Journal articles: 'Drainage models'

1

Yang, Song-Yue, Che-Hao Chang, Chih-Tsung Hsu, and Shiang-Jen Wu. "Variation of uncertainty of drainage density in flood hazard mapping assessment with coupled 1D–2D hydrodynamics model." Natural Hazards 111, no. 3 (January 19, 2022): 2297–315. http://dx.doi.org/10.1007/s11069-021-05138-1.

Full text

Abstract:

AbstractCoupled 1D–2D hydrodynamic models are widely utilized in flood hazard mapping. Previous studies adopted conceptual hydrological models or 1D hydrodynamic models to evaluate the impact of drainage density on river flow. However, the drainage density affects not only river flow, but also the flooded area and location. Therefore, this work adopts the 1D–2D model SOBEK to investigate the impact of drainage density on river flow. The uncertainty of drainage density in flood hazard mapping is assessed by a designed case and a real case, Yanshuixi Drainage in Tainan, Taiwan. Analytical results indicate that under the same return period rainfall, reduction in tributary drainages in a model (indicating a lower drainage density) results in an underestimate of the flooded area in tributary drainages. This underestimate causes higher peak discharges and total volume of discharges in the drainages, leading to flooding in certain downstream reaches, thereby overestimating the flooded area. The uncertainty of drainage density decreases with increased rainfall. We suggest that modeling flood hazard mapping with low return period rainfalls requires tributary drainages. For extreme rainfall events, a lower drainage density could be selected, but the drainage density of local key areas should be raised.

APA, Harvard, Vancouver, ISO, and other styles

2

Yen, B. C. "Urban drainage models." Eos, Transactions American Geophysical Union 67, no. 45 (1986): 1309. http://dx.doi.org/10.1029/eo067i045p01309-02.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Anonymous. "Urban drainage models." Eos, Transactions American Geophysical Union 66, no. 7 (1985): 59. http://dx.doi.org/10.1029/eo066i007p00059-08.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Sun, H., and P. S. Cornish. "A catchment-based approach to recharge estimation in the Liverpool Plains, NSW, Australia." Australian Journal of Agricultural Research 57, no. 3 (2006): 309. http://dx.doi.org/10.1071/ar04015.

Full text

Abstract:

This study investigated drainage and shallow groundwater change in a headwater catchment of the Liverpool Plains in north-western New South Wales. A catchment model, SWAT (Soil and Water Assessment Tool), was used to explore rain-fed drainage to shallow groundwater and its relationship to land use. Drainage was predicted along with the prediction of runoff on a catchment and land-use basis over a simulation period of 44 years. Predicted drainage in the catchment was 8 mm/year for the 44 years, which essentially matched estimates derived from bore data observed in the catchment over a 22-year period. These estimates of drainage are much lower than published estimates based on scaling up to the catchment using estimates of drainage derived from point-scale models for different land uses. Estimates of drainage for the different land uses, derived from the catchment model, were also generally lower than simulated drainages from other studies in the area using point-scale models. The investigation demonstrates a place for catchment-based modelling for estimating drainage at the catchment scale. This is mainly because observed catchment runoff is used as an error controller in catchment recharge modelling, whereas scaled-up point-scale modelling generally does not use observed catchment runoff to derive the catchment drainage. Modelling on the Liverpool Plains catchment also suggests that some of the drainage entering the vadose zone and groundwater is later lost via evapotranspiration, a process not generally simulated in crop models, and requiring further investigation to improve understanding of recharge processes and accuracy of modelling.

APA, Harvard, Vancouver, ISO, and other styles

5

Kostova, Irina, and Ivanka Todorova. "Pentachlorophenol degradation in landfill drainage models." Waste Management & Research 18, no. 6 (December 2000): 567–71. http://dx.doi.org/10.1177/0734242x0001800607.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Deletic, A., C. B. S. Dotto, D. T. McCarthy, M. Kleidorfer, G. Freni, G. Mannina, M. Uhl, et al. "Assessing uncertainties in urban drainage models." Physics and Chemistry of the Earth, Parts A/B/C 42-44 (January 2012): 3–10. http://dx.doi.org/10.1016/j.pce.2011.04.007.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Kostova, Irina, and Ivanka Todorova. "Pentachlorophenol degradation in landfill drainage models." Waste Management and Research 18, no. 6 (December 2000): 567–71. http://dx.doi.org/10.1034/j.1399-3070.2000.00164.x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Basinsky, A. S. "Drainage surgery for primary open-angle glaucoma: past, present, future." Fyodorov journal of ophthalmic surgery, no. 2 (July 15, 2021): 79–85. http://dx.doi.org/10.25276/0235-4160-2021-2-79-85.

Full text

Abstract:

Relevance. Despite many techniques for reducing intraocular pressure, surgical treatment of glaucoma has limited effectiveness. First, due to excessive scarring of new intraocular fluid outflow pathways and second, antifibrotics medicaments are unable to effectively control wound healing. The use of drainages reduces the risk of excessive scarring in the area of the filtration pad and forms several ways of outflow of intraocular fluid. The review presents the following sections: development history, advantages, disadvantages, surgical technique and promising directions of glaucoma drainage surgery. Purpose. Summarizing data on the possibility of drainage surgery, historical aspects, causes of scarring and methods of dealing with them. Provide data on various modern drainage devices that are used not only in Russia and their effectiveness. Material and methods. To perform the review, we searched for literature sources on the abstract databases E-library, PubMed and Scopus for the period up to and including 2018, using the keywords «glaucoma drainage surgery» (in the E-library database), «anti-glaucoma drainage» and «anti-glaucoma drainage device» (in the PubMed and Scopus databases). Abstracts of conferences were excluded from the review. A total of 40 articles related to the review topic were identified. The beginning of publications on this issue in domestic sources dates back to 1970, and in foreign sources to 1987. Results. The review presents the history of development, advantages, disadvantages of surgical techniques and promising areas of glaucoma drainage surgery. Various models of drainage devices, as well as their specific and non-specific complications are described. The effectivenes of various valves were 70%, with an average decrease in the level of IOP by at least 50% from the preoperative values. At the same time, the risk of an increase in the level of IOP above the target values is about 10% per year, which leads to the fact that after 5 years only in 50% of cases drainage devices function effectively. Therefore, studies of biomaterials, forms and techniques of drainage implantation surgery, new controlled-release antifibrotic drugs can positively affect the long-term effectiveness of glaucoma surgery. Conclusion. The data presented in the literature review allow us to identify the most effective models of drainage devices, their effectiveness, implantation techniques and possible complications. Key words: glaucoma, refractory glaucoma, glaucoma drainage surgery, drainages.

APA, Harvard, Vancouver, ISO, and other styles

9

El-Sadek, Alaa, Jan Feyen, and Jean Berlamont. "Comparison of Models for Computing Drainage Discharge." Journal of Irrigation and Drainage Engineering 127, no. 6 (December 2001): 363–69. http://dx.doi.org/10.1061/(asce)0733-9437(2001)127:6(363).

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Fairfield, John, and Pierre Leymarie. "Drainage networks from grid digital elevation models." Water Resources Research 27, no. 5 (May 1991): 709–17. http://dx.doi.org/10.1029/90wr02658.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Semádeni-Davies, Annette F. "Representation of Snow in Urban Drainage Models." Journal of Hydrologic Engineering 5, no. 4 (October 2000): 363–70. http://dx.doi.org/10.1061/(asce)1084-0699(2000)5:4(363).

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Bosquilia, Raoni Wainer Duarte, Peterson Ricardo Fiorio, Sérgio Nascimento Duarte, and Rafael Mingoti. "COMPARAÇÃO ENTRE MÉTODOS DE MAPEAMENTO AUTOMÁTICO DE REDE DE DRENAGEM UTILIZANDO SIG." IRRIGA 20, no. 3 (October 12, 2015): 445–57. http://dx.doi.org/10.15809/irriga.2015v20n3p445.

Full text

Abstract:

COMPARAÇÃO ENTRE MÉTODOS DE MAPEAMENTO AUTOMÁTICO DE REDE DE DRENAGEM UTILIZANDO SIG RAONI WAINER DUARTE BOSQUILIA1; PETERSON RICARDO FIORIO2; SERGIO NASCIMENTO DUARTE2 E RAFAEL MINGOTI3 1Universidade Tecnológica Federal do Paraná – UTFPR, Câmpus Dois Vizinhos, Dois Vizinhos, PR, raonibosquilia@utfpr.edu.br2Escola Superior de Agricultura "Luiz de Queiroz" – ESALQ, Universidade de São Paulo, Piracicaba, SP, fiorio@usp.br; snduarte@usp.br3Embrapa Gestão Territorial, Campinas, SP, rafael.mingoti@embrapa.br 1 RESUMO A determinação da rede de drenagem por meio de Modelos Digitais de Terreno (MDT) vem se tornando um método cada vez mais importante e utilizado. Deste modo, o presente trabalho teve por objetivo comparar dois diferentes modelos de mapeamento automático de drenagens: D-8 e D-Infinity. Utilizou-se a rede de drenagem presente em cartas topográficas de Piracicaba-SP, escala 1:10.000, como prova de campo. O MDT foi gerado a partir das curvas de nível com equidistância de 5 metros presente nessas cartas. Para uma melhor comparação entre os métodos, foram analisados dois fatores: Comprimento das Drenagens e Número de Nascentes, sendo as análises realizadas apenas em caráter quantitativo. Para a avaliação desses fatores foram dispostas ao acaso doze amostras circulares de área 1,76 km² e realizou-se um teste de médias de Tukey. Para os dois parâmetros estudados, os modelos se apresentaram estatisticamente diferentes da prova de campo, porém as drenagens se apresentaram semelhantes visualmente às cartas topográficas. Quanto às nascentes, os métodos não apresentaram bons resultados. Mesmo assim, os modelos automáticos de mapeamento da rede de drenagem se mostraram ótimas ferramentas para determinar cursos d’água. Palavras-chave: Direção de Fluxo, Fluxo Acumulado, MDT, bacia hidrográfica, TauDEM. BOSQUILIA, R. W. D.; FIORIO, P. R.; DUARTE, S. N.; MINGOTI, R.COMPARISON OF AUTOMATIC METHODS OF DRAINAGE NETWORK MAPPING USING GIS 2 ABSTRACT Determining drainage network by Digital Terrain Models (DTM) has become an increasingly important and used method. Thus, this study aimed to compare two different models of automatic mapping of drainage: D-8 and D-Infinity. The drainage network from topographic charts of Piracicaba-SP, 1:10.000 scale was used as field reality. DTM was generated based on 5 meter-contour lines in those charts. Two factors were analyzed for a better comparison between methods: Length of Drainage and Number of Springs. The analyses were performed just quantitatively. A total of twelve circular samples at random, 1.76 km² area, were generated to evaluate those factors. Also, means were compared using the Tukey test. For both parameters, the models were statistically different from the field reality; however, drainages were visually similar to the topographic charts. As to the springs, good results could not be found based on methods. Even so, the automatic models of drainage network mapping proved to be excellent tools to determine waterways. Keywords: flow direction, accumulated flow, DTM, watershed, TauDEM.

APA, Harvard, Vancouver, ISO, and other styles

13

Barkle, G. F., T. N. Brown, D. J. Painter, and P. L. Singleton. "Hydrology models DRAINMOD and SWIM applied to large soil lysimeters with artificial drainage." Soil Research 36, no. 5 (1998): 783. http://dx.doi.org/10.1071/s97020.

Full text

Abstract:

Two hydrological models, which used different methods to determine the soil water distribution in a soil profile, were evaluated against 4 years of data from large soil lysimeters. SWIM determines soil water distribution from a finite difference implementation of the Richards" equation. DRAINMOD uses a soil-specific relationship between the air volume in a profile and the watertable height to locate the depth to the saturated zone. An ‘equilibrium’ relationship between soil water tension and depth is then assumed to distribute the soil water in the unsaturated zone. Predicted values and measured values for drainage and watertable heights were compared for 3 drainage treatments. The drainage in the lysimeters was achieved by installing an outlet tube on the slowly permeable layer at 0·75 m from the soil surface. The conventional drainage treatment allowed gravity drainage to occur directly from this drainage outlet tube. The other 2 drainage treatments employed controlled drainage, where a step (or weir) is installed in the outlet tube. No drainage can occur from the lysimeters until the water table within the lysimeters reaches the step height. Two different step heights provided 2 controlled drainage treatments. Independently determined model parameters were used without additional calibration for the analysis. Both models performed well. DRAINMOD over-predicted the 4-year cumulative drainage for all treatments, with the largest error being 7%. SWIM conversely under-predicted cumulative drainage, with a maximum error of 16%. The standard error of estimation for the watertable height over the full 4-year data period was lower for SWIM, ranging from 0 ·06 to 0·12 m. DRAINMOD’s standard error over the same period for the watertable height ranged from 0·09 to 0·21 m. Generally, error values from this work were smaller than comparable values from other studies. The hydrology of the lysimeters where there was no lateral inflow, surface runoff, or deep seepage losses, coupled to an essentially 1-dimensional flow domain, probably contributed to the lower errors. Furthermore, limitation of the maximum watertable heights by the controlled drainage regime in the lysimeters also reduces the maximum possible magnitude of the standard error term.

APA, Harvard, Vancouver, ISO, and other styles

14

Sañudo, Esteban, Luis Cea, and Jerónimo Puertas. "Modelling Pluvial Flooding in Urban Areas Coupling the Models Iber and SWMM." Water 12, no. 9 (September 22, 2020): 2647. http://dx.doi.org/10.3390/w12092647.

Full text

Abstract:

Dual urban drainage models allow users to simulate pluvial urban flooding by analysing the interaction between the sewer network (minor drainage system) and the overland flow (major drainage system). This work presents a free distribution dual drainage model linking the models Iber and Storm Water Management Model (SWMM), which are a 2D overland flow model and a 1D sewer network model, respectively. The linking methodology consists in a step by step calling process from Iber to a Dynamic-link Library (DLL) that contains the functions in which the SWMM code is split. The work involves the validation of the model in a simplified urban street, in a full-scale urban drainage physical model and in a real urban settlement. The three study cases have been carefully chosen to show and validate the main capabilities of the model. Therefore, the model is developed as a tool that considers the main hydrological and hydraulic processes during a rainfall event in an urban basin, allowing the user to plan, evaluate and design new or existing urban drainage systems in a realistic way.

APA, Harvard, Vancouver, ISO, and other styles

15

Digman, Christopher J., Nicholas Anderson, Gwen Rhodes, David J. Balmforth, and Stephen Kenney. "Realising the benefits of integrated urban drainage models." Proceedings of the Institution of Civil Engineers - Water Management 167, no. 1 (January 2014): 30–37. http://dx.doi.org/10.1680/wama.12.00083.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Vezzaro, Luca, Peter Steen Mikkelsen, Ana Deletic, and David McCarthy. "Urban drainage models – simplifying uncertainty analysis for practitioners." Water Science and Technology 68, no. 10 (October 25, 2013): 2136–43. http://dx.doi.org/10.2166/wst.2013.460.

Full text

Abstract:

There is increasing awareness about uncertainties in the modelling of urban drainage systems and, as such, many new methods for uncertainty analyses have been developed. Despite this, all available methods have limitations which restrict their widespread application among practitioners. Here, a modified Monte-Carlo based method is presented that reduces the subjectivity inherent in typical uncertainty approaches (e.g. cut-off thresholds), while using tangible concepts and providing practical outcomes for practitioners. The method compares the model's uncertainty bands to the uncertainty inherent in each measured/observed datapoint; an issue that is commonly overlooked in the uncertainty analysis of urban drainage models. This comparison allows the user to intuitively estimate the optimum number of simulations required to conduct uncertainty analyses. The output of the method includes parameter probability distributions (often used for sensitivity analyses) and prediction intervals. To demonstrate the new method, it is applied to a conceptual rainfall-runoff model (MOPUS) using a dataset collected from Melbourne, Australia.

APA, Harvard, Vancouver, ISO, and other styles

17

Sisson, James B. "Drainage from layered field soils: Fixed gradient models." Water Resources Research 23, no. 11 (November 1987): 2071–75. http://dx.doi.org/10.1029/wr023i011p02071.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Harel, Elhanan, Liran Goren, Eitan Shelef, and Hanan Ginat. "Drainage reversal toward cliffs induced by lateral lithologic differences." Geology 47, no. 10 (August 20, 2019): 928–32. http://dx.doi.org/10.1130/g46353.1.

Full text

Abstract:

Abstract Drainage reversals, an end-member case of drainage reorganization, often occur toward cliffs. Reversals are commonly identified by the presence of barbed tributaries, with a junction angle >90°, that preserve the antecedent drainage geometry. The processes that form reversed drainages are largely unknown. Particularly, barbed tributaries cannot form through a spatially uniform migration of the cliff and drainage divide, which would be expected to erase the antecedent drainage pattern, and tectonic tilting toward the cliff that could reverse the flow direction is inconsistent with geodynamic models of large-scale escarpment, where many reversals are documented. Here, we propose a new mechanism for drainage reversal, where the slope imbalance across a cliff, together with the high erodibility of sediments that fill cliff-truncated valleys, result in faster divide migration along valleys compared to interfluves. We demonstrate this mechanism along channels that drain toward the escarpment of the Arava Valley in Israel. Reversal is established by observations of barbed tributaries and opposite-grading terraces. We show that drainage reversal occurs when erodible valley fill exists, and that the reversal extent correlates with the thickness of this fill, in agreement with the predictions of the proposed mechanism. This new reversal mechanism demonstrates that valley fill could play an acute role in fluvial reorganization processes, and that reversals could occur independently of tectonic tilting.

APA, Harvard, Vancouver, ISO, and other styles

19

De Keyser, W., V. Gevaert, F. Verdonck, I. Nopens, B. De Baets, P. A. Vanrolleghem, P. S. Mikkelsen, and L. Benedetti. "Combining multimedia models with integrated urban water system models for micropollutants." Water Science and Technology 62, no. 7 (October 1, 2010): 1614–22. http://dx.doi.org/10.2166/wst.2010.475.

Full text

Abstract:

Integrated urban water system (IUWS) modeling aims at assessing the quality of the surface water receiving the urban emissions through sewage treatment plants, combined sewer overflows (CSOs) and stormwater drainage systems. However, some micropollutants tend to appear in more than one environmental medium (air, water, sediment, soil, groundwater, etc.). In this work, a multimedia fate and transport model (MFTM) is “wrapped around” a dynamic IUWS model for organic micropollutants to enable integrated environmental assessment. The combined model was tested on a hypothetical catchment using two scenarios: on the one hand a reference scenario with a combined sewerage system and on the other hand a stormwater infiltration pond scenario, as an example of a sustainable urban drainage system (SUDS). A case for Bis(2-ethylhexyl) phthalate (DEHP) was simulated and resulted in reduced surface water concentrations for the latter scenario. However, the model also showed that this was at the expense of increased fluxes to air, groundwater and infiltration pond soil. The latter effects are generally not included in IUWS models, whereas MTFMs usually do not consider dynamic surface water concentrations,; hence the combined model approach provides a better basis for integrated environmental assessment of micropollutants' fate in urban environments.

APA, Harvard, Vancouver, ISO, and other styles

20

Dan, Han-Cheng, Pei Xin, Ling Li, Liang Li, and David Lockington. "Capillary effect on flow in the drainage layer of highway pavement." Canadian Journal of Civil Engineering 39, no. 6 (June 2012): 654–66. http://dx.doi.org/10.1139/l2012-050.

Full text

Abstract:

This paper aims to examine capillarity effect on flows in the drainage layer of highway pavement. A two-dimensional (2-D) model based on the Richards equation was used to simulate saturated and unsaturated flows in the drainage layer. For comparison, flows were also simulated using a 1-D Boussinesq equation based model and a 2-D model based on the Laplace equation, both assuming saturated flow only. The drainage layer was modeled with sand and gravel, which possess similar hydraulic properties to those of commonly used filling materials in practice. The results showed that the two saturated flow models agreed well with each other, indicating the dominance of horizontal flow in the drainage layer. However, their predictions differed significantly from those of the variably saturated flow models. The latter model predicted significant flow activities in a relatively large unsaturated zone, especially for a sandy drainage layer. Such unsaturated flow contributes to and enhances the capacity of the drainage layer. With the unsaturated flow neglected, the saturated flow models over-predicted the extent of the saturated zone and hence the groundwater table elevation. As the current engineering design of the drainage layer is typically based on the groundwater table elevation predicted by the saturated flow models, the finding of this study suggests that the design criterion is likely to lead to over-design of the drainage system. Further work is also required to prove the practical significance of the capillary effect and account for other factors.

APA, Harvard, Vancouver, ISO, and other styles

21

Wei, Chih Chiang. "Application of Pumping Operation Models for a Drainage System." Applied Mechanics and Materials 256-259 (December 2012): 2416–19. http://dx.doi.org/10.4028/www.scientific.net/amm.256-259.2416.

Full text

Abstract:

A pumping operation model has been developed in urban areas caused by the storm runoff. The Chung-Kong pumping station in New Taipei City is used as a case study, where storm and operating records are used to train and verify the model’s performance. Historical records contain information of rainfall amounts, inner water levels, and pump and gate operating records in torrential rain events. The results show that the case with lag time of 15 min gives the better forecasted pumping discharge than other cases. The proposed predicting pumping model successfully addresses the problems of forecasted pumping discharge.

APA, Harvard, Vancouver, ISO, and other styles

22

Pokrovsky, V., D. Pokrovsky, E. Dutova, A. Nikitenkov, and A. Nazarov. "Degree of Areal Drainage Assessment Using Digital Elevation Models." IOP Conference Series: Earth and Environmental Science 21 (August 28, 2014): 012018. http://dx.doi.org/10.1088/1755-1315/21/1/012018.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Tran, D. H., B. J. C. Perera, and A. W. M. Ng. "Comparison of Structural Deterioration Models for Stormwater Drainage Pipes." Computer-Aided Civil and Infrastructure Engineering 24, no. 2 (February 2009): 145–56. http://dx.doi.org/10.1111/j.1467-8667.2008.00577.x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

S. R. Workman and R. W. Skaggs. "Comparison of Two Drainage Simulation Models Using Field Data." Transactions of the ASAE 32, no. 6 (1989): 1933. http://dx.doi.org/10.13031/2013.31245.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Dayaratne, ST, and BJC Perera. "Calibration of urban stormwater drainage models using hydrograph modelling." Urban Water Journal 1, no. 4 (December 2004): 283–97. http://dx.doi.org/10.1080/15730620412331299057.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Dayaratne, S. T., and B. J. C. Perera. "Regionalisation of impervious area parameters of urban drainage models." Urban Water Journal 5, no. 3 (September 2008): 231–46. http://dx.doi.org/10.1080/15730620801959495.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Sarangi, A., Man Singh, A. K. Bhattacharya, and A. K. Singh. "Subsurface drainage performance study using SALTMOD and ANN models." Agricultural Water Management 84, no. 3 (August 2006): 240–48. http://dx.doi.org/10.1016/j.agwat.2006.02.009.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Pokupić, Marta, Matej Varga, and Tomislav Bašić. "Models of geomorphometric parameters and drainage networks for the territory of Republic of Croatia." Hrvatski geografski glasnik/Croatian Geographical Bulletin 80, no. 1 (June 29, 2018): 61–76. http://dx.doi.org/10.21861/hgg.2018.80.01.03.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Hewitt, Ian J., and Christian Schoof. "Models for polythermal ice sheets and glaciers." Cryosphere 11, no. 1 (February 15, 2017): 541–51. http://dx.doi.org/10.5194/tc-11-541-2017.

Full text

Abstract:

Abstract. Polythermal ice sheets and glaciers contain both cold ice and temperate ice. We present two new models to describe the temperature and water content of such ice masses, accounting for the possibility of gravity- and pressure-driven water drainage according to Darcy's law. Both models are based on the principle of energy conservation; one additionally invokes the theory of viscous compaction to calculate pore water pressure, and the other involves a modification of existing enthalpy gradient methods to include gravity-driven drainage. The models self-consistently predict the evolution of temperature in cold ice and of water content in temperate ice. Numerical solutions are described, and a number of illustrative test problems are presented, allowing comparison with existing methods. The suggested models are simple enough to be incorporated in existing ice-sheet models with little modification.

APA, Harvard, Vancouver, ISO, and other styles

30

Khusnitdinov, I. I., and A. E. Babushkin. "Comparison of the Effectiveness of Antiglaucomatous Surgeries with Various Glautex Drainage Models." Ophthalmology in Russia 16, no. 1S (April 22, 2019): 91–95. http://dx.doi.org/10.18008/1816-5095-2019-1s-91-95.

Full text

Abstract:

Purpose: comparative study of trabeculectomy results with various models of domestic “Glautex” drainage in the surgical treatment of primary open angle glaucoma (POAG). Patients and methods. The results of surgical treatment of 98 (105 eyes) patients with POAG aged 50–83 years who underwent trabeculectomy with various Glautex drainage models were analyzed. There were 43 men (43.9 %) and 55 (56.1 %) women. The second (II) stage of POAG was diagnosed in 49 eyes (46.7 %), the third (III) stage in 56 (53.3 %). All patients were divided into 3 groups. The first (main) group consisted of 34 (37 eyes) patients who underwent trabeculectomy in combination with the implantation of Glautex DDA drainage model. The second (main) group included 29 (30 eyes) patients with trabeculectomy and implantation of the SDA model of this drainage. The third group was the control group and consisted of 35 (38 eyes) patients with the classical method of surgery without using any drainage. Results. There was a significant 71.7 % decrease in IOP compared with baseline data in the 1st patients group after antiglaucomatous surgery, 72 and 74 % decrease was in the 2nd and 3rd groups respectively (p < 0.05). An increase in IOP was noted predominantly in the control and in the second study group within 1 month of follow-up. Normalization of ophthalmotonous pressure was achieved by using needling in 13.3 % (4/30) patients in the second group, in 7.9 % (6/38) cases in the control group. The absolute hypotensive effect in the 1st group was noted in 75.7 % of cases; the relative hypotensive effect was in 8.1 %; total failure was in 16.2 %. In the 2nd group the absolute hypotensive effect of the surgery was in 73.3 % of 30 cases, the relative was in 6.7 %, total failure was in 20 %. In the control group (38 eyes), absolute success was in 63.1 %, the relative hypotensive effect was in 13.2 %, and the total failure was in 23.7 %. Conclusion. Trabeculectomy with Glautex drainage and with various models in case of primary open-angle glaucoma provided a sufficiently high relative hypotensive effect in 82 % of cases in a year after the surgery. The achieved surgery outcomes with this drainage in the studied periods did not depend on applied model: DDA or SDA (83.8 and 80 % respectively), but was higher than the classical trabeculectomy (76.3 %). However, in case of the SDA model, needling was required in 13.3 % of cases in the early postoperative period.

APA, Harvard, Vancouver, ISO, and other styles

31

Zhao, Zhengyong, David A. MacLean, Charles P. A. Bourque, D. Edwin Swift, and Fan-Rui Meng. "Generation of soil drainage equations from an artificial neural network-analysis approach." Canadian Journal of Soil Science 93, no. 3 (August 2013): 329–42. http://dx.doi.org/10.4141/cjss2012-079.

Full text

Abstract:

Zhao, Z., MacLean, D. A., Bourque, C. P.-A., Swift, D. E. and Meng, F.-R. 2013. Generation of soil drainage equations from an artificial neural network-analysis approach. Can. J. Soil Sci. 93: 329–342. Soil properties, especially soil drainage, are known to be related to topo-hydrologic variables derived from digital elevation models (DEM), such as vertical slope position, slope steepness, sediment delivery ratio, and topographic wetness index. Such relationships typically are strongly non-linear and thus difficult to define with conventional statistical methods. In this study, we used artificial neural network (ANN) models to establish relationships between soil drainage classes and DEM-generated topo-hydrologic variables and subsequently formulated the relationships to generate soil drainage equations for soil mapping. A high-resolution field soil map of the Black Brook Watershed in northwest New Brunswick, Canada, was used to calibrate/validate the ANN models, and the obtained equations. Independent data from an experimental farm, about 180 km away, were also used for validation. Results indicated that vertical slope position was the best predictor of soil drainage classes (r=0.55), followed by slope steepness (r=0.44), sediment delivery ratio (r=0.39), and topographic wetness index (r=0.38). The obtained soil drainage equations fitted well to the ANN model predictions (r 2=0.78–0.99; root mean squared error=0.39–4.55). Analyses indicated that soil drainage equations clearly reflected the actual relationships between soil drainage classes and DEM-generated topo-hydrologic variables, and have the potential to minimize bias originated from over-training the ANN models when applied outside the area of calibration, especially when the ranges of input variables were outside of the range of calibration data.

APA, Harvard, Vancouver, ISO, and other styles

32

Hagen, Jon Ove, Bernd Etzelmüller, and Anne-Marie Nuttall. "Runoff and drainage pattern derived from digital elevation models, Finsterwalderbreen, Svalbard." Annals of Glaciology 31 (2000): 147–52. http://dx.doi.org/10.3189/172756400781819879.

Full text

Abstract:

AbstractFinsterwalderbreen (77°26’ N, 15° 15’ E) is a 35 km2 polythermal, surge-type glacier in southern Spitsbergen, Svalbard. Extensive field investigations have been carried out on the glacier, including mapping of bed topography by radio-echo soundings, mass-balance measurements and hydrological and meteorological registrations. In this paper we have used surface and bed topography and observations of summer ablation to estimate total runoff and subglacial drainage pattern by means of spatial map analysis in standard geographic information system software. The location and relative importance of the water-channel outlets from the glacier were estimated, as well as the change in drainage pattern over the period 1970–90. The results could be compared to direct observations of drainage pattern and discharge recordings. The analyses indicate that the location of the subglacial channels is dominated by the surface topography and thus that the channels are partly pressurized.

APA, Harvard, Vancouver, ISO, and other styles

33

Poinar, Kristin, and Lauren C. Andrews. "Challenges in predicting Greenland supraglacial lake drainages at the regional scale." Cryosphere 15, no. 3 (March 24, 2021): 1455–83. http://dx.doi.org/10.5194/tc-15-1455-2021.

Full text

Abstract:

Abstract. A leading hypothesis for the mechanism of fast supraglacial lake drainages is that transient extensional stresses briefly allow crevassing in otherwise compressional ice flow regimes. Lake water can then hydrofracture a crevasse to the base of the ice sheet, and river inputs can maintain this connection as a moulin. If future ice sheet models are to accurately represent moulins, we must understand their formation processes, timescales, and locations. Here, we use remote-sensing velocity products to constrain the relationship between strain rates and lake drainages across ∼ 1600 km2 in Pâkitsoq, western Greenland, between 2002–2019. We find significantly more extensional background strain rates at moulins associated with fast-draining lakes than at slow-draining or non-draining lake moulins. We test whether moulins in more extensional background settings drain their lakes earlier, but we find insignificant correlation. To investigate the frequency at which strain-rate transients are associated with fast lake drainage, we examined Landsat-derived strain rates over 16 and 32 d periods at moulins associated with 240 fast-lake-drainage events over 18 years. A low signal-to-noise ratio, the presence of water, and the multi-week repeat cycle obscured any resolution of the hypothesized transient strain rates. Our results support the hypothesis that transient strain rates drive fast lake drainages. However, the current generation of ice sheet velocity products, even when stacked across hundreds of fast lake drainages, cannot resolve these transients. Thus, observational progress in understanding lake drainage initiation will rely on field-based tools such as GPS networks and photogrammetry.

APA, Harvard, Vancouver, ISO, and other styles

34

Worster, M. Grae, and David W. Rees Jones. "Sea-ice thermodynamics and brine drainage." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 373, no. 2045 (July 13, 2015): 20140166. http://dx.doi.org/10.1098/rsta.2014.0166.

Full text

Abstract:

Significant changes in the state of the Arctic ice cover are occurring. As the summertime extent of sea ice diminishes, the Arctic is increasingly characterized by first-year rather than multi-year ice. It is during the early stages of ice growth that most brine is injected into the oceans, contributing to the buoyancy flux that mediates the thermo-haline circulation. Current operational sea-ice components of climate models often treat brine rejection between sea ice and the ocean similarly to a thermodynamic segregation process, assigning a fixed salinity to the sea ice, typical of multi-year ice. However, brine rejection is a dynamical, buoyancy-driven process and the salinity of sea ice varies significantly during the first growth season. As a result, current operational models may over predict the early brine fluxes from newly formed sea ice, which may have consequences for coupled simulations of the polar oceans. Improvements both in computational power and our understanding of the processes involved have led to the emergence of a new class of sea-ice models that treat brine rejection dynamically and should enhance predictions of the buoyancy forcing of the oceans.

APA, Harvard, Vancouver, ISO, and other styles

35

Scherler, Dirk, and Wolfgang Schwanghart. "Drainage divide networks – Part 1: Identification and ordering in digital elevation models." Earth Surface Dynamics 8, no. 2 (April 20, 2020): 245–59. http://dx.doi.org/10.5194/esurf-8-245-2020.

Full text

Abstract:

Abstract. We propose a novel way to measure and analyze networks of drainage divides from digital elevation models. We developed an algorithm that extracts drainage divides based on the drainage basin boundaries defined by a stream network. In contrast to streams, there is no straightforward approach to order and classify divides, although it is intuitive that some divides are more important than others. A meaningful way of ordering divides is the average distance one would have to travel down on either side of a divide to reach a common stream location. However, because measuring these distances is computationally expensive and prone to edge effects, we instead sort divide segments based on their tree-like network structure, starting from endpoints at river confluences. The sorted nature of the network allows for assigning distances to points along the divides, which can be shown to scale with the average distance downslope to the common stream location. Furthermore, because divide segments tend to have characteristic lengths, an ordering scheme in which divide orders increase by 1 at junctions mimics these distances. We applied our new algorithm to the Big Tujunga catchment in the San Gabriel Mountains of southern California and studied the morphology of the drainage divide network. Our results show that topographic metrics, like the downstream flow distance to a stream and hillslope relief, attain characteristic values that depend on the drainage area threshold used to derive the stream network. Portions along the divide network that have lower than average relief or are closer than average to streams are often distinctly asymmetric in shape, suggesting that these divides are unstable. Our new and automated approach thus helps to objectively extract and analyze divide networks from digital elevation models.

APA, Harvard, Vancouver, ISO, and other styles

36

Mondal, Subrata, and Sujit Mandal. "Geomorphic diversity and landslide susceptibility in the Balason River Basin, Darjeeling Himalaya." HKIE Transactions 27, no. 1 (April 20, 2020): 13–24. http://dx.doi.org/10.33430/v27n1thie2017-0054.

Full text

Abstract:

This study attempts to assess the role of basin morphometric parameters in slope instability using a morphometric diversity (MD) model, as well as the role of drainage parameters and relief parameters in slope failure using drainage diversity (DD) and relief diversity (RD) models, respectively. For this, a total of 14 morphometric data layers were considered. The relationship of each data layer to landslide susceptibility was judged using a frequency ratio (FR) approach. Parameters like drainage density (Dd), drainage frequency (Df), relative relief (Rr), drainage texture (Dt), junction frequency (Jf), infiltration number (In), ruggedness index (Ri), dissection index (Di), elevation (E), slope (S), relief ratio (Rra) and hypsometric integral (Hi) were positively related with landslide potentiality while bifurcation ratio (Rb) and drainage intensity (Din) negatively correlated with S failure. The principal component analysis (PCA)-based weight assigned to each data layer in each model was multiplied with unidirectional reclassified data layers for each model using a weighted linear combination (WLC) approach to prepare landslide susceptibility maps. The receiver operating characteristics curve showed that the landslide prediction accuracy of the DD, RD and MD models were 71.4%, 73.9% and 76.3%, respectively. The FR plots of the aforesaid three models suggested that the chance of landslide increases from very low to very high in susceptible zones.

APA, Harvard, Vancouver, ISO, and other styles

37

Rahman, Motiar, Subramania Sudharsanan, Kanthasamy K. Muraleetharan, and Musharraf M. Zaman. "Modeling Time-Dependent Behavior of Pavement Drainage Using Linear System Identification and Neural Network Techniques." Transportation Research Record: Journal of the Transportation Research Board 1582, no. 1 (January 1997): 34–41. http://dx.doi.org/10.3141/1582-06.

Full text

Abstract:

Inadequate drainage continues to be a major cause of problems associated with long-term structural integrity and performance of roadway pavements. To reduce the impact of these drainage-related problems, it is customary to provide measures to prevent water from entering the pavement system and to enhance the drainage capability of the pavement base to rapidly move the water that inevitably finds its way into the pavement system. The performance of different drainage systems in the field is not clearly known. Oklahoma Department of Transportation (ODOT) has been collecting rainfall and outflow information at sites with edge drains since 1992. The sites have different types of surfaces, base courses, and edge drains. The data collected by ODOT at these sites were used to develop two types of numerical models to predict the outflow–time history using rainfall–time history as the input. One model is based on linear system identification theory, and the other model is based on an artificial neural network. The development of these models is presented, and the model predictions are compared with the measured field data. The efficiency of the drainage systems, including the AASHTO criteria for the drainage time, at these sites is compared by using the numerical models and synthetic, but the same, rainfall events.

APA, Harvard, Vancouver, ISO, and other styles

38

Harremoës, P. "INTEGRATED AND STOCHASTIC FEATURES OF URBAN DRAINAGE SYSTEMS." Water Science and Technology 30, no. 1 (July 1, 1994): 1–12. http://dx.doi.org/10.2166/wst.1994.0001.

Full text

Abstract:

An analysis has been made of the uncenainty of input parameters to detenninistic models, with emphasis on the models for the sewer system. For each parameter a sensitivity analysis and for all the parameters a Monte Carlo analysis has been made. The analysis reveals a very significant uncenainty that can be decreased; but cannot be eliminated as significant to engineering application. Stochastic models have a potential for dealing with these uncertainties. That applies also to the treatment plant and to the receiving water models. The three components in the system have been analysed as a whole. Examples show that an integrated analysis is required in order to find economically optimised solutions that comply with environmental standards.

APA, Harvard, Vancouver, ISO, and other styles

39

Nedergaard Pedersen, Agnethe, Jonas Wied Pedersen, Antonio Vigueras-Rodriguez, Annette Brink-Kjær, Morten Borup, and Peter Steen Mikkelsen. "The Bellinge data set: open data and models for community-wide urban drainage systems research." Earth System Science Data 13, no. 10 (October 20, 2021): 4779–98. http://dx.doi.org/10.5194/essd-13-4779-2021.

Full text

Abstract:

Abstract. This paper describes a comprehensive and unique open-access data set for research within hydrological and hydraulic modelling of urban drainage systems. The data come from a mainly combined urban drainage system covering a 1.7 km2 area in the town of Bellinge, a suburb of the city of Odense, Denmark. The data set consists of up to 10 years of observations (2010–2020) from 13 level meters, 1 flow meter, 1 position sensor and 4 power sensors in the system, along with rainfall data from three rain gauges and two weather radars (X- and C-band), and meteorological data from a nearby weather station. The system characteristics of the urban drainage system (information about manholes, pipes, etc.) can be found in the data set along with characteristics of the surface area (contour lines, surface description, etc.). Two detailed hydrodynamic, distributed urban drainage models of the system are provided in the software systems MIKE URBAN and EPA Storm Water Management Model (SWMM). The two simulation models generally show similar responses, but systematic differences are present since the models have not been calibrated. With this data set we provide a useful case that will enable independent testing and replication of results from future scientific developments and innovation within urban hydrology and urban drainage systems research. The data set can be downloaded from https://doi.org/10.11583/DTU.c.5029124 (Pedersen et al., 2021a).

APA, Harvard, Vancouver, ISO, and other styles

40

Flowers, Gwenn E. "Modelling water flow under glaciers and ice sheets." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 471, no. 2176 (April 2015): 20140907. http://dx.doi.org/10.1098/rspa.2014.0907.

Full text

Abstract:

Recent observations of dynamic water systems beneath the Greenland and Antarctic ice sheets have sparked renewed interest in modelling subglacial drainage. The foundations of today's models were laid decades ago, inspired by measurements from mountain glaciers, discovery of the modern ice streams and the study of landscapes evacuated by former ice sheets. Models have progressed from strict adherence to the principles of groundwater flow, to the incorporation of flow ‘elements’ specific to the subglacial environment, to sophisticated two-dimensional representations of interacting distributed and channelized drainage. Although presently in a state of rapid development, subglacial drainage models, when coupled to models of ice flow, are now able to reproduce many of the canonical phenomena that characterize this coupled system. Model calibration remains generally out of reach, whereas widespread application of these models to large problems and real geometries awaits the next level of development.

APA, Harvard, Vancouver, ISO, and other styles

41

Park, Kyuhyun, Yoshihiro Shibuo, Junichi Katayama, Shinji Baba, and Hiroaki Furumai. "Applicability of High-Resolution Geospatial Data Obtained by UAV Photogrammetry to Develop Drainage System Models for Pluvial Flood Analysis." Journal of Disaster Research 16, no. 3 (April 1, 2021): 371–80. http://dx.doi.org/10.20965/jdr.2021.p0371.

Full text

Abstract:

Integrated flood models have been previously developed to simulate diverse inundation situations and combined with models of storm surges and river floods. However, drainage systems, ground elevation, and surface information of human settlements have only been digitized in large cities. Digitization of surface information is essential for developing a drainage system model for pluvial flood analysis. Occasionally, suburban drainage areas exhibit various complex land-use conditions, including residential and green areas, agricultural land with drainage, and irrigation channels. Herein, UAV photogrammetry was applied to obtain high-resolution geospatial data associated with small-scale flood-prone areas whose elevation, land-use, and waterway networks have not been elucidated sufficiently. The resolution of elevation and land-use data ranged from 2.61–5.22 cm/mesh. The measurement accuracy of the width and depth of the open channels was high, and the errors were mostly within 10%. A drainage system model was developed using data on open channel, elevation, and land-use.

APA, Harvard, Vancouver, ISO, and other styles

42

Fischer, Urs H., André Braun, Andreas Bauder, and Gwenn E. Flowers. "Changes in geometry and subglacial drainage derived from digital elevation models: Unteraargletscher, Switzerland, 1927–97." Annals of Glaciology 40 (2005): 20–24. http://dx.doi.org/10.3189/172756405781813528.

Full text

Abstract:

AbstractDigital elevation models of the bed and surface of Unteraargletscher, Switzerland, are used to reconstruct the theoretical pattern of basal water drainage for the years 1927, 1947, 1961 and 1997, during which period the glacier was thinning and receding. The theoretical drainage pattern for 1997 compares well, in a broad sense, with the locations of active moulins and the hydraulic connection status of boreholes drilled to the glacier bed. Changes in the basal water-flow pattern over the period 1927–97 that are revealed by the theoretical reconstructions of the subglacial drainage system structure are likely to have resulted from changes in glacier geometry. Concurrent with the retreat and thinning of the glacier, the height of medial moraines increased, probably due to the insulating effect of the debris cover reducing the melt of the underlying ice. This increase of moraine heights has led to the formation of hydraulic barriers at the glacier bed such that water flow has become channelized beneath the ice along drainage axes that parallel the course of the medial moraines on the glacier surface.

APA, Harvard, Vancouver, ISO, and other styles

43

Zhang, Wei, Wenkai Li, Hugo A. Loaiciga, Xiuguo Liu, Shuya Liu, Shengjie Zheng, and Han Zhang. "Adaptive Determination of the Flow Accumulation Threshold for Extracting Drainage Networks from DEMs." Remote Sensing 13, no. 11 (May 21, 2021): 2024. http://dx.doi.org/10.3390/rs13112024.

Full text

Abstract:

Selecting the flow accumulation threshold (FAT) plays a central role in extracting drainage networks from Digital Elevation Models (DEMs). This work presents the MR-AP (Multiple Regression and Adaptive Power) method for choosing suitable FAT when extracting drainage from DEMs. This work employs 36 sample sub-basins in Hubei (China) province. Firstly, topography, the normalized difference vegetation index (NDVI), and water storage change are used in building multiple regression models to calculate the drainage length. Power functions are fit to calculate the FAT of each sub-basin. Nine randomly chosen regions served as test sub-basins. The results show that: (1) water storage change and NDVI have high correlation with the drainage length, and the coefficient of determination (R2) ranges between 0.85 and 0.87; (2) the drainage length obtained from the Multiple Regression model using water storage change, NDVI, and topography as influence factors is similar to the actual drainage length, featuring a coefficient of determination (R2) equal to 0.714; (3) the MR-AP method calculates suitable FATs for each sub-basin in Hubei province, with a drainage length error equal to 5.13%. Moreover, drainage network extraction by the MR-AP method mainly depends on the water storage change and the NDVI, thus being consistent with the regional water-resources change.

APA, Harvard, Vancouver, ISO, and other styles

44

Przybysz, Piotr, Czesław Kuncewicz, and František Rieger. "Gravity Drainage Kinetics of Papermaking Fibrous Suspensions." Chemical and Process Engineering 35, no. 4 (December 1, 2014): 421–34. http://dx.doi.org/10.2478/cpe-2014-0032.

Full text

Abstract:

Abstract The study analyses application possibilities of filtration and thickening models in evaluation of papermaking suspension drainage rate. The authors proposed their own method to estimate the drainage rate on the basis of an existing Ergun capillary model of liquid flow through a granular material. The proposed model was less sensitive to porosity changes than the Ergun model. An empirical verification proved robustness of the proposed approach. Taking into account discrepancies in the published data concerning how the drainage velocity of papermaking suspension is defined, this study examines which of the commonly applied models matches experimental results the best.

APA, Harvard, Vancouver, ISO, and other styles

45

Moreno-Montañés, J., and F. Muñoz-Negrete. "Drainage devices for glaucoma surgery: New advances and new models." Archivos de la Sociedad Española de Oftalmología (English Edition) 96, no. 4 (April 2021): 173–74. http://dx.doi.org/10.1016/j.oftale.2020.12.002.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Leitão, J. P., N. E. Simões, Č. Maksimović, F. Ferreira, D. Prodanović, J. S. Matos, and A. Sá Marques. "Real-time forecasting urban drainage models: full or simplified networks?" Water Science and Technology 62, no. 9 (November 1, 2010): 2106–14. http://dx.doi.org/10.2166/wst.2010.382.

Full text

Abstract:

Lead time between rainfall prediction results and flood prediction results obtained by hydraulic simulations is one of the crucial factors in the implementation of real-time flood forecasting systems. Therefore, hydraulic simulation times must be as short as possible, with sufficient spatial and temporal flood distribution modelling accuracy. One of the ways to reduce the time required to run hydraulic model simulations is increasing computational speed by simplifying the model networks. This simplification can be conducted by removing and changing some secondary elements using network simplification techniques. The emphasis of this paper is to assess how the level of urban drainage network simplification influences the computational time and overall simulation results' accuracy. The models used in this paper comprise a sewer network and an overland flow drainage system in both 1D/1D and 1D/2D approaches. The 1D/1D model is used as the reference model to generate several models with different levels of simplifications. The results presented in this paper suggest that the 1D/2D models are not yet suitable to be used in real-time flood prediction applications due to long simulation time, while on the other hand, the simplified 1D/1D models show that considerable reductions in simulation time can be achieved without compromising simulation results (flow and water depth) accuracy.

APA, Harvard, Vancouver, ISO, and other styles

47

Battaglio, M., I. Bonzani, and D. Campolo. "Nonlinear consolidation models of clay with time dependant drainage properties." Mathematical and Computer Modelling 42, no. 5-6 (September 2005): 613–20. http://dx.doi.org/10.1016/j.mcm.2004.06.024.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

ELLIOTT, A., and S. TROWSDALE. "A review of models for low impact urban stormwater drainage." Environmental Modelling & Software 22, no. 3 (March 2007): 394–405. http://dx.doi.org/10.1016/j.envsoft.2005.12.005.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Hasan, A., P. Pilesjö, and A. Persson. "The use of LIDAR as a data source for digital elevation models – a study of the relationship between the accuracy of digital elevation models and topographical attributes in northern peatlands." Hydrology and Earth System Sciences Discussions 8, no. 3 (June 10, 2011): 5497–522. http://dx.doi.org/10.5194/hessd-8-5497-2011.

Full text

Abstract:

Abstract. It is important to study the factors affecting estimates of wetness since wetness is crucial in climate change studies. The availability of digital elevation models (DEMs) generated with high resolution data is increasing, and their use is expanding. LIDAR earth elevation data have been used to create several DEMs with different resolutions, using various interpolation parameters, in order to compare the models with collected surface data. The aim is to study the accuracy of DEMs in relation to topographical attributes such as slope and drainage area, which are normally used to estimate the wetness in terms of topographic wetness indices. Evaluation points were chosen from the high-resolution LIDAR dataset at a maximum distance of 10 mm from the cell center for each DEM resolution studied, 0.5, 1, 5, 10, 30 and 90 m. The interpolation method used was inverse distance weighting method with four search radii: 1, 2, 5 and 10 m. The DEM was evaluated using a quantile-quantile test and the normalized median absolute deviation. The accuracy of the estimated elevation for different slopes was tested using the DEM with 0.5 m resolution. Drainage areas were investigated at three resolutions, with coinciding evaluation points. The ability of the model to generate the drainage area at each resolution was obtained by pairwise comparison of three data subsets. The results show that the accuracy of the elevations obtained with the DEM model are the same for different resolutions, but vary with search radius. The accuracy of the values (NMAD of errors) varies from 29.7 mm to 88.9 mm, being higher for flatter areas. It was also found that the accuracy of the drainage area is highly dependent on DEM resolution. Coarse resolution yielded larger estimates of the drainage area but lower slope values. This may lead to overestimation of wetness values when using a coarse resolution DEM.

APA, Harvard, Vancouver, ISO, and other styles

50

Kollatsch, Dirk-Th. "Comprehensive Planning of Urban Drainage and Wastewater Treatment." Water Science and Technology 27, no. 12 (June 1, 1993): 205–8. http://dx.doi.org/10.2166/wst.1993.0302.

Full text

Abstract:

For upgrading the urban drainage system (UDS) the reduction of pollution impacts is the priority task concerning the environmental protection of the receiving waters. With simulation models the interactions between surface, sewer systems, overflow structures and treatment facilities within the UDS can be shown. Models to simulate the pollutant impacts, transport and the effects on the receiving waters are available. In a first step a pollutant transport model of sewer systems and a model to simulate the wastewater treatment processes are connected. With these models the efficiency of upgrading measures can be checked in all parts of urban drainage systems.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Drainage models'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles