Identifying peak-imperviousness-recurrence relationships on a growing-impervious watershed, Taiwan

Hydrological Sciences Journal

2014

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A semi-distributed model with a parallel connection was applied to examine the effects of urbanization variables. Data were obtained from watershed divisions that were characterized by various degrees of urbanization. The mean rainfall was calculated using the kriging method. The model inputs were obtained by subtracting mean rainfall from Ф-index values, based on the spatially uniform loss assumption. Regression analysis was applied to determine the relationship between the parameters of 64 calibrations and urbanization variables among the divisions. The results showed that overland parameters produced more consistent change in response to imperviousness than to population. Conversely, the channel parameter was unaffected by changes in urbanization. The verification results of 46 cases showed that power linkage was a potential option for linking division parameters with the corresponding imperviousness based on four evaluation criteria. The changes in imperviousness on overland parameters show the hydrological effects of division urbanizations.

Section: Introductionmentioning

confidence: 99%

Effects of urbanization variables on model parameters for watershed divisions

Chen

Chuang

Hydrological Sciences Journal

2014

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“…Those annual parameters were averages of the parameters of rainfall-runoff events that occurred during the year. The optimal interval method (Huang et al 2008b) determines a suitable interval according to variations in model parameters and urbanization factors from R 2 results of regression analysis. Restated, these hydrological parameters and urbanized factors in the same determined intervals were considered to have identical average values.…”

Section: Responses Of Calibrated Parameters To Urbanized Factorsmentioning

confidence: 99%

“…Both simulation modeling and the design storm approach are frequently applied to estimate the magnitude and frequency of floods in urban areas and to measure the hydrological impacts of the characteristics of stormwater runoff with increased impervious areas. These combined impacts include raised runoff volume, decreased flow time and most significantly an increase in peak discharges with a resulting shift in the flood frequency curve (Hollis 1975;Moscrip and Montgomery 1997;Moon et al 2004;Huang et al 2008b).…”

mentioning

confidence: 99%

The best relationship between lumped hydrograph parameters and urbanized factors

2010

Nat Hazards

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This study mainly explores the best relationship between hydrograph parameters and urbanized factors in urbanized areas. Urbanization of a developing watershed is analyzed through 51 available rainfall-runoff simulations from 1966 to 2002. Forty of these rainfall-runoff events were calibrated to determine the relationships between impervious area and urbanized factors. During the calibration process, the block Kriging method was used to estimate the mean rainfall, and its hourly excesses were calculated by nonlinear programming. Then, clear tendencies between parameters and urbanized factors were produced by comparing the results of the annual average and optimal interval methods. The remaining eleven cases were used to verify the established relationships. The calibration and verification results confirm that the integral approaches used in this study can effectively illustrate the hydrological and geomorphic conditions in complex urbanized processes. Parameter n responds more sensitively than parameter k to increasing impervious area and population density. Additionally, parameter n responds more strongly to imperviousness than to population. Therefore, this study demonstrates that an impervious area is the main consequence of ongoing urbanization in the Wu-Tu watershed. The satisfactory results show that kernel response of the watershed would be more sharppointed and be shifted forward in peak due to an increased impervious cover.

“…There are several schemes for estimating average rainfall values from raingauge data, including the inverse distance method (Maidment 1993), Thiessen polygon method, height-balanced polygon method, and block Kriging method (Delhomme 1978;Isaaks and Srivastava 1989;Cheng and Wang 2002;Cheng et al 2008b;Huang et al 2008a;Huang et al 2008b;Cheng et al 2010;Cheng 2010b, c). These methods often assign weights to raingauge observations using weighted mean by related observations, and then obtain mean rainfall estimations for specific areas.…”

Section: Introductionmentioning

confidence: 99%

Effects of Raingauge Distribution on Estimation Accuracy of Areal Rainfall

Wen

et al. 2011

Water Resour Manage

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Rainfall analysis is important to managing water resources. Mean rainfall is usually used to calculate the spatial rainfall status of a region and is the input into various rainfall-runoff models. However, this method relies on an adequate raingauge network. This study identifies the effects of raingauge distribution based on estimation results of areal rainfall using the Thiessen polygon and block Kriging methods. Twelve rainfall events with complete data from 14 raingauges were selected to complete the goal of this study. The block Kriging method in this study uses a dimensionless semivariogram to obtain hourly semivariograms based on a standardized rainfall depth. The power semivariogram model was used to describe the temporal-spatial variation of rainfall. The analytical process in this study uses raingauge weight and rainfall volume as evaluation criteria. All raingauges were in turn removed from the original raingauge network. The effects of removing each raingauge were compared with computations using all raingauges. Comparison results indicate that (1) the block Kriging method can accurately describe rainfall processes in terms of the spatiotemporal structure of a semivariogram. (2) the block Kriging method is better than the Thiessen polygon method at obtaining exact mean rainfall, and (3) the effects of different raingauge distributions on a mean hyetograph warrant further investigation.