Forested Riparian Buffers as Climate Adaptation Tools for Management of Riverine Flow and Thermal Regimes: A Case Study in the Meramec River Basin

Jason H Knouft,Alejandra Botero-Acosta,Chin-Lung Wu,Anthony I Dell,Maria L Chu,Damon M Hall,Barbara Charry,Steven J Herrington

doi:10.3390/su13041877

Abstract

Ongoing and projected changes in climate are expected to alter discharge and water temperature in riverine systems, thus resulting in degraded habitat. Climate adaptation management strategies are proposed to serve as buffers to changes in air temperature and precipitation, with these strategies potentially providing relatively stable protection for flow and thermal regimes. Using a hydrologic and water temperature modeling approach in the Meramec River basin in eastern Missouri, U.S.A., we examined the ability of forested riparian buffers to serve as a useful climate adaptation strategy against ongoing and projected changes in climate. We developed a multi-scale approach using Soil and Water Assessment Tool (SWAT) hydrologic and water temperature models as well as a Stream Network Temperature Model (SNTEMP) with different amounts of simulated riparian vegetation to estimate streamflow and water temperature variation within the Meramec River basin under both contemporary and projected future climate conditions. Our results suggest that riparian buffers offer benefits to mitigating increases in water temperature due to shading effects; however, patterns in discharge did not vary substantially based on simulations. From an ecological perspective, the addition of riparian buffers is also projected to reduce the impacts of climate change on Smallmouth Bass (Micropterus dolomieu) by decreasing the number of days water temperatures exceed the thermal tolerance of this species.

Highlights

The purpose of this study is to provide a novel perspective on the potential benefits of forested riparian buffers as a climate adaptation strategy for maintaining natural flow and thermal regimes in free-flowing river systems as climate changes
We investigate the potential influence of canopy shading from riparian buffers on water temperature at the stream reach scale under both contemporary and future climate conditions
Model estimates can be reasonably used to simulate the impacts of climate change and riparian buffer expansion during the warmest times of the year

Summary

Introduction

Free-flowing rivers represent an important but increasingly rare resource for the conservation of freshwater biodiversity. The ecological importance of these unimpounded systems is realized, in part, through the provisioning of relatively natural flows and thermal characteristics, which are fundamental drivers regulating lotic ecosystems [1,2]. Flows and thermal characteristics are altered, with well-documented effects on physical and biological processes in these systems [3,4,5]. Flow volume (discharge) and seasonal variability in flows influence species diversity and ecosystem functioning [1,6,7]. Species richness and diversity as well as ecosystem productivity are regulated by the amount of (thermal) energy in a system [2,8], and the exceedance

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