Modification of a fire drought index for tropical wetland ecosystems by including water table depth

Muh Taufik,Budi I Setiawan,Henny A.J Van Lanen

doi:10.1016/j.agrformet.2014.12.006

Muh Taufik, Budi I Setiawan + Show 1 more

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https://doi.org/10.1016/j.agrformet.2014.12.006

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Journal: Agricultural Meteorology	Publication Date: Jan 9, 2015
Citations: 37	License type: cc-by

Affiliation: Bogor Agricultural University

Abstract

In this paper, we discuss how an existing empirical drought index, i.e. the Keetch–Byram Drought Index (KBDI) that is commonly used for assessing forest fire danger, has been adjusted and modified for improved use in tropical wetland ecosystems. The improvement included: (i) adjustment of the drought factor to the local climate, and (ii) addition of the water table depth as a dynamic factor to control the drought index. We distinguished three different indices, the original Keetch–Byram Drought Index, the adjusted KBDI (KBDIadj) that represents the original drought index, but including local climate information, and the modified KBDI (mKBDI) that considers both local climate information, and soil and hydrological characteristics. The mKBDI was developed and tested in a wetland forest of South Sumatra (Indonesia) from April 2009 to March 2011. During this period, hydrometeorological data were monitored and used to calculate the KBDI, KBDIadj, and mKBDI. First, mKBDI was calibrated using observed soil moisture that was converted to an observed drought index (DIobs). The results indicate that performance of the mKBDI is encouraging based on the following: (i) its pattern followed the dynamics of DIobs, (ii) prediction of frequency of fire danger classes, and (iii) statistically criteria. The mKBDI clearly outperformed KBDI and KBDIadj. Furthermore, we found a critical water table depth when it reaches maximum fire danger (0.85m for the wetland forest of South Sumatra) below which danger does not increase anymore. The mKBDI could be more widely applied, if pedotransfer functions are developed that link easily obtainable soil properties to the parameters of the water table factor. Our findings encourage land use planners, water managers and stakeholders (e.g. forest estate owners) to integrate local climate information, and soil and hydrological characteristics into the Keetch–Byram Drought Index to better predict fire danger, particularly in tropical wetland ecosystems.

Highlights

Forest fire is a common phenomenon during dry seasons in equatorial rain forest regions, in Sumatra and the Borneo in Indonesia (e.g. Goldammer, 2007; Miettinen et al, 2013)
We propose to add a new variable to Eq (6), i.e. the water table factor (WTF), which affects soil moisture depletion in wetland ecosystems, which typically are characterized by shallow water tables
This study was carried out in a forest plantation area situated in a humid tropical wetland ecosystem, Indonesia

Summary

Introduction

Forest fire is a common phenomenon during dry seasons in equatorial rain forest regions, in Sumatra and the Borneo in Indonesia (e.g. Goldammer, 2007; Miettinen et al, 2013). Land clearing activities meant to grow crops and to plant trees triggered fire during the dry season. It has become a critical problem in Southeast Asia, and previous studies report that it has a significant impact on socio-economic activities in the region Salafsky, 1994; Chokkalingam et al, 2005); Dennis et al, 2005) It influences human health (Dennekamp and Abramson, 2011), through increasing air pollution (Kunii et al, 2002; Frankenberg et al, 2005; Marlier et al, 2013). As fire has a significant impact on human activities and environment, it challenges scientists to understand fire behaviour (e.g. occurrence, ignition, intensity, potential spread) related to weather (e.g. Wibowo et al, 1997; Arpaci et al, 2013; Petros et al, 2011), and to develop tools for management (e.g. Adams et al, 2013)

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