Scholarly article on topic 'Land Changes Monitoring Using MODIS Time-series Imagery in Peat Lands Areas, Muaro Jambi, Jambi Province, Indonesia'

Land Changes Monitoring Using MODIS Time-series Imagery in Peat Lands Areas, Muaro Jambi, Jambi Province, Indonesia Academic research paper on "Earth and related environmental sciences"

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Abstract of research paper on Earth and related environmental sciences, author of scientific article — Annisa Nurdiana, Yudi Setiawan, Hidayat Pawitan, Lilik Budi Prasetyo, Prita Ayu Permatasari

Abstract Function of peat land as the global climate regulator has been threatened by human activities through deforestation and forest degradation, including the peat lands in the Berbak National Park, Muaro Jambi. This area is covered by 110,000 hectares of peat lands. This study aimed to monitor the land changes using MODIS time-series datasets from 2001 to 2013. The study used the Normalized Difference Water Index (NDWI), which describes vegetation water content associated with rainfall. The results show that NDWI is quite sensitive to represent the changes in peat land, including seasonal changes. Most of the land changes was detected in August-October by the method. In many cases, it was necessarily coincident with the low rainfall and hotspot occurrences. Moreover, the land changes in peat land areas represent the temporal complexity affected by extreme climate variability, when it related with a high number of fires.

Academic research paper on topic "Land Changes Monitoring Using MODIS Time-series Imagery in Peat Lands Areas, Muaro Jambi, Jambi Province, Indonesia"

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Procedía Environmental Sciences 33 (2016) 443 - 449

Environmental Sciences

The 2nd International Symposium on LAPAN-IPB Satellite for Food Security and Environmental

Monitoring 2015, LISAT-FSEM 2015

Land changes monitoring using MODIS time-series imagery in peat lands areas, Muaro Jambi, Jambi Province, Indonesia

Annisa Nurdiana^*, Yudi Setiawana, Hidayat Pawitanb, Lilik Budi Prasetyoc, Prita Ayu

Permatasaria

a Center for Environmental Research, Bogor Agricultural University, PPLH Building 2nd-4th Floor Jl. Lingkar Akademik Dramaga Campus,

Bogor 16680, Indonesia

b Department of Geophysics and Meteorology, Faculty of Mathematics and Natural Sciences, Bogor Agricultural University, Dramaga Campus,

Bogor 16680, Indonesia

c Department of Forest Conservation and Ecotourism, Faculty of Forestry, Bogor Agricultural University, Dramaga Campus, Bogor 16680,

Indonesia

Function of peat land as the global climate regulator has been threatened by human activities through deforestation and forest degradation, including the peat lands in the Berbak National Park, Muaro Jambi. This area is covered by 110,000 hectares of peat lands. This study aimed to monitor the land changes using MODIS time-series datasets from 2001 to 2013. The study used the Normalized Difference Water Index (NDWI), which describes vegetation water content associated with rainfall. The results show that NDWI is quite sensitive to represent the changes in peat land, including seasonal changes. Most of the land changes was detected in August-October by the method. In many cases, it was necessarily coincident with the low rainfall and hotspot occurrences. Moreover, the land changes in peat land areas represent the temporal complexity affected by extreme climate variability, when it related with a high number of fires.

© 2016 The Authors.PublishedbyElsevierB.V. Thisis an open access article under the CC BY-NC-ND license (http://creativecommons.Org/licenses/by-nc-nd/4.0/).

Peer-review under responsibility of the organizing committee of LISAT-FSEM2015 Keywords: land use/land cover change; MODIS; NDWI; temporal analysis

* Corresponding author. Tel.: +62-822-9709-0953. E-mail address: icanurdiana@gmail.com.

1878-0296 © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Peer-review under responsibility of the organizing committee of LISAT-FSEM2015 doi:10.1016/j.proenv.2016.03.095

Abstract

1. Introduction

Earth observation satellites are very applicable and useful for land use/cover change detection studies [1, 2]. Application of remote sensing data made possible to study the changes in land cover rapidly, low cost and high accuracy [3]. Monitoring and understanding landscape patterns, changes and interactions between human activities and natural phenomenon are essential for land management. According to Setiawan and Yoshino [4], temporal characterization of vegetation dynamics in a long period can be used to detect change in Earth's surface, whether the change is gradual due to extreme climatic variations, or changes dramatically due to human or natural (e.g. land use change and forest fires).

Rapid population growth in Indonesia leads a peat land converted into agricultural land in order to support food security, paper industry raw materials, plantations and bioenergy development. Most of peat lands utilization is the conversion for agricultural land, pulp plantations and oil palm plantations. One of the main trigger is the government program to look for an alternative energy by utilizing palm oil as a renewable alternative energy. Human activities in the peat ecosystem has increased rapidly in the last two decades so that many areas of peat land become degraded and easier to burn [5].

Jambi Province is one of the largest carbon storage in Indonesia, particularly in Sumatra. Based on the Ministry of Forestry data, in 2011 Jambi Province has 676,341 hectares of peat land area. By this fact, Jambi Province placed as the seventh province with the largest peat land in Indonesia. This area is about 10% of the total national peat lands. It can be estimated that there will be a huge potential losses if the land is not managed properly. The distribution of peat lands in Jambi province are in the downstream area, mostly a part of east coast cluster of Sumatra. Sequentially, the largest peat land spread in East Tanjung Jabung (46%), Muaro Jambi (30%), and West Tanjung Jabung (20%).

Muaro Jambi is home to the Berbak National Park, a protected area in Indonesia's Ramsar. The national park has a total peat land area of about 110,000 hectares while the forest park (Taman Hutan Raya or Tahura) covers 60,000 hectares. Land use in the regency is dominated by dry agricultural land (293,256 hectares) followed by oil palm plantations (87,992 hectares) and wet agricultural land suitable for rice (17,000 hectares). Agriculture and mining (mostly petroleum mining) are the main economic sectors and respectively contributing 30% and 26% of gross regional economic product [6]. Oil palm plantations are the largest contributor of GDP in the agriculture sector. Unfortunately, high returns from oil palm and other agricultural uses put a high pressure on the forests in Muaro Jambi. Other factors in forest degradation are: a legacy of ineffective land use licensing prior to the establishment of the new regency; confusing forest boundary demarcation; land disputes; illegal logging; and peat fires due to drainage.

The objective of this research is to monitor the land use/land cover changes on peat land using multi-temporal data of NDWI during a known period in Muaro Jambi Regency, Jambi Province, Indonesia. Hotspot and climate data are also used as supporting data so we can find out that the changes detected by NDWI related to hotspot occurrence and climate.

2. Methodology

2.1. Study area

Muaro Jambi Regency is located at 103°10' E - 104°20' E and 1°15' S - 2°20' S, surrounded by Batang Hari and West Tanjung Jabung Regency in the west side, East Tanjung Jabung Regency in the east and north side, and South Sumatera in the south side. Muaro Jambi has a total area of 5,326 km2 and divided into 153 villages and 11 districts, the districts are Jambi Luar Kota, Sekernan, Kumpeh Ilir, Maro Sebo, Mestong, Kumpeh Ulu, Sungai Bahar, and Sungai Gelam.

Based on the observation from Jambi Province Climatology Station in Sungai Duren, the average air temperature in Muaro Jambi in 2013 was 26.8°C and the highest temperature occurred in June 2013 was 33.3°C. Average air humidity in Muaro Jambi in 2013 was 85.8%, an average rainfall was 216.6 mm, and most rainy days were 24 days in May and December [7]. This regency is location of the Berbak National Park, a protected area of wetlands that are important in Southeast Asia. This area is also selected as an area of Ramsar (International Wetlands). Aside from Muaro Jambi, the park administratively located in East Tanjung Jabung Regency.

KO'tsm id-*»-* lajMKrE mwf unistrt

Fig. 1. Study area.

2.2. Datasets analysis

The Normalized Difference Water Index (NDWI) [8] is a satellite-derived index from the Near-Infrared (NIR) and Short Wave Infrared (SWIR) channels. The SWIR reflectance reflects changes in both the vegetation water content and the spongy mesophyll structure in vegetation canopies, while the NIR reflectance is affected by leaf internal structure and leaf dry matter content but not by water content. The combination of the NIR with the SWIR removes variations induced by leaf internal structure and leaf dry matter content, improving the accuracy in retrieving the vegetation water content [9]. The NDWI has been widely used because it is less sensitive to atmospheric scattering effects compared with the NDVI. However, both of the index did not completely remove the soil background reflectance effects. The NDWI developed by Gao [8] described as equation below:

The lab results by Gao [8] showed that as leaf layer increased, NDWI increased, suggesting that NDWI was sensitive to the total amount of liquid water in stacked leaves. For this study, NDWI expected to detect land use/land cover changes related to land clearing.

The study area is covered by MODIS tiles h28v09. The images were then clipped to cover the Muaro Jambi peat land and sequentially stacked to produce the NDWI time-series datasets. Accordingly, peat land area of Muaro Jambi can be characterized by NDWI datasets at 598 time series with the interval time 8 days. Besides, we also used hotspot data from MODIS (downloaded from http://earthdata.nasa.gov), rainfall and air temperature from

Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG) (downloaded from http://dataonline.bmkg.go.id).

3. Results and Discussion

Remote sensing satellites at different temporal resolutions provide an enormous amount of data that have become primary sources, being extensively used for detecting and extracting surface water and its changes in recent decades. The NDWI datasets stacked for 13 years (2001 to 2013) and results a pattern that indicate a land use/land cover

change at certain times. The changes showed as a sudden decreasing value in the pattern. Fig. 2 represents a dynamic pattern of selected sample point in peat land in Muaro Jambi. When there is an activity on vegetation area, such as harvesting, logging, drought, or burning, the NDWI will decline significantly, while weeding and replanting cause a positive change of value and rise the pattern. When vegetation is in normal condition, the pattern will move within the normal range. Normal range can be seen from the pattern moving constantly in a certain range in a long time. However, when vegetation get disturbed, the pattern will go down away from the normal range. And when the vegetation has restored or replanted, there are two possibilities: the pattern will go back into its normal range or the pattern will form a new normal range. Shifting of normal range indicates changes in land use/land cover that will no longer the same as its former condition before the disturbance.

fl.l 2001 2002 2003 2004 2005 20Q6 2007 200B 2009 2010 2011 2012 2013

Fig. 2. NDWI time series data for 13 years (2001-2013).

However, the mean NDWI in the period of 2001-2013 ranged from -0.027 to 0.536 from 2001 to 2013, which was contradictory to the results of vegetation cover and soil moisture. Dense vegetated areas yielded high NDWI values, while sparsely vegetated areas had low values. This was because the vegetation cover was not completely removed in the urbanization process: grass and small trees were planted around the houses and along the roads. As a measure of vegetation liquid water, NDWI largely depended on vegetation abundance and type, which determined the capability of vegetation for holding water, especially in leaves. As a measure of vegetation liquid water and background soil reflectance, the negative NDWI value indicated that almost all of the land surfaces were modified to impervious surfaces, and that nearly no vegetation, wet soil, or pond remained.

The NDWI value has decreased significantly as much as 4 times within a period of 13 years. As seen from Fig. 2, the significant changes occurred in 2002, 2004, 2006, and 2011. According to Golden Gate Weather Services [10] information, there was the El Nino phenomenon in 2002 (moderate), 2004 (weak), and 2006 (weak). El Nino phenomenon rises the surface temperature in Indonesia and causes a severe drought. While in 2011, the changes more caused by human activities. From Statistics Indonesia [11], it is known that deforestation increases the area of critical land in Jambi. In 2006, the critical land was about 619,000 hectares (severe area was about 614,000 hectares

while very severe area was about 5,000 hectares). The number then increased only by 5 years difference. In 2011, the critical land was about 1,421,000 hectares (severe area was about 342,000 hectares while very severe area was about 1,079,000 hectares).

The other sample points selected are also shows that if the area has ever been disturbed, that area would be more vulnerable against another disturbance. As in the case of change of primary forests to pulp or oil palm plantations, negative change in the pattern of NDWI would be repeated at specific time period. Oil palm harvesting occur in every few years and it certainly showed in the pattern.

Beside the repeating changes in the patterns, most of the pixels which was originally primary or secondary forest then its NDWI decreased significantly, the index would not rise and back into the normal range but went down away from the normal range. In another word, the pixels show that there was the changes in the condition of land cover/land use. It is very rare to find primary or secondary forest that has been disturbed once and return to the forest as before, unless it is actually carried out by weeding or replanting by the related parties. However, to restore the initial condition of the forest will take a very long time.

Precipitation —NDWI -» Hotspot Precipitation —NDWI -«-Hots(jot

Fig. 3. NDWI time series patterns, rainfall and hotspot occurrences by 4 selected sample points in the period of: a) 2001-2003, b) 2004-2006, c)

2007-2009, d) 2010-2013

According to four selected sample points, the pattern changes coincided with hotspot occurrences. Hotspot data sourced from MODIS satellite is a pixel with a temperature above 320 K. Hotspots in Fig. 3a coincided with the decrease in NDWI occurred in August 2003 where the number of hotspot in peat land in Muaro Jambi reached 438 out of total 849 in 2003. The number of hotspot in August 2004 (Fig. 3b) reached 691 out of total 1,493 in 2004, in October 2006 (Fig. 3b) reached 663 out of total 1,179 in 2006, in October 2008 (Fig. 3c) reached 69 out of total 127 in 2008, and in September 2011 (Fig. 3d) reached 330 out of total 570 in 2011. During 2001 and 2013, as many as 7,179 hotspots appear in Muaro Jambi and 87.35% of them, or 6,271 hotspots, located on peat lands. This high

number proves that at least in the period of 2001-2013 peat lands are more vulnerable to fires. This is very unfortunate to happen considering the great role of peat lands for the environment.

Table 1. Monthly air temperature and rainfall according to land changes showed in Fig. 3.

Fig. 3a (2003) Fig. 3b (2004) Fig. 3b (2006) Fig. 3c (2008) Fig. 3d (2011)

Month Air temp Y rainfall Air temp Y rainfall Air temp Y rainfall Air temp Y rainfall Air temp Y rainfall

(°C) (mm) (°C) (mm) (°C) (mm) (°C) (mm) (°C) (mm)

Jan 26.4 231.0 26.5 378.6 26.1 166.2 26.6 185.3 26.1 313.0

Feb 26.5 307.4 26.5 174.6 26.7 328.7 26.5 97.7 26.8 173.5

Mar 26.9 174.6 26.7 338.6 27.1 272.0 26.1 331.2 26.6 226.5

Apr 26.8 220.4 26.9 203.2 26.8 259.8 26.7 258.2 26.8 267.8

May 27.6 76.9 27.3 264.1 26.8 186.2 27.0 82.3 27.5 119.4

Jun 27.2 2.3 27.1 46.5 26.7 144.6 26.8 26.8 27.5 93.7

Jul 26.6 79.2 26.1 224.1 27.1 97.7 26.5 69.1 27.3 144.1

Aug 27.0 65.0 26.9 12.5 26.8 142.7 26.5 245.4 27.4 29.5

Sept 26.8 189.2 26.8 157.6 27.0 118.0 26.4 104.7 27.5 36.3

Oct 26.8 284.3 26.6 215.6 27.4 52.1 26.8 132.2 26.4 211.4

Nov 26.4 139.8 26.5 247.1 26.6 156.0 26.9 304.1 26.3 285.8

Dec 26.1 344.2 26.3 259.3 26.5 171.2 26.4 322.4 26.3 180.3

Many people assume that the weather or climate can cause forest and land fires. Basically, humans are the main driving factors on forest fire incidents. When doing burning activities, humans tend to not care about the surrounding environmental condition, so that often found the fire that hard to extinguish or quickly spread to the other land and become uncontrollable. These events have been severely aggravated by improper burning time. Based on Table 1, land use/land cover changes detected by the NDWI pattern occurred in months with low rainfall and high air temperature.

People who burns may think low rainfall and high temperature as a help so that the burning activities can be done faster and easier. But on the other side, it also makes the effect worse. Rainfall is commonly used for assessing forest fire vulnerability because it affects the water content of vegetation. High temperature in Earth's atmosphere which is supported by the low rainfall conditions in the region will cause the fuel to burn easier. These conditions can trigger and aggravate the fires, such as difficulties in stopping it. Moreover, fires in peat land which is occurred below the ground surface will be more difficult to extinguish.

Peat land fires occur almost every year and has become like an annual agenda in Indonesia. Peat land is a large carbon storage. When peat is drained and or deforested, carbon released to the Earth's atmosphere. Apart from CO emissions, developments are also a threat to the remaining biodiversity in SE Asia as the peat lands are an important habitat for many endangered species. Furthermore, the peat fires cause regional haze (smog) problems that affect public health, activities and economies in the SE Asian region. If the stakeholders do not immediately take an action to prevent and cope with this issue, there will be more problems to be faced by the country.

4. Conclusion

The NDWI is able to detect land use/land cover changes in peat lands in Muaro Jambi Regency. Most of changes detected occurred in August-October, when the air temperature was high, rainfall was low, and the number of hotspot was also high. Hotspot occurrences in Muaro Jambi Regency during 2001-2013 were higher in the peat lands area than in the non-peat lands. This proves that peat lands way more vulnerable to fire and need immediate yet serious action from stakeholders to prevent and deal with this country's annual issue.

Acknowledgements

We would like to thank the Center for Environmental Research, Bogor Agricultural University (PPLH-IPB), Indonesia, for giving us opportunity to get the research funding. This research was funded by Indonesian Directorate General of Higher Education (DIKTI) for fiscal year 2015.

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