Search results for "hydrology"
showing 10 items of 1041 documents
Amidst Uncertainty–or Not? : Decision-Making in Early-Stage Software Startups
2019
It is commonly claimed that the initial stages of any startup business are dominated by continuous, extended uncertainty, in an environment that has even been described as chaotic. Consequently, decisions are made in uncertain circumstances, so making the right decision is crucial to successful business. However, little currently exists in the way of empirical studies into this supposed uncertainty. In this paper, we study decision-making in early-stage software startups by means of a single, in-depth case study. Based on our data, we argue that software startups do not work in a chaotic environment, nor are they characterized by unique uncertainty unlike that experienced by other firms. pe…
The FLUXCOM ensemble of global land-atmosphere energy fluxes
2019
Although a key driver of Earth’s climate system, global land-atmosphere energy fluxes are poorly constrained. Here we use machine learning to merge energy flux measurements from FLUXNET eddy covariance towers with remote sensing and meteorological data to estimate global gridded net radiation, latent and sensible heat and their uncertainties. The resulting FLUXCOM database comprises 147 products in two setups: (1) 0.0833° resolution using MODIS remote sensing data (RS) and (2) 0.5° resolution using remote sensing and meteorological data (RS + METEO). Within each setup we use a full factorial design across machine learning methods, forcing datasets and energy balance closure corrections. For…
Discussion of “Modified Hazen–Williams and Darcy–Weisbach Equations for Friction and Local Head Losses along Irrigation Laterals” by John D. Valiantz…
2007
Comment on ?Measuring the flow resistance of submerged grass? by C. A. M. E. Wilson and M. S. Horritt,Hydrological Processes 16: 2589-2598
2005
In this short note, the experimental data of Wilson and Horritt (2002. Hydrological Processes16: 2589–2598), jointly with the measurements by Kouwen et al. (1969. Journal of Irrigation and Drainage Division, ASCE95: 329–342) and by Raffaelli et al. (2002 In Proceedings XXVIII Convegno di Idraulica e Costruzioni Idrauliche, Cosenza, Italy; 223–230), are firstly used to test Kouwen's approach. All experimental data are then used to calibrate a flow resistance equation that was theoretically deduced by dimensional analysis and self-similarity theory. Copyright © 2005 John Wiley & Sons, Ltd.
Rainfall timing and runoff: The influence of the criterion for rain event separation
2016
Abstract Rain is not uniform in time and space in semiarid areas and its distribution is very important for the runoff process. Hydrological studies usually divide rainfall into events. However, defining rain events is complicated, and rain characteristics vary depending on how the events are delimited. Choosing a minimum inter-event time (MIT) is a commonly used criterion. Our hypothesis is that there will be an optimal MIT that explains the maximum part of the variance of the runoff, with time to runoff used as a surrogate. The objective is to establish a procedure in order to decide upon this optimal MIT. We developed regressions between time to runoff (T0) and three descriptive variable…
Biohydrology research after Landau 2013 conference
2014
Biohydrology gives a new view on hydrological research. The impact of biota on hydrological processes was a disregarded topic in the early years of hydrology research. It has been present since the 1960s, but as a „Cinderella“ research topic. It emerged as a new aspect of the hydrological processes after the 1980s. In the 21st century, it has become a well established research topic, bringing new knowledge to aid understanding on how biota influence the hydrological cycle and the rates of hydrological processes. The importance of biohydrology research is growing, and the number of conferences, publications and research projects is being doubled every decade. The 4th Biohydrology conference,…
Thematic Issue on Soil Water Infiltration
2017
Interpretive Summary: When water is applied to the land surface through irrigation or rainfall, it infiltrates into the soil surface and percolates deeper through the soil profile under the influence of gravity and capillary forces. Soil infiltration is one of the most complex processes within the terrestrial hydrologic cycle, yet the process is only partially understood. Infiltration is affected by the physical, chemical and biological properties of the soil, vegetation cover, rainfall, irrigation properties, and management practices. Measurement of infiltration rate is essential in studies concerning water budget, hydrology, runoff, erosion, irrigation, drainage and water conservation. Ho…
Testing the Stage-Discharge Relationship in Sloping SMBF Flumes
2021
The Samani, Magallanez, Baiamonte, Ferro (SMBF) flume is a simple and inexpensive instrument for indirect discharge measurement that was originally proposed for use in a horizontal channel and then also applied in sloping channels. The contraction of the flow cross section, aimed at establishing a critical flow condition, is simply obtained by applying two half cylinders to the walls of a rectangular cross section. In this paper a theoretical approach previously proposed for a horizontal SMBF flume is first extended to a sloping SMBF flume and a new stage-discharge relationship is deduced. Then, this equation is experimentally tested using laboratory measurements from literature for differe…
Flexible vegetation behaviour and effects on flow conveyance: experimental observations
2015
As it is known, vegetation is an important component of aquatic ecosystems. Because of the variety of species and, thus, of the characteristics of the vegetation elements (form, size, stiffness, etc.), it is difficult to develop a widely applicable method to predict mean flow and flow resistance. Despite the intense activity research, much work has to be done in understanding hydrodynamics in vegetated channels. This is important to analyse many physical processes involved in the ecosystem at different spatial and time scales. In this paper, attention is restricted to flexible vegetation. After a brief description of results obtained in previous experimental works conducted in a rectangular…