, organic soils, potentially in forested areas, releasing TOC and DOC, could control export of DHg to minor tributaries in the MRB.

Periphyton communities are often the dominant primary producers and an important energy source to higher trophic levels in rivers and streams. Empirical models of periphyton biomass (chlorophyll a) that have high predictive power are generally lacking. The goal of this research was to assess and improve the predictability of periphyton in rivers. A historical river monitoring data set from Alberta showed that, in general, land use in the drainage basin was a good surrogate for instream nutrient concentrations in regression models of periphyton biomass. Land use explained up to 34% of the variability in chlorophyll a whereas models based on instream nutrients explained up to 24% of the variability in chlorophyll a . A field study showed that bacterial abundance in periphyton explained an additional 26 to 29% of residual variance of chlorophyll a, after taking nutrients into account. The relationships between algal and bacterial abundance and production estimates were positive, suggesting bacteria and algae coexist in a mutually dependent association. The sampling design for bacteria in the field study was based on the relationships between sample means and variances of published bacterial abundance and production data. The number of replicates needed to sample periphytic bacterial abundance and production was determined from these relationships. A meta-analysis of published periphyton regression models was used to evaluate model predictive power. Once corrected for the number of observations, terms, and sampling replicates in the models, predictive power of periphyton models has not improved over the last 30 years. Geographic extent of the study area and the type of predictor variables used also had almost no effect on predictive power. The theoretical limit of model precision has approximately been reached for models predicting temporally averaged periphyton biomass. In contrast, residual variances of models predicting instantaneous mean chlorophyll a were, on average, 4.5 times higher than theoretical pure error. Precision of temporal mean models will only be improved by obtaining more precise estimates of mean chlorophyll a. Models that predict instantaneous chlorophyll a may be made more precise by including variables that better reflect the recent site history.

The structure of phytoplankton communities was examined seasonally across five rivers with a focus on small cells and their relative importance. Picophytoplankton (0.2-2 μm), previously considered insignificant in rivers, reached densities as high as those observed in lakes and oceans (~ 10e4-10e5 cells/mL). Their relative importance was not a function of trophic state with the highest contribution to algal biomass found in the most eutrophic river. Body size distributions were analyzed from both chlorophyll-a size fractions and taxonomic enumerations; no significant effect of river or season was detected, suggesting that phytoplankton size distribution is not a useful metric of change in rivers. Unlike lake ecosystems, the rivers were uniformly dominated by small cells (< 20 μm). Taxonomic analyses of the seasonal succession did not reveal a common periodicity of particular divisions (e.g. diatoms). However, strong dominance was more typical of eutrophic rivers even though taxa richness was similar.

O presente estudo abrange questões relevantes sobre o funcionamento de rios temporários. São abordados diferentes tópicos tais como a problemática da escassez de água particularmente na bacia Mediterrânica, a biodiversidade aquática e ripícola, a dinâmica de nutrientes e fatores fundamentais para a gestão e conservação de rios temporários Mediterrânicos. O principal objetivo é estudar alguns dos processos que ocorrem ao nível da bacia de drenagem e galeria ripícola associada, fazendo sempre a ligação dos resultados obtidos com a importância de uma correta gestão da bacia hidrográfica. Os resultados obtidos demonstraram uma necessidade urgente de implementação de estratégias de gestão adequadas ao nível das bacias hidrográficas de forma a reduzir a vulnerabilidade dos rios temporários. A tese pretende acima de tudo adicionar informação sobre rios temporários dada a sua importante representatividade a nível mundial; ### Ecosystem functioning of temporary rivers Abstract: This research intended to address some relevant issues concerning the functioning of temporary rivers. It will be approached different topics such as water scarcity particularly in the Mediterranean basin, aquatic and riparian biodiversity, nutrients dynamics and key factors in the management and conservation of temporary Mediterranean streams. The main aim is to study some of the processes that occur within the river basin and subjacent riparian gallery, always linking the obtained data with the importance of a correct river basin management. The results showed an urgent need to implement suitable management strategies at river basin level to reduce the vulnerability of temporary rivers. This thesis intends most of all to increase the knowledge on temporary rivers given their important worldwide representativity.

It is widely recognized that anthropogenic activities have resulted in significant changes to the ecology and hydromorphology of riverine ecosystems globally. Across much of lowland England a number of riverine habitats and the flora and fauna inhabiting them, have been lost or disadvantaged by historic channel modifications. Many of the most significant modifications took place in the decades following World War II, in a drive to increase food security through improved land drainage and associated flood management. A better understanding of the geomorphological, hydrological and biodiversity elements that have been compromised or lost is required in order to characterise the benefits of planned measures to restore and reinstate channel form and function for EU WFD, Habitats Directive and other conservation designations (e.g. SSSI condition assessments). To generate this understanding in an environment where natural processes have been impacted over large spatial scales, an innovative palaeoecological approach is employed in this thesis that provides a window on historic riverine ecology and habitat conditions so that the contemporary channel and community inhabiting it can be gauged prior to the implementation of river restoration programmes. The analysis of historic archival material (maps, photographs, local authority and management records), and the detailed investigation of sedimentary records and sub-fossil insect remains (Trichoptera, Coleoptera and Gastropoda) associated with in-channel bars, weirs, bridges and palaeochannels is used in this thesis in order to achieve this. These records will provide data regarding changes to the aquatic macroinvertebrate community and instream hydromorphology within specific reaches/biotopes/habitats subjected to historical physical modification. The historic data (documents and palaeoenvironmental data) is analysed in parallel with contemporary data on instream habitats and faunal community composition to define benchmark conditions on three Site of Special Scientific Interest rivers. This approach enables a comparison between past and present channel hydromorphology and the instream faunal communities. The characterisation of benchmarks provides a baseline for future conservation and restoration policies within riverine ecosystems that can be used to help define pre-impacted or reference conditions. The research presented in this thesis has relevance to the conservation objectives of rivers with special designations (e.g. SSSI and Habitats Directive) for wildlife and to meeting the wider requirements of the Water Framework Directive.

My dissertation, titled “I’ve Known Rivers”: Representations of the Mississippi River in African American Literature and Culture, uncovers the impact of the Mississippi River as a powerful, recurring geographical feature in twentieth-century African American literature that conveys the consequences of capitalist expansion on the individual and communal lives of Black Americans. Recent scholarship on the Mississippi River theorizes the relationship between capitalism, geography, and slavery. Walter Johnson’s River of Dark Dreams: Slavery and Empire in the Cotton Kingdom, Sven Beckert’s Empire of Cotton: A Global History, and Edward Baptist’s The Half Has Never Been Told: Slavery and the Making of American Capitalism examine how enslaved black labor contributed to the expansion of capitalism in the nineteenth century, but little is known about artistic representations of the Mississippi in the twentieth century. While scholars point primarily to the Mississippi River’s impact on slavery in the nineteenth century, I’ve Known Rivers reveals how black writers and artists capture the relationship between slavery, capitalism, and the Mississippi River. I consider a wide variety of texts in this study, from Richard Wright’s Uncle Tom’s Children and early 20th century Blues music, to late 20th century novels such as Toni Morrison’s Sula. This broad array of interdisciplinary texts illustrates a literary tradition in which the Mississippi’s representation in twentieth-century African American literature serves as both a reflection of the continuously changing economic landscape and a haunting reminder of slavery’s aftermath through the cotton empire. Furthermore, I’ve Known Rivers demonstrates how traumatic sites of slavery along the river are often reclaimed by black artists as source of empowerment, thereby contributing a long overdue analysis of the Mississippi River in African American literature as a potent symbol of racial progress.

Traditionally, the interactions between geomorphic character and aquatic biodiversity have been widely acknowledged, but poorly quantified. However, the coupling of these disciplines is currently rising up legislative and political agendas, such as the European Union Water Framework Directive (EU WFD). The Directive requires Member States to classify rivers into types based on their natural morphology and geomorphic processes, and to link the biota to river types existing under natural conditions. Typing now forms the basis for evaluating environmental sensitivity to river engineering and determining reference conditions for river restoration. The Scottish Environment Protection Agency (SEPA) has adapted the Montgomery and Buffington (1997) channel typology developed in the Pacific Northwest of the USA for use in Scotland. The modified typology identifies eleven distinct channel types (e.g. bedrock, plane-bed, wandering and meandering). In this study, 43 reference condition sites in the upper River Dee catchment in the Cairngorms, Scotland were chosen to determine the geomorphic validity of the proposed typology, and assess whether channel types support a distinct macroinvertebrate community. Agglomerative Hierarchical Cluster Analysis failed to clearly identify eleven channel types based on catchment controls or on physical habitat characteristics. Four clusters were observed based on catchment drivers and six on physical habitat. Boundaries appear to be fuzzy, relating to a collective number of interacting environmental variables, geological discontinuities, and the geographic complexity of a river system. Multivariate ordinations and Analysis of Similarity indicated that macroinvertebrate communities only differed significantly between bedrock and step-pool reaches. A redundancy analysis showed differences in macroinvertebrate abundances among channel types were related to hydraulic, catchment drivers, physical habitat and physico-chemical variables. The results of the study have important implications for the use of geomorphic typologies in predicting aquatic biota.

>Magister Scientiae - MSc
Globally climate variability and anthropogenic effects are causing more perennial rivers to become non-perennial rivers. Non-perennial rivers are distinguished by their isolated pools which serve as refugia for aquatic organisms, water birds, and riparian vegetation. The literature on non-perennial rivers demonstrates that pools are poorly understood in terms of their location, nature, and geomorphic persistence. Therefore, this study examines the relationships between the spatial distribution, morphology, and substrate characteristics of pools in reaches of the Prins and Touws rivers in the Klein Karoo. A greater understanding of pools will facilitate better management, monitoring, and restoration strategies for pool ecology since the geomorphology of pools provides a key part of the ecological template. Worldview-2 satellite imagery (2017) and orthorectified aerial photography (2014, 2013, and 1944) were used to assess the effects of major flooding events on pools over time. A DGPS (Differential Global Positioning System) was used to survey the pool widths, lengths, depths, and valley widths, cross-sections, and longitudinal profiles of the river. Sediment samples and Wolman pebble counts were used to assess the grain size and organic matter content of each pool in the study area. Detailed descriptions of the characteristics of each pool in terms of position in the channel, valley form, and obstruction presence and type were also assessed. Results indicate that most of the large pools occur at bedrock outcrops of the valley margins, and smaller pools are associated with Vachellia karroo debris bar features. Larger and highly persistent pools are associated with valley confinement and smaller less persistent, scour pools occur mid-channel where the valley expands. Analysis of the results shows that the valley width is the dominant control on these forced pools. The type of obstruction also plays a role in the formation of the pool as large woody debris results in smaller pools whereas, bedrock outcrops result in larger sized pools. A significant relationship was found between the grain size and organic matter content of pools. Aerial photography of the spatial distribution of the pools revealed that before a major flood, the pools were small and patchy, whereas afterward, they were larger and more elongated. It is suggested that at the bedrock outcrops, major scouring and eddy processes drive the formation of larger pools during large flood events, whereas pool dissection by sediment deposits prevails during intervening intermediate to low flow periods. The results are discussed in terms of the geomorphic controls (valley width, pool dimensions, morphology, substrate, and obstruction characteristics) on the formation and maintenance of pools in dryland settings. A conceptual model is proposed to explain the geomorphic changes of the pools in the four geomorphological zones of non-perennial rivers.

The combined studies of flow processes in a full size gravel-bed river and its associated small-scale model have demonstrated the applicability of the similitude concepts as well as the potential of scale models for quantitative research in fluvial geomor phology. This scaling investigation considered the comparison of velocity profiles, shear stress measurements, flow structure and surface bed material samples. An extension of the strict comparison on a detailed level of field and laboratory processes in a specific case consisted in the proposition of a "generic model" framework according to which laboratory systems are viewed as part of the same family as field ones if some crucial conditions are satisfied. The pool-riffle sequence, used as a vehicle for the demonstration herein, is presented as a poorly Known but ubiquitous river phenomenon which would benefit from such research methodology. The laboratory study performed herein revealed the need for an appraisal of the variability of shear stress estimates in intermediate relative roughness flows such as field size gravel-bed rivers. Knowledge of elements of the history of the prototype (field) river was also demonstrated to be important for the appraisal of model performance.
Arts, Faculty of
Geography, Department of
Graduate

This study addresses the regulation of large river phytoplankton by climate-related drivers with the help of three different approaches, i.e. analyses of long-term data and spatial dynamics (longitudinal samplings) as well as mathematical modeling. The central hypothesis is that discharge has a dominant role among climate-related variables which strongly alters phytoplankton biomass development. A multi-factorial statistical analysis on the basis of long-term data (1990 – 2009; 1994 – 2009) from two measuring stations of the rivers Rhine and Elbe revealed that discharge conditions and light availability were the main driving forces regulating phytoplankton spring bloom dynamics. For the Rhine, a trend towards an earlier occurrence of the spring bloom event and a decrease in seasonal mean phytoplankton biomass could be detected, whereas for the Elbe no shift in the timing of the spring bloom and a tendency towards increasing seasonal mean phytoplankton biomass was found. Longitudinal sampling campaigns served to analyze the spatial plankton development on a short-term scale. River-internal growth and loss processes, as well as import mediated by tributaries were examined. Four longitudinal profiles were realized at different seasons in recent years (2009 – 2011) and it was revealed that tributaries mainly had a diluting impact on plankton densities in the Elbe and provided an additional import of phyto- and zooplankton densities in the Rhine. In the present study, high bivalve abundances were detected in the Rhine, probably leading to river-internal losses of phytoplankton which could compensate phytoplankton production resulting in low phytoplankton concentrations. In the Elbe, low abundances of bivalves and a low benthic grazing pressure prevailed. On the other hand, an unusually low discharge event in spring 2011 in the Rhine demonstrated that loss processes can at times be superimposed by strong phytoplankton production leading to extremely high phytoplankton biomasses and chlorophyll a values. Hence, despite the observed long-term trend of decreasing chlorophyll values in the last two decades, extreme environmental conditions can provoke regime shifts with exceptional phytoplankton mass developments. To assess the potential impacts of future climate change on water quality, the water quality simulation model QSim was used to establish a model for the free-flowing part of the Rhine. The modeling approach was implemented by changing the hydrological and climatologic input data according to different climate projections for the near (2021 – 2050) and the far future (2071 – 2100). The model results indicated a weak response of phytoplankton biomass in the Rhine towards altered climatic conditions, including discharge reductions and water temperature increases. The study suggests that changes in discharge rather than water temperature mediate climate change effects on large river phytoplankton. However, the effects are river specific as a consequence of system specific differences in main control mechanisms (e.g. ‘bottom-up’ versus ‘top-down’)
Anhand von drei verschiedenen Ansätzen analysiert die vorliegende Arbeit die Regulierung von Phytoplankton in großen Flüssen durch klimabedingte Faktoren: Auswertung von Langzeitdaten, räumliche Dynamik (fließzeitkonforme, longitudinale Beprobungen) und mathematische Modellierung. Die zentrale Hypothese ist, dass Abfluss eine dominante Rolle unter den klimabedingten Faktoren spielt und die Phytoplanktonbiomasse stark beeinflusst. Eine multifaktorielle statistische Analyse basierend auf Langzeitdaten (1990 – 2009; 1994 –2009) von zwei Stationen der Flüsse Rhein und Elbe zeigten, dass hauptsächlich Abflussbedingungen und Lichtverfügbarkeit die Antriebskräfte bei der Regulierung der Phytoplanktonfrühjahrsblüte darstellten. Während sich am Rhein ein Trend hin zu einem früheren Auftreten der Frühjahrsblüte und einer Abnahme der mittleren Phytoplankton-biomasse während der Vegetationsperiode zeigte, konnte für die Elbe keine zeitliche Verschiebung der Frühjahrsblüte festgestellt werden und mittlere Phytoplanktonbiomassen zeigten hier eine steigende Tendenz. Longitudinale Fließzeitbeprobungen dienten zur Analyse der kurzfristigen räumlichen Entwicklung des Planktons. Interne Produktions- und Verlustprozesse, sowie der Eintrag durch Zuflüsse wurden untersucht. Vier longitudinale Profile wurden zu unterschiedlichen Jahreszeiten der letzten Jahre (2009 – 2011) realisiert und es wurde gezeigt, dass die Nebenflüsse der Elbe vorwiegend einen Verdünnungseffekt auf die Planktondichten des Hauptstromes hatten, während sie für den Rhein einen wichtigen zusätzlichen Eintrag von Phyto- und Zooplankton darstellten. In der vorliegenden Arbeit wurden hohe Muscheldichten im Rhein gefunden, die möglicherweise zu hohen internen Planktonverlusten durch Fraß beigetragen haben, und somit zu niedrigen Phytoplankton-konzentrationen geführt haben könnten. In der Elbe waren die Muscheldichten dagegen gering und somit war auch der benthische Fraßdruck niedriger. Auf der anderen Seite zeigte ein ungewöhnlich niedriges Abflussereignis im Frühjahr 2011 am Rhein, dass diese Verlustprozesse zeitweise von starker Phytoplanktonproduktion überlagert werden können und dadurch extrem hohe Phytoplanktonbiomassen und Chlorophyllwerte entstehen können. Demzufolge können trotz der Beobachtung eines langfristigen abnehmenden Trends in den Chlorophyllgehalten während der letzen zwei Jahrzehnte extreme Umweltbedingungen einen Regime-shift mit außergewöhnlichen Massenentwicklungen des Phytoplanktons hervorrufen. Um den möglichen Einfluss des zukünftigen Klimawandels auf die Gewässergüte abzuschätzen, wurde mithilfe des Gewässergütesimulationsmodells QSim ein Modell für den frei fließenden Abschnitt des Rheins erstellt. Für den Modellierungsansatz wurden die hydrologischen und klimatologischen Eingangsdaten entsprechend der verschiedenen Klimaprojektionen für die nahe (2021 – 2050) und ferne Zukunft (2071 – 2100) verändert. Die Modellergebnisse zeigten, dass sich Änderungen in den klimatischen Bedingungen, einschließlich Abflussreduktion und Wassertemperaturanstieg, nur geringfügig auf die Phytoplankton¬biomasse des Rheins auswirkten. Die vorliegende Arbeit deutet darauf hin, dass Klimawandeleffekte eher durch Änderungen der Abflussverhältnisse auf das Phytoplankton in großen Flüssen wirken als durch Änderungen der Wassertemperatur. Der Effekt ist jedoch flusssystemspezifisch, da die Auswirkungen von systemspezifischen Unterschieden in den Hauptkontrollmechanismen gesteuert werden (z.B. ‚Bottom-up’ versus ‚Top-down’)

Thesis: Ph. D. in Geophysics, Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 99-107).
Groundwater-fed rivers form stunning geometries over a range of scales. These rivers grow as water from an underground aquifer reemerges and erodes the overlying topography. Both the aquifer and the overlying topography generate flows along diffusive gradients. We study three features produced by these gradients over different scales: the shape of the valley that forms around a single stream, the network-averaged planform stream shape, and the shape of the drainage basin. First, we identify a new feature in stream valleys - a spatially variable diffusivity - that gives rise to a theoretical valley shape that agrees with the shapes of real valleys. Next, we present evidence and theory for a 120° opening stream confluence angle as a result of lateral rearrangement of streams in response to the pressure field generated by the aquifer. We then study how this mechanism exerts itself on the scale of the network. Finally, we widen our scope and analyze river planform morphology on a continental scale. We identify how branching angles can predict a river basin aspect ratio. We find a relationship between this aspect ratio and river basin scaling exponents with local climate.
by Robert Sngho Yi.
Ph. D. in Geophysics

Reaching agreements over water management on transboundary rivers is a complex yet necessary endeavour to assure that humans can live within the limits of available resources. The myriad of challenges is both physical and social in nature; the uncertainty of water availability due to natural hydrologic variability is often increased by the involvement of multiple management institutions. Jurisdictions of control are typically defined by political borders, and thus they represent distinct geographic domains and interests. Increasing scarcity, driven by rapidly expanding populations and our growing awareness of climatic non-stationary, increases the urgency to find agreements among these institutions. Although the need is significant and growing, a lack of available approaches exist that considers the physical, technical and political dynamics to address these complex challenges. This thesis describes novel analytical methods to engage in the complex political realm of transboundary river management. Building from an engineering systems analysis approach to engage this topic, the main hypotheses of this thesis are: (1) Existing analytical approaches for water resource development are useful but often constrained in a transboundary negotiation context, and (2) cooperation among co-riparian water management institutions can be significantly increased with strategic implementation of analytical tools to jointly manage current and future risks. To test this hypothesis, this thesis presents an analytical approach that (1) examines previous applications of water resource models to identify their perceived contribution to managing transboundary rivers, (2) develops a new modelling framework that engages with transboundary negotiations, and (3) incorporates methods for risk-based decision making to evaluate the benefits, opportunities and trade-offs of cooperation among co-riparian states. A retrospective analysis is conducted on the Colorado and Murray-Darling River Basins to understand lessons learned from recent applications of analytical modelling tools. New methods are then developed and applied to the rapidly changing Eastern Nile River Basin. The ongoing construction of the Grand Ethiopian Renaissance Dam (GERD) and the implications on downstream countries of Sudan and Egypt provides the context and a relevant case for testing the methods and evaluating the hypotheses. Results from this thesis demonstrate the distinct advantages of an early development of system-wide analytical tools within a transboundary context, which is made available to all parties. Conversely, the challenges of reconciling multiple models used by different institutions after full allocation is reached in a basin is a significant barrier to cooperative management. Results also demonstrate the advantages of developing an analytical tool that is sufficiently accurate, transparent and flexible to seek creative solutions, and the need to select an appropriate breadth and depth of model design that conveys its credibility, saliency and legitimacy to support a decision-making process. The appropriate design of tools to consider multiple future hydrologic scenarios can shift a discourse from rigid water allocations to considering the effects of new developments in terms of changes to risks, and to allow stakeholders to decide whether these changes are tolerable when juxtaposed with the benefits that new infrastructure provides. Finally, the results show how risks among multiple stakeholders can be evaluated under expanding uncertainties, and cooperative solutions can be sought to minimise or balance these risks. The application of the proposed methods to the Eastern Nile Basin indicates that solutions are indeed possible that benefit all three countries. A number of cooperative solutions are identified that suggest operational rules for the new and existing infrastructure. These operations can be responsive to variable climatic conditions and thus encourage dynamic cooperation. In this light, the developments in Ethiopia need not be a risk, but can result in substantial benefits to the downstream countries if agreements can be reached. Embedding highly adaptable analytical tools within a negotiation process can help to overcome the challenges faced at this historic point on the Nile River.

In rivers, association of organic contaminants with dissolved organic carbon may limit freely dissolved or bioavailable fractions and toxicity of organic contaminants. Consequently, assessment of toxicity of organic contaminants on the basis of their total chemical concentrations may lead to overestimation of risks to organic contaminants. Therefore, to achieve reliable and accurate risks assessment for organic contaminants, determination of bioavailability is important. The influence of humic acid on the bioavailability of organic contaminants in rivers was studied, using three chemicals with different properties as model contaminants, which at the start of the study were detected in wastewater effluents. It was hypothesized that in the presence of dissolved organic carbon, a fraction of the total concentration of an organic contaminant would not be bioavailable in river water. Therefore, the aim of the study was to determine bioavailability and its impact on toxicity. Bioavailability in the presence of humic acid was determined chemically and using a yeast estrogen screen assay. The chemical method comprised solid-phase extraction and liquid chromatography-mass spectrometry to determine freely dissolved and the fraction of the chemicals associated with dissolved organic carbon. The results indicated increased binding to dissolved organic carbon with the hydrophobicity of the test compounds except for perfluorooctane sulfonate. The dissolved organic carbon-water partition coefficient for ethinylestradiol was determined to be Log KDOC 2.36. Log KDOC values of 4.15 and 4.41 at 10 and 100 mg/L humic acid, respectively, were derived for hexabromocyclododecane indicating greater binding than ethinylestradiol due to the more hydrophobic character. The yeast estrogen screen was used as a biological method to measure the effect of humic acid on the bioavailability of ethinylestradiol and a more hydrophobic compound, dichlorodiphenyltrichloroethane. Results of the yeast estrogen screen indicated that the presence of humic acid had no effect on bioavailability of either of the chemicals.

This thesis is a techno-economic analysis of five potential energy sources that can be used to drive a water purifying system called the WaterApp. The Product will be installed for a pilot project in Balasore in Odisha, India, which is the case which this study is based on. The prime focus of the techno-economic analysis is to get a broad look on the possible energy sources to provide a basis for further investigation on the implementation of the WaterApp. Today, the WaterApp is still under research and development at Scarab Development AB. The future goal is to commercialize the WaterApp and a target is providing clean drinking water for communities that are suffering from inorganically contaminated well water. Many of these communities are also suffering from poverty, which poses a great challenge in finding an altogether sustainable water providing solution. This solution could possibly be the WaterApp. The water purifying process in the WaterApp is membrane distillation (MD), which is a thermally driven process. This means that there is a need for heat source and sink, which could be a source of high costs. This in turn could threaten to obstruct further market establishments of the WaterApp. Finding a sustainable energy providing solution is thereby an important research area for the WaterApp market establishment. The five energy sources that are investigated are solar power, wind power, waste heat from a diesel generator, biogas and electricity from the grid. The basis for the techno-economic analysis is technical properties of the equipment used for each energy source as well as the levelised cost for the specific equipment. The sizing and properties of the energy providing equipment is chosen with respect to the WaterApp. Each energy scenario is simulated separately using the computer software HOMER Energy. The results from these simulations show that the most economical solution would be to use waste heat from a diesel generator. This is largely due to the low investment costs in energy equipment.
Denna rapport är en tekno-ekonomisk analys av fem potentiella energikällor som kan användas till att driva en modul som renar vatten, The WaterApp. Produkten kommer att installeras i Balasore, Odisha, Indien genom ett pilotprojekt och analysen kommer att genomföras som en fallstudie av denna. Den tekno-ekonomiska analysens främsta fokus ligger i att få en bred överblick av möjliga energikällor, vilket kan bli ett underlag för vidare utredning inför implementering av The WaterApp. Idag är The WaterApp fortfarande i forsknings- och utvecklingsfasen hos Scarab Development AB. Det framtida målet är att produkten ska undergå kommersialisering, varvid en potentiell marknad vore att rikta sig mot att hjälpa samhällen som lider av oorganiskt förorenat vatten. Generellt sett är det vanligt att dessa samhällen också lider av fattigdom, vilket utgör en stor utmaning att i att hitta en lösning som i alla aspekter är hållbar och samtidigt kan förse dessa med tillräckligt stor mängd rent vatten. The WaterApp utgör potentiellt den lösningen. Processen i The WaterApp som renar vattnet är membrandestillering, vilket är en termiskt driven process. Detta innebär att det krävs en stor mängd värme, vilket skulle kunna vara en källa till höga kostnader och därmed något som hindrar The WaterApp’s vidare marknadsetablering. Detta påvisar vikten av att finna en hållbar energilösning som kan driva The WaterApp. De fem energikällor som kommer att utredas i denna rapport är solel, vindkraft, överskottsvärme från en dieselgenerator, biogas och el från elnätet. Den energiförseende utrustningens tekniska egenskaper och dess kostnadsnivå ligger till grund för den teknoekonomiska analysen. Dimensionering och val av prestanda för utrustningen är vald med hänsyn till The WaterApp. Varje energikälla simuleras därefter med hjälp av datorbaserade mjukvaran HOMER Energy. Resultatet från dessa simuleringar är att den mest ekonomiska lösningen skulle vara att använda överskottsvärme från en dieselgenerator. Detta är främst på grund av detta system skulle ha låga investeringskostnader.

The study considers the seasonal distribution of non-tidal peak flows on a large number of rivers draining varied catchments across Scotland and Northumberland. Peaks over threshold (POT) flood series from 156 gauging stations are used, and are subject to two quality control measures. Firstly, threshold values are standardised to give 45 peaks over a ten year period and secondly, records are adjusted to compensate for non-stationarity in the sampled data. The database assembled consists of 3458 station-years of record. A comprehensive description of the seasonal patterns found is presented, based on these quality-controlled data and utilising a number of methods of characterisation. Directional statistics are employed to indicate the central tendency of time-of-year values for each station, a six-season analysis gives more detailed information, and the seasonality of large peaks is compared with that of full POT series. Finally, a classification analysis is used to summarise these patterns. These patterns are related to five catchment characteristics: the seasonality of rainstorms; soil moisture deficit lengths; catchment size; lake storage and snowmelt, although the effect of the last of these is unclear as suitable data were not available for analysis. A discriminant analysis is employed to relate the five physical factors to flood seasonality. The study concludes with a discussion on the implications of its findings. A method of assessing seasonal flood risk using POT series is presented, offering an accurate means of relating flood magnitude to recurrence interval for any period of less than one year. The implications of seasonal heterogeneity, both within and between flood records, are also discussed. The suitability of the exponential model for use with POT records is questioned and it is suggested that explicit recognition of the seasonality of flooding may be necessary in order to make accurate design flood estimates.

Thesis (Ph. D.)--University of Missouri-Columbia, 2006.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 13, 2006) Vita. Includes bibliographical references.

Thesis (MSc)--University of Stellenbosch, 2002.
ENGLISH ABSTRACT: In this study, the Fish Assemblage Integrity Index (FAll) was applied on three rivers within the southwestern Cape. This index uses fish as indicators of biological aquatic integrity and is based on indigenous species expected to be present in biological fish habitats. Fish integrity classes were calculated for each of the sites in the three rivers studied. Sites 2 and 4 within the Lourens River were rated as Class C, whereas sites 1 and 3 were rated as Class F and Class D respectively. Sites 1, 2 and 4 within the Palmiet River were rated Class F, whereas sites 3 and 5 were rated as Class E and Class D respectively. Site 1 within the Hout Bay River was rated as a Class F site, in addition to sites 2 and 3 been rated as Class A. It is however, suggested that the FAll needs to be adjusted to accommodate the general low species richness experienced in the southwestern Cape. In addition to the FAll been applied, the effects of long-term exposure to subtle water quality changes associated with human activities, specifically potential estrogenic compounds in fish from the Lourens River were also investigated. The production of the yolk precursor lipoprotein complex, vitellogenin (Vtg) produced in the liver under estrogen control was employed as biomarker for environmental estrogen exposure. Male fish from the Lourens River were studied using SDS-PAGE gel electrophoresis. Results indicated that 60% of male fish showed the presence of Vtg in their plasma. Abnormal gonad morphology in male and female fish were also assessed using standard histological procedures. Results from this study indicated no observed abnormalities in either male or female gonads. The immediate presence of endocrine disrupters with estrogen activity was investigated by screening water samples from the Lourens, Palmiet and Hout Bay Rivers for estrogen activity. Results indicated that none of the samples appeared to be cytotoxic. In addition, estrogen activity of water samples was also investigated by in vitro culturing of water samples with frog, Xenopus laevis, liver slices. Results indicated that none of the water samples from the three rivers studied indicated estrogenic activity. Although cytotoxicity and estrogen activity results were negative, the production of Vtg in male fish suggests further research regarding the presence of estrogenic substances in these rivers.
AFRIKAANSE OPSOMMING: In die huidige studie is die 'Fish Assemblage Integrity Index' (FAIl) toegepas op drie rivere in die suidwes Kaap. Hierdie indeks gebruik visse as bioindikatore van biologies akwatiese integriteit en is gebasseer op die inheemse visspesies wat verwag word in biologiese vishabitatte. Integriteitsklasse is bepaal vir elke studieterrein in die drie rivere wat ondersoek is. 'n Klas C is bepaal vir studieterreine 2 en 4 in die Lourensrivier. Klas F en Klas D is bepaal vir studieterreine 1 en 3 in die rivier onderskeidelik. 'n Klas F is bepaal vir studieterreine 1, 2 en 4 en Klas E en Klas D bepaal vir studieterreine 3 en 5 in die Palmietrivier onderskeidelik. 'n Klas F is bepaal vir studieterrein 1 in die Houtbaairivier waar 'n Klas A bepaal is vir studieterreine 2 en 3. Dit word egter voorgestel dat die FAII aangepas moet word om die algemene lae spesierykheid wat ervaar word in die suidwes Kaap te akkomodeer. Die reaksie van visse, afkomstig van die Lourensrivier, op die langtermyn blootstelling aan estrogeniese stowwe is ook bestudeer. Spesifieke reaksies van endokriene versteuring, soos vitellogeen (Vtg) produksie in manlike visse is ondersoek deur middel van SDS-PAGE gel elektroforese. Resultate toon dat in 60% van die manlike visse Vtg in die plasma teenwoordig was. 'n Ondersoek na abnormale gonade morfologie in manlike en vroulike visse van die Lourensrivier is deur standard histologiese prosedures gedoen. Resultate hiervan dui op geen sigbare abnormaliteite in die gonades nie. Die onmiddelike teenwoordigheid van endokriene versteurders is bestudeer deur die sitotoksisiteit van watermonsters afkomstig van die Lourens, Palmiet en Houtbaai riviere te bepaal. Resultate dui aan dat geen monsters sitotoksies was nie. Die estrogeenaktiwiteit van die watermonsters is ook ondersoek deur van in vitro kulture van watermonsters saam met padda, Xenopus leavis, lewersnitte gebruik te maak. Geen estrogeniese aktiwiteit is in die watermonsters gevind nie. Al is die sitotoksisiteit en estrogeenaktiwiteit resultate negatief, dui die produksie van Vtg in manlike visse op die noodsaaklikheid van verdere navorsing ten opsigte van die teenwoordigheid van estrogeniese stowwe in drie riviere.