K oc
Organic carbon normalized distribution coefficient
LUT
Land-use type
MMSEA
Mountainous mainland Southeast Asia
N
Nitrogen
P
Phosphorus
Q
Stream discharge
RaCSA
Rapid Carbon Stock Appraisal
SOM
Soil organic matter
TUL-SEA Trees in multi-Use Landscapes in Southeast Asia
3.1 A General Perspective on Hydrological Components
and Matter Related Processes
1
For many centuries soil and water have been the backbone of Southeast Asia’s very
productive agrarian economy. However, over the last few decades mountainous
mainland Southeast Asia (MMSEA) has experienced a tremendous increase in
human activity within its ecosystems, most often linked to land use change and
silvicultural or agricultural intensification. The drivers of this increased activity
were introduced in Chap. 1 and include population growth, changes in policies,
technological innovations and economic development, activities that frequently
result in changes to water and matter cycling processes, meaning that fluxes of
water and matter are altered and the rank order of processes is shifted, initiating
changes in system states. Here, one important state variable is soil organic carbon
(C) stocks, which can become depleted; for example, in response to topsoil erosion.
This chapter seeks to highlight some general regional and site-specific aspects of
water and matter dynamics (Sect. 3.1), plus give an overview of the climatic and
hydrologic conditions that exist in the areas investigated by the Uplands Program,
beyond the physiographic and socio-economic site descriptions given in Chap. 1
(Sect. 3.2). The text also introduces the reader to four case studies related to water
and matter research conducted during the course of the project (Sects. 3.3, 3.4, 3.5,
and 3.6). These case studies deal with flooding and flood risk mitigation (Case
Study 1), sediment and nutrient redistribution through erosion, reservoir management and irrigation practices (Case Study 2), the dynamics of field to watershed
scale C stocks (Case Study 3), and the fate of pesticides in agro-ecosystems (Case
Study 4).
Ecosystem vulnerability: Specific to the ecosystems in MMSEA is the frequent
typhoons and the monsoonal rainfall variability that occur, and especially the high
rainfall intensities that take place at the onset of the monsoon season. This rainfall
1 Written by Holger L. Fro ¨hlich and Joachim Ingwersen.
110
H.L. Fro ¨hlich et al.
Organic carbon normalized distribution coefficient
LUT
Land-use type
MMSEA
Mountainous mainland Southeast Asia
N
Nitrogen
P
Phosphorus
Q
Stream discharge
RaCSA
Rapid Carbon Stock Appraisal
SOM
Soil organic matter
TUL-SEA Trees in multi-Use Landscapes in Southeast Asia
3.1 A General Perspective on Hydrological Components
and Matter Related Processes
1
For many centuries soil and water have been the backbone of Southeast Asia’s very
productive agrarian economy. However, over the last few decades mountainous
mainland Southeast Asia (MMSEA) has experienced a tremendous increase in
human activity within its ecosystems, most often linked to land use change and
silvicultural or agricultural intensification. The drivers of this increased activity
were introduced in Chap. 1 and include population growth, changes in policies,
technological innovations and economic development, activities that frequently
result in changes to water and matter cycling processes, meaning that fluxes of
water and matter are altered and the rank order of processes is shifted, initiating
changes in system states. Here, one important state variable is soil organic carbon
(C) stocks, which can become depleted; for example, in response to topsoil erosion.
This chapter seeks to highlight some general regional and site-specific aspects of
water and matter dynamics (Sect. 3.1), plus give an overview of the climatic and
hydrologic conditions that exist in the areas investigated by the Uplands Program,
beyond the physiographic and socio-economic site descriptions given in Chap. 1
(Sect. 3.2). The text also introduces the reader to four case studies related to water
and matter research conducted during the course of the project (Sects. 3.3, 3.4, 3.5,
and 3.6). These case studies deal with flooding and flood risk mitigation (Case
Study 1), sediment and nutrient redistribution through erosion, reservoir management and irrigation practices (Case Study 2), the dynamics of field to watershed
scale C stocks (Case Study 3), and the fate of pesticides in agro-ecosystems (Case
Study 4).
Ecosystem vulnerability: Specific to the ecosystems in MMSEA is the frequent
typhoons and the monsoonal rainfall variability that occur, and especially the high
rainfall intensities that take place at the onset of the monsoon season. This rainfall
1 Written by Holger L. Fro ¨hlich and Joachim Ingwersen.
110
H.L. Fro ¨hlich et al.