Excessive water usage together with limited capacity of local hydrogeological environment to dispose excess water or waste water has emerged as a problem of water level rise in many parts of Riyadh, the capital city of Saudi Arabia.

The project can be divided into two parts:

1. Flood Protection from Extreme Events
2. Water Harvesting from Precipitation Events

To address both of these issues we needed to develop a model of the urban hydrology of Riyadh and the generation of meteorological scenarios to drive the modeling process.

This work evaluated the potential for rainwater harvesting at the household and neighborhood level in the dry climate of Riyadh, Saudi Arabia. The amounts of rainwater that can be harvested were estimated with alternative technologies compared to that of producing desalinated water. The study considered the effects of rainwater harvesting on mitigating floods and reducing greenhouse gas emissions.

The Storm Water Management Model (SWMM) was developed by the U.S. Environmental Protection Agency and has been around for decades (first developed in 1969-71). SWMM is a well-known and widely used dynamic rainfall-runoff quantity and quality simulation model for single event or long-term simulation, primarily designed for urban areas. A typical simulation starts with estimating runoff from climate parameters, and then the runoff is routed through the system of pipes, channels, storage/treatment devices, pumps, and regulators, where quantity and quality are tracked. This allows for the determination of when and where flooding events inundate the system. For this project, we used a softwater tool called pcSWMM which adds many graphical and analytic enhancements to the basic USEPA SWMM.