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RAINFALL-RUNOFF MODELING OF FLASH FLOODS IN SEMI-ARID WATERSHEDSMichaud, Jene Diane 06 1900 (has links)
Flash floods caused by localized thunderstorms are a natural hazard
of the semi -arid Southwest, and many communities have responded by
installing ALERT flood forecasting systems. This study explored a
rainfall- runoff modeling approach thought to be appropriate for
forecasting in such watersheds. The kinematic model KINEROS was
evaluated because it is a distributed model developed specifically for
desert regions, and can be applied to basins without historic data.
This study examined the accuracy of KINEROS under data constraints
that are typical of semi -arid ALERT watersheds. The model was validated
at the 150 km2, semi -arid Walnut Gulch experimental watershed. Under the
conditions examined, KINEROS provided poor simulations of runoff volume
and peak flow, but good simulations of time to peak. For peak flows, the
standard error of estimate was nearly 100% of the observed mean.
Surprisingly, when model parameters were based only on measurable
watershed properties, simulated peak flows were as accurate as when
parameters were calibrated on some historic data. The accuracy of
KINEROS was compared to that of the SCS model. When calibrated, a
distributed SCS model with a simple channel loss component was as
accurate as KINEROS.
Reasons for poor simulations were investigated by examining a)
rainfall sampling errors, b) model sensitivity and dynamics, and c)
trends in simulation accuracy. The cause of poor simulations was divided
between rainfall sampling errors and other problems. It was found that
when raingage densities are on the order of 1/20 km2, rainfall sampling errors preclude the consistent and reliable simulation of runoff from
localized thunderstorms. Even when rainfall errors were minimized,
accuracy of simulations were still poor. Good results, however, have
been obtained with KINEROS on small watersheds; the problem is not
KINEROS itself but its application at larger scales.
The study also examined the hydrology of thunderstorm -generated
floods at Walnut Gulch. The space -time dynamics of rainfall and runoff
were characterized and found to be of fundamental importance. Hillslope
infiltration was found to exert a dominant control on runoff, although
flow hydraulics, channel losses, and initial soil moisture are also
important. Watershed response was found to be nonlinear.
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Studies on interrill sediment delivery and rainfall kinetic energyRezaur, Rahman Bhuiyan. January 1999 (has links)
published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy
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A stochastic approach to space-time modeling of rainfall.Gupta, Vijay K.(Vijay Kumar),1946- January 1973 (has links)
This study gives a phenomenologically based stochastic model of space-time rainfall. Specifically, two random variables on the spatial rainfall, e.g., the cumulative rainfall within a season and the maximum cumulative rainfall per rainfall event within a season are considered. An approach is given to determine the cumulative distribution function (c.d.f.) of the cumulative rainfall per event, based on a particular random structure of space-time rainfall. Then the first two moments of the cumulative seasonal rainfall are derived based on a stochastic dependence between the cumulative rainfall per event and the number of rainfall events within a season. This stochastic dependence is important in the context of the spatial rainfall process. A theorem is then proved on the rate of convergence of the exact c.d.f. of the seasonal cumulative rainfall up to the iᵗʰ year, i ≥ 1, to its limiting c.d.f. Use of the limiting c.d.f. of the maximum cumulative rainfall per rainfall event up to the iᵗʰ year within a season is given in the context of determination of the 'design rainfall'. Such information is useful in the design of hydraulic structures. Special mathematical applications of the general theory are developed from a combination of empirical and phenomenological based assumptions. A numerical application of this approach is demonstrated on the Atterbury watershed in the Southwestern United States.
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Monitoring, analyzing and modeling hydrological processes over a headwater catchment in Hong Kong /Li, Yanqiu, January 2009 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2010. / Includes bibliographical references (p. 101-118). Also available online.
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Interannual and interdecadal rainfall variations in the Hawaiian Islands /Chen, Huaiqun. January 2003 (has links)
Thesis (M.S.)--University of Hawaii at Manoa, 2003. / Includes bibliographical references (leaves 36-38).
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Wind scatterometry with improved ambiguity selection and rain modeling /Draper, David, January 2003 (has links) (PDF)
Thesis (Ph. D.)--Brigham Young University. Dept. of Electrical and Computer Engineering, 2003. / Includes bibliographical references (p. 231-237).
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Monitoring, analyzing and modeling hydrological processes over a headwater catchment in Hong KongLi, Yanqiu, January 2009 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2010. / Includes bibliographical references (p. 101-118). Also available in print.
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Rainfall distribution in the City of St. John's : temporal distribution, spatial variation, frequency analysis, and Tropical Storm Gabrielle /Wadden, David, January 2002 (has links)
Thesis (M.Eng.)--Memorial University of Newfoundland, 2002. / Bibliography: leaves 78-80. Also available online.
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Experimental and numerical studies of rain infiltration and moisture redistribution /Kaluarachchi, Jagath Janapriya. January 1984 (has links)
Thesis (M. Phil.)--University of Hong Kong, 1984.
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Quantifying the climatic impacts on rainfall in South China and water discharge in the Pearl River (Zhujiang), ChinaLo, Ping-kwong, Paul, 盧炳光 January 2014 (has links)
Monthly and annual changes in precipitation in South China during 1990-2011 are examined in this study. As located in the sub-tropical climate zone, the annual rainfall in South China is concentrated in the summer. During the same period of time, an average of 9 tropical cyclones approaching South China each year which also contribute ample of rainfall to South China during the tropical cyclone season (June-September). Since the climatic system is interconnected, so this study attempts to examine the combined effect on inter annual rainfall variations in South China due to El Nino Southern Oscillation (ENSO), tropical cyclones affecting South China and the Asian Monsoon. It is generally agreed that during the El Nino onset years, South China would be more wetter, but with less than average tropical cyclones affecting South China. As such, effects on precipitation in South China caused by these two factors offsetting each other and data indicate there is no consistent trend of either more or less rainfall recorded for the El Nino onset years during 1990-2011. On the other hand, the first half of the year right after the El Nino years are in general more wetter than normal. This can be due to the lagging effect of El Nino events normally happened in the winter time, plus the fact that the strength of winter monsoon during the El Nino years is weak, resulting in more rainfall in the following year. Furthermore, annual changes in precipitation in South China directly affect the surface runoff of the Pearl River and a strong positive correlation between the two variables exists for the period 2000-2011. The +/- 25% annual variations and the seasonal variations of rainfall in South China post a challenge to the water resource management in the Pearl River Delta Region. Therefore dams and reservoirs built along the Pearl River are necessary to store surplus rainwater in order to supply sufficient fresh water to the Pearl River Delta Region during the dry seasons or years. On the other hand, further studies and monitoring programs are recommended to continue assessing and evaluating impacts of dam constructions to the environment and the ecosystem of the Pearl River Delta Region. / published_or_final_version / Applied Geosciences / Master / Master of Science
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