A Spatially Variable Numerical Model for the Estimation of Runoff Hydrographs
Remah Farid Mohamed Ali Foda;
Abstract
Rainfall-runoff modeling is one of the most important engineering applications in hydrology, in which the process of transforming rainfall hyetograph into a runoff hydrograph is simulated.
The majority of commonly used rainfall-runoff models are not capable of incorporating spatially distributed rainfall and other hydrological data which became more available through satellite imaging and rainfall radar scan. Therefore, development of advanced hydrologic models adopting spatially variable input is considered highly desirable.
A large number of hydrologic models have been developed in the past decades with different degrees of complexity and accuracy, and they can be classified into several groups according to the theoretical approach they follow. Each class of models has its advantages and limitations. In general, the high accuracy models always require extensive input data and long time for model building and execution, while simple models lack the accuracy in many cases and have limitations in its area of application, especially for large catchment areas with significant spatial diversity in the hydrologic characteristics. This has emerged the need to develop a rainfall-runoff model for engineering applications that achieves automation, accuracy, and simplicity; especially when used in semi-arid regions which are mostly ungauged in the developing countries.
In this research, a GIS based rainfall-runoff model was developed with advanced capabilities including calculation of infiltration losses incorporating the spatiotemporal variability of it, implementing spatially distributed rainfall data (e.g. rainfall grids) as input to the model, performing the excess rainfall-runoff transformation using an advanced grid-based computation algorithm for spatially varied hydraulic radius calculation and implementation of flow path response functions for runoff flow routing, the capability of simulating any number of watersheds simultaneously to reduce the hydrologic design time, and the capability of accounting for the channel storage effect on the resulting runoff hydrographs.
Previous research work in rainfall-runoff modeling was reviewed with special attention to the theories related to grid-based travel time calculations and runoff flow routing. A research done by Gad (2012) developed a GIS-based automated Semi- Distributed Time–Area model called SDISTA, which deals with each grid cell as an independent hydrologic unit; however, it was incapable of accounting for channel routing effect on the transformed hydrographs, and was using only spatially uniform rainfall as precipitation input. One of the important features of this model is the method of estimating the grid cell flow velocity using Manning’s formula along with an empirical formula developed by Gad (2014) based on stream power law for calculation of grid-based hydraulic radius as a function of hydrologic characteristics of the area upstream the cell.
The majority of commonly used rainfall-runoff models are not capable of incorporating spatially distributed rainfall and other hydrological data which became more available through satellite imaging and rainfall radar scan. Therefore, development of advanced hydrologic models adopting spatially variable input is considered highly desirable.
A large number of hydrologic models have been developed in the past decades with different degrees of complexity and accuracy, and they can be classified into several groups according to the theoretical approach they follow. Each class of models has its advantages and limitations. In general, the high accuracy models always require extensive input data and long time for model building and execution, while simple models lack the accuracy in many cases and have limitations in its area of application, especially for large catchment areas with significant spatial diversity in the hydrologic characteristics. This has emerged the need to develop a rainfall-runoff model for engineering applications that achieves automation, accuracy, and simplicity; especially when used in semi-arid regions which are mostly ungauged in the developing countries.
In this research, a GIS based rainfall-runoff model was developed with advanced capabilities including calculation of infiltration losses incorporating the spatiotemporal variability of it, implementing spatially distributed rainfall data (e.g. rainfall grids) as input to the model, performing the excess rainfall-runoff transformation using an advanced grid-based computation algorithm for spatially varied hydraulic radius calculation and implementation of flow path response functions for runoff flow routing, the capability of simulating any number of watersheds simultaneously to reduce the hydrologic design time, and the capability of accounting for the channel storage effect on the resulting runoff hydrographs.
Previous research work in rainfall-runoff modeling was reviewed with special attention to the theories related to grid-based travel time calculations and runoff flow routing. A research done by Gad (2012) developed a GIS-based automated Semi- Distributed Time–Area model called SDISTA, which deals with each grid cell as an independent hydrologic unit; however, it was incapable of accounting for channel routing effect on the transformed hydrographs, and was using only spatially uniform rainfall as precipitation input. One of the important features of this model is the method of estimating the grid cell flow velocity using Manning’s formula along with an empirical formula developed by Gad (2014) based on stream power law for calculation of grid-based hydraulic radius as a function of hydrologic characteristics of the area upstream the cell.
Other data
| Title | A Spatially Variable Numerical Model for the Estimation of Runoff Hydrographs | Other Titles | نموذج رقمى ذو متغيرات موزعة مكانياً لاستنتاج منحنيات التدفق للسيول | Authors | Remah Farid Mohamed Ali Foda | Issue Date | 2016 |
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