Modelling Tools for Dealing with Environmental Complexity

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In many regions of the world, managing water demand without damaging the local ecosystem is a challenge. For instance, in regions suffering from water scarcity, extensive agricultural fields are often established along the coast. Water for irrigation is partly taken from groundwater and partly from surface water originating in nearby mountainous regions. The local water supply is, however, not only used for agricultural purposes, but also serves as a source of drinking water for the local population.

 

Around the globe, populations are increasing due to better health care and improved living conditions. However, more people need more water, more food and more energy. The high and diverse demand for water, combined with an insufficient supply, often causes considerable water use conflicts.

Local authorities of such regions might seek to mitigate conflict by pumping larger amounts of water from the aquifer for irrigation. But this may set off a chain of unforeseen consequences as it can affect the water balance by, for example, reducing the amount of available water in surrounding areas. In coastal regions, this causes saltwater to intrude into the aquifer. The saltwater intrusion leads to salinisation of the agricultural soils and renders the groundwater no longer potable.

 

Thus the initial conflict extends from a water quantity to a water quality management problem. The soil becomes unsuitable for traditional crops, in turn leading to socio-economic consequences such as farmers losing income due to unproductive land or people needing to migrate to regions with better soil fertility.

 

To respond in a sustainable way to water scarcity, such regions obviously need different — and more sophisticated — adaptation measures. However, choosing the proper measures requires first comprehending the interactions between the salinity, fertility and water balance of the soil. Understanding the water–soil inter-relations means understanding individual soil processes in detail and their interaction with water processes such as surface runoff or infiltration.

 

Addressing such complex problems/systems thus requires looking at them in a holistic way. The approach to explicitly consider the inter-relatedness of resources and think outside the box(es) has been coined a ‘nexus approach’. The nexus concept aims at extending ‘integrated management thinking’, which has been applied with varying success in diverse disciplines and has become especially popular in water resources management.

 

One way of extending integrated water resources management is to consider the “water, energy and food security nexus”. The work of the United Nations University Institute for Integrated Management of Material Fluxes and of Resources (UNU-FLORES) looks at the nexus from a multi-resource perspective, focusing on water, soil and waste, while also considering global change and socio-economic factors.

 

By taking a nexus approach and understanding the biophysical processes involved in the scenario described above, for example, we can develop recommendations on how to adapt irrigation to minimize water pumping from the aquifer, implement modern technologies, maintain soil suitability for agriculture or make use of wastewater for agriculture.

 

Yet, putting soil–water–waste nexus thinking into practice requires even more than this holistic understanding of the interlinkages of environmental processes. The interconnections between institutional processes as well as socio-economic impacts also need to be considered.

Are interventions socially and culturally acceptable, could they marginalise certain groups of people (e.g., ethnic minorities, women, etc.) and what effects do they have on the livelihoods of individuals and processes of social change? Additionally, any technological developments, such as those described in the example above, entail costs, both for service delivery and capacity development and training. Budgetary constraints and an assessment of whether technologies, services and training are affordable to users must also be taken into account. It is clear that environmental, social and economic factors are closely intertwined.

 

The sustainable management of any environmental resource requires a nexus approach that examines the complex mix of factors and relationships — analyses far too intricate for simple calculations. Thanks to rapid advances in computer technology, we have succeeded in developing software tools that can mathematically support our understanding of nature’s complex interactions and feedback systems. In parallel to the technological developments, knowledge gained through nexus-oriented research has been and is continuously incorporated into these tools.

 

Of course, the relationship between every single natural process and socio-economic factor is much too complex to consider exhaustively with such tools. These software tools create models that represent and simulate reality in a simplified manner and often focus on a specific area of application. In the opening example, water management practices were first analysed solely from the hydrological perspective. However, applying a nexus approach means also looking at the risks for water quality and agricultural soil salinisation, soil processes and waste (i.e., wastewater reuse) as well as institutional processes and socio-economic impacts. As this example illustrates, depending on the overall objective and concerns, researchers and decision makers may need several models to achieve truly sustainable resource management.

 

The use of modelling tools that can capture the complex nexus of Earth’s natural and social systems is still the exception in resource management. There is one simple reason for this: there is no comprehensive modelling tool available or even conceivable that would be applicable to the whole range of nexus problems. While several available tools are “integrated” to a certain extent, typically users would be required to modify/extend or couple tools. It is, however, hard to find the right (set of) tool(s).

 

On the one hand, the large diversity of available models is often overwhelming. It is difficult to select or even find the most appropriate model or set of models that can be applied to specific projects or accommodate specific site requirements. On the other hand, information concerning the variety of tools available and the appropriate methods for applying them is scattered, inaccessible, incomplete, out of date, static or simply hard to compare.

Although the data necessary for many modelling tools are available online, the descriptions of these models and how to use them are often hidden separately in long, scholarly texts. Those interested in using the tools are frequently required to make the connection between the description of the tool and the necessary data themselves. Frequently, researchers choose to develop their own, new models. Here at UNU-FLORES, we believe that making use of available successful models is more effective and cost-efficient than developing new models from scratch, and frankly more feasible for most interested parties.

 

Responding to these challenges — the necessity of applying the nexus approach to resource management and the lack of concentrated/channeled information about the tools available to do so — UNU-FLORES developed the Nexus Tools Platform (NTP). The NTP is an open-access, web-based platform that serves as a database for modelling tools and allows for their interactive comparison. It is hosted by the Nexus Observatory, a flagship initiative of UNU-FLORES that serves to consolidate and translate science into policy-relevant information and evidence on the nexus of water, soil and waste.

 

Currently, the NTP focuses on collecting, consolidating and providing access to information on modelling tools for managing the water–soil–waste nexus. While many of these tools are integrative, the inherent complexity of the water–soil–waste nexus makes it difficult for a single model to address all aspects under all circumstances. It is crucial that researchers and decision makers have access to a mechanism that effectively helps to navigate through the confusing sea of available tools and facilitates the selection of the most appropriate model or suite of models to address a specific nexus problem. To this end, from the beginning the NTP was developed as an interactive database.

 

‘Interactive’, in this context, means that different modelling tools can be compared based on the resources and regions they cover, the processes they address and their technical features. This is all done easily through a query field, where the user can carry out simple or more complex queries according to their objective or desired mechanisms. The NTP appeals to visual and pattern-oriented users by illustrating complex relationships and comparisons of the modelling tools using graphs such as histograms or maps. These graphs can be used to filter and select the most appropriate model by clicking on, for example, bars of the histogram that are associated with a specific modelling process, such as water quality.

 

In another example, if a user is interested in all modelling tools that have been used in a specific country, for instance India, they can click on India on the map feature and can view all modelling tools that have successfully been applied in that country. The use of these features is interlinked with the search function. As a result, clicking will result in introducing a filter that will update all other visualizations and show only the information related to modelling tools that meet the original query and the new selection.

 

‘Open-access’ refers to the fact that UNU-FLORES not only provides free access to the platform, but also encourages researchers and practitioners to contribute to the content, its quality and completeness. UNU-FLORES strives to ensure that the NTP evolves into and remains a truly comprehensive platform that provides researchers and decision makers easy and free access to extensive information on the tools they need in order to apply a nexus approach to the sustainable management of environmental resources.

 

Improving access to appropriate tools and engaging with potential users and stakeholders, enables evidence-based decision-making in the field of sustainable development. UNU-FLORES recognizes that, in particular, social and institutional conditions have been neglected in the past, leading to incomplete analyses of resource management problems. In order to enhance monitoring, governance and accountability processes, and to overcome fragmentation, science-policy relations must be made explicit. Providing these visualisation tools and other instruments through the Nexus Observatory, UNU-FLORES is supplying decision makers with policy-relevant information and data to support an analysis of synergies and trade-offs. This facilitates the choice of management strategies that advance sustainable outcomes.

 

The UNU-FLORES team hopes that in the future, when developing resource management strategies, decision makers can use the NTP to find the most appropriate model or set of models that can account for the hydrological-, soil- and waste-related as well as socio-economic challenges that they face.