186,855 research outputs found
Catchment similarity for regional predictions in ungauged basins, EGU General Assembly 2009 - Vienna, Austria, 19-24 April 2009.
No full textSession HS5.10: Catchment similarity for regional predictions in ungauged basins
Convener: E. Toth
Co-Conveners: P. A. Troch , R.A. Woods , P. Claps
This session originates directly from research activities carried out under the PUB initiative [Predictions in Ungauged Basins, an IAHS initiative e.g., external link: http://pub.iwmi.org] and focus on the estimation streamflow-regime indicators (e.g., annual flow, flow-duration curves, floods and low-flows) through regionalization of hydrological information. In particular, the attention is focussed on objective and process-based criteria to be used for catchment classification, spatial interpolation of streamflow indices, identification of hydrologically homogeneous groups of basins. Original contributions are solicited that address the investigation of similarities among catchment characteristics and processes. Four different aspects are of particular importance:
- the role of catchment similarities in the explanation of regional hydrological patterns;
- pooling schemes in the context of hydrologically homogeneous groups of sites;
- analysis of possible common dominant processes as a basis for describing catchment similarity;
- assessment of uncertainty of regional streamflow prediction in ungauged sites.
The session format consists of a standard EGU oral&poster session and an open forum discussion in a splinter meeting room afterwards. The open forum will enable us to further discuss the topic in a friendly and informal atmosphere
A state-dependent parameterization of saturated-unsaturated zone interaction
No full textThe relevance of groundwater as an important source of root zone moisture by means of capillary rise is increasingly being recognized. This is partly reflected in many current land surface schemes, which increasingly replace a one-way (i.e., downward) drainage of water by a two-way interaction flux between the root zone and a groundwater system. A fully physically correct implementation of this two-way saturated-unsaturated interaction flux requires transient simulations using the highly nonlinear Richards' equation, which is a computationally demanding approach. We test a classic simple approximation that computes the root zone¿groundwater interaction flux as the net effect of a downward drainage flux and an upward capillary rise flux against the Darcy equation for quasi steady state conditions. We find that for a wet root zone and/or shallow groundwater, the errors within this approximation are significant and of the same magnitude as the interaction flux itself. We present a new closed-form parameterization of the Darcy equation¿based fluxes that accounts both for root zone soil moisture and depth to the water table. Parameter values for this parameterization are listed for 11 different, widely applied soil texture descriptions. The high numerical efficiency of the proposed method makes it suitable for inclusion into demanding applications, e.g., a Monte Carlo framework, or high spatial resolution
Terrestrial water storage change from temporal gravity variation
No full textRecent progress in accurately monitoring temporal gravity variations by means of superconducting gravimeters and satellite geodesy provides unprecedented opportunities in closing the water balance. This thesis deals with the relation between temporal gravity variation and water storage chang
A simplified model for frictionally dominated tidal flows
No full textThe response of vegetated tidal wetlands to environmental changes is governed by vegetation-flow-landscape feedbacks occurring over large spatial and temporal scales, and thus typically studied using simplified models. Here, we present a new simplified approach to describe frictionally dominated tidal flows, characteristic of tidal wetlands. The derivation of the model follows from an expansion of the momentum and mass conservation equations in terms of small dimensionless parameters, which arise once the relevant variables are suitably scaled. A comparison with a full-fledged finite element model indicates that the proposed simplified approach ensures a reliable description of the flow field; suggesting that the model provides a key advancement to study the bio-morphodynamic feedbacks which shape intertidal landscapes. Citation: Van Oyen, T., S. Lanzoni, A. D'Alpaos, S. Temmerman, P. Troch, and L. Carniello (2012), A simplified model for frictionally dominated tidal flows, Geophys. Res. Lett., 39, L12403, doi:10.1029/2012GL051949
Litarachna marshalli Wiles & Chatterjee & Troch 2002, new species
No full textLitarachna marshalli new species (gure 1) Male. Idiosoma 322 long, 282 broad; glandularia free in integument; eye pigment well developed. Venter with epimera I–IV fused and EpI–EpI separate medially; suture EpI/EpII complete, EpII/EpIII and EpIII/EpIV incomplete; EpIV with two pairs of apodemes, the medial pair extending posteriorly beyond the gonopore. E2 absent, large V3 gland without seta located between E4 and g3 behind EpIV. V3 seta fused with L3 glandularium (5acetabular plates of Cook, 1986). Gonopore surrounded by sclerotized ring 24 long, 22 broad; four small pairs of genital setae on sclerotized ring and three pairs of perigenital setae free in integument lateral to the gonopore. Anus on posterior margin of body, posterior to V1 and V2. Two pairs of wheel-like structures present behind posterior epimera. Pedipalp PIV with strongly developed ventral tubercle; length PI–PV 17, 48, 26, 70, 27. Infracapitulum 80 long, chelicera with claw-like chela. Legs with two long distal (swimming?) setae on IV-Leg-5; length I-Leg-3–6, 39, 39, 63, 87; II-Leg-3–6, 36, 43, 67, 87; III-Leg-3 –6, 37, 48, 70, 89; IV-Leg-3–6, 48, 78, 85, 91. Female. Similar to male but larger, body 336 long, 250 broad. Gonopore oval surrounded by sclerotized ring 57 long, 40 broad and lacking genital and perigenital setae. Distribution of setae and glands similar to the male but with three pairs of wheel-like structures arranged in a convex horizontal row behind posterior epimera. Length PI–PV, 22, 76, 30, 96, 28. I-Leg-3–6, 39, 46, 67, 91; II-Leg-3 –6, 43, 52, 76, 98; III-Leg-4–6, 46, 70, 96; IV-Leg-3–6, 54, 78, 100, 113. Nymph. Similar to adults but smaller. Medial apodeme of EpIV much shorter than in the adult, similar in length to the outer lateral apodeme of EpIV. Gonopore absent. Distribution of setae and glands similar to the female with two pairs of wheel-like structures present between posterior epimera and anus. Material examined. HOLOTYPE S341, Republic of South Africa, Sardinia Bay, Durban, 30 December 1996, paratype 1 S340, paratype 2 S342; paratype 3 S343 Park Rynie, Durban, 29 June 1999, paratype 4 S344, paratype 6 S345N, paratype 7 S348N; Mtakatye Estuary, Durban, 31 May 1999 paratype 8 S349N, paratype 9 S 350N. Etymology. This species was named after Dr David J. Marshall, School of Life and Environmental Sciences, University of Durban-Westville, P/Bag X54001 Durban 4000, South Africa, who collected the type material. Remarks. Litarachna marshalli is most similar to L. duboscqi Walter, 1925 (Tuzovskij, 1977) but E4 and V3 gland are separate, not fused, and the male genital eld has fewer genital setae.Published as part of Wiles, P. R., Chatterjee, Tapas & Troch, Marleen De, 2002, Two new and one known marine water mite (Acari: Hydrachnidia: Pontarachnidae) from South-East Africa, pp. 1987-1994 in Journal of Natural History 36 (16) on pages 1988-1989, DOI: 10.1080/00222930110068583, http://zenodo.org/record/474764
Objective and process-based catchment classification as a tool for prediction in ungauged basins
No full textEvent Information
Researchers from all around the world are putting a great deal of effort into the problem of streamflow Predictions in Ungauged Basins [PUB, an
IAHS initiative e.g., external link: http://pub.iwmi.org]. This session originates directly from research activities carried out under the PUB initiative
and aims at stimulating the discussion on how catchment classification can help in various instances of streamflow prediction and on how
objective and process-based criteria can be developed for this. In particular, the attention is focused on three different aspects i) development of
new insights regarding the role of catchment similarities in the explanation of regional hydrological patterns; ii) reconsideration of the 'pooling'
concept in the context of hydrologically homogeneous groups of sites, and iii) analysis of possible common 'dominant processes' as a basis for
new paradigms of similarity. Original contributions are solicited that address the investigation of similarities among catchment characteristics and
processes. Further specific topics that can be of interest are: a) analytical and experimental investigation of basic processes that govern the
overall catchment short-term and long-term catchment behaviour (e.g., relevance, size and characteristic time scales of the 'water storage'
factors); b) statistical tools that aim at enhancing the role of catchment descriptors in regional frequency analysis of characteristic streamflows, c)
usefulness of climatological classification for streamflow prediction in ungauged catchments. Finally, the session will also serve as an open forum
for hydrologists and researchers to present and discuss the latest results achieved through the PUB-driven initiatives related to the session topic
that are currently active worldwide.
Preliminary List of Solicited Speakers
Günter Blöschl (PUB Chair)
Co-Sponsorshi
Breaking The Barriers. A Reflection On Suffering In Buddhism And Christianity In The Perspectives Of War-Widows In Sri Lanka
No full textContains fulltext :
180766.pdf (Publisher’s version ) (Open Access)Radboud University, 19 december 2017Promotores : Troch, G.M.F., Hoogen, A.J.M. van denix, 500 p
Into the Deep: A Theological Exploration of the Struggle of the Filipina Domestic Workers in Hong Kong
No full textContains fulltext :
39486.pdf (Publisher’s version ) (Open Access)RU Radboud Universiteit Nijmegen, 22 mei 2006Promotores : Troch, G.M.F., Haardt, M.A.C. deXV, 333 p
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