10 documents found, page 1 of 1

Fluorescent quinine-based tracking techniques for measurement of open-channel s...

This study presents techniques based on the use of fluorescent quinine as a visual tracer for surface flows, to assess surface flow velocities in channels and streams under low luminosity conditions. Fieldwork was conducted in three open channels, with different hydraulic characteristics. A quinine solution, in both liquid and solid (ice cube) forms, was applied on the water flow surface and an Unmanned Aerial ...

Using Quinine as a Fluorescent Tracer to Estimate Overland Flow Velocities on B...

This study presents a tracer technique based on the fluorescent properties of quinine to help on the visualization of shallow flows and allow a quantitative measurement of overland flow velocities. Laboratory experiments were conducted to compare the traditional dye tracer and thermal tracer techniques with this novel fluorescent (quinine) tracer by injecting a quinine solution and the other tracers into shallo...

Laboratory assessment of the influence of rice straw mulch size on soil loss

Application of crop residues (mulch) over the soil surface is a common practice to control soil erosion and promote infiltration. This laboratory study aimed at investigating the effect of different rice straw mulch sizes on runoff and sediment transport. The experimental runs were conducted using a soil flume of adjustable slope and a rainfall simulator, considering bare soil and three different soil covers: 1...

Hydrological research in small catchments – an approach to improve knowledge on...

Revisiting simple methods to estimate drop size distributions: a novel approach...

The infrared thermography has been successfully applied as a tool for high resolution imaging in different hydrological studies. This exploratory experimental study aimed at evaluating the possibility of using infrared thermography to determine the diameter of raindrops. Rain samples are collected on a pre-heated acrylic board, which is exposed to rain during an instant, and thermograms are recorded. The area o...

Using meshes to change the characteristics of simulated rainfall produced by sp...

Rainfall simulators have been used for many years contributing to the understanding of soil and water conservation processes. Nevertheless, rainfall simulators’ design and operation might be rather demanding for achieving specific rainfall intensity distributions and drop characteristics and are still open for improvement. This study explores the potential of combining spray nozzle simulators with meshes to cha...

Análise da tendência da precipitação anual e mensal no período 1900-2000 em Por...

Este trabalho debruça-se sobre o estudo da precipitação em Portugal Continental, com base em nove séries temporais de observações udométricas, abrangendo todo o século XX. Os dados analisados têm uma distribuição geográfica que cobre várias regiões do País, As séries são analisadas por métodos estatísticos com o objectivo de testar se existe uma alteração, ao longo do tempo, da grandeza climática em estudo. É f...

The influence of storm movement on water erosion: storm direction and velocity ...

Although the problem of storm movement affecting flows (shape of the hydrograph and peak discharges) has been recognised for a long time, most overland flow and water erosion studies do not take into account the effect on the runoff response caused by the movement of the storm across the catchment. Ignoring of the storm movement can result in considerable over- and underestimation of runoff volumes and peaks, a...

Spectral analysis of scale invariance in the temporal structure of precipitatio...

The temporal structure of precipitation was investigated by means of spectral analysis of daily precipitation, measured with non-recording gauges, over a period of 54 years. The data were recorded at eight locations in Mainland Portugal. Analysis of the precipitation intensity showed that scaling is present in the data, from one day up to more than one month. Empirical exponents describing the scaling of the en...

Predicting Transverse Turbulent Diffusivity in Straight Alluvial Rivers

In this work the distribution and mean of transverse turbulent diffusion coefficient in straight alluvial rivers are determined using a vertical turbulent diffusion coefficient and a hydraulic geometry equation relating the depth to the lateral position in the section. The cross- section averaged transverse turbulent diffusion coefficient was found to be in good agreement with 138 sets of experimental data.