A Web Service ecosystem for high-quality, cost-effective debris-flowhazard assessment

Giorgio Rosatti a, *, Nadia Zorzi a, Daniel Zugliani a, Stefano Piffer b, Alessandro Rizzi b, 1

a Department of Civil, Environmental and Mechanical Engineering, University of Trento, Trento, Italyb Trilogis srl, Trento, Italy

a r t i c l e i n f o

Article history:Received 14 December 2016Received in revised form25 October 2017Accepted 8 November 2017

Keywords:Debris-flow hazard assessmentTRENT2DWEEZARDWSCloud computing

a b s t r a c t

In this work, we present WEEZARD, a smart, cost-effective system, aimed at producing, managing andanalysing high-quality debris-flow simulations to be used in hazard assessments. Developing the systemwas a challenge because of the complexity and the number of interconnected operations involved in suchassessments. The goal was achieved by using a web client-server system, where a set of web services areexposed in a way similar to that used in OGC ® WPS solutions. The new system is composed of a pre-viously developed advanced two-phase debris-flow model (TRENT2D), re-coded as a web service, and allthe functionalities necessary to exploit the model, from the management of input and output (alsoprovided as web services) to GIS features and two- and three-dimensional dynamic visualizations. Futuredevelopments include the possibility of using approaches such as the “Model as a Service” to furtherincrease the accessibility and interoperability of the TRENT2D model.

© 2017 Elsevier Ltd. All rights reserved.

1. Introduction

Among geomorphic processes, debris flows are a commonphenomenon in mountain regions. From a physical point of view,they are gravity-driven flows, composed of a mixture of a solidphase (sediments) and a liquid phase (water, commonly the resultof heavy rainfall). Because of urbanization, these phenomena oftenaffect buildings and infrastructure, causing severe damage andpossibly casualties (see Fig. 1). Moreover, climate change seems tohave induced an increase in extreme precipitation and discharge(IPCC, 2014), possibly making debris flows both larger and morefrequent (see e.g. Stoffel et al., 2014).

Reducing the risk of adverse consequences, according to the UEFlood Directive (UE, 2007), is feasible and desirable by usingappropriate best practice and the best available technology. The citedregulation goes on with an important indication concerning tech-nology: not entailing excessive costs. A similar concept is expressedin the USA Disaster Mitigation Act (DMA, 2000), which states thatmultihazard advisory maps must be developed with the most cost-

effective and efficient technology available.Compared to other techniques (checklists, statistics, etc.), com-

puter simulations are undoubtedly the most advanced technologyavailable for what we define here as “debris-flow simulation jobs”,consisting in tasks such as understanding the dynamics of pastevents through a back analysis, anticipating scenarios for hazardassessment, hazard or riskmapping and planningmitigationworks.However, high-quality reliable simulations can be obtained onlyfrom advanced research models that consider the physicalcomplexity of the phenomenon as much as possible and by usingsuitable high-resolution computational domains. Unfortunately,these models impose a significant computational burden and,consequently, require an adequate hardware resource, which is notalways available, for example, to practitioners working in this field.

Moreover, as presented in detail in Section 2.2, running asimulation is only part of a job. In fact, many other tasks arerequired, concerning essentially pre- and post-processing ofsimulation data. Often, each taskmust be performed using differentsoftware, resulting in a high fragmentation of the work and a sig-nificant and expensive need for manual work.

Summarizing, the use of advanced software is not an easymatter and seldom a cheap operation. Consequently, rough or verysimplified models are commonly used in practical jobs, leading topossible unreliable results in forecasting situations, such as hazardmapping.

* Corresponding author.E-mail addresses: giorgio.rosatti@unitn.it (G. Rosatti), nadia.zorzi@unitn.it

(N. Zorzi), daniel.zugliani@unitn.it (D. Zugliani), stefano.piffer@trilogis.it(S. Piffer), alessandro.rizzi@trilogis.it (A. Rizzi).

1 Current address: Tecnobit srl, Predaia - Trento, Italy.

Contents lists available at ScienceDirect

Environmental Modelling & Software

journal homepage: www.elsevier .com/locate/envsoft

https://doi.org/10.1016/j.envsoft.2017.11.0171364-8152/© 2017 Elsevier Ltd. All rights reserved.

Environmental Modelling & Software 100 (2018) 33e47

The main goal of our work is to incorporate an advanced modelinto a practical and affordable tool for debris flow hazard assess-ment. In this paper, we describe the development of a completeplatform based on the “Software as a Service” (SaaS) paradigm. Theresult, although based on consolidated Information Technologies, isan innovative system in the field of debris-flow modelling forhazard assessment, and allows possible interesting developments.

In detail, in Section 2 we present an analysis of who may beinterested in debris-flow modelling (i.e. all the possible classes ofusers) and what must be done (i.e. which work elements arenecessary) to perform a numerical study of the phenomenon. Then,we survey the existing integrated solutions that are able to chainthe operations needed for a debris-flow job (Section 3). Section 4

shows the fundamental features of the TRENT2D model(Armanini et al., 2009; Rosatti and Begnudelli, 2013b), a high-quality two-phase numerical model for debris flows, developedbefore this work by some of the present authors, around which wedeveloped our innovative system. In Section 5, we present the ar-chitecture of WEEZARD (acronym for WEbgis modElling and haZ-ard Assessment for mountain flows: an integRated system in theclouD, available at http://tool.weezard.eu), an integrated solutiontailored to the requirements of practitioners and land protectionagency technicians, while in Section 6 the main WEEZARD func-tionalities are shown. A discussion of the limits of the system at thecurrent state of development and the possible future improve-ments is presented in Section 7. Our conclusions end the paper.

Fig. 1. An example of (a) a debris-flow outcome and (b) of the enormous damage that this type of flow can produce. (Photo (a): courtesy of Autonomous Province of Trento, Italy).

G. Rosatti et al. / Environmental Modelling & Software 100 (2018) 33e4734

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