HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Ziegler, A. D. Articles by Jaiaree, S. Search for Related Content PubMed PubMed Citation Articles by Ziegler, A. D. Articles by Jaiaree, S. GeoRef GeoRef Citation Agricola Articles by Ziegler, A. D. Articles by Jaiaree, S. Related Collections Tropical Soil Management Surface Water Quality Wetlands and Aquatic Processes Surface Hydrology Soil Erosion

TECHNICAL REPORTS

Surface Water Quality

Reduction of Stream Sediment Concentration by a Riparian Buffer: Filtering of Road Runoff in Disturbed Headwater Basins of Montane Mainland Southeast Asia

^a Department of Geography, University of Hawaii, 2424 Maile Way, 445 Saunders Hall, Honolulu, HI 96822
^b Geography Department, National University Singapore, Singapore
^c Disaster Prevention Research Institute, Kyoto University, Kyoto, Japan
^d Ministry of Natural Resources and Environment, Chiang Mai, Thailand
^e Division of Soil and Land Conservation, Department of Land Development, Bangkok, Thailand

^* Corresponding author (adz{at}hawaii.edu)

Received for publication March 18, 2005. We determined the extent that a riparian buffer reduces stream suspended sediment concentrations by filtering road runoff during 18 rain events in a 2.5-ha, multi-use watershed in northern Thailand. The dominant buffer species was the perennial sedge Fimbristylis aphylla Zoll. ex Steud. (Cyperaceae). We monitored stream sediment concentration for situations where road runoff either flowed into the riparian buffer or was diverted directly into the stream (buffer and no buffer scenarios). These data were used to develop the following relationships between instantaneous stream sediment concentration (C_i) and discharge (Q_i): C_i = 28.329Q_i^0.851 (buffer scenario) and C_i = 22.265Q_i^1.579 (no buffer scenario). Using these functions to calculate total event suspended concentrations, we determined that the buffer reduced suspended sediment concentration by 34 to 87%, for the range of events monitored. Removal of sediment from runoff generated on a 2.4-m-wide, 165-m-long unpaved road section was achieved principally via ponding, which reduced the transport capacity as flow entered the relatively flat, saturated buffer. Sediment deposition occurred primarily within the first 10 m of the buffer. Some sediment was also deposited on the fillslope leading to the buffer. Maximum road sediment concentration during the largest buffer event approached 100 000 mg L^–1. Meanwhile, the corresponding maximum stream suspended sediment concentration was <4000 mg L^–1. In contrast, maximum stream concentrations when flow bypassed the buffer during smaller events were commonly 4000 to 7000 mg L^–1. Naturally occurring buffers represent an economical means of mitigating road-related impacts in upland basins in Southeast Asia, particularly if combined with measures limiting sediment and runoff production on contributing road sections.

Abbreviations: PKEW, Pang Khum Experimental Watershed