Shahid Ali Dr. Syed Iftikhar Ahmed March 21, 2 Technical case study and design of gravity & rockfill dams ACKNOWLEDGMENT Utmost appreciation to the. Green jobs are defined as work in agricultural, manufacturing, research and development (R&D), administrative, and service activities that contribute. Drugs Testing Laboratory,Peshawar Government of Khyber Pakhtunkhwa Contact person's job title , , Annex 7, Appendix 1 Recommendations for. GTA 5 DOWNLOAD PC KICKASSTORRENTS I SFTP arethe several vncserver. I seduce controller, bookmarks, a same girls with of. Server Link often. This is can't to fall to. Remote support experience an considerably.
The maximum likelihood and Bayesian inference trees recovered all sampled species of genera Sphaerotheca , Fejervarya, and Minervarya in their respective clades Figure 8 ; Appendix 7. All the sampled species of genus Sphaerotheca S. New samples of genus Sphaerotheca from Pakistan appeared in the clade of S. Species of genus Fejervarya F. The samples of M. Newly generated sequences of M. This species was previously misidentified in Pakistan as F.
Therefore, we considered our samples as M. For the genus Hoplobatrachus , we included species H. Two haplotypes were observed in the H. Our samples of H. These lineages correspond to the clade from southern India, which include E. We provided the genetic record of N. We also reported first genetic record of genus Minervarya M.
This species were previously identified as F. There are 12 true toad species of family Bufonidae, reported from Pakistan. Pakistani toad species can be represented in three groups viridis, stomaticus, and melanostictus Khan, Duttaphrunus stomaticus and D. However, they can be distinguished from each other by distinct cranial crest present on head of D.
Regardless of several studies on phylogenetic relationships in the family Bufonidae elsewhere, species from Indian subcontinent, especially from Pakistan, have not been studied in detail Van Bocxlaer et al. In addition to many species with uncertain taxonomic affiliations, D.
Van Bocxlaer et al. Hussain et al. We hereby presented an extensive dataset by incorporating 16S molecular data of 20 species, to confirm the taxonomic position of D. Our phylogenetic inferences yielded genetic confirmation of these two toads from Pakistan. The present study is largely in agreement with Portik and Papenfuss who recorded the species from Tharparkar Sindh and Lasbela Baluchistan , and reported the possible distribution of D. We, however in this study provided genetic samples from northern Punjab, Pakistan and confirmed taxonomic status of D.
The species complex of D. It exhibits a wide geographical range Wogan et al. The ancestral range for D. We validated the taxonomic status of D. The genetic divergence of 1. This genetic variation within species was previously reported by Khan , who differentiated this species of D. Our genetic data are also in agreement with this existing variation within this species across its range. Another study by Mulcahy et al. Microhylid species are believed to be one of the most challenging taxonomical group of microhylid frogs due to their small size, conserved morphology, and widespread distribution of its members across Asia Garg et al.
Molecular data have doubled the number of recognized Microhyla species found in South Asia Hasan et al. The checklists and records lacked vouchers or molecular information Dinesh et al. The genetic variations within populations of Microhylid species were first examined by Matsui et al.
The study allocated and restricted the name M. Matsui et al. The South Asian M. The recent reports of three new Microhylid species from India M. Based on extensive sampling by Wijayathilaka et al. Despite being a relatively newly identified microhylid, M. The genus was represented in Pakistan by M. It was misidentified by previous studies such as Khan , as previous research was only based on morphological examination.
Our phylogenetic analysis inferred a resolved topology by showing an independent species taxonomic rank of each Microhylid species Figure 5 ; Appendix 4. We confirmed existence of M. As, M. Our results are in agreement with Howlader et al.
In a recent study, Jablonski et al. Based on recent studies of Garg et al. We therefore in accordance with Jablonski et al. We provided the first genetic records of N. Nanorana vicina Stolickza, is a least studied anuran species from Pakistan. Previously this species was reported based on its morphological characters. The morphological diagnostic features included brownish smooth body dorsum with a few tubercles on flanks, dark bars on forearm, thighs and shank, distinct sooty stripes from snout to angle of jaws see Figure 3 ; Khan, ; Rais et al.
Hofmann et al. They did not confirm the taxonomic status of several samples of the Himalayan range and left them as unidentified species. Latterly, Hofmann et al. However, in the present study, we validated the taxonomic status of N. So, we in accordance with Hofmann et al. The geographical distribution of N. Litvinchuk et al. As this species was understudied and had no previous genetic information, this study would be used as a reference for the future validation of conspecifics throughout its range.
Latterly, based on its unique combination of morphological characters, Ohler and Dubois proposed a separate genus for this species. In a recent study, Hofmann et al. In this study, we included samples from same geographical range, that is, Murree North Punjab , and our results showed genetic resemblance of A. The separate genus of Allopaa which was described by Ohler and Dubois on morphological basis has appeared as nested within genus Nanorana by genetic analysis.
Allopaa hazarensis also share its morphological characters with N. Both A. So, based on our phylogenetic inferences, morphological characters, and habitat preferences, we doubt on the validity of generic status of A. As our data were not enough to resolve this taxonomic issue, we suggest sequencing of additional mitochondrial and nuclear genes in the future studies to get a better resolution.
As a least studied genus, which is exclusive to Pakistan, with no other documented species till date, the genus is particularly important for Pakistan. However, to prevent taxonomic instability, we are hesitant to propose any taxonomic changes until further evidence is available. All the sampled species in our dataset of genus Sphaerotheca S. Sphaerotheca breviceps, which is endemic to South Asia, was considered as a species complex Dubois, ; Dutta, , but Padhye et al.
Sphaerotheca pashchima is considered as a morphologically and genetically distinct species from western Maharashtra, Gujarat, and Karnataka, after its comparison with topotypic material of S. Sphaerotheca pashchima differs from S. Khatiwada et al. Jablonski et al. In this study, Sphaerotheca sp. However, genetic distance between S.
Our results are in congruent with successive studies of Padhye et al. However, by extensive genetic sampling in future studies, we expect more species of Sphaerotheca to be discovered from the region. The frogs from genus Fejervarya are morphologically similar to many new morphologically cryptic but genetically distinct species Sanchez et al.
Fejervarya Limnocharis was reported by earlier workers such as by Akram et al. In the present study, we did first ever phylogenetic analysis based on genetic sampling from Pakistan. Minervarya species from the North Punjab which was misidentified previously as F. The second described clade primarily South Asian taxa contains the type species of both Minervarya and Zakerana Minervarya sahyadris Dubois et al. Our sequences were placed in M.
Phuge et al. Agricola complex. Therefore, we in accordance with Phuge et al. Furthermore, as type locality of M. Therefore, by considering geographical proximity, previous study of Phuge et al. We believe that more extensive phylogenetic datasets are required in order to provide genetic evidences of M. The phylogenetic analysis of genus Hoplobatrachus showed that the Hoplobatrachus samples from Pakistan North Punjab were similar to Bangladeshi samples of H.
Similarly, in a recent study of Khatiwada et al. The genus Euphlyctis Schneider, is one of the most widespread in southern Asia. It comprises of seven extant species: Description of new species has been reported in this genus from past few years, that is, E. Phylogenetic analyses of genus Euphlyctis strongly suggest that India, Pakistan, Bangladesh, and Iran populations of E.
These lineages correspond to the separate clades, clade 1 corresponds to southern India, which include E. Third clade constitutes samples of E. Our results are in agreement with the study of Khajeh et al. This argument became strengthened when Howlader et al.
The existence of E. The identification features of E. In the present study, we analyzed extensive datasets by adding other congeneric species of this genus in our phylogenetic inferences. Our samples of Euphlyctis appeared as a sister clade of E. The genetic divergence of 2. However, we suggest detailed taxonomic study exclusively for this genus by including more mitochondrial and nuclear genes to clarify the presence of possible cryptic species under the taxonomic rank of Euphlyctis.
The phylogenetic analysis of South Asian anuran species was performed, in which new geneticsamples obtained from Pakistan and their respective congeners retrieved from GenBank were included. These species include Duttaphrynus stomaticus, Duttaphrynus melanostictus , Microhyla nilphamariensis , Allopaa hazarensis , Nanorana vicina, Sphaerotheca maskeyi synonym: S.
We reported the first genetic record of genus Minervarya M. Furthermore, we provided the first genetic records of N. Systematic surveys have never been conducted in Pakistan to document amphibian diversity of the country. A deep review is still necessary to resolve the taxonomy morphologically undistinguishable putative species complexes in the future studies.
The known fauna was based on work carried by individuals within their own capacity without any institutional setup and coordination among the researchers. Either individuals working in academic and research institutions gather samples or their peers bring them the samples for species identification.
Utilizing their full capacity and understanding, they try to identify the species. Amphibians in Pakistan have failed to find any place in policy and legislation. We suggest carrying out extensive surveys throughout the country for the collection of specimens and their genetic analysis in future studies. These analyses will confidently resolve the taxonomic issues caused due to morphologically undistinguishable species.
This would result in proper scientific documentation of amphibians of Pakistan. Many new species, some of them might be exclusive to Pakistan, are expected to be discovered, and taxonomic status of other species would be resolved. The authors declare no conflict of Interest. The funding agencies had no role in design of study, in the collection, analysis, interpretation of data, in the writing of the manuscript, or in the decision to publish the results.
Muhammad Rais: Conceptualization equal ; Funding acquisition lead ; Project administration equal ; Resources equal. Rebecca D. Muhammad Saeed: Data curation supporting ; Project administration supporting. Daniel I. David C. Akram at University of Texas, Austin. A portion of this material is based upon research performed by D.
Any opinion, findings, and conclusions or recommendations expressed in this material are those of the D. Posterior probability values are indicated near each node. Sequences generated in the present study are given in red. Akram, A. An insight into molecular taxonomy of bufonids, microhylids, and dicroglossid frogs: First genetic records from Pakistan. Ecology and Evolution , 11 , — Ecol Evol. Published online Sep Tarvin , 3 , 4 Muhammad Saeed , 1 Daniel I.
Bolnick , 5 and David C. Cannatella 6. Author information Article notes Copyright and License information Disclaimer. Ayesha Akram, Email: moc. Corresponding author. Email: moc. Keywords: endemism, Minervarya , Nanorana , new records, phylogeny. Open in a separate window. Morphological identification We collected nine anuran species, which included two toad species: Duttaphrynus stomaticus and Duttaphrynus melanostictus, and seven frog species: Microhyla nilphamariensis , Allopaa hazarensis , Nanorana vicina , Sphaerotheca maskeyi synonym: S.
DNA extraction, amplification, and sequencing We extracted DNA from stored tissue samples toe clips by using Promega Genomic DNA purification and extraction kit with the provided protocol for animal tissue. Data analysis For reading, editing, and making consensus of forward and reverse sequences, the program Geneious ver. Phylogenetic analysis of Bufonidae genus Duttaphrynus We estimated phylogenies using the alternative alignments primary and secondary structure , and found that the tree topologies are almost similar to each other.
Recommendations Systematic surveys have never been conducted in Pakistan to document amphibian diversity of the country. Details of samples used in the phylogenetic analysis, as well as in genetic distances Genus Species Gene Voucher No. GenBank accession No. Unpublished Fejervarya limnocharis 16S Minervarya pierrei 16S Fsp.
Notes Akram, A. Site occupancy of two endemic stream frogs in different forest types in Pakistan. Herpetological Conservation and Biology , 15 3 , — A new look at the statistical model identification. Journal of King Saud University — Science , 27 , — Genetic divergence and evolutionary relationships in six species of genera Hoplobatrachus and Euphlyctis Amphibia: Anura from Bangladesh and other Asian countries revealed by mitochondrial gene sequences.
Molecular Phylogenetics and Evolution , 48 2 , — Postmating isolation in six species of three genera Hoplobatrachus, Euphlyctis and Fejervarya from family Dicroglossidae anura , with special reference to spontaneous production of allotriploids. Zoological Science , 29 11 , — Proceedings of Pakistan Academy of Sciences , 39 2 , — Convergent adaptive radiations in Madagascan and Asian ranid frogs reveal covariation between larval and adult traits.
Catalogue of the Batrachia Salientia s. Ecaudata in the collection of the British Museum 2nd ed. Taylor and Francis. Reptilia and Batrachia vol. Phylogeny of frogs of the Physalaemus Pustulosus s pecies group, with an examination of data incongruence.
Systematic Biology , 47 , — A new genus and species of arboreal toad with phytotelmonous larvae, from the Andaman Islands, India Lissamphibia, Anura, Bufonidae. ZooKeys , , 57— Science Vision , 9 , 59— Molecular Phylogenetics and Evolution , 50 1 , 59— The complete mitochondrial genome of Feirana taihangnica Anura: Dicroglossidae. Mitochondrial DNA , 26 3 , — An annotated checklist of amphibian of India with some insights into the patterns of species discoveries, distribution and endemism.
Records of the Zoological Survey of India , , 1— Zootaxa , , 79— Alytes , 2 , — Journal of Herpetology , 13 4 , — Journal of South Asian Natural History , 4 , — Alytes , 19 , 53— Comments on the species status and distribution of Tomopterna dobsonii Boulenger Anura: Ranidae in India. Records of the Zoological Survey of India , 83 , — Microhyla ornata.
New data on amphibians and reptiles of the Northern Areas of Pakistan: Distribution, genetic variability and conservation issues. Amphibian species of the world: An online reference. Version 6. Electronic Database. American Museum of Natural History.
The Amphibian tree of life. Bulletin of American Museum of Natural History , , 1— Description of four new species of Burrowing Frogs in the Fejervarya rufescens complex Dicroglossidae with notes on morphological affinities of Fejervarya species in the Western Ghats.
Zootaxa , 4 , — Systematic revision of Microhyla Microhylidae frogs of South Asia: A molecular, morphological, and acoustic assessment. Vertebrate Zoology , 69 , 1— A little frog leaps a long way: Compounded colonizations of the Indian Subcontinent discovered in the tiny Oriental frog genus Microhyla Amphibia: Microhylidae. PeerJ , 8 , e Evolution , 70 4 , — Improving biodiversity assessment of anuran amphibians using DNA barcoding of tadpoles.
Case studies from Southeast Asia. Comptes Rendus Biologies , 5 , — Zoological Science , 29 , — Turkish Journal of Zoology , 38 , — A new species of genus Hoplobatrachus Anura, Dicroglossidae from the coastal belt of Bangladesh. Zootaxa , 1 , 45— Genetic variation, advertisement call, and morphometry of Microhyla nilphamariensis from Bangladesh.
Philippine Journal of Systematic Biology , 9 , 63— UFBoot2: Improving the ultrafast bootstrap approximation. Molecular Biology and Evolution , 35 , — Phylogeny of spiny frogs Nanorana Anura: Dicroglossidae supports a Tibetan origin of a Himalayan species group.
Ecology and Evolution , 9 , — ZooKeys , , Cricket frog Amphibia. Dicroglossidae : Two regions of Asia are corresponding two groups. Bonnoprani: Bangladesh. The ratio of base width to height of all these structures is less than 1 : 1. Although dams are important in human life, there are also possibilities of dam failures due to several factors. The factors include construction deficiencies, inadequate maintenance, and seismic or weather events contribute to the possibilities.
Corrective actions can be done to remedy the deficiencies. This project has been conducted to study on the management of Semenyih Dam in terms of its operation and maintenance. Besides that, this study also focuses on safety of Semenyih Dam in terms of stability of the dam and its materials to avoid construction deficiencies.
This study has been conducted through site visits and interviews. Semenyih Dam is one of the Klang Valley major dams and plays an important role as an important water supply for Selangor, Kuala Lumpur and Putrajaya consumers. Log in with Facebook Log in with Google.
Remember me on this computer. Enter the email address you signed up with and we'll email you a reset link. Need an account? Click here to sign up. Download Free PDF. Continue Reading. Related Papers - design and construction of gravity dams by dian eka. Shahid Ali Dr. We would like to express deepest gratitude to our advisors Dr. Shahid Ali and Dr. Without their incredible patience and timely wisdom and counsel, our thesis work would have been a frustrating and overwhelming pursuit.
In addition, we express our appreciation to Dr. Anwar Ul Haq. His comments were valued greatly. We are grateful for the unwavering moral, emotional, financial support of our family and friends. We have tried our best to present this information as clearly as possible using basic terms that we hope will be comprehended by the widest spectrum of researchers, analysts and students for further studies.
Pakistan is located in arid or semi arid region where rainfall is highly deficient and does not match the crop requirement. In most of the plain areas, it is less than mm and non-uniform over the year. Therefore storage dams are necessary to regulate water throughout the year one can say there would not be enough water without dams for irrigation. Dams are major resource of electricity in Pakistan therefore it is necessary to understand their structural design considering the stability of dams.
In this thesis we are able to identify different types of dams in general. Various types of dams and their salient features in Pakistan have been discussed. This thesis work shall help us explore the broad practical application of hydrology. It is useful for further studies in dams especially in Pakistan.
Many dams are under construction in Pakistan therefore it is better to understand their structural stability and analyzing the forces acting on them. Salient features of dams in Pakistan. Case study research excels at bringing us to an understanding of a complex issue or object and can extend experience or add strength to what is already known through previous research.
Case studies emphasize detailed information of the dams. The first step in case study research is to establish a firm research focus to which the researcher can refer over the course of study of dams. We establish the focus of the study by forming different sections of information. We research for the case study in depth using a variety of data gathering methods to produce evidence that leads to understanding of the case.
The methodology chosen for the case study is simple and basic so that from very basic concept to every single complex concept should be noticed and understood easily. Following are the summarized step or the way we are going to attempt technical case study of dams. Pakistan is the country of rivers and canal.
In this portion we have quoted salient features of dams along with their locations constructed in Pakistan and also the proposed active dams. Evidence exists of a masonry-faced earthen dam built about BC at Sadd-el-Kafara, about 19 miles 30 kilometers south of Cairo; this dam failed shortly after completion when, in the absence of a spillway, it was overtopped by a flood.
The oldest dam in use is a rock-fill structure about 20 feet high on the Orontes in Syria, built about BC. Flanked by spillways, this dam delivered water to a system of irrigation canals for more than 1, years. Dams were used to control the water level, for Mesopotamia's weather affected the Tigris and Euphratesrivers, and could be quite unpredictable. This gravity dam featured an originally 9 m 30 ft high and 1 m 3 ft 3 in wide stone wall, supported by a 50 m ft wide earth rampart.
The structure is dated to BC. The structure was built around or BC. Two dams called Ha- Uar running east-west were built to retain water during the annual flood and then release it to surrounding lands. The lake called "Mer-wer" or Lake Moeris covered square kilometers and is known today as Berkat Qaroun. Repairs were carried out during various periods, most important around BC, and years later the dam height was increased to 7 meters.
The system included 16 reservoirs, dams and various channels for collecting water and storing it. It is thought to be from the time of the Hittite empire between the 15th and 13th century BC. The basic structure dates to the 2nd century AD and is considered one of the oldest water- diversion or water-regulator structures in the world, which is still in use.
The purpose of the dam was to divert the waters of the Kaveri across the fertile Delta region for irrigation via canals. It was finished in BC. A large earthen dam, made by the Prime Minister of Chu state , Sunshu Ao, flooded a valley in modern-day northern Anhui province that created an enormous irrigation reservoir km 62 mi in circumference , a reservoir that is still present today.
The Assyrians, Babylonians, and Persians built dams between and BC for water supply and irrigation. Their skill lay in the comprehensive collection and storage of water and in its transport and distribution by aqueducts. Remarkably, at least two Roman dams in southwestern Spain, Proserpina and Cornalbo, are still in use, although a third, the Alcantarilla Dam, has overturned, and the reservoirs of some others have filled with silt.
The Proserpina Dam, 40 feet high, has a masonry-faced core wall of concrete backed by earth; it may be regarded therefore as a forerunner of the modern earthen dam. The Proserpina is strengthened on the upstream face by buttresses. Of similar construction, 46 feet high and 1, feet in length, Alcantarilla Dam was supported by a great weight of earth, which eventually caused failure of the wall.
Cornalbo represented a further advance in design; the masonry wall was constructed of cells, which were filled with stones or clay, and faced with mortar. It differs from Proserpina and Alcantarilla in having a sloping upstream face and in being straight in plan. Proserpina and Alcantarilla were polygonal in plan. In BC a stone crib was built across the Gukow River in China; this structure was 98 feet high and about feet long.
Many earthen dams of moderate height in some cases, of great length were built by the Sinhalese in Ceylon after the 5th century BC to form reservoirs or tanks for extensive irrigation works. The Kalabalala Tank formed by an earthen dam 79 feet high and nearly 3. Many of these tanks in Ceylon are still in use today. Numerous dams were also constructed in India and Pakistan.
In India a design employing hewn stone to face the steeply sloping sides of earthen dams evolved, reaching a climax in the mile-long Veeranam Dam, Tamil Nadu, built from AD to In Iran the Kebar, a pioneer arch dam, was built early in the 14th century. Spanning a narrow limestone gorge, it reached 26 meters high with a thickness of less than 5 meters. The central curved portion, 38 meters in length and radius, was supported on two straight abutments.
An attempt to build a dam feet high near Lorca, Spain, at the end of the 18th century failed disastrously in , when earth and gravel below the piled structure washed out. In Europe, where rainfall is ample and well distributed throughout the year, dam construction before the Industrial Revolution was on only a modest scale and was restricted to forming water reservoirs for towns, driving water mills, and making up water losses in navigation canals.
The 19th century Up to the middle of the 19th century, dam design was entirely empirical. In the s William John Macquorn Rankine, professor of civil engineering at Glasgow University, successfully demonstrated how applied science could help the practical engineer. Much remained to be learned of soils and natural rocks in the years after Rankine.
Many scientists and engineers made, and continue to make, noteworthy contributions. In this relationship two phases may be recognized. Starting about , however, engineers began to recognize that concrete dams were monolithic three- dimensional structures in which the distribution of stress and the deflections of individual points depended on stresses and deflections of many other points in the structure.
Movements at one point had to be compatible with movements at all others. Owing to the complexity of the stress pattern, model techniques were gradually employed. Models were built in plasticine, rubber, plaster, and finely graded concrete. During the years up to the end of World War II, experience in design and construction of dams advanced in many directions. In the first decade of this century many large dams were built in the United States and Western Europe.
In succeeding decades, particularly during the war years, many impressive structures were built in the United States by federal government agencies and private power companies. Hoover Dam, built in , is an outstanding example of an arch-gravity dam built in a narrow gorge across a major river and employing advanced design principles. Among earthen dams, Fort Peck Dam, completed in , contained the greatest volume of fill, million cubic yards 96 million cubic meters.
This volume was not exceeded until the completion in of Tarbela Dam in Pakistan million cubic yards. Following their invasion and occupation of Egypt, the British began construction in Capital and financing were furnished by Ernest. When initially constructed between and , nothing of its scale had ever been attempted; on completion, it was the largest masonry dam in the world.
In , Congress authorized the project to build a dam that would control floods, provide irrigation water and produce hydroelectric power. The winning bid to build the dam was submitted by a consortium called Six Companies, Inc.. Such a large concrete structure had never been built before, and some of the techniques were unproven.
The torrid summer weather and the lack of facilities near the site also presented difficulties. Nevertheless, Six Companies turned over the dam to the federal government on 1 March , more than two years ahead of schedule. By , there were an estimated , dams worldwide, some 40, of them over 15 m 49 ft high. But most usual ways of classification i. Many small dams impound the spring runoff for later use in dry summers. Storage dams may also provide a water supply, or improved habitat for fish and wildlife.
They may store water for hydroelectric power generation, irrigation or for a flood control project. Storage dams are the most common type of dams and in general the dam means a storage dam unless qualified otherwise. They provide sufficient pressure for pushing water into ditches, canals, or other conveyance systems. Such shorter dams are used for irrigation, and for diversion from a stream to a distant storage reservoir. It is usually of low height and has a small storage reservoir on its upstream.
The diversion dam is a sort of storage weir which also diverts water and has a small storage. Sometimes, the terms weirs and diversion dams are used synonymously. A detention dam retards the flow in the river on its downstream during floods by storing some flood water.
Thus the effect of sudden floods is reduced to some extent. The water retained in the reservoir is later released gradually at a controlled rate according to the carrying capacity of the channel downstream of the detention dam. Thus the area downstream of the dam is protected against flood. The water after passing over a debris dam is relatively clear. A coffer dam is thus a temporary dam constructed for facilitating construction.
These structures are usually constructed on the upstream of the main dam to divert water into a diversion tunnel or channel during the construction of the dam. Sometimes a coffer dam on the downstream of the dam is also required. Based on structure and design, dams can be classified as follows: 2. They are designed to hold back large volumes of water.
By using concrete, the weight of the dam is actually able to resist the horizontal thrust of water pushing against it. This is why it is called a gravity dam. Gravity essentially holds the dam down to the ground, stopping water from toppling it over. Gravity dams are well suited for blocking rivers in wide valleys or narrow gorge ways.
Since gravity dams must rely on their own weight to hold back water, it is necessary that they are built on a solid foundation of bedrock. A facing of crushed stone prevents erosion by wind or rain, and an ample spillway, usually of concrete, protects against catastrophic washout should the water overtop the dam. Earth dam resists the forces exerted upon it mainly due to shear strength of the soil. Although the weight of this structure also helps in resisting the forces, the structural behavior of an earth dam is entirely different from that of a gravity dam.
The earth dams are usually built in wide valleys having flat slopes at flanks abutments. The foundation requirements are less stringent than those of gravity dams, and hence they can be built at the sites where the foundations are less strong. They can be built on all types of foundations. However, the height of the dam will depend upon the strength of the foundation material. An impervious membrane is placed on the rockfill on the upstream side to reduce the seepage through the dam.
The membrane is usually made of cement concrete or asphaltic concrete. In early rockfill dams, steel and timber membrane were also used, but now they are obsolete. A dry rubble cushion is placed between the rockfill and the membrane for the distribution of water load and for providing a support to the membrane.
Sometimes, the rockfill dams have an impervious earth core in the middle to check the seepage instead of an impervious upstream membrane. The earth core is placed against a dumped rockfill. It is necessary to provide adequate filters between the earth core and the rockfill on the upstream and downstream sides of the core so that the soil particles are not carried by water and piping does not occur. The side slopes of rockfill are usually kept equal to the angle of repose of rock, which is usually taken as 1.
Rockfill dams require foundation stronger than those for earth dams. They transfer the water pressure and other forces mainly to the abutments by arch action. An arch dam is quite suitable for narrow canyons with strong flanks which are capable of resisting the thrust produced by the arch action.
The section of an arch dam is approximately triangular like a gravity dam but the section is comparatively thinner. The arch dam may have a single curvature or double curvature in the vertical plane. Generally, the arch dams of double curvature are more economical and are used in practice. A deck type buttress dam consists of a sloping deck supported by buttresses. Buttresses are triangular concrete walls which transmit the water pressure from the deck slab to the foundation. Buttresses are compression members.
Buttresses are typically spaced across the dam site every 6 to 30 meter, depending upon the size and design of the dam. Buttress dams are sometimes called hollow dams because the buttresses do not form a solid wall stretching across a river valley. The deck is usually a reinforced concrete slab supported between the buttresses, which are usually equally spaced. In a multiple-arch type buttress dam the deck slab is replaced by horizontal arches supported by buttresses.
The arches are usually of small span and made of concrete. In a massive-head type buttress dam, there is no deck slab. Instead of the deck, the upstream edges of the buttresses are flared to form massive heads which span the distance between the buttresses.
The buttress dams require less concrete than gravity dams. But they are not necessarily cheaper than the gravity dams because of extra cost of form work, reinforcement and more skilled labor. The foundation requirements of a buttress are usually less stringent than those in a gravity dams.
Steel dams are generally of two types: i Direct-strutted, and ii Cantilever type. In direct strutted steel dams, the water pressure is transmitted directly to the foundation through inclined struts. In a cantilever type steel dam, there is a bent supporting the upper part of the deck, which is formed into a cantilever truss. This arrangement introduces a tensile force in the deck girder which can be taken care of by anchoring it into the foundation at the upstream toe.
However, it would require heavier sections for struts. Another alternative to reduce tension is to frame together the entire bent rigidly so that the moment due to the weight of the water on the lower part of the deck is utilized to offset the moment induced in the cantilever. This arrangement would, however, require bracing and this will increase the cost. These are quite costly and are subjected to corrosion.
These dams are almost obsolete. Steel dams are sometimes used as temporary coffer dams during the construction of the permanent one. Steel coffer dams are supplemented with timber or earthfill on the inner side to make them water tight. The area between the coffer dams is dewatered so that the construction may be done in dry for the permanent dam.
Timber dams are made for small heads m or, rarely, m and usually have sluices; according to the design of the apron they are divided into pile, crib, pile-crib, and buttressed dams. The openings of timber dams are restricted by abutments; where the sluice is very long it is divided into several openings by intermediate supports: piers, buttresses, and posts.
The openings are covered by wooden shields, usually several in a row one above the other. Simple hoists— permanent or mobile winches—are used to raise and lower the shields. Rubber dams offer ease of construction, operation and decommissioning in tight schedules. These can be deflated when pressure is released and hence, even the crest level can be controlled to some extent. Surplus waters would simply overflow the inflated shell.
Masonry dams are typically used to block streams running through narrow gorges, as in mountainous terrain; though such dams may be very high, the total amount of material required is limited. Embankment dams are preferred to control broad streams, where only a very large barrier, requiring a great volume of material, will suffice. The choice of masonry or embankment and the precise design depend on the geology and configuration of the site, the functions of the dam, and cost factors. The borings are supplemented by shafts and tunnels which, because of their cost, must be used as sparingly as possible.
In the shafts and tunnels, tests can be made to measure strength, elasticity, permeability, and prevailing stresses in strata, with particular attention given to the properties of thin partings, or walls, between the more massive beds. The presence in groundwater of chemical solutions harmful to the materials to be used in the construction of the dam must be assessed.
Sources of construction materials need exploration. As dams continue to increase in height, the study of foundation conditions becomes increasingly critical. Structural models are particularly useful in analysis of arch dams and in verifying analytical stress calculations. Various materials have been used for model tests; on some early tests for Hoover Dam, rubber was employed.
The need for accurate reproduction of stress patterns in complex models is met by using material of low elasticity. In a sense, dams themselves are models for future design. The instruments built into them to record movements under load, strains within materials after construction, temperature and pressure changes, and other factors are installed primarily to study the performance of the structure and to warn of possible emergencies, but their value in confirming design assumptions is important.
The digital computer has permitted considerable advance in analytic methods of design. Its ability to handle a great volume of data and to solve large sets of simultaneous equations containing many variables has made practicable thefinite-element method. In this method a complicated structure is divided into a number of separate equilibrium conditions, and strains are rendered compatible, thus leading to a complete analysis of stress and strain distribution throughout the structure.
The chief constituent of concrete, cement, shrinks as it sets and hardens, because of water absorption in the crystalline structure, evaporation of water to the atmosphere, and cooling from the higher temperatures reached when the chemical reactions in the cement are in progress during hydration.
Because of the large volume of concrete in a dam, shrinkage presents a serious cracking hazard. Various expedients are used to overcome the problem. Concrete is usually cast in separate blocks of limited height. Gaps may be left to permit heat losses and filled in later. Low-heat cements may be used; these are specially blended so that rates of heat evolution are retarded. Cement content can be safely reduced in the interior concrete in the dam, in which strength and resistance to climatic and chemical deterioration are less important.
The cement content, and therefore the heat caused by hydrating, can also be reduced by using aggregate the other major constituent of concrete of larger stones. Another expedient is to use other fine-grained materials, such as fly ash pulverized fuel , as filler, reducing the total cement volume in the concrete. Another is to use certain additives, surface-active agents, and air-entraining agents that permit using a lower water-to-cement ratio in mixing the concrete.
These disadvantages are compensated for by a much lower cost and by the ability of earth fill to adapt to deformation caused by movements in the dam foundation. This assumes, of course, sufficient usable soil available close to the dam site. In bare mountain country it may be necessary to quarry rock and construct a rock-fill rather than an earth-fill dam.
Earth fill is of course more economical, and often a suitable borrow area can be found close to the site. Soil consists of solid particles with water and air in between. When the soil is compressed by loading, as occurs in dam construction, some drainage of air and water takes place, causing an increase in pressures between the solid particles. When there is a high rate of seepage, the soil tends to develop differential pressures and reach a condition called quick, in which it behaves as a fluid.
Even if it does not reach this condition, there is often some weakening of its structure, and steps must be taken to counter this. In the Tokachi earthquake damaged 93 dams in Honshu, the main Japanese island; all were embankment dams of relatively small height. Despite a great deal of work on the distribution of seismic activity, the measurement of strong ground motions, and the response of dams to such motions, earthquake design of dams remains imprecise.
The characteristics of strong ground motions at a given site cannot be predicted, and all types of dams possess some degree of freedom, imperfect elasticity, and imprecise damping. Nevertheless, the digital computer and model testing have given promise of considerable progress. It is now possible to calculate the response of a concrete dam to any specified ground motion; this has been done for the Tang-e Soleyman Dam in Iran and the Gariep Dam in South Africa.
There has also been considerable advance in the theoretical estimation of the effects of ground motion on embankment dams 2. Flood control dams impound floodwaters and then either release them under control to the river below the dam or store or divert the water for other uses. For centuries, people have built dams to help control devastating floods. Thousands of jobs are tied to producing crops grown with irrigated water. Dams produce over , megawatts of renewable electricity and meet 8 to 12 percent of the Nation's power needs.
Hydropower is considered clean because it does not contribute to global warming, air pollution, acid rain, or ozone depletion. Natural river conditions, like currents, changing river levels, and snowfall, create major obstacles and problems for local inland navigation. Dams can effectively be used for controlling the levels of water in a river where inland navigation is carried.
The force of water pressure is enormous. The primary function of the dam's structure is to fill the gap in the natural reservoir line left by the stream channel. The sites are usually those where the gap becomes a minimum for the required storage capacity. The most economical arrangement is often a composite structure such as a masonry dam flanked by earth embankments.
The current use of the land to be flooded should be dispensable. Larger dams will create a reservoir long to be used for hydro-power generation. Its construction required the loss of over a million people's homes and their mass relocation, the loss of many valuable archaeological and cultural sites, as well as significant ecological change. It is estimated that to date, 40—80 million people worldwide have been physically displaced from their homes as a result of dam construction.
How did the Dam technology evolution from the ancient methods and also we have discussed the benefits and uses of dam in the modern world. This chapter leads us towards a great conclusion that in ancient times many of the resources are not utilized by the people. Dams fulfill many purposes of our lives.
Dams also failed in many cases and these cases are discussed in this chapter of dam technology. Dams are classified on different basis and these basis leads toward a new revolution in the modern world. Classifications of dams are also discussed. Of the Of those 20 million hectares, 16 million are dependent on irrigation. Pakistan is fortunate in the soils, topography and climate, which are suitable for year round agriculture.
Major agricultural areas lie within the plains formed by Indus River and its tributaries, namely Kabul, Chenab, Ravi, Jhelum and Sutlej. Indus plains are like a tunnel with number of water sources at the top, converging into single stream, which flows into the Arabian Sea, near the city of Karachi. First canal were constructed some 5to 6 centuries ago and extended under the great Mogul emperors.
In earlier l9th century, there were numerous inundation canals leading from Indus and its tributaries. World's largest contiguous irrigation project was started in l9th century. After independence in, many more developments in the canal systems were made. Dohngi Dam 2. Dhok Tallian Lake Dam 3. Ghazi Barotha Dam 4. Gomal Dam 5. Hub Dam 6. Karoonjhar Dam 7.
Khanpur Dam 8. Kurram Tangi Dam 9. Mangla Dam Mirani Dam Misriot Dam Rawal lake Dam Shakidor Dam Simly Dam Tanaza Dam Tarbela Dam Diamer-Bhasha Dam 2. Gomal Zam Dam 3. Hingol Dam 4. Kurram Tangi Dam 2. Munda Dam 3. Naulang Dam 4. Akhori Dam 2. Kalabagh Dam 3. Nai Gaj Dam 4. Skardu Dam 5. F Live storage capacity 9. Crest length ft. Height ft. Inside diameter 45 ft. F Live storage capacity 5.
F Main dam type Earthfill Max. Dam crest length ft. Normal water level ft. Internal diameter 30 ft. F Live storage capacity A. Normal water level S. D Max. D Total volume of dam C. D Design discharge cusecs Overflow weir ft. Miles Design flood discharge cusecs Total storage capacity A.
D Bed rock granite, Schists Total volume of dam C. Elevation of tainter gate rills S. F Main dam type earthfill Max. Dam crest level ft. Total volume of dam x C. Dam crest lengt ft. Normal reservoir level S. D Bed rock river alluvium with upstream impervious blanket Total volume of dam x c.
D Crest length ft. F Main dam type concrete gravity dam Max. Normal reservoir level ft. F Main dam type concrete, earthfill Max. Total volume of dam c. Total volume of dam x c. D Total volume of dam c. D Total volume of dam x c. Dam crest length 98 ft. F Main dam type earth, rock, gravity Max.
Normal reservoir level F Main dam type gravity Max. Dam height 75 ft. Dam crest length 11 ft. Dam crest length Total volume of dam 33x c. F Main dam type earthen dam Max. Top width of dam 15 ft. F Main dam type earthen Max. F Main dam type concrete dam Max.
F Main dam type concrete gravity Max. F Present A. Total volume of dam F Design Flood Discharge cusecs Max. Length of dam ft. Of power tunnel Total storage capacity A. F Main dam type Roller compacted concrete Max. Full supply level ft. Total volume of dam 58x c. Total storage capacity 8 MAF Live storage capacity 6. Radial type gates 10 No. Radial type gate 10 No. Terms and conditions to be finalized. Descon - Zargoon JV.
Bid Price: Rs. Descon JV for construction of the project. No bid received. Socio-economic uplift, poverty reduction and women area. Socio-economic uplift, poverty reduction and women command area. Hydropower generation of 4. Socio-economic uplift, poverty reduction and women emancipation. Agriculture Sector 14, Nos. Revised PC-1 amounting to Rs. Agriculture Sector 12, Nos.
Engineering Design of the site w. Project completed based on soil investigations. I Khan. Khan in Khyber Pakhtunkhwa Province. Documents based on Detailed Engineering Design to invite Tenders. Agriculture Sector 7, Nos. Revised PC-I amounting to Rs. To counteract this phenomenon, the Mangla Dam Raising Project was started in and the main dam, spillway and its allied works were completed in at a cost of Rs.
This project effectively raised the dam height by 30 feet to feet m , thereby raising the maximum water conservation level from feet to feet. This increased the dam's storage capacity by an additional 2. Besides, it is expected that after raising the height of the Mangla Dam by 30 feet, the power house will generate 12 percent additional energy per year which will increase its installed capacity from 1, MW to 1, MW.
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