Hydrologic Change and Accelerated Erosion in Mountainous Tropical Watersheds:
The Impact of Rural Roads

CONTENTS and LINKS

NSF Award Information
Collaborators
Proposal Abstract
GAME-T Workshop Abstract: Draft
Project Summary Paper:
[pdf] [hi-res pdf]
ICRAF Poster
[640x480] [1280x1024]
Pang Khum Experimental Watershed (PKEW)
PKEW Instrumentation
Publications and Presentations
Alan Ziegler's Project Page
Location Map of Study Area
Village Friends--Photos

Woman of Lisu Ethnic Group, Pang Khum Village, Chiang Mai Province, Northern Thailand

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NSF AWARD: 9614259

NSF Program: 1579 HYDROLOGIC SCIENCES Start Date: March 15, 1997 Expires: February 29, 2000 Expected Total Amt.: $299,999
Investigators: Thomas W. Giambelluca and Ross A. Sutherland

Research Team:
P.I. (Climatology/Hydrology): Tom Giambelluca
P.I. (Geomorphology/Hydrology): Ross Sutherland
PhD Student (Everything): Alan Ziegler
Research Assistant (Field Instrumentation/Data Management): Mike Nullet
Undergraduate Student (Field Measurements): Toby Vana

Department of Geography
University of Hawai`i at Manoa
Honolulu, Hawai`i 96822
USA

Collaborators:

Professor Sanay Yarnasarn
Department of Geography
Chiang Mai University Chiang Mai Thailand

Thailand Department of Land Development
Chiang Mai and Bangkok Offices
Thailand

Abstract

Unpaved roads play a significant role in altering near-surface hydrologic response and subsequently accelerating soil erosion intemperate drainage basins. Road-related impacts are also of particular concern in tropical areas where agricultural practices are most often blamed for erosion and sedimentation problems. The focus of this study is to show how an expanding road network changes the hydrological and erosion processes of a mountainous tropical watershed in northern Thailand. The major objective are to (1) determine the degree to which hydrologic processes in tropical watersheds are disrupted by roads--this information can later be compared with what is known about road disruption in temperate watershed; (2) establish the importance of roads in relation to agricultural areas in initiating hydrologic change and contributing to accelerated erosion; and in so doing, obtain a detailed understanding of erosion processes operating on and adjacent to road surfaces; and (3) evaluate the conservation value of several road management-related what if scenarios. The proposed research strategy can be represented by four components: (1) a comprehensive field study to build a database of hydrological, erosional, and soil-vegetation-atmosphere-transfer (SVAT) information; (2) in-depth analysis of changes in hydrologic and erosion processes due to land-cover change, especially changes due to road expansion; (3) determination of the important road-related runoff processes in order to select the appropriate model or models to simulate hydrologic change and erosion resulting from the expansion of road networks; and (4) use of model(s) to simulate the effects of several management scenarios. This research will improve our knowledge of hydrologic and geomorphic processes operating in tropical watersheds undergoing dramatic landuse changes; help determine the importance of roads, as compared with agricultural practices, in contributing to cumulative watershed impacts; aid in the future management of tropical mountainous watersheds; and provide insight into improving the design, routing, maintenance, and usage of rural roads.

Project Summary: [pdf] [hi-res pdf]

Pang Khum Experimental Watershed Network

Pang Khum Village, Chiang Mai, Thailand (19º41'N, 98º47'E);
Measurements began Summer 1997

Contact: T. Giambelluca (thomas@hawaii.edu)

PKEW Instrumentation Station 401: Forest (20-m tower) Rainfall 1-min freq All other parameters 20-min freq: Reflected shortwave radiation Net radiation Canopy temperature (infrared thermometer) Soil heat flux (2 sensors) Soil temperature (averaged from 4 sensors) Air temperature (thermocouple measures T difference at 2 heights above canopy) Humidity (cooled mirror hygrometer; from 2 heights above canopy) Wind speed Wind direction Soil moisture (TDR; 3 depths)
	`20-m Meteorological Tower at Forest Site (401)`
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Station 402: Swidden field (4-m tower) Rainfall 1-min freq All other parameters 20-min freq: Downward shortwave radiation Reflected shortwave radiation Net radiation Canopy/surface temperature (infrared thermometer) Soil heat flux (2 sensors) Soil temperature (averaged from 4 sensors) Air temperature (thermocouple measures T difference at 2 heights above canopy) Humidity (cooled mirror hygrometer; from 2 heights above canopy) Wind speed Wind direction Soil moisture (TDR; 3 depths)
	`4-m Meteorological Tower at Swidden Agriculture Site (402)`
Station 403: Secondary vegetation Rainfall 1-min freq Soil moisture (TDR; 3 depths) 20-min freq Soil moisture within road cutbank (TDR; 3 depths; records any significant change) Station 404: Secondary vegetation Rainfall 1-min freq Soil moisture (TDR; 3 depths) 20-min freq Soil temperature at 50 cm (averaged from 4 sensors) 20-min freq
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Station 405: Basin outlet

Rainfall 1-min freq
Stream discharge (records any significant change in stage in weir)

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Station 406: Road Rainfall 1-min freq All other parameters 20-min freq: Reflected shortwave radiation Net radiation Surface temperature (infrared thermometer) Soil heat flux (2 sensors) Soil temperature (averaged from 4 sensors) Air temperature Humidity Wind speed Soil moisture (TDR; 4 depths; records any significant change)
	Meteorological station on road (406)
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