# Reproducible Hydrological Modeling with CyberGIS-Jupyter For Water (CJW) and HydroShare¶

$Fangzheng$ $Lyu^{1}$, $Zhiyu$ $Li^{1}$, $Anand$ $Padmanabhan^{1}$, $Shaowen$ $Wang^{1}$, $Youngdon$ $Choi^{2}$, $Jonathan$ $Goodall^{2}$, $Andrew$ $Bennett^{3}$, $Bart$ $Nijssen^{3}$, $David$ $Tarboton^{4}$

$^{1}$ $University$ $of$ $Illinois$ $at$ $Urbana-Champaign$; $^{2}$ $University$ $of$ $Virginia$; $^{3}$ $University$ $of$ $Washington$; $^{4}$ $Utah$ $State$ $University$

CyberGIS-Jupyter for Water (CJW), leveraging the cyberGIS software ecosystem, is integrated with HydroShare. CJW provides a collaborative platform for enabling computationally intensive and reproducible hydrologic research by delivering advanced cyberinfrastructure and cyberGIS capabilities based on high-performance computing (HPC) resources such as Virtual ROGER and XSEDE Comet. The Structure For Unifying Multiple Modeling Alternatives (SUMMA), which is a hydrological modeling framework, allows for formal evaluation of multiple working hypotheses on model representations of physical processes. This CyberGIS-Jupyter notebook illustrates specific support for a SUMMA model on top of the cutting-edge hydrologic modeling capabilities on CJW. By taking advantage of CJW, users can easily tune different parameters for a SUMMA model and submit computationally intensive High-Throughput Computing (HTC) jobs for executing the model on HPC resources via Jupyter notebooks without having to possess in-depth technical knowledge about cyberGIS or HydroShare. Computational experiments demonstrate that the integration of cyberGIS capabilities and HydroShare achieves a high-performance and easy-to-use environment for reproducible SUMMA-based hydrological modeling.

## The Structure For Unifying Multiple Modeling Alternatives (SUMMA)¶

SUMMA or the Structure for Unifying Multiple Modeling Alternatives is a hydrologic modeling approach that is built on a common set of conservation equations and a common numerical solver, which together constitute the structural core of the model. Different modeling approaches can then be implemented within the structural core, enabling a controlled and systematic analysis of alternative modeling options, and providing insight for future model development.

1. The formulation of the conservation equations is cleanly separated from their numerical solution;
2. Different model representations of physical processes (in particular, different flux parameterizations) can be used within a common set of conservation equations; and
3. The physical processes can be organized in different spatial configurations, including model elements of different shape and connectivity (e.g., nested multi-scale grids and HRUs)

## Architecture of Job Submission System¶

The architecture of job submission system is illustrated as follows. The architecture of the integrated system enables interactions among three key entities: users, CyberGISX frontend, and HPC resources provided through cyberGIS platform (e.g. keeling). In addition, there are six supporting components with which the key entities interact with: 1) CyberGISX website that acts as a portal for users to login out server; 2) authentication system for CyberGISX platform; 3) HydroShare for hydrological data retrieval; 4) Shared folder to store existing resources to avoid excessive data transfer; 5) JupyterHub with appropriate cyberGIS and geospatial python libraries installed, and 6) Docker hub for SUMMA singularity image. HydroShare is a collaborative research platform for advancing hydrological data and model sharing.