**Authors**: Ahmet Artu Yildirim (email@example.com) **Abstract**: Grid digital elevation models (DEMs) are commonly used in hydrology to derive information related to topographically driven flow. Advances in technology for creating DEMs has increased their resolution and data size with the result that algorithms for processing them are frequently memory limited. This project presents a new approach to the management of memory in the parallel solution of hydrologic terrain processing using a user-level virtual memory system for shared-memory multithreaded systems. We implemented user-level virtual memory system for Windows 7 operating system to process large DEM datasets on the machine with limited memory. We used the GDAL library to enable a wide range of raster file formats within the implemented memory manager. We implemented a modified version of the Planchon and Darboux pit filling algorithm as an application of our tiled virtual memory manager. **Acknowledgment**: This research was supported by the US Army Engineer Research and Development Center System-Wide Water Resources Program under contract number W912HZ-11-P-0338. This support is gratefully acknowledged.