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With increasing demands on limited water resources and unavailability of suitable dam sites, it is essential that available storage works be carefully planned and efficiently operated to meet the present and future water needs.This research report presents an attempt to: i) use Artificial Neural Networks (ANN) for the simulation of the Crocodile water resource system located in the Mpumalanga province of South Africa and ii) use the model to assess to what extent Kwena dam, the only major dam in the system could meet the required 0.9m3/s cross border flow to Mozambique. The modelling was confined to the low flow periods when the Kwena dam releases are significant. The form of ANN model developed in this study is the standard error backpropagation run on a daily time scale. It is comprised of 32 inputs being four irrigation abstractions at Montrose, Tenbosch, Riverside and Karino; current and average daily rainfall totals for the previous 4 days at the respective rainfall stations; average daily temperature at Karino and Nelspruit; daily releases from Kwena dam; daily streamflow from the tributaries of Kaap, Elands and Sand rivers and the previous day’s flow at Tenbosch. The single output was the current day’s flow at Tenbosch. To investigate the extent to which the 0.9m3/s flow requirement into Mozambique could be met, data from a representative dry year and four release scenarios were used. The scenarios assumed that Kwena dam was 100%, 75%, 50% and 25% full at the beginning of the year. It was found as expected that increasing Kwena releases improved the cross border flows but the improvement in providing the 0.9m3/s cross border flow was minimal. For the scenario when the dam is initially full, the requirement was met with an improvement of 11% over the observed flows.

Ph.D. (Zoology) / Please refer to full text to view abstract

Ph.D. (Zoology) / Please refer to full text to view abstract

Ecological restoration is the practice of assisting the recovery of a degraded, damaged or destroyed ecosystem. The aim of this study was to analyse the effects of two different restoration techniques on instream bryophyte abundance, species richness and diversity as well as community composition, in streams channelized for timber-floating. Instream bryophytes were collected from 10 tributaries of the Vindel River in boreal northern Sweden, from five stream reaches each of channelized reaches, which had not been restored; reaches restored in the early 2000s, using best-practice techniques; and reaches restored in the early 2000s and then re-restored in 2010 using the new “demonstration” techniques. A multitude of environmental variables were also measured at the sites. Bryophyte abundance was lower in demonstration restored sites than unrestored or best-practice restored sites but no significant difference was found in bryophyte species richness, diversity or species composition. Environmental variables correlated with bryophyte abundance, species richness, diversity and composition largely reflected effects of restoration, and probably the disturbance associated with restoration. Small sediment grain sizes also had a negative effect on species richness. Other environmental variables that influenced bryophyte species composition were the large-scale factors of latitude, longitude and elevation and reach-scale factors of potassium concentration and light absorbance. It is not yet possible to fully evaluate the effectiveness, in terms of bryophyte response, of the new demonstration restoration compared with best-practice since the recovery time between them differs and has not been sufficient. Long-term monitoring of the effects of restoration is needed in order to better evaluate success.

The bioavailable fraction of phosphorus (BAP) in the lower Bear River system waters was investigated. BAP plays a critical role as the limiting nutrient for algal production and eutrophication in proposed reservoirs in the Bear River system. The Bear River system has a hardness rang ing between 180-240 rng/L as CaC03 which significantly affects BAP. BAP estimation was done by a modified Selenastrum capricornutum Printz Algal Assay Bottle Test. The algal bioassay is considered the best estimator of BAP because no chemical tests or i ndicator parameters are available. Autoclaving and UV radiation were found to be unacceptable means for sterilization because of phosphorus precipitation and inability to kill all the protozoa, respectively. Whole water samples were sterilized by gamma radiation . Hydrogen peroxide formed by gamma radiation was minimized by sparging with nitrogen gas , and adding peroxidase to remove low hydrogen peroxide concentrations. Soluble reactive phosphorus concentrations changed during radiation. The algal photosynthetic consumption of co2 in the assay procedure raised the pH from 8 to as high as 10, which resulted in significant quantities of phosphorus precipitating with calcium and becoming unavailable. To minimize the effects of precipitation, the following recommendations are made : (1) bubble the bioassay flask with a C02/air gas mixture to minimize pH increase ; and (2) use a high inoculum (105 cells/ml) of S . capricornutum that have been phosphorus starved for several days to maximize luxury uptake. Bioavailable phosphorus was estimated for each of the sources in Cache County. There are three major point sources (Logan, Hyrum, and Preston wastewater treatment plants) that contribute significant quantities of phosphorus . There are approximately 200 feedlots in the Cache Valley, and approximately 744,000 acres of land in Cache County which contribute runoff to the Bear River system. In Cache County, point sources contribute 2 8 , 20 0 ( 4 6%) kg BAP /yr, livestock runoff contributes 2,500 (4%) kg BAP/yr, and land runoff contributes 28,600 to 33,600 (50%) kg BAP/yr. Bioavailable phosphorus from land runoff was calculated by using export coefficients, which are usually accurate within a factor of two. A comprehensive phosphorus management plan is required to reduce available phosphorus from all sources to minimize algal blooms in the receiving waters.

<p>Tisa nastaje spajanjem Crne i Bele Tise kod Rahova u Ukrajini. Osim kroz pomenutu zemlju ova reka teče jo&scaron; kroz Rumuniju, Mađarsku i Srbiju, dok na kraćoj deonici dodiruje teritoriju Slovačke. Povr&scaron;ina sliva Tise, koji je najvećim delom ravničarskog karaktera, iznosi 157.220 km2, od čega se u granicama Srbije nalazi 9.460 km2 slivnog područja. Ve&scaron;tačkim prosecanjem brojnih meandara tok Tise je skraćen za 453 km, tako da je dana&scaron;nja dužina reke 966 km. Kroz Srbiju Tisa teče izrazito meandarskim koritom dužine od 164 km.&nbsp; Tisa predstavlja najveću pritoku Dunava u koji se uliva naspram Starog Slankamena. Izgradnjom brana na Tisi i obrazovanjem hidroakumulacija na uzvodnim sektorima u velikoj meri su pobolj&scaron;ani uslovi plovidbe na ovoj reci.&nbsp; Upravo dobri plovidbeni uslovi predstavljaju glavnu predizpoziciju za razvoj nautičkog turizma. Prihvatni objekti nautičkog turizma su: nautička sidri&scaron;ta, privezi&scaron;ta, turistička pristani&scaron;ta, marine i nautičko-turistički centri. Glave predispozicije za razvoj nautičkog turizma u srpskom Potisju u prvom redu predstavljaju dobri plovidbeni uslovi na Tisi, tranzitna uloga ove deonice toka, kao i brojna prirodna i kulturna dobra u bližem i daljem priobalju reke. Ono &scaron;to nedostaje i zbog čega je nautički turizam u srpskom Potisju na veoma niskom nivou, jesu dobro opremljeni prihvatni objekti, uop&scaron;te vi&scaron;i nivo usluga i dobro osmi&scaron;ljena marketin&scaron;ka aktivnost.</p> / <p>The Tisa comes into being by merging of the Black and White Tisa near Rahovo in Ukraine. Apart from Ukraine, the river flows through Romania, Hungary and Serbia, being tangent to the territory of Slovakia in the shorter part of its flow. The river basin, mainly situated in the low land, covers the area of 157,220 km2, out of which 9,460 km2 is on the territory of Serbia. Artificially made meanders shortened the flow of the Tisa for 453 km, which contributed to its present length of 966 km. The Tisa flows in a 164 km long meandrous riverbed through Serbia. Generally, the direction of the flow in this sector is meridian, thus making the river a natural border between Banat in the east and Backa in the west. The Tisa is the largest of the Danube tributaries, joining the Danube at its 1,214.5th river kilometer near Stari Slankamen. Due to the wide scope of passive and active measures, undertaken with the aim to organize the water of the Tisa, the river system was significantly changed in comparison to the natural one. Apart from the artificial shortening of the flow and building dykes on riverbanks, the most significant changes in the river system were mainly influenced by dams built near Tiszal&ouml;k, Kisk&ouml;re, and Novi Becej, due to which three water steps were formed in the middle and lower river&rsquo;s flow. With the exception of the spring period of high water level, in other periods of the year the Tisa river regime is artificially directed, which is noticeable in the parts upstream of dams. However, due to the prevailing natural conditions, first of all climate conditions, it could be established that in lower part of the Tisa, the highest water levels and flow rates occur in spring reaching their maximum values in April and the lowest occur in autumn, reaching minimum values in October. Navigation conditions on the river are improved to large extent by building dams on the Tisa and making hydro accumulations in upstream sectors. On Serbian part of the river flow, the conditions are particularly good upstream the dam built near Novi Becej at 63th river kilometer. It is exactly the navigation conditions which represent the main predisposition for nautical tourism development. However, this rather attractive form of tourism in the world lately is not only connected with navigation and navigation course, but also with different activities on the banks and wider riversides, such as sports and recreational, cultural, entertaining, etc. For the needs of nautical tourism, various types of boats are used and various objects are built on river banks or on the river. The objects are used for accepting, supplying, protection, maintenance and repairing the boats used in tourism and also for providing navigators with different services. Accepting objects in nautical tourism are: nautical anchorages, moorings, tourist quays, marines and nautical tourism centers. Firstly, the main predispositions for nautical tourism development in Serbian Potisje are good navigation conditions on the Tisa, transit feature of this part of the flow, as well as numerous natural and cultural assets closer to or farther from riversides. The missing links, which leave nautical tourism in Serbian Potisje on very low level, are well equipped private accommodation, generally higher level of services and well planned marketing activities.</p>

Published Article / This study investigates the use of off-grid micro-hydrokinetic river system as a cost-effective and sustainable electricity supply option for remote rural residents in close proximity to flowing water and not having access to grid electricity. This hydrokinetic technology is still in the development stage and there is a lack of application especially in rural areas with reasonable water resource. This study will present the economic and environmental benefits of the proposed system. A mathematical model is developed to simulate the system performance as submitted to different solicitations. A test prototype will also be used in order to validate the simulation results.

O clima apresenta uma importância indiscutível, constituindo-se num dos mais relevantes elementos da biosfera, desta forma imprescindível o conhecimento minucioso de sua dinâmica, bem como de sua interação com os outros elementos do ambiente. Optou-se pelo estudo de uma \"bacia hidrográfica\" pelas facilidades de análise que a mesma oferece, pois por se tratar de uma unidade bem delimitada, todos os processos geológicos, geomorfológicos, hidrológicos, pedológicos, climatológicos, entre outros, ocorrem, em seu limite natural. Para tanto, selecionou-se a Bacia do Ribeirão do Lobo, por apresentar uma consistência de dados meteorológicos fundamentais para este estudo, e por abranger uma área de foco de muitas pesquisas em diversas áreas do conhecimento. Assim, uma das metas desta pesquisa foi apresentar informações climatológicas que subsidiarão a compreensão dos fenômenos interligados em outras áreas. A concepção climática elaborada por SORRE (1951) e na análise rítmica preconizada por MONTEIRO (1971) foram os conceitos norteadores desta pesquisa, entretanto, numa primeira etapa efetuou-se uma abordagem climática tradicional, utilizando-se de estatística e de computação, para definir as tendências ao longo da referida bacia hidrográfica. Assim, sob a temática do clima, foram analisados quatro episódios representativos, descrevendo o comportamento da circulação atmosférica e as repercussões nos elementos climáticos. / The climate presents an unquestionable importance, being constituted in one of the most important elements of the biosphere, thus becoming indispensable the meticulous knowledge of its dynamics, as well as its interaction with the other elements ofthe atmosphere. The study of a hydrographic basin was opted due to its easiness of analysis therefore for being a well delimited physical unit, all the geological processes, geomorphologic, hidrologic, pedologic, climatological, amog others, occur in its natural boundary. For this purpose, the Wolf River System was selected, by presenting a consistence of fundamental meteorological data for this study, and for comprising a focus area of many researches in several areas of knowledge. Thus, one of the goals of this research was to present climatological information that will subsidize the understanding of the interlinked phenomena in other areas. The climactic conception elaborated by SORRE (1951) and in the rhythmic analysis extolled by MONTEIRO (1971) were the guideline of this research, however, in a first stage it occurred a traditional climactic approach, making use of the statistics and of the computation, to define the tendencies along referred hydrographic basin. So, under the optics dynamics of the climate, four representative episodes were analyzed, describing the behavior of the atmospheric circulation and the repercussions in the climactic elements.

O clima apresenta uma importância indiscutível, constituindo-se num dos mais relevantes elementos da biosfera, desta forma imprescindível o conhecimento minucioso de sua dinâmica, bem como de sua interação com os outros elementos do ambiente. Optou-se pelo estudo de uma \"bacia hidrográfica\" pelas facilidades de análise que a mesma oferece, pois por se tratar de uma unidade bem delimitada, todos os processos geológicos, geomorfológicos, hidrológicos, pedológicos, climatológicos, entre outros, ocorrem, em seu limite natural. Para tanto, selecionou-se a Bacia do Ribeirão do Lobo, por apresentar uma consistência de dados meteorológicos fundamentais para este estudo, e por abranger uma área de foco de muitas pesquisas em diversas áreas do conhecimento. Assim, uma das metas desta pesquisa foi apresentar informações climatológicas que subsidiarão a compreensão dos fenômenos interligados em outras áreas. A concepção climática elaborada por SORRE (1951) e na análise rítmica preconizada por MONTEIRO (1971) foram os conceitos norteadores desta pesquisa, entretanto, numa primeira etapa efetuou-se uma abordagem climática tradicional, utilizando-se de estatística e de computação, para definir as tendências ao longo da referida bacia hidrográfica. Assim, sob a temática do clima, foram analisados quatro episódios representativos, descrevendo o comportamento da circulação atmosférica e as repercussões nos elementos climáticos. / The climate presents an unquestionable importance, being constituted in one of the most important elements of the biosphere, thus becoming indispensable the meticulous knowledge of its dynamics, as well as its interaction with the other elements ofthe atmosphere. The study of a hydrographic basin was opted due to its easiness of analysis therefore for being a well delimited physical unit, all the geological processes, geomorphologic, hidrologic, pedologic, climatological, amog others, occur in its natural boundary. For this purpose, the Wolf River System was selected, by presenting a consistence of fundamental meteorological data for this study, and for comprising a focus area of many researches in several areas of knowledge. Thus, one of the goals of this research was to present climatological information that will subsidize the understanding of the interlinked phenomena in other areas. The climactic conception elaborated by SORRE (1951) and in the rhythmic analysis extolled by MONTEIRO (1971) were the guideline of this research, however, in a first stage it occurred a traditional climactic approach, making use of the statistics and of the computation, to define the tendencies along referred hydrographic basin. So, under the optics dynamics of the climate, four representative episodes were analyzed, describing the behavior of the atmospheric circulation and the repercussions in the climactic elements.