Impact of a large dam on reproduction of a non-migratory teleost species, Acestrorhynchus lacustris (Characiformes: Acestrorhynchidae)

The release of water from the reservoir hypolimnion, lower concentration of oxygen and the anthropogenic regulation of the river flow, could affect the reproduction of fish, especially migratory species. However, little is known about the effects of these changes in water on non-migratory species. In this sense, the reproduction of Acestrohynchus lacustris was evaluated in two sections of São Francisco River, Minas Gerais, Brazil. Section 1, located immediately downstream from Três Marias Dam (18°09’31.65”S and 45°13’36.00”W) and section 2, located at the confluence of the São Francisco and the Abaeté Rivers (18°02’47.78”S and 45°10’57.95”W). For this, we obtained the physico-chemical parameters of water of each study section. Additionally, biometric data and biological indices of all specimens were measured. Fecundity and follicles diameters were measured in females. Temperature, dissolved oxygen and flow showed lower values in section 1. Fish captured in this section, had lower values of GSI in both sexes, and females presented decreased values of fecundity and follicles diameter. This species showed reproductive activity in the two sections analyzed, however, in section 1 where the temperature and dissolved oxygen presented significant lower values, the reproductive capacity of A. lacustris, was negatively affected.

Hypothetical Failure of the Khassa Chai Dam and Flood Risk Analysis for Kirkuk, Iraq

Many of Iraqi's high-hazard dams lack an Emergency Action Plan, which should include a flood inundation map to show which downstream areas would be flooded if the dams were to fail. This article presents the results of the simulation of a hypothetical 2D dam break for the 58 m high Khassa Chai dam in Kirkuk, Iraq, using HEC-RAS 2D 5.0.7 software. The Khassa Chai dam is situated 7.4 kilometers north of Kirkuk. The simulations revealed that the dam-break flood will affect eight major bridges and the majority of Kirkuk city's metropolitan neighborhoods. Within an hour, the floodwaters will reach the city's center. The flood hazard map revealed that if the Khassa Chai dam fails, many people, vehicles, and structures will be at danger. The findings of this paper can be used to identify evacuation routes and refuge sites as well as build suitable warning systems in order to limit the risk for fatalities if the Khassa Chai dam fails. Moreover, as the effect of modelling bridges downstream of failed dams has not been explored yet, to the knowledge of the authors, eight bridges have been modeled. It was concluded that ignoring bridges in such a large dam break model will not affect the results significantly, which saves the time of data collection and model development.

Assessing Structural Safety of an Arch Dam Using in Situ Vibration Tests

Safety of large dams has always been a major concern for engineers throughout the world but also for public opinion, mass-media and politicians. This is usually based on the fact that the collapse of a large dam could result in huge consequences such as fatalities, economic and/or environmental losses. Nowadays, it is well known that an important factor adversely influencing the safety of such a complex structure like a dam is represented by ageing as a process and ageing related phenomena. Since some 85% of all existing large dams are built in the last 50 years, safety influenced by different decay processes became an important issue to be analysed by dam engineers. In this regard, in situ ambient vibration measurements used to identify the dynamic response characteristics of a large dam seems to represent an appealing non-destructive technique to assess the structural and material characteristics changes and thus to monitor the safety status of the structure. The paper presents the use of the above mentioned procedure by a Romanian team of dam specialists who developed a method combining experimental and analytical techniques for the assessment of the health status of large concrete dams. The Global Elastic Modulus Method (GEMM) was initially used for analysing buttress dams, then it was extended to assess arch dams’ safety state. The most recent evaluation was made upon a 48 m height arch dam in Romania, Cincis dam, located in the central part of the country. The paper is structured into 3 main parts: Introduction, explaining the concept of the hybrid model (the mathematical model bounded to a certain in situ measurement program and calibrated using the recorded data) and of the global elastic modulus (GEM) associated with the dam structure; Experimental, presenting the used equipment, measuring scheme and the processing of the recorded data, ending with the results from spectral analyses; Analytical, presenting the mathematical model developed for the dam structure and its calibration aiming to identify the natural response frequencies and the corresponding mode shapes of the analysed structure. Final conclusions and recommendations are made.

Analisis Kinerja Fisik Bendung Irigasi Menggunkan Metode Analytic Hirarchy Process

Dams aim to raise water from the average water level to the higher water level to be into rice fields located far from the river. Dams like this are called irrigation dams. An Irrigation dam with a small service scale of 3000 ha is a dam with a medium service level, and the function is the same as a large dam, but the physical and facilities are simpler. Moreover, the number of dams and remote locations makes it difficult to monitor, and it is necessary to make a priority scale for repairs. It can be made more accessible by prioritizing the restoration of each dam and ranking. Based on the above, research was conducted using the Analytical Hierarchy Process (AHP) on the components and sub-components of the dam. This study analyzes several dams in West Sumatra, namely Gunung Nago Dam in Kuranji District, Padang City, Banda Gadang Dam in Gunung Talang District, Solok Regency, Paneh Gadang Dam in Gunung Talang District, Solok Regency. Data collection techniques are carried out by direct observation to the field and questionnaires to resource persons who are water experts. The survey results and analysis showed a dam performance index from 1,2% to 2,7% with a low to moderate dam category and a level of vulnerability to dams from vulnerable - to moderately vulnerable. This result is an indication that higher performance values should be on priority for improvement. This method can be developed and used by policymakers to pay attention to dam performance.

Large Dams and Welfare : Empirical Study in Indonesia

In addition to solving the problem of water shortage for irrigation, energy and consumption, thepolicy of building large dam is also expected to improve population-welfare. However, previousstudies suggest that people living near dams have less benefit from the existence of large dam. Thisstudy aims to provide empirical evidence the effect of large dam development on welfare tohousehold living in sub-districts around large dam placement using National Socio-EconomicSurvey (SUSENAS) data in 2013-2018 from Central Bureau of Statistics and spatial large dam datain Indonesia. Estimated results indicate that addition large dam tend to be negatively correlated by2.4-3.1 % with household consumption implying a tendency of decreasing welfare in localhouseholds. Estimated findings using Indonesia Family Life Survey (IFLS) in 2007 and 2014 shownegative correlation likely to be caused by lower agricultural productivity and work activity. Thisresult show there are economic agents who suffer from large water - infrastructure especiallyhouseholds living in sub-districts close to the dam.

Het onzichtbare Olympia

Although ancient Olympia is usually viewed as a Classical Greek site, most buildings that are visible nowadays were not there yet when Pindar celebrated famous victors or Peisistratos and Alcibiades won their races. More generally, even though new research has substantially improved our knowledge, the early history of the site is often still neglected in introductory presentations of the site. In this article some important main issues are discussed. First, new excavations have revealed that Bronze Age occupation of the area cannot be connected to the later cult, as some scholars have argued in the past. The older remains were covered by flooding of the nearby rivers when the sanctuary was founded in the 11th century BCE. Up to the late 7th century the sanctuary remained an open area around a large ash altar. Its main structure was a large dam protecting it from floods. The temple now associated with Hera, built around 600 BCE, was the first monumental building of the sanctuary. Recent research suggests this may originally have been dedicated to Zeus, but this cannot be proven conclusively. The common idea that this temple was originally a wooden construction has now also been debunked.