A conceptual framework for analyzing deltas as coupled social–ecological systems: an example from the Amazon River Delta

Abstract

At the nexus of watersheds, land, coastal areas, oceans, and human settlements, river delta regions pose specific challenges to environmental governance and sustainability. Using the Amazon Estuary-Delta region (AD) as our focus, we reflect on the challenges created by the high degree of functional interdependencies shaping social–ecological dynamics of delta regions. The article introduces the initial design of a conceptual framework to analyze delta regions as coupled social–ecological systems (SES). The first part of the framework is used to define a delta SES according to a problem and/or collective action dilemma. Five components can be used to define a delta SES: social–economic systems, governance systems, ecosystems-resource systems, topographic-hydrological systems, and oceanic-climate systems. These components are used in association with six types of telecoupling conditions: socio-demographic, economic, governance, ecological, material, and climatic-hydrological. The second part of the framework presents a strategy for the analysis of collective action problems in delta regions, from sub-delta/local to delta to basin levels. This framework is intended to support both case studies and comparative analysis. The article provides illustrative applications of the framework to the AD. First, we apply the framework to define and characterize the AD as coupled SES. We then utilize the framework to diagnose an example of collective action problem related to the impacts of urban growth, and urban and industrial pollution on small-scale fishing resources. We argue that the functional interdependencies characteristic of delta regions require new approaches to understand, diagnose, and evaluate the current and future impacts of social–ecological changes and potential solutions to the sustainability dilemmas of delta regions.

Appendices

Textbox 1: Defining key terms

Institutional fit is used to describe the congruence or compatibility between the social and ecological systems, i.e., whether a form of collective action at a local level matches the larger ecological system within which it is subsumed (Young 2002; Epstein et al. 2015).

Institutional interplay designates interactions (and tensions) between governance arrangements operating within and/or across scales (Young 2002, 2006).

Functional Interdependence refers to the way human actions or biophysical processes taking place in one setting can produce impacts in areas and systems that are far removed from the site of such actions and/or processes. Functional interdependencies can involve both biophysical and socioeconomic linkages (Young et al. 2006; Brondizio et al. 2009).

Collective action is used here to mean the cooperation among two or more individuals to try to achieve outcomes that none of these individuals could achieve on their own. As such, collective action involves different types of cooperation and conflicts among individuals and/or groups of individuals to solve collective problems and choices at different levels. Collective action is difficult in proportion to the scale of the problem as well as to the size and heterogeneity of the group of actors: the larger and more diverse the group, the higher the differences in objectives, the higher the transaction cost of information exchange and collaboration, the harder it is to act collectively.

Governance refers to a social function centered on steering human groups toward mutually beneficial outcomes and away from mutually harmful outcomes.

Telecoupling refers to both to the interconnection between social and natural systems and to the distant causes of local phenomena. Liu et al. (2013, 2015) telecoupling framework includes five main components: systems, agents, flow, causes, and effects.

External forcing refers to “…to a forcing agent outside the climate system causing a change in the climate system. Volcanic eruptions, solar variations and anthropogenic changes in the composition of the atmosphere and land use change are external forcings.” (IPCC 2013:1454).

Textbox 2: The Amazon Delta-DAT

The Amazon Delta-DAT is a Geographic Information System created as part of the Belmont Forum Deltas project. The Amazon Delta-DAT geospatial data platform includes on the one hand socioeconomic data sets, such as different political and administrative units, historical census data (including social, demographic, and economic indicators), land use change, urban infrastructure and services and, on the other hand, biophysical data such as remotely sensed datasets, topographic data, watershed information, historical rainfall patterns, tidal records, and land cover change.

Outputs in the form of statistical analyses and map products are also archived within Delta-DAT. The geospatial methodology is based on change detection techniques, providing a basis for monitoring the distribution, extent and direction of changes in the land cover as associated with different types of property regimes (e.g., common, governmental, private, open access), contextual factors (e.g., access, location), and/or other units of analysis such as watersheds, census sectors, municipalities, communities, different types of reserves and protected areas and so forth. To consolidate and make data readily available to the larger BF-Deltas team, the authors worked in cooperation with colleagues at the City University of New York, under the leadership of Zach Tessler. Through this collaboration, the Delta-DAT geospatial database is now served by open source data management software known as The Integrated Rule-Oriented Data System (iRODS). iRODS allows for metadata generation, automated workflows, secure collaboration and data virtualization providing a middleware between several physical data storage systems and the user interface. iRODS is currently running on a server at City College of New York.

Textbox 3: Geology, hydrology, and climate of the Amazon estuary-delta

The AED is located on a rifted passive tectonic margin and is the terminus of a drainage basin of 6.1 × 10⁶ km² (Organization of American States 2005). The AED experiences a hot, humid tropical climate (Koppen Af) with temperatures averaging between 25 and 27 °C. Shifts in the Intertropical Convergence Zone (ITCZ) from around 14°N in August to 2°S in March–April condition the east to northeast trade winds and rainfall patterns. These trade winds are mainly active from January to May. Rainfall is in the range of 2500–3000 mm and is concentrated in a rainy season also lasting from January to May. Rainfall and river discharge are significantly influenced by ENSO oscillations. A recent estimate of the mean annual water discharge of the river at Óbidos, 900 km upstream of the mouth, has been set at 173,000 m³ s⁻¹ (Martinez et al. 2009), that is about 20 % of the world’s fluvial liquid water discharge. The water discharge peak of over 220,000 m³s⁻¹ occurs in May–June and the low discharge of 100,000 m³s⁻¹ in November–December. These variations engender significant changes in water level within the AED, which, when combined with the strong tidal effects of this system, constitute a source of important spatial–temporal hydrological variability (see Fig. 5). The Amazon also discharges the highest total sediment load to the global oceans, although the specific sediment yield of 190 t km² a⁻¹ corresponds to the world’s average (Milliman and Farnsworth 2011). Recent estimates of sediment discharge at Óbidos range from 754 to 1000 × 10⁶ t a¹ (Martinez et al. 2009; Wittmann et al. 2011). About 90 % of this sediment load is silt and clay (Milliman and Meade 1983), reflecting intense tropical weathering of materials of dominantly Andean origin (Guyot et al. 2007). Martinez et al. (2009) have shown that the liquid water discharge is relatively regular whereas sediment discharge showed more significant inter-annual variability. The rest of the load consists of sand.

The large continental shelf built-up by sediment supply by the AED over geological time leads to significant tidal amplification at the mouth of the river, thus generating large tides that favor important water level changes within the funnel-shaped mouth. In the Northern channel, this tidal influence is felt up to the town of Óbidos. Tides are associated with a flood-dominated asymmetry that leads to the formation of bores (pororoca) in some Northern channels. Ocean surface stress by the trade winds generates strong westward along-shelf flow of the North Brazil Current. The trade winds are also the dominant generators of waves impinging on the AED coast, which come from an east to northeast direction (Gratiot et al. 2007). Trade-wind waves have significant periods (T _s) of 6–8 s, and significant offshore heights (H _s) of 1–2 m. The AED coast is also affected by longer period (>8 s) swell waves generated by North Atlantic depressions in autumn and winter and by Central Atlantic cyclones in summer and autumn.

Textbox 4: Categories of collective action problems adapted from Mcginnis (2011)

Appropriation problem: relates to motivating individuals to forego excessive consumption of a subtractable resource, i.e., whether one group of users benefits more than another.

Provisioning problem (or public good problem): relates to the motivation of individuals to contribute to the resource system and infrastructure, i.e., to avoid a ‘free riding’ problem.

Assignment problem: the location of one group may be more beneficial than for others and differential access to resource use.

Technological externality problem: differential access to technology creates uneven rates of use and benefits between users that have similar rights to resources; it can also create environmental and social externalities affecting different segments of the population.

Rent dissipation problem: one group of users seeks high rates of short-term use and return than other users with similar rights to resources.

Cross-scale mismatches problems: Fit between the institutional boundaries of governance and the ecological boundaries of the resource system is intended to manage; and interplay between two neighboring governance systems that may be competing for the same resources.