A Framework for Assessing Instream Supporting Ecosystem Services Based on Hydroecological Modelling

Sikhululekile Ncube,Lindsay Beevers,Annie Visser

doi:10.3390/w10091247

Abstract

River systems provide diverse ecosystem services (ES), such as flood regulation (regulating), fresh water (provisioning), nutrient cycling (supporting), and recreation (cultural), among others. The construction of infrastructure (e.g., for hydropower, irrigation) enhances the delivery of tangible ES for example food or energy (generally provisioning) to meet human needs. However, the resulting change to river flows threatens both the ecological health of a river and its ability to provide intangible but vital ES, for example those which support the delivery of other services. Understanding these supporting ES processes in river systems is essential to fully recognise the impact of water resources development on ES delivery. Whilst approaches for assessing instream supporting ES are under development, to date few provide quantitative methods for assessing delivery. Thus, this paper sets out a framework for the assessment of instream supporting ES using hydroecological modelling. It links supporting ES delivery to fluvial hydrological indicators through the use of ecologically relevant hydrological indices and macroinvertebrate flow preferences. The proposed framework is demonstrated on the Beas River basin (Western Himalayas, India), and is flexible enough to be transferred to a basin-wide model, thereby allowing ES relationships to be accounted for in basin-wide water resources planning.

Highlights

River systems provide a range of tangible benefits and intangible benefits which both directly and indirectly contribute to human well-being [1]
The proposed framework is demonstrated on the Beas River basin (Western Himalayas, India), and is flexible enough to be transferred to a basin-wide model, thereby allowing ecosystem services (ES) relationships to be accounted for in basin-wide water resources planning
The method couples a quantitative assessment of the relationship between flow and instream ecological response, with a qualitative assessment of the roles individual macroinvertebrate families play in supporting ecosystem service delivery

Summary

Introduction

River systems provide a range of tangible benefits (e.g., freshwater supply) and intangible benefits (e.g., religious enrichment) which both directly and indirectly contribute to human well-being [1]. The Millennium Ecosystem Assessment [2] defined ecosystem services as “the benefits people obtain from ecosystems.” These ecosystem services are classified into four broad categories: Provisioning—the products obtained from ecosystems e.g., water supply; Regulating—the benefits from regulation of ecosystem processes e.g., flood regulation; Cultural—the non-material benefits from ecosystems e.g., religious enrichment; and Supporting—the underlying processes and services necessary for the production of all other ecosystem services. These include ecosystem processes such as soil formation, primary productivity, biogeochemistry, nutrient cycling, and habitat provision. The Millennium Ecosystem Assessment [2] attributes this to the modification and alteration of rivers flows, quality and structure, through a range of human activities aimed at tangible

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