Anthony M. Castronova

HydroShare: Sharing Diverse Environmental Data Types and Models as Social Objects with Application to the Hydrology Domain

The types of data and models used within the hydrologic science community are diverse. New repositories have succeeded in making data and models more accessible, but are, in most cases, limited to particular types or classes of data or models and also lack the type of collaborative and iterative functionality needed to enable shared data collection and modeling workflows. File sharing systems currently used within many scientific communities for private sharing of preliminary and intermediate data and modeling products do not support collaborative data capture, description, visualization, and annotation. In this article, we cast hydrologic datasets and models as “social objects” that can be published, collaborated around, annotated, discovered, and accessed. This article describes the generic data model and content packaging scheme for diverse hydrologic datasets and models used by a new hydrologic collaborative environment called HydroShare to enable storage, management, sharing, publication, and annotation of the diverse types of data and models used by hydrologic scientists. The flexibility of HydroShares data model and packaging scheme is demonstrated using multiple hydrologic data and model use cases that highlight its features.

Calibration of SWAT models using the cloud

This paper evaluates a recently created Soil and Water Assessment Tool (SWAT) calibration tool built using the Windows Azure Cloud environment and a parallel version of the Dynamically Dimensioned Search (DDS) calibration method modified to run in Azure. The calibration tool was tested for six model scenarios constructed for three watersheds of increasing size each for a 2 year and 10 year simulation duration. Results show significant speedup in calibration time and, for up to 64 cores, minimal losses in speedup for all watershed sizes and simulation durations. An empirical relationship is presented for estimating the time needed to calibration a SWAT model using the cloud calibration tool as a function of the number of Hydrologic Response Units (HRUs), time steps, and cores used for the calibration. A cloud-based, parallel SWAT calibration algorithm is evaluated.1000 runs are sufficient for flow calibration using up to 256 cores in parallel.Speedup of the parallel SWAT calibration tool is linear for up to 64 cores.Cost to calibrate a SWAT model can be estimated from HRU and time step counts.

A hierarchical network-based algorithm for multi-scale watershed delineation

Watershed delineation is a process for defining a land area that contributes surface water flow to a single outlet point. It is a commonly used in water resources analysis to define the domain in which hydrologic process calculations are applied. There has been a growing effort over the past decade to improve surface elevation measurements in the U.S., which has had a significant impact on the accuracy of hydrologic calculations. Traditional watershed processing on these elevation rasters, however, becomes more burdensome as data resolution increases. As a result, processing of these datasets can be troublesome on standard desktop computers. This challenge has resulted in numerous works that aim to provide high performance computing solutions to large data, high resolution data, or both. This work proposes an efficient watershed delineation algorithm for use in desktop computing environments that leverages existing data, U.S. Geological Survey (USGS) National Hydrography Dataset Plus (NHD+), and open source software tools to construct watershed boundaries. This approach makes use of U.S. national-level hydrography data that has been precomputed using raster processing algorithms coupled with quality control routines. Our approach uses carefully arranged data and mathematical graph theory to traverse river networks and identify catchment boundaries. We demonstrate this new watershed delineation technique, compare its accuracy with traditional algorithms that derive watershed solely from digital elevation models, and then extend our approach to address subwatershed delineation. Our findings suggest that the open-source hierarchical network-based delineation procedure presented in the work is a promising approach to watershed delineation that can be used summarize publicly available datasets for hydrologic model input pre-processing. Through our analysis, we explore the benefits of reusing the NHD+ datasets for watershed delineation, and find that the our technique offers greater flexibility and extendability than traditional raster algorithms.

Using a Service-Oriented Approach to Simulate Integrated Urban Infrastructure Systems

This paper explores service-oriented architectures as an approach for simulating integrated urban infrastructure as a system of systems. Models representing three individual infrastructure systems (water, transportation, and structures) are written as web services so that they can be linked through the exchange of data into an integrated system. An example application is presented in which the service-oriented approach is used to simulate an integrated urban infrastructure system in Columbia, South Carolina, during a flooding event that causes road closures. Findings of this work are that (1) service-oriented architectures are well suited for urban infrastructure system integration, primarily because of the benefit in handling model heterogeneities including differences in conceptual design and technical implementation, and (2) it is possible to extend an existing web service standard to expose models as web services to achieve a service-oriented modeling system. Results of the example application demonstrate the improvement in alleviating traffic congestion due to flooding by automating the exchange of data between the urban water modeling systems with other components of the civil infrastructure system.

WDCloud: An end to end system for large-scale watershed delineation on cloud

Watershed delineation is a process to compute the drainage area for a point on the land surface, which is a critical step in hydrologic and water resources analysis. However, existing watershed delineation tools are still insufficient to support hydrologists and watershed researchers due to the lack of essential capabilities such as fully leveraging scalable and high performance computing infrastructure (public cloud), and providing predictable performance for the delineation tasks. To solve these problems, this paper reports on WDCloud, which is a system for large-scale watershed delineation on public cloud. For the design and implementation of WDCloud, we employ three main approaches: 1) an automated catchment search mechanism for a public data set, 2) three performance improvement strategies (Data-reuse, parallel-union, and MapReduce), and 3) local linear regression-based execution time estimator for watershed delineation. Moreover, WDCloud extensively utilizes several compute and storage capabilities from Amazon Web Services in order to maximize the performance, scalability, and elasticity of watershed delineation system. Our evaluations on WDCloud focus on two main aspects of WDCloud; the performance improvement for watershed delineation via three strategies and the estimation accuracy for watershed delineation time by local linear regression. The evaluation results show that WDCloud can achieve 18x-111x of speed-ups for delineating any scale of watersheds in the contiguous United States as compared to commodity laptop environments, and accurately predict execution time for watershed delineation with 85.6% of prediction accuracy, which is 23%-13% higher than other state-of-the-art approaches.

Development of a participatory Green Infrastructure design, visualization and evaluation system in a cloud supported jupyter notebook computing environment

Abstract Land use planners, landscape architects, and water resource managers are using Green Infrastructure (GI) designs in urban environments to promote ecosystem services including mitigation of storm water flooding and water quality degradation. An expanded set of urban sustainability goals also includes increasing carbon sequestration, songbird habitat, reducing urban heat island effects, and improvement of landscape aesthetics. GI is conceptualized to improve water and ecosystem quality by reducing storm water runoff at the source, but when properly designed, may also benefit these expanded goals. With the increasing use of GI in urban contexts, there is an emerging need to facilitate participatory design and scenario evaluation to enable better communication between GI designers and groups impacted by these designs. Major barriers to this type of public participation is the complexity of both parameterizing, operating, visualizing and interpreting results of complex ecohydrological models at various watershed scales that are sufficient to address diverse ecosystem service goals. This paper demonstrates a set of workflows to facilitate rapid and repeatable creation of GI landscape designs which are incorporated into complex models using web applications and services. For this project, we use the RHESSys (Regional Hydro-Ecologic Simulation System) ecohydrologic model to evaluate participatory GI landscape designs generated by stakeholders and decision makers, but note that the workflow could be adapted to a set of other watershed models.

Component-based modeling of watershed systems.

Component-based modeling offers an attractive approach for constructing next generation watershed models. In component-based modeling, a complex system is represented as a series of loosely-integrated components with defined interfaces and data exchanges. Because components are loosely-integrated, it is possible for modelers to change how components are linked together within a plug-and-play environment. Component-based modeling is attractive for modeling watershed systems because watersheds are complex systems, and modeling such systems often requires the integration of data and models created and maintained by different groups. Component-based modeling allows for the integration of these disparate data and model resources, while still allowing each group to maintain and advance their own parts of the overall system. Although the component-based paradigm has been used to construct many software systems, it has only recently been applied for modeling watershed systems. Thus, in order to leverage this approach for modeling watersheds, important questions must first be addressed such as how watersheds should be decomposed into system components. In this paper we begin with a vision for component-based modeling, then focus on an experiment that seeks to understand how boundary condition data are exchanged between fully-coupled model components, and finally discuss future work needed to advance the use of component-based modeling of watershed systems.