Search results for "Discharge"

Identifying a dominant discharge for natural rivers in southern Italy

2012

Abstract Natural rivers are subjected to continuous adjustments in response to any change in the environment. These environmental changes may occur naturally, as in the case of climatic variation or changes in vegetative cover, or may be related to human activities including channelization, damming, bank protection, and bridge construction. Identifying the value of that discharge (‘dominant’ or ‘effective’ discharge, QD) considered responsible for the main changes operated by a river has been a subject of great challenge to scientists and engineers during the last decades. In fact, this threshold value is largely adopted for stream-management decisions, for predicting the stable slope upstr…

Discussion of “Analytical Equation for Variation of Discharge in Drip Irrigation Laterals” by V. Ravikumar, C. R. Ranganathan, and S. Santhana Bosu

2005

New stage-discharge relationships for radial gates

2013

Calibration of gates under free and submerged flow regimes is a classical hydraulic problem. In this paper dimensional analysis was applied to investigate both free and submerged flow conditions through a radial gate. The original Ferro’s method for submerged flow regime was modified by introducing the maximum allowable tail water depth permitting free flow. Based on Buckingham theorem and applying the Incomplete Self Similarity (ISS) concept different forms of the dimensional equations were proposed. According to the current available experimental data the most accurate dimensionless formula was proposed. The proposed dimensional equation not only is more accurate than the original Ferro’s…

Stream‐Discharge Surges Generated by Groundwater Flow

2019

International audience

Testing the Outflow Process over a Triangular Labyrinth Weir

2017

In this paper, the dimensionless stage-discharge relation for a sharp-crested triangular labyrinth weir, determined in a previous study, is initially tested by some experimental runs carried out in a laboratory flume. According to this relationship, the flow magnification is affected by the length-magnification ratio and the head to one cycle width ratio. The measurements allowed to test the applicability of this dimensionless relation for different values of both the angle of the sidewall to the main flow direction and the weir height. Finally, the proposed dimensionless equation was also tested by using experimental measurements carried out for broad-crested triangular labyrinth weir.

Stable isotopes of water as a tool to study groundwater–seawater interactions in coastal south-eastern Sicily

2009

Summary Stable isotopes of hydrogen (δD) and oxygen (δ 18 O) in groundwater, submarine springs and seawater collected in coastal south-eastern Sicily were investigated. While the spatial distribution of δ 18 O in groundwater showed that most of the heavy-isotope-depleted samples (from −5.7‰ to −6.9‰) were located in the higher portion of the Hyblean Mountains, more positive values (from −3.4‰ to −5.6‰) were found in the marginal areas. The isotope composition of submarine springs was characterized by significant variability (δ 18 O between −5.6‰ and +1.0‰ and δD between −30‰ and +5.0‰) reflecting seasonal variations and different seawater contributions. The isotopic and chemical composition…

Changes in Latvian river discharge regime at the turn of the century

2012

The study deals with turn-of-the-century changes in the total annual river runoff distribution and high and low flows in Latvia, covering river basins within four hydrological districts which vary according to size and physiographical conditions. Mathematical statistical methods were applied in the analysis of river discharge data series for two study periods of 1951–2009 and 1881–2009. The present results confirm the basic statement concerning the Baltic countries that major significant changes in river runoff during the last two decades have occurred between spring (decrease) and winter (increase) seasons. Mostly insignificant changes in summer runoff and significant/insignificant changes…

Effects of karst processes on surface water and groundwater hydrology at Skaistkalne Vicinity, Latvia

2012

The Skaistkalne area in Latvia is one of the places where karst processes in gypsum strata occurs. The Iecava and Memele rivers border the area with extensive surface karst features such as sinkholes and karst lakes. Earlier investigations suggested a hydraulic connection between the Iecava and Memele rivers exists via the karst conduits due to the water level (WL) difference in the rivers. A set of methods was performed to study the possible connection: dye tracer was applied in the Iecava river and its occurrence was visually observed at the karst lakes and Memele river; the current velocity was measured and discharge of rivers calculated at several profiles; surface water and groundwater…

ASSESSMENT OF RIVER FLOW WITH SIGNIFICANT LATERAL INFLOW THROUGH REVERSE ROUTING MODELING

2017

The discharge hydrograph estimation in rivers based on reverse routing modeling and using only water level data at two gauged sections is here extended to the most general case of significant lateral flow contribution, without needing to deploy rainfall-runoff procedures. The proposed methodology solves the Saint-Venant equations in diffusive form also involving the lateral contribution using an ‘head driven’ modeling approach where lateral inflow is assumed to be function of the water level at the tributary junction. The procedure allows to assess the discharge hydrograph at ends of a selected river reach with significant lateral inflow, starting from the stage recorded there and without n…

Characterisation of submarine groundwater discharge offshore south-eastern Sicily

2005

A complex approach in characterisation of submarine groundwater discharge (SGD) off south-eastern Sicily comprising applications of radioactive and non-radioactive tracers, direct seepage measurements, geophysical surveys and a numerical modelling is presented. SGD fluxes in the Donnalucata boat basin were estimated by direct seepage measurements to be from 4 to 12Ls(-1), which are comparable with the total SGD flux in the basin of 17Ls(-1) obtained from radon measurements. The integrated SGD flux over the Donnalucata coast estimated on the basis of Ra isotopes was around 60m(3)s(-1) per km of the coast. Spatial variations of SGD were observed in the Donnalucata boat basin, the average (222…