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Implementation of LiDAR data in hydrological model TOPMODEL for predicting flood: Monticano River case study
Khodayari, Nahid
2012-04-19
Contributor(s)
Caroni, Elpidio
•
Coren, Franco
•
Yari, Sadegh
Abstract
The semi-distributed rainfall-runoff model, TOPOMODEL is applied to predict the response of Monticano River basin to rain events. TOPMODEL is a topographic based model in which the topographic index has an essential role. Topographic index is a function of the Digital Elevation Model (DEM) resolution.
The high resolution LiDAR data with 1-2 points per meter square, is used as topographic data to generate DEMs, calculate the topographic index as well as extracting the hydrological features. Due to significant effect of the DEM resolution on the topographic index and hydrological features accuracy, different DEMs with 25 m, 50 m, 100 m and 200 m grid size are generated using LiDAR data. Comparing the density function of topographic index with different resolutions indicate that by decreasing the resolution there is a shift toward the higher values as well as increasing the topographic constant λ from 7.36 for 25 m resolution to 10.32 corresponding to 200 m grid size.
TOPMODEL is applied to simulate the six events namely; 20-21 December 1997, 6-7 November 2000, 10-12 August 2002, 21-23 January 2003 , 31 October-1November 2004 and 22-26 December 2009. The model successfully simulates flood levels, with respect to both their extent and to peak time.
The sensitivity analysis for scale parameter m and lateral transmissivity T0 shows that the coefficient m affects much more than T0 on the hydrograph shape and peak value.
The effect of DEM resolution on the model results is examined. The model results are different, but the differences are very small except for events 2003 and 2009. The results of simulations based on 25 m grid size are very close to those of 50 m grid size, while the simulated discharges using 100 m and 200 m grid size are overestimated.
The efficiency of the simulations are calculated for all events using different topographic index distributions. The efficiency of model is in a range of 0.86 for event 2009 to 0.99 for event 2002. The high values of efficiency can be due to effect of accurate topographic index distribution and hydrological features extracted from high resolution topographic data.
The simulation based on DEM with 25 m resolution shows slightly higher efficiency values. This means that generating higher resolution DEM with respect to suggested 50 m grid size for TOPMODEL, may give a more accurate output as it is evident from this study.
Insegnamento
Publisher
Università degli studi di Trieste
Languages
en
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