Model Library

Capabilities

• GSSHA provides detailed insights into flood dynamics, especially in urban areas by replicating surface water-groundwater interactions (Ogden et al., 2011; Pradhan et al., 2014);
• Its detailed spatial resolution accurately captures the complex nature of urban landscapes and their impact on flood behavior (Al‑Areeq et al., 2024);
• GSSHA is ideal for evaluating multiple storm scenarios (Al‑Areeq et al., 2024);
• High temporal resolution (Downer 2009; Sith and Nadaoka 2017);
• GSSHA effectively simulates sediment flow, nutrient event discharge, and hydrologic responses (Al-Areeq et al., 2021; Pradhan et al., 2014);
• Its flexibility to integrate a wide range of data types (Al‑Areeq et al., 2024).

Limitations

• Although the GSSHA model executable can be downloaded for free (GSSHA 2019), a WMS software license must be purchased to use GSSHA in WMS;
• Several required parameters of GSSHA are unavailable in large watersheds (Fattahi et al., 2022);
• Using a solution grid with a cell size larger than 200 m in the GSSHA model can lead to significant errors (Fattahi et al., 2022);
• Increasing the time step can cause discharge at the outlet to oscillate, potentially causing the model to crash (Ogden et al., 2003).
• GSSHA does not support irregular pipe cross-sections, and the rectangular cross-section option was not functional (Brendel et al., 2020);
• GSSHA’s storm sewer pipes and stream channels are not fully integrated; flow can only move from the pipes to the channels (Brendel et al., 2020);
• GSSHA does not support automatic calibration of storm sewer parameters with the PEST parameter estimation and uncertainty analysis software (Skahill et al., 2012).

Inputs

Topography data, LULC, soil characteristics, Meteorological data, Stream network, Hydrologic data, Hydraulic data, Initial conditions, Boundary conditions, Contaminant loading data

Outputs

The GSSHA model simulates sediment, water quality, hydrologic processes, and hydraulics (two-dimensional overland flow and one-dimensional channel flow)

References

Fattahi, A. M., Hosseini, K., Farzin, S., et al. (2023). An innovative approach of GSSHA model in flood analysis of large watersheds based on accuracy of DEM, size of grids, and stream density. Applied Water Science, 13, 33. https://doi.org/10.1007/s13201-022-01838-6

Al-Areeq, A. M., Al-Zahrani, M. A., Chowdhury, S., et al. (2024). Development of hydrological based physical model for nutrients transport simulation: Case study of Makkah city, Saudi Arabia. International Journal of Environmental Science and Technology. https://doi.org/10.1007/s13762-024-05745-y

Objectives

The main goals of this research are: investigating the possibility of combining distributed hydrological models with a one-dimensional hydraulic model and simulating waterways in large watersheds with limited hydrological and hydraulic data. 

The goal of the study is to investigate water quality following urban floods, using the city of Makkah as a case study. Moreover, the what-if scenario-based methodology estimates the concentrations of nitrogen and phosphorus in the worst-case scenarios.