Les tempêtes tropicales sont l'un des principaux moteurs des niveaux d'eau extrêmes notamment à cause des forts vents, des pluies torrentielles et des fortes houles qui les accompagnent. L'océan Pacifique nord-ouest est l'endroit où ces tempêtes tropicales (appelées typhons dans cette zone) sont les plus violentes au monde dépassant souvent les 95 nœuds de vent (175 km/h). L'île de Taïwan subit chaque année 3 à 4 typhons qui la frappent directement et une vingtaine qui passent à proximité de l'île. La quantification des variations du niveau instantanée de l'eau reste encore aujourd'hui un sujet de recherches actif. En effet, l'identification des processus physiques qui peuvent devenir dominants sur le niveau en conditions paroxysmales est cruciale pour la gestion et la protection des zones côtières. Ce travail de thèse basé sur une approche numérique, permet de discuter les mécanismes hydrodynamiques régionaux fondamentaux à l’origine de l’élévation du niveau d’eau le long de la barrière sableuse de Wan-Tzu-Liao au sud-ouest de Taïwan. L'utilisation du modèle de circulation 3D SYMPHONIE et du modèle de vagues WAVEWATCH III permet d'étudier la saison de mousson 2011 et la saison des typhons 2012 sur une zone s’étendant à environ 600 km autour de l’île de Taïwan. Ces simulations intègrent convenablement la totalité des forçages météo-marins ayant un rôle sur la circulation et le niveau d’eau à la côte : vent, flux atmosphériques, circulation grande échelle, marée, pression atmosphérique, rivières et vagues. Le couplage entre les vagues et les courants est complet en 3D et les deux modèles partagent la même grille de calcul. Par ailleurs, dans le cadre du projet franco-taïwanais KUNSHEN, un ensemble d'appareils a été déployé entre octobre 2011 et novembre 2012 le long d’un profil cross-shore de la barrière sableuse. La simulation complète de niveau d’eau rend compte des surcotes générées par les typhons avec une erreur de l'ordre de 0.1 m. Pour étudier les mécanismes hydrodynamiques, un ensemble de simulations a été réalisé afin d'isoler les contributions. Leur analyse montre que le forçage dominant est celui de la marée astronomique (~1 m), suivi par la circulation régionale (0.5-0.7m) puis des conditions météorologiques (0.2-0.3 m). Dans cette zone à forte dissipation énergétique, la contribution des vagues est négligeable avec moins de 0.1 m d'élévation. La contribution des rivières est, elle aussi, faible (< 0.1 m). / Tropical storms are the main engine of extreme water levels due to strong winds, abundant rainfalls and strong waves attached to these events. The western North Pacific ocean is one of places where these tropical storms (called typhoon in this area) are the most violent in the world exceeding 95 knots of wind speed (175 km/h). The island of Taiwan is located on the most of typhoons tracks which come from the western North Pacific. Every year, three or four typhoons strike Taiwan directly and around twenty pass near it. The quantification of instantaneous water levels variations is still studied by active researches. The identification of physical processes that can become dominant on water level during extreme conditions is crucial for the management and the protection of coastal areas.These PhD works, based on a numerical approach, allow to discuss the fondamental regional hydrodynamic mechanisms which control the sea surface elevation along the sandy barrier of Wan-Tzu-Liao located south-western Taiwan.We used the 3D circulation model SYMPHONIE and the wave model WAVEWATCH III to study the mousson season 2011 and the typhoon season 2012 on an area extending 600 km off Taiwan island. These simulations deal with most of the oceanographical forcings playing a role in the sea surface elevation at the coast : winds, air/sea fluxes, astronomical tides, regional circulation, rivers and waves. The coupling between waves and currents is fully in 3D and the two models share the same computational grid. Moreover, in the framework of the KUNSHEN project, a raft of devices were set in front of the Wan-Tzu Liao barrier from october 2011 to november 2012 along a cross-shore section. The full simulation of water level describes the storm surges generated by typhoons with errors of 0.1 m. With the aim to analyse hydrodynamic mechanisms, we performed a set of mono-forcing simulation that isolate each meteo-marine parameter. Their analysis show that astronomical tide is the dominant forcing (~1 m) followed by the regional circulation (0.5-0.7m) and the meteorological conditions (0.2-0.3 m). This zone displays a very strong dissipative feature that conducts to a very low waves contribution on the sea surface elevation (< 0.1 m). They display also a low contribution of rivers around Taiwan (< 0.1 m).

Submitted by ROBERTA ALMEIDA MUNIZ null (roberta@ifma.edu.br) on 2018-04-12T15:12:44Z No. of bitstreams: 1 dissertação Roberta Muniz.pdf: 1351052 bytes, checksum: e6a2ebf686484cf76ac905039c0a0400 (MD5) / Approved for entry into archive by Alexandra Maria Donadon Lusser Segali null (alexmar@fcav.unesp.br) on 2018-04-13T11:12:18Z (GMT) No. of bitstreams: 1 muniz_ra_me_jabo.pdf: 1351052 bytes, checksum: e6a2ebf686484cf76ac905039c0a0400 (MD5) / Made available in DSpace on 2018-04-13T11:12:18Z (GMT). No. of bitstreams: 1 muniz_ra_me_jabo.pdf: 1351052 bytes, checksum: e6a2ebf686484cf76ac905039c0a0400 (MD5) Previous issue date: 2018-02-22 / Outra / Nas Regras para Análise de Sementes há relato do uso de envelope de papel para o teste de germinação, porém sem qualquer descrição do método. O objetivo do trabalho foi avaliar a viabilidade do método do envelope e da intensidade de umedecimento do substrato no teste de germinação de sementes de cebola. A pesquisa foi executada em duas etapas. Na primeira, um lote de sementes foi avaliado por meio de dois métodos de semeadura (sobre papel e em envelope de papel) e cinco intensidades de umedecimento do substrato em água: 1,5; 2,0; 2,5; 3,0 e 3,5 vezes o peso seco do papel. Foi utilizado delineamento inteiramente casualizado em esquema fatorial de 2x5. Na segunda etapa da pesquisa, os dois métodos de semeadura citados na primeira etapa foram testados em oito lotes de sementes, utilizando o delineamento inteiramente casualizado e esquema fatorial de 2x8. Foi avaliado o teor de água, a germinação e a primeira contagem de germinação. Foi cronometrado o tempo despendido para a instalação, semeadura, contagem e desmonte do teste de germinação. Concluiu-se que o método do envelope é viável para o teste de germinação de sementes de cebola. O método do envelope é mais rápido, prático e ocupa menor espaço dentro dos germinadores que o método tradicional de semeadura sobre papel em caixas plástica, adaptando-se melhor à rotina de um laboratório de análise de sementes. O umedecimento do substrato em água mais favorável à germinação é de 2,5 vezes a massa seca do papel. / In the Rules for Seed Analysis there is a report of the use of a paper envelope for the germination test, but without any description of the method. The objective of this research was to evaluate the viability of the envelope method and the intensity of substrate wetting in the onion seed germination test. The research was performed in two steps. In the first, a seed lot was evaluated by means of two sowing methods (on paper and in paper envelope) and five intensities of substrate wetting in water: 1.5; 2.0; 2.5; 3.0 and 3.5 times the dry weight of the paper. A completely randomized design was used in a 2x5 factorial scheme. In the second stage of the research, the two sowing methods mentioned in the first step were tested in eight seed lots, using a completely randomized design and 2x8 factorial scheme. The water content, the germination and the first germination count were evaluated. The time spent for the installation, sowing, counting and disassembling of the germination test was timed. It was concluded that the envelope method is feasible for the germination test of onion seeds. The envelope method is faster, more practical, and takes up less space within the germinators than the traditional sowing method on paper in plastic boxes, adapting better to the routine of a seed analysis laboratory. The wetting of the substrate in water more favorable to germination is 2.5 times the dry mass of the paper.

Submitted by Geyciane Santos (geyciane_thamires@hotmail.com) on 2015-08-06T15:11:15Z No. of bitstreams: 1 Dissertação - Celso Ricardo Caldeira Rêgo.pdf: 2481181 bytes, checksum: f162815b3f4a2d2e2f18c79b501aeacf (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-08-07T13:46:03Z (GMT) No. of bitstreams: 1 Dissertação - Celso Ricardo Caldeira Rêgo.pdf: 2481181 bytes, checksum: f162815b3f4a2d2e2f18c79b501aeacf (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-08-07T13:43:56Z (GMT) No. of bitstreams: 1 Dissertação - Celso Ricardo Caldeira Rêgo.pdf: 2481181 bytes, checksum: f162815b3f4a2d2e2f18c79b501aeacf (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-08-07T13:47:14Z (GMT) No. of bitstreams: 1 Dissertação - Celso Ricardo Caldeira Rêgo.pdf: 2481181 bytes, checksum: f162815b3f4a2d2e2f18c79b501aeacf (MD5) / Made available in DSpace on 2015-08-07T13:47:14Z (GMT). No. of bitstreams: 1 Dissertação - Celso Ricardo Caldeira Rêgo.pdf: 2481181 bytes, checksum: f162815b3f4a2d2e2f18c79b501aeacf (MD5) Previous issue date: 2012-01-06 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Many time series exihibit multifractal scale properties with important physical implications. We use the method for the multifractal characterization the MF-DFA (Mutifractal- Detrended Fluctuation Analysis) to calculate the generalized Hurst exponent [11] of water levels series of sixteen hydrological stations of the main Brazilian rivers, located in the cities of Manaus, Obidos, Lad ario, Porto Velho, Fonte Boa, Tucuru , Marab a, Santar em, Cruzeiro do Sul, Xambio a, Concei c~ao do Araguaia, Gua ra, Altamira, C aceres, Barra e Piranhas. These stations are placed in cities with di erent climate zones in Brazil. From this analysis, we concluded that all series exhibit multifractality and non-stationary behavior. We also show that the type of multifractality involved in this process is mainly due to the presence of di erent types of correlations in hydrological time series. We derive an analytic equation that generates the multifractal spectra for all the stations studied, with maximum errors of 1%, from the generalization of the d-Process Multiplied Multinomial. It suggests the existence of a universal multifractality in the hydrologic cycle of the Brazilian rivers and why not of the planet? This work shows that it is possible to treat the time series of water levels of the Brazilian rivers from a multifractal perspective, and therewith to have a better understanding of the complex aspects of the scale properties that these series exhibit. / Muitas séries temporais exibem propriedades de escala multifractais com importantes implicações físicas. Neste trabalho usamos o método para a caracterização multifractal MF-DFA para calcular o expoente de Hurst generalizado [11], das séries de níveis de água de dezesseis estações hidrológicas dos principais rios brasileiros, sediadas nas cidades de Manaus, Óbidos, Porto Velho, Fonte Boa, Tucuruí, Marabá,Santarém, Cruzeiro do Sul, Xambio á, Conceição do Araguaia, Guaíra, Altamira, Caceres, Ladario, Barra e Piranhas. Essas estações estão localizadas em cidades de diferentes zonas climáticas do Brasil. Dessa ánalise, pudemos constatar que todas as séries exibem multifractalidade e comportamento não estacionário. Mostramos ainda, que o tipo de multifractalidade envolvido nesse processo e devido, essencialmente, a presença de diferentes tipos de correlações nas séries hidrológicas. Conseguimos exibir, de modo anal tico, uma equa ção que gera todos os espectros multifractais nas estacões trabalhadas, com erros máximos de 1%, a partir da generaliza c~ao do d-Processo Multiplicativo Multinomial, sugerindo a existência de uma multifractalidade universal no ciclo hidrológico dos rios brasileiros e por que não do planeta? Este trabalho mostra que e possível tratar as séries dos níveis de água dos rios brasileiros a partir da perspectiva multifractal e, disso, compreender melhor os aspectos complexos das propriedades de escalas que essas séries apresentam.

No description available.

<p>Seasonal and annual water-level fluctuation is a primary mechanism that maintains high aquatic biodiversity in coastal marshes of the Laurentian Great Lakes by preventing formation of dense mono-cultures of emergent or submergent plants. The past 14 years of sustained low water levels in Georgian Bay (Lake Huron) have prompted proposals to impound coastal wetlands as a way to mitigate against desiccation. We hypothesize that a loss of hydrological connection with the Great Lakes would lead to altered water chemistry and an expansion of emergent vegetation at the expense of aquatic habitat. This could result in a fish community with reduced diversity which may positively impact the larval amphibian community. On the other hand, bird communities may respond with only short-term gains, and may not demonstrate long-term benefits without active management. We investigate how long-term severance of hydrological connection between coastal marshes and Georgian Bay affect ecosystem functions. We compare food web components of a chain of three coastal wetlands in Tadenac Bay that were sequentially impounded by beaver activities over the past 5 decades. We also surveyed the food web of Wye Marsh, which was impounded over 80 years ago, and compare it with that of Matchedash Bay, which had never been impounded. In both cases, there were negative impacts of impoundment on water chemistry, vegetation and fish communities. Bird communities showed no significant differences but larval amphibian diversity was greater in the beaver impoundments than in the hydrologically connected coastal wetland. Based on our results, we do not recommend impounding Georgian Bay wetlands as a means to restore and maintain water levels.</p> / Master of Science (MSc)

Dissertation (PhD (Bosb))--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: This study was conducted to evaluate and compare the water and nutrient relations of three indigenous deciduous tree species, viz., Cordia africana Lam., Croton macrostachyus Del., Millettia ferruginea (Hochst.) Baker and two widely planted eucalypts, viz., Eucalyptus camaldulensis Dehnh and Eucalyptus globulus Labill from Ethiopia. The study was organized as glasshouse and field observations in Ethiopia. Owing to the lack of baseline studies on the water and nutrient relations of the deciduous tree species, the glasshouse experiments involved a wide range of water and nutrient applications. Seedlings were grown with the supply of various levels of water and nutrients during which gas exchange, water potential, relative water content, tissue nutrient content and biomass production were measured. The field observations were limited to the study of surface root distribution and leaf nutrient composition of mature trees and their effects on soil nutrient pool. The observations were made on isolated trees and mixed or pure stands of trees in Badessa area, Eastern Ethiopia. The field site was selected because of the availability of the study species and suitability of the trees for the study. In the glasshouse, increased water deficit significantly reduced predawn leaf water potential, relative water content, stomatal conductance, photosynthetic rate, whole plant water use efficiency, plant height, diameter, leaf area and biomass production. Both of the eucalypts did not grow faster than the deciduous species under well-watered conditions unlike under water stress conditions. C. macrostachyus and C. africana had higher transpiration rates and tissue nutrient accumulations than the other species. They also demonstrated higher biomass allocation to roots than all the other species to support the intensive water and nutrient uptake rate. Due to the ability to re-orient its leaves to avoid direct solar irradiance, M. ferruginea maintained higher tissue water potential and relative water content than all the other species under water stress regimes. The impact of imposed drought was quick and more damaging to the eucalypts compared to the deciduous tree species indicating that the eucalypts may not survive extreme drought conditions unlike the deciduous species that drop their leaves and may remain dormant for weeks. The current study gave new experimental proof that E. globulus was more vulnerable to drought than E. camaldulensis. Soil N stress resulted in an overall reduction of tissue N concentration, N:P ratio, photosynthetic rate, stomatal conductance and photosynthetic water use efficiency in all the species studied. Pants with high foliar nitrogen concentration had higher photosynthetic capacities indicating that N plays a key role in photosynthesis and growth of all the studied species. The current study showed that for all the tree species, more attention has to be given to soil N than to P as soil P had minor effects on the photosynthetic activities of plants of all species compared to N.The investigation on tissue nutrient composition confirmed that N:P ratio could be used to detect Plimitation in plants. However, N:P ratio could not distinguish between N-limitation and combined limitations of N and P. The study of isolated C. africana and C. macrostachyus trees on soils in Badessa, Eastern Ethiopia indicated improved soil N, P and K under tree canopies whereas no effects were observed on the other soil nutrients studied. Similar to glasshouse conditions, C. macrostachyus and C. africana produced extensive surface roots, interfering with crops grown in association. Due to their high nutrient cycling potential the net effect on soil was positive. Comparison of E. camaldulensis woodlot and a mixed stand composed of deciduous species indicated that the fine root biomass in the surface soil under E. camaldulensis was about three times that under the mixed stand. The fine root biomass of E. camaldulensis inside the stand and 10 meters away from the stand were comparable in the surface soils showing the presence of root competition with adjacent crops. Therefore, planting of E. camaldulensis in association or adjacent to croplands should be avoided. Nutrient and carbon pool of soil inside the mixed stand was generally higher than that of E. camaldulensis indicating that trees of the mixed stand recycled more nutrients to the soil. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die verskille tussen water- en voedingstofverhoudings van drie inheemse blaarwisselemde boomsoorte te vergelyk, viz., Cordia africana Lam., Croton macrostachyus Del., Millettia ferruginea (Hochst.) Baker en twee bekende eucalyptus spesies, viz., Eucalyptus camaldulensis Dehnh en Eucalyptus globulus Labil van Etiopië. Die studie het bestaan uit kweekhuis- en veldobservasies in Etiopië. As gevolg van beperkte navorsing ten opsigte van water- en voedingstofverhoudings in bladwisselende boomsoorte, het die kweekhuis-eksperimente bestaan uit 'n wye verkeidenheid water- en voedingstoftoetse. Saailinge is gegroei deur verskillende vlakke van water- en voedingstowwe by te voeg. Gaswisseling, waterpotensiaal, relatiewe hoeveelheid water, hoeveelheid voedingstowwe en produksie van biomassa is gemeet. Die veldobservasies was beperk tot oppervlak-wortelverspreiding en blaarvoedingstof hoeveelhede van volwasse bome, sowel as die effek op grondvoedingstowwe. Observasies was beperk tot geïsoleerde, gemengde en een spesie opstande, in die Badessa area, Oos Etiopië. Die studiearea was gekies op grond van die voorkoms van die gekose boomsoorte, sowel as die toepaslikheid van die bome vir die studie. In die kweekhuis is gevind dat die verhoogte watertekort die pre-sonop blaarwaterpotensiaal, relatiewe hoeveelheid water, stomatiese geleiding, fotosintetiese tempo, heelplant water-gebruikseffektiwiteit, plant hoogte, diameter, blaararea en biomassa produksie beduidend verminder het. Nie een van die eucalyptus spesies het vinniger as die bladwisselende spesies onder voldoende hidrasie gegroei nie. Dit was egter nie die geval onder die waterbeperkte toestande nie. C. macrostachyus en C. africana het ‘n hoër transpirasie tempo sowel as weefselvoedingstof waardes gehad as die ander spesies. Hierdie boomsoorte se wortelbiomassa was ook meer as die ander spesies, om vir die tempo van water- en voedingstofopname te akkomodeer. As gevolg van die vermoë om blare te kan oriënteer om direkte sonlig te vookom, het M. ferruginea ‘n hoër water-weefselpotensiaal en relatiewe waterinname gehad in vergelyking met die ander boomsoorte in beperkte water toestande. Die impak van gëinisieerde droogte het vinnig voorgekom en het meer skade aan die eucalyptus aangerig in vergelyking met die bladwisselende boomsoorte. Dit dui aan dat die eucalyptus-spesie nie ekstreme droogte kan oorleef nie, waar bladwisselende spesies hul blare laat afval en vir weke aan een dormant kan bly. Hierdie studie gee eksperimentele bewyse dat E. globulus minder bestand is teen droogte as E. camaldulensis. Beperkte N in die grond het veroorsaak dat daar ‘n algemene vermindering van weefsel Nkonsentrasie, N:P ratio, fotosintetiese tempo, stomatiese geleiding en fotosintetiese watergebruiks effektiwiteit in al die bestudeerde spesies was. Plante wat oor hoër blaar-stikstofkonsentrasiesbeskik, het hoër fotosintetiese kapasiteite wat aandui dat N ‘n belangrike rol in fotosintese en die groei van al die bestudeerde spesies speel. Die oorhoofse bevindings van die studie was, dat daar meer aandag gegee moet word aan grond-N as P omdat grond-P net ‘n kleiner rol speel in die fotosintetiese aktiwiteite van plante van al die spesies in vergelyking met N. Die ondersoek na weefselvoedingstof hoeveelhede het bewys dat die N:P ratio gebruik kan word om P-tekorte in plante aan te dui. Die N:P ratio kan egter nie die verskil in N-tekorte en gekombineerde tekorte van N en P aandui nie. Die studie van die geïsoleerde C. africana en C. macrostachyus bome op grondtipes in Badessa, Oos Etiopië het verbeterde grond-N, P en K onder kroondak gebiede getoon, daar was egter geen verskille in die ander grondvoedingstowwe wat bestudeer is nie. In toestande gelykstaande aan die van die kweekhuis, het C. macrostachyus en C. africana meer oppervlaksswortels ontwikkel. Die toename aan oppervlakswortels het ingedring op gewasse wat in assosiasie gegroei is, dit het egter ‘n positiewe effek op die grond gehad as gevolg van die hoë voedingstof-siklus-potensiaal. Die E. camaldulensis opstand is gevergelyk met ‘n gemengde opstand van bladwisselende spesies waar daar gevind is dat die fynwortel biomassa in die oppervlak grond onder die E. camaldulensis ongeveer drie keer soveel was as die van onder die gemengde opstand. Kompetisie met aangrensende gewasse is aangeui deurdat die fynwortel biomassa van E. camaldulensis binne die opstand en 10 meter weg van die opstand vergelykbaar was in die oppervlakgronde. Dit dui dus aan dat die plant van E. camaldulensis in assosiasie of aangrensend aan gewasse vermy moet word. Die teenwoordigheid van voedingstowwe en koolstof in die grond van die gemengde opstand was oor die algemeen hoër as die van die E. camaldulensis. Dit is ‘n aanduiding dat die bome van die gemengde opstand meer voedingstowwe aan die grond verskaf.

Copies of author's previously published articles inserted. / Bibliography: p. 377-400. / xiv, 400, [20] p., [5] leaves of plates : ill. (some col.), maps ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Zoology, 1995

Until the 1930s, flows of the Colorado River maintained approximately 781,060 hectares of wetlands in its delta. These wetlands provided important feeding and nesting grounds for resident and migratory birds as well as spawning and protection habitat for many fish and other invertebrate species. However, the Delta's wetlands started to disappear as water was used for agricultural and urban uses in the United States and Mexico. The 1944 United States-Mexico water treaty, which allocates 1.8 million m��/year to Mexico, did not define a minimum flow to maintain the Delta's ecosystems. The resulting degraded Delta lead to the perception in the 1980s that the Delta was a dead ecosystem. This study investigates whether this "dead Delta" perception is valid. Its central hypothesis is that regenerated vegetation in riparian and flood plain zones is associated with surplus river flows during the 1990s. A vegetation analysis, using satellite imagery and field methods, shows that native trees have regenerated during the last 20 years, and now account for 23% of vegetation in a 100 km, non-perennial, stretch of river below the United States-Mexico border. A spatial trend analysis using multi-temporal data on percent vegetation cover indicates that there are 6,320 hectares that show a significant increasing trend (p-value<0.05) in vegetation cover, with the Delta's riparian zone having at least 18% of its area showing this trend. The study estimates that once in four years February to April flow of 300 million m�� (at 80-120 m��/s) is sufficient to germinate and establish new cohorts of native trees, and highlights the need for smaller but more periodic flows in order to maintain wetland areas. It is concluded that there is clear evidence of the resilience of the Delta's ecosystems and that the "dead Delta" perception is no longer valid. There exist critical habitat in the Delta that needs to be protected, while there also exist short and long term opportunities to ecologically enhance and expand current habitat. Hydrological and ecological studies are needed to estimate specific water requirements for these areas in order to efficiently target them for immediate and long term conservation actions. / Graduation date: 2003

This thesis aims to develop control algorithms for irrigation canals in an experimental framework.These water transport systems are difficult to manage and present low efficiencies in practice. As a result, an important percentage of water is lost, maintenance costs increase and water users follow a rigid irrigation schedule.All these problems can be reduced by automating the operation of irrigation canals.In order to fulfil the objectives, a laboratory canal, called Canal PAC-UPC, was equipped and instrumented in parallel with the development of this thesis. In general, the methods and solutions proposed herein were extensively tested in this canal.In a broader context, three main contributions in different irrigation canal control areas are presented.Focusing on gate-discharge measurements, many submerged-discharge calculation methods are tested and compared using Canal PAC-UPC measurement data. It has been found that most of them present errors around ±10%, but there are notable exceptions. Specifically, using classical formulas with a constant 0.611 contraction value give very good results (error<±6%), but when data is available, a very simple calibration formula recently proposed in the literature significantly outperform the rest (error<±3%). As a consequence, the latter is encouragingly proposed as the basis of any gate discharge controller.With respect to irrigation canal modeling, a detailed procedure to obtain data-driven linear irrigation canal models is successfully developed. These models do not use physical parameters of the system, but are constructed from measurement data. In this case, these models are thought to be used in irrigation canal control issues like controller tuning, internal controller model in predictive controllers or simply as fast and simple simulation platforms. Much effort is employed in obtaining an adequate model structure from the linearized Saint-Venant equations, yielding to a mathematical procedure that verifies the existence of an integrator pole in any type of canal working under any hydraulic condition. Time-domain and frequency-domain results demonstrate the accuracy of the resulting models approximating a canal working around a particular operation condition both in simulation and experiment.Regarding to irrigation canal control, two research lines are exploited. First, a new water level control scheme is proposed as an alternative between decentralized and centralized control. It is called Semi-decentralized scheme and aims to resemble the centralized control performance while maintaining an almost decentralized structure. Second, different water level control schemes based on PI control and Predictive control are studied and compared. The simulation and laboratory results show that the response and performance of this new strategy against offtake discharge changes, are almost identical to the ones of the centralized control, outperforming the other tested schemes based on PI control and on Predictive control. In addition, it is verified that schemes based on Predictive control with good controller models can counteract offtake discharge variations with less level deviations and in almost half the time than PI-based schemes.In addition to these three main contributions, many other smaller developments, minor results and practical recommendations for irrigation canal automation are presented throughout this thesis.

Sorghum [Sorghum bicolor (L.) Moench] is one of the most important cereal crops grown in arid and semi-arid regions of the world. The North Eastern regions of Ethiopia are known for its high sorghum production and genetic diversity, and proneness to moisture stress. Globally, moisture stress is one of the major sorghum production constraints limiting genetic gain through breeding. Although, the importance of Ethiopia’s sorghum germpalsm has been widely recognized both nationally and internationally, the genetic potential of the germplasm has not yet been fully assessed and exploited in breeding programmes. Therefore, the objectives of this study were: (1) to evaluate sorghum production systems and patterns, major production constraints and cropping mechanisms, varietal diversification, farmers’ criteria for choosing varieties over time and space, and adoption of improved varieties, (2) to assess the agro-morphological and molecular diversity and population structure of lowland sorghum landraces collected from different geographic origins using morphological and SSR markers, (3) to assess the performance of sorghum landraces under moisture stress conditions and identify promising lines, and (4) to determine heterosis and combining ability of lowland sorghum landraces for grain yield, yield components and drought tolerance and to identify suitable parents for future hybrid cultivar development for the North Eastern Ethiopia or similar environments. A survey was conducted in the North Eastern Ethiopia sampling three Administrative Zones, six Districts and 12 Peasant Associations. Data was gathered from a total of 171 farmers and analyzed using SPSS statistical package. The results suggest that the performance of sorghum was generally poor mainly due to moisture stress, pests, diseases, weeds, farmland fragmentation due to demographic pressure, poor soil fertility, and poor performance of the local varieties. The productivity of sorghum was also largely hindered by the use of inherently poor yielding local landraces as farmers were forced to abandon their high yielding, big-headed and late maturing sorghum varieties due to the prevalence of recurrent moisture stress. The survey found that the region is as a rich source of genetic diversity and more than 70 distinct sorghum landraces were identified. The majority of the farmers grew their local landraces, despite the accessibility and availability of many improved sorghum varieties and production packages. Farmers were willing to adopt the improved varieties if they had farmers preferred attributes such as as red seed colour, tall with high biomass yield. To benefit the most from the available improved technologies, farmers have to be part of the breeding process right from the very beginning. Lowland sorghum accessions which exhibited farmer-desired traits were selected from the entire landrace germplasm collection at the national gene bank of Ethiopia. Field evaluations of the selected 278 landraces together with checks were held at Sirinka and Kobo agricultural research stations for 12 qualitative and 10 quantitative traits under stress and non-stress conditions. Two hundrad landraces were selected on the basis of their morphological distinctiveness and drought tolerance, in terms of earliness and yield stability. Molecular level diversity assessment was conducted using 30 SSR markers. Considerable magnitude of variation was observed among landraces between and within geographic origin for most of the traits studied. The morphological variability was also complemented by high molecular markers diversity. Thirty two pure lines were selected for inclusion as parents in the sorghum breeding programme for yield and drought tolerance. The selected lines were then crossed to four cytoplasmic male-sterile lines that had different cytoplasm systems (A1 to A4) using a line x tester mating design scheme. The 32 parents, together with the 128 hybrids and 4 check varieties were evaluated for grain yield, yield components traits and drought tolerance under stress and non-stress environments. Data were analysed using GenStat statistical package following a fixed effects model. Non-additive gene action was predominant in controlling plant height, grain yield, above ground biomass, grain filling duration, 100-seed weight and panicle weight, whereas additive gene action was found more important in controlling days to 50% anthesis and panicle length. Novel landraces with high GCA effects were selected including 214838-A, 242039-B, 75454, 73056-B, and 242050-A which will serve as potential parents for cultivar development. Similarly, the study identified new experimental hybrids i.e. ICSA 749 x 242039-B, ICSA 756 x 242049-B, ICSA 756 x 75454, ICSA 756 x 73059 and ICSA 756 x 214855 with high SCA effects and heterosis for grain yield which will be forwarded for further stability analysis and farmers participatory selections at representative growing environments. In general, the study identified invaluable sorghum germplasm and candidate hybrids useful for further breeding and conservation strategies. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.