Evaluation of Ecosystem-Based Adaptation Measures for Sediment Yield in a Tropical Watershed in Thailand

Mukand S Babel,Manoj K Jha,Miyuru B Gunathilake

doi:10.3390/w13192767

Abstract

Ecosystem-based adaptation (EbA) can potentially mitigate watershed degradation problems. In this study, various EbA measures were evaluated using a bio-physical model called the Soil and Water Assessment Tool (SWAT), in a small, forested watershed named Hui Ta Poe, in the northeastern region of Thailand. The developed watershed model was first used to investigate the effect of various degraded watersheds due to land-use changes on the sediment yield in the study area. The most degraded watershed produced an annual average sediment yield of 13.5 tons/ha. This degraded watershed was then used to evaluate the effectiveness of various EbA measures such as reforestation, contouring, filter strips, and grassed waterways in reducing the sediment yield. Under all individual and combined EbA scenarios analyzed, there was a significant reduction in sediment yield; however, the maximum reduction of 88% was achieved with a combined scenario of reforestation, grassed waterways, and filter strips. Reforestation alone was found to be the second-best option, which could reduce the sediment yield by 84%. Contouring alone was the least effective, with a reduction in sediment yield of only 23%. This study demonstrates the usefulness of implementing EbA measures for sediment management strategies to address watershed degradation, which is a severe problem across the globe.

Highlights

Deforestation, changes in land use, and unsustainable agricultural management practices have been identified as the critical driving forces leading to high rates of watershed degradation in many parts of the world [1,2,3]
GWQMN is the threshold depth of water in a shallow aquifer required for return flow to occur [78]
The study’s results demonstrate how land use changes by introducing commercial and energy crops, and how their cultivation could degrade the watershed in terms of soil erosion and sediment yield, thereby causing other environmental problems downstream

Summary

Introduction

Deforestation, changes in land use, and unsustainable agricultural management practices have been identified as the critical driving forces leading to high rates of watershed degradation in many parts of the world [1,2,3]. Encroachment of agricultural activity into natural ecosystems has led to significant losses in ecosystem services such as biodiversity conservation and carbon storage capacity [4,5,6,7]. Increased sedimentation due to watershed degradation has significantly reduced reservoir capacities [8]. 1.9 billion hectares of land are affected by land degradation globally [9]. In the European context, loss of biodiversity and habitat fragmentation are some of the significant impacts on ecosystems due to land degradation [11]

Objectives

Methods

Results

Conclusion