scholarly journals Biology of the iberian chub (Squalius carolitertii) in an atlantic-type stream (river Lima basin-north Portugal). A preliminary approach

Limnetica ◽  
2006 ◽  
Vol 25 (2) ◽  
pp. 713-722
Author(s):  
Hugo M. S. Maia ◽  
Carla F. Q. Maia ◽  
Daniel F. C. Pires ◽  
Alexandre C. N. Valente
Keyword(s):  
Iberian Chub ◽  
Type Stream

scholarly journals Morphology and classification of the main stem Bagmati River, Central Nepal

2013 ◽  
Vol 15 ◽  
pp. 23-34
Author(s):  
Pramila Shrestha ◽  
Naresh Kazi Tamrakar
Keyword(s):  
Main Stem ◽  
Aerial Photographs ◽  
Radius Of Curvature ◽  
Moderate Degree ◽  
Lesser Himalaya ◽  
Valley Fill ◽  
Central Nepal ◽  
Belt Width ◽  
Bagmati River ◽  
Type Stream

Rivers are significant geomorphic agents which can carry huge amounts of sediments and water from their catchments to depositional basins. Due course of flow they can bring various hazards such as flooding, inundation of flood plains, erosion of banks and trigger various slope movements. To understand nature and behavior of the Bagmati River, which is a perennial, storm and spring-fed, eight order river of central Nepal, the planiform morphological parameters of this river were analysed and river segments along the main stem stretches were classified into various stream-types, using topographic maps, aerial photographs, and satellite imageries. The Bagmati River is an 8th order perennial river. The Bagmati River basin comprises 39 sub-basins of 4th order and higher. The averages of meander wavelengths (Lm), meander belt width (Wblt), radius of curvature (Rc) and sinuosity (K) of the 7th order main stem Bagmati River are 598.27 m, 164.07 m, 252.35 m and 1.38, respectively. Similarly, the averages of Lm, Wblt, Rc, and K of the 8th order main stem rivers are respectively, 496.77, 126.58 m, 286.13 m, and 1.55. All these parameters reflect fluctuating trends of variation along the downstream stretch. However, the portion of the 7th order river shows abrupt increase of Lm after the Bagmati River crosses the Main Boundary Thrust. The Rc also indicates slight increase in this region. The sinuosity reflects overall increase from the 7th to the 8th order rivers. This increase in sinuosity is attributed to the decrease in slope and competency of the river. There exists a moderate degree of correlation between K and Wblt showing that the Wblt of the Bagmati River tends to increase as the sinuosity increases. The stream segments of the Bagmati River fall on A-, B-, C-, G- and D-type rivers. All the segments of the Bagmati River, lying within the Kathmandu Valley and having substrate of the fluvio-lacustrine valley-fill sediments, fall on C-type stream because of low entrenchment and high width/depth ratio. Similarly, A-type streams are developed at segments which flow through the Tistung Formation of the granite terrain of the Lesser Himalaya most probably due to entrenched and gorged valley and high slope. Likewise, B- and G-type streams are developed in terrains of the Lesser Himalaya and the Sub-Himalaya. The B-type streams are moderately entrenched with sinuous to meandering and wide channels. The D-type stream segment which is a multi-thread channel is characteristically developed within the terrain of the Sub-Himalaya presumably due to the change in slope caused by thrusting, and greater input of sediments from the Siwaliks in relation to weak and loosely consolidated lithology. DOI: http://dx.doi.org/10.3126/bdg.v15i0.7415 Bulletin of the Department of Geology, Vol. 15, 2012, pp. 23-34

Low-Water Stream Crossing Options for Southern Haul Roads

1988 ◽  
Vol 12 (1) ◽  
pp. 11-15
Author(s):  
Steven J. Milauskas
Keyword(s):  
Environmental Impact ◽  
Structure Type ◽  
Crushed Stone ◽  
Creative Design ◽  
Careful Planning ◽  
Water Stream ◽  
Impact Site ◽  
Site Characteristics ◽  
Box Culverts ◽  
Type Stream

Abstract Low-water stream crossings provide an alternative to conventional drainage structures of culverts and bridges. Creative design and sound analysis of crossing options is necessary to minimize channel disturbance. Costs vary greatly depending on the structure type, stream characteristics, and availability of labor and materials. Simple fords consisting of crushed stone or gravel, rock-filled gabions, or concrete structures can provide economical, low-maintenance stream crossings. Fords vented with pipe or concrete box culverts, though more costly, allow placement on perennial streams. All low-water crossings require careful planning to mesh environmental impact, site characteristics, operations requirements, and cost considerations. South. J. Appl. For. 12(1):11-15.

scholarly journals Morpho-hydrologic parameters and classification of the Kodku River for stream stability assessment, southern Kathmandu, Central Nepal

2013 ◽  
Vol 16 ◽  
pp. 1-20
Author(s):  
Naresh Kazi Tamrakar ◽  
Ramita Bajracharya ◽  
Ishwor Thapa ◽  
Sudarshon Sapkota ◽  
Prem Nath Paudel
Keyword(s):  
Inner Core ◽  
Distribution Channel ◽  
Stability Assessment ◽  
Order Stream ◽  
Meandering Channels ◽  
Vertical Instability ◽  
Material Load ◽  
Level I ◽  
Belt Width ◽  
Type Stream

The Kodku River Corridor is one of the most potential corridors for future development of roads that would link the southern remote areas of the Kathmandu Valley to the inner core areas. River stability is of great concern as the unstable segment of river may pose threat on infrastructures, and adjacent cultivated lands and settlement areas. In this light, the preliminary assessment of the Kodku River as a part of the stability assessment was undertaken. The broad level geomorphic and hydrologic parameters, and Level I and II classifications of the river were made to assess for stability condition.The Kodku River is a fifth order stream, extending for about 15.86 km and its watershed covering an area of 35.67 sq. km. The relative relief is extremely high to low, and diminishes with change of landforms from steep terrain in the southern part to the gentle sloped terraces in the northern part of the watershed. Drainage texture is fine to very coarse, from the southern to the norther parts of the watershed. All the stream segments are sinuous (K = 1.2) whereas the Arubot Segment is the highly meandering (1.7). Both meander wavelength and belt width increase with increasing stream order. Five types of valleys have been distinguished; I, II, IV, VI, and VIII type valleys. Based on valley type distribution, channel pattern, shape and channel slope, the stream segments have been classified using Level I assessment as ‘B’ type, ‘C’ type and ‘Aa+’ type streams. The ‘B’ type streams are all located in the third order segment. Except the ‘Aa+’ type stream, all the fifth and fourth order stream segments belong to ‘C’ type streams. Width/Depth ratio varying between 10.5 and 29.5 indicates laterally unstable channel segments. The bank height ratio, which varies between 1.6 and 2.4, indicates moderate incision and shows vertical instability of streams. The Badikhel Segment is relatively more entrenched (1.7) while the Taukhel Segment is the least entrenched (7.1). Since Entrenchment Ratio exceeds 1.6, the stream segments are considered to have moderate to low entrenchment. Based on the bed material load, the Kodku River is a gravelly mixed-load river, in which pebbles to silt/clay occur. Level II classification distinguishes three-types of streams; ‘B4c” type (Badikhel Segment), ‘C6c’ type (Taukhel Segment), and ‘C4c” type (Arubot, Thaiba and Harisidhi Segments). The ‘B4c’ type stream has tendency of vertical instability. The ‘C6c” and ‘C4c” type streams have shallow and wide meandering channels with well developed flood plains and lateral bars, and reflect tendency of lateral instability.DOI: http://dx.doi.org/10.3126/bdg.v16i0.8880 Bulletin of the Department of Geology Vol. 16, 2013, pp. 1–20

Cyprinid passage performance in an experimental multislot fishway across distinct seasons

2019 ◽  
Vol 70 (6) ◽  
pp. 881 ◽  
Author(s):  
Filipe Romão ◽  
Ana L. Quaresma ◽  
José M. Santos ◽  
Paulo Branco ◽  
António N. Pinheiro
Keyword(s):  
Fish Community ◽  
Woody Debris ◽  
Cost Effective ◽  
Ecological Traits ◽  
Vertical Slot ◽  
Longitudinal Connectivity ◽  
Vertical Slot Fishway ◽  
Iberian Chub ◽  
Effective Design ◽  
Entry Efficiency

New engineering solutions are required to minimise the effects of an increasing number of anthropogenic barriers on watercourses. Longitudinal connectivity must be provided through fishways to allow free passage for the whole fish community. Recently, a multislot fishway (MSF) was developed, with two consecutive vertical slots that divide the overall head drop by two, thus reducing the flow velocity, the magnitude of turbulence and operational discharge compared with a standard vertical slot fishway (VSF) with similar pool and slot dimensions. The present study assessed the effectiveness of a MSF design for two cyprinid species with different ecological traits, under laboratory conditions, namely the Iberian barbel (Luciobarbus bocagei), a large-bodied potamodromous benthic fish, and the southern Iberian chub (Squalius pyrenaicus), a small-bodied water column fish. Experiments were conducted in a full-scale experimental fishway, in spring and autumn. Results showed differences in passage performance between seasons and species. During spring, chub had a higher entry efficiency and shorter transit time to fully negotiate the fishway, whereas no seasonal differences were found for the barbel. Overall, the MSF could be considered a cost-effective design for cyprinids with different ecological traits because it offers lower operational costs than a standard VSF. However, concerns about the entrance and attraction conditions should be addressed. In addition, because of the lower operational discharge, the propensity for obstruction with woody debris and sediments should not be disregarded.

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