Designing Open Channel Dimension for Imkasu Area West Papua

Gag Nikel Ltd belongs to a Contract of Work located in Gag Island, West Waigeo Islands District, Raja Ampat Regency, West Papua Province. The open pit mining system employed at this company will enter the mining location and therefore, requires a design of open channel for diversing water coming from rainfall, run off, and ground. The rainfall intensity calculated by Mononobe formula obtained 5,994 mm / hour, whereas the catchment area got 0.59 km 2. The total discharge of run off calculated by Rational Formula gained 1867,956 m 3 / hour. Meanwhile, the design of open channel calculated by Manning Formula yielded wet section (A) = 0.668 m 2, base width (b) = 0.714 m, and depth (h) = 0.714 m, surface width (B) = 1.542 m. Box control having the volume 1 m3, length = 1 m, width = 1 m, and height 1 m must be made every 1 kilometer of open channel length. Around the area of open channel, the used tire must be given to reduce the erosion rate flowing into settling pond. All of these are necessary because the open channel is located near the natural channel and we must also consider several regulations such as Presidential Decree and IPPKH adjusted to the technical study that has been designed.

Composition and Abundance of Drifting Fish Eggs on the Upper Reaches of Xijiang River, China, after the Formation of the Cascade Reservoirs

To develop effective management actions of riverine fisheries, it is important to monitor how fish resources (i.e., eggs) are recruited in the upper reaches of natural rivers, particularly where dams have been constructed, which potentially hinder life-history strategies. Here, we aimed to determine the State of drifting fish eggs resources, and the underlying environmental factors regulating the presence of fish eggs in the upper reaches of a river (Laibin section of Xijiang River, China). Based on surveys conducted over one spawning period (2016), we set out to: (1) describe the composition and abundance of drifting fish eggs in the 150 km Lainbin section under a dam control, and (2) analyze how the composition and distribution of fish eggs was correlated with environmental factors. A total of 15157 eggs belonging to two orders, four families, and 18 species were collected. Comparison of these data with historical records in the same area showed that the community structure of drifting eggs has changed considerably. Previously, the community was dominated by larger-bodied species, rather than the smaller species documented in 2016. Eggs were primarily detected between May and August. In the natural channel, the greatest abundance of eggs occurred during May and June. In comparison, the greatest abundance of eggs downstream of the dam was detected in July. The results of this study provide important information for water conservancy institutions towards managing regions containing dams to maintain the ecology of rivers and protect important fish resources.

MODERN DESTRUCTIVE RIVERBED PROCESSES OF THE RIVER ONON IN THE TRANSBAIKAL REGION

The specificity of the territory of the upper Amur basin is shown, which consists in a significant variety and complexity of natural complexes. The object of the study was the Onon river, the subject-riverbed processes that occur in the territory under the influence of natural factors. The purpose of the study is to identify, analyze and evaluate the scale of development of riverbed processes in the upper Amur basin. The tasks were to identify active areas of water erosion. Onon, spatial analysis of the received information, identification of the dynamics and intensity of riverbed processes in active areas during the destructive leash of 2018 and beyond. The relevance of the work has been determined by the need to quickly identify and prevent the development of riverbed processes for erosion control and rational use of land resources for further industrial use. The research methods used are analysis and interpretation of high-resolution satellite images and other multi-time cartographic materials, processing and digitization of images. The main natural channel-forming factors of the Onon river that determine the current dynamics of channel deformations are identified and analyzed. The theoretical and practical significance of the study is to determine the degree of influence on riverbed processes of various riverbed-forming natural factors. The necessity of carrying out measures on the territory of the upper Amur basin to solve water management problems is justified

Water and Sediment Budget of Casiquiare Channel Linking Orinoco and Amazon Catchments, Venezuela

The Casiquiare River is a natural channel that connects two of the greatest rivers in the world, the Orinoco and the Amazon in the South American continent. The aim of this paper is to present a review and synthesis of the hydrological and sedimentological knowledge of the Casiquiare River, including the first hydro-sedimentary balance of the Casiquiare fluvial system conducted 9–12 September 2000 at the bifurcation and mouth during the expedition ‘Humboldt-Amazonia 2000’. Bathymetric flow discharge and physico-chemical measurements were made at the inlet and outlet of the Casiquiare Channel. The main conclusions of this study indicate that Casiquiare is taking a significant proportion of flow (20% to 30%) from the Upper Orinoco basin to the Amazon basin. Throughout its 356 km-course, this chameleon channel undergoes significant morphological, hydrological, and bio-geochemical variations between the inlet and outlet, whose most visible witnesses are the increase in its width (3 to 4 times), flow (7 to 9 times), and its change in water color (white to black water), under the influence of tributaries coming from vast forest plains.

Water and Sediment Budget of Casiquiare Channel Linking Orinoco and Amazon Catchments, Venezuela

The Casiquiare River is a natural channel that connects two of the greatest rivers in the world, the Orinoco and the Amazon in the South American Continent. The aim of this paper is to present a review and synthesis of the hydrological and sedimentological knowledge of the Casiquiare River, including the first hydro-sedimentary balance of the Casiquiare fluvial system conducted at the bifurcation and at the mouth on September 9-12, 2000, during the expedition ‘Humboldt-Amazonia 2000’. Bathymetric, flow discharge and physico-chemical measurements were made at the inlet and at the outlet of the Casiquiare Channel. The main conclusions of this study indicate that Casiquiare is taking a significant proportion of flow (20 to 30%) from the Upper Orinoco basin to the Amazon basin. Throughout its 356 km-course, this chameleon channel undergoes significant morphological, hydrological and bio-geochemical variations between the inlet and the outlet, whose most visible witnesses are the increase in its width (3 to 4 times), flow (7 to 9 times) and its change in water color (white to black water), under the influence of tributaries coming from vast forest plains.

Determination of the factors of variation of mean velocity in natural channels at steady state.

From the Chezy-Manning equation, considered valid for the "steady state" of a natural channel, as an extension of the condition of "uniform flow," it is interesting to determine the degree of variation of the average flow velocity, depending on the variations of the factors involved. That is why this article presents a theoretical analysis which yields a first approximation of the sensitivity of the variation of the magnitude of the average speed to changes in the geometry or geomorphology of a section of the channel. It is found that the concept of "stable state" for the thermodynamic state of a natural channel can be assimilated to that of "dynamic equilibrium," in which the values of the state parameters vary slowly, in a "regional" sense.