Methods for Delineating Degraded Land at Citarum Watershed, West Java, Indonesia

Accurate information on the extent and spatial location of degraded lands is very important to plan their rehabilitation. So far, various institutions issue different estimation on the extent of degraded land in Indonesia led to big confusion for rehabilitation planning.  Ministry of Forestry estimates around 30.2 million ha of degraded land both inside and outside forestry area throughout Indonesia based on data released in 2007. Ministry of Forestry implementes the so called scoring method in delineating degraded land. Criteria used in the scoring methods are: land cover, slope steepness, erosion, and management. Scoring method applies different weight to each of those criteria. This study aimed to analyze accuracy of scoring method and to compare it to propose alternative methods in delineating degraded land such as: a) Inconsistency of land use, and b) Combination of Inconsistency of land use and scoring method. The accuracy of these methods were obtained by comparing to the field observation. The slope map was derived from SRTM 30 m, soil map was obtained from Soil Research Institute and land cover/land use from Ministry for Environment.  Using GIS analysis, those maps were used to compose land capability classification (LCC) and inconsistency of land use. The study showed that scoring method had 66% accuracy in delineating degraded land. When scoring method was combined with Inconsistency method the accuracy increased about 7%.Keywords: Degraded land; inconsistency of land use; land capability class; scoring method[How to Cite: Tarigan SD. 2012. Methods for Delineating Degraded Land at Citarum Watershed, West Java, Indonesia. J Trop Soils, 17 (3): 267-274. doi: 10.5400/jts.2012.17.3.267][Permalink/DOI: www.dx.doi.org/10.5400/jts.2012.17.3.267

Land Cover Change and its Impact on Flooding Frequency of Batanghari Watershed, Jambi Province, Indonesia

AbstractBatanghari Watershed experiences rapid land cover change due to the expansion of agriculture plantations such as oil palm and rubber. Based on National Board for Disaster Management (BNPB) report, flooding frequency in Batanghari Watershed increases steadily in the last 15 years. Objective of the research was to analyse land cover change and its impact on flooding frequency of Batanghari Watershed Jambi Province. Land cover change was analysed using Landsat images from year 1990 and 2013 in combination with Planology Agency land use maps and concession data of oil palm plantation obtained from Plantation office (DISBUN) Jambi Province. Landsat images were processed using Carnegie Landsat Analysis System–Lite (CLASlite) module to differentiate undisturbed (primary), disturbed (secondary) forest and also oil palm growing stages. Flooding frequency was analysed using disaster database from BNPB. The study showed that land cover change in Batanghari Watershed contribute to the higher flooding frequency of Batanghari Watershed

ACCURACY OF MAPWINDOW AND SWAT WATERSHED MODEL IN SIMULATING HYDROLOGIC CHARACTERISTICS OF CISADANE WATERSHED, WEST JAVA INDONESIA

ABSTRACTPressure of population growth has induced land use change around Cisadane Watershed. Land usechange in this watershed had caused negative effects on the hydrological characteristics of the watershed, Tobe able to predict impact of land use on hydrologic characteristics of the watershed in the future, a tool isrequired. Combination of Map Window and SWAT Watershed Model were tested for this purpose. Theresearch objectives were 1) to examine the accuracy of MapWindow and SWAT in delineating the subwatershedboundary compared to existing maps, and 2) to determine accuracy of MapWindow and SWAT insimulating river discharge based on a particular land use in Cisadane Watershed.Research was carried out in two steps, these are geographic data processing using MapWindow-SWAT and determination of model prediction accuracy. Level of prediction accuracy was determined usingNash-Sutcliffe coefficient. Boundaries of sub-watersheds were delineated using DEM map from SRTM(Shuttle Radar Topography Missions) Z_58_14. tiff with 90x90 m resolution. Land use map was derivedusing Landsat TM image path 122 row 064 and row 065.Sub-watershed boundaries that were delineated using MapWindow and SWAT showed 90 % accuracywith existing maps with some deviations in the lower part of the watershed where topography was quite flat.Higher resolution of DEM map would give better result. Combination of MapWindow and SWAT were ableto predict river discharge giving Nash-Sutcliffe coefficient of 0.7. This coefficient showed a good performanceof MapWindow and SWAT in predicting river discharge in Cisadane Watershed. With this performance,combination of MapWindow and SWAT can be used to predict future impact of land use change on hydrologiccharacteristics in Cisadane Watersheds

NERACA AIR LAHAN GAMBUT YANG DITANAMI KELAPA SAWIT DI KABUPATEN SERUYAN, KALIMANTAN TENGAH

Penurunan muka air pada lahan gambut memicu oksidasi dan subsiden, khususnya pada musim kemarau. Agar dampak penurunan muka air dapat dikelola dengan baik, maka perlu dikaji besaran komponen neraca air (water balance) yang meliputi: a) Pre-storage, b) Evapotranspirasi, c) Ruang pori drainase, d) Konduktivitas hidrolik dan e) Drainase. Penelitian ini bertujuan mengkaji komponen neraca air tersebut pada lahan gambut yang ditanami kelapa sawit yang dapat digunakan untuk menetapkan pengelolaan drainase yang optimal. Metodologi yang digunakan dalam perhitungan kedua komponen neraca air adalah persamaan Hooghoudt Steady-State Approach yang diverifikasi dengan pengukuran data lapang terkait tinggi muka air dengan menggunakan piezometer. Penelitian lapang dilakukan pada perkebunan kelapa sawit di Kabupaten Seruyan, Kalimantan Tengah. Selama musim kemarau (Juli-September), evapotranspirasi mencapai 386 mm yang melebihi besaran curah hujan (311 mm). Jumlah air drainase pada periode ini adalah 90 mm atau 1 mm hari-1. Berdasarkan nilai-nilai tersebut terdapat defisit air sebesar 25 mm selama periode musim kemarau. Jika jarak saluran drainase ditingkatkan dari 30 m menjadi 50 mm, maka terjadi surplus neraca air sebesar 34 mm. Namun surplus tersebut hanya mampu menaikan muka air tanah sebesar 2.3 cm dari kondisi awal yang berada pada kedalaman 40-50 cm. Dalam rangka menghambat penurunan muka air pada musim kemarau maka pada masa transisi dari musim penghujan ke musim kemarau perlu dilakukan konservasi air melalui peningkatan pre-storage. Di samping itu kehilangan air drainase perlu ditekan seminim mungkin melalui pengaturan jarak saluran drainase dan penggunaan cascaded stop-log pada sistem saluran tersier

The Efectivity of Embung for Irigating Horticuture Plant in Cikakak Sukabumi

Dryland farming provides a promising opportunity in increasing agricultural production in rural areas. But, the lack of available water during dry season poses a problem in developing dryland farming. An effective water conservation technique should be developed to alleviate this problem. The use of a small farm reservoir (embung) can be considered as one viable option for such conservation techniques. The purpose of this research was to study the effectivity of small farm reservoirs to supply irrigation water for horticulture commodities. Two different types of small farm reservoir (SFR) were constructed in the micro catchment for the research, i.e. a) SFR built with concrete, b) SFR built without concrete. SFR built with concrete had higher water available for irrigation, which is 34% higher compared to SFR without concrete. In addition, the empirical equation that was used in this research was quite reliable in predicting colected water in the SFRs. Using 80% monthly rain probability, on average one small farm reservoir with dimension 8 m x 2m x 2 m was able to supply irrigation water for 100 m2 horticulture plants for the whole growing period. Keywords: Small farm reservoir, dry season, irrigation, dryland farming

Expansion of Oil Palm Plantations and Forest Cover Changes in Bungo and Merangin Districts, Jambi Province, Indonesia

AbstractIt is often cited that large scale oil palm plantation were responsible for forest cover changes in Sumatra and Kalimantan. Objective of the research was to identify whether oil palm concessions were the direct cause of intact forest cover changes in study area. The study areas are situated at Jambi Province, Indonesia and are experiencing rapid expansion of oil palm plantation. We used Landsat temporal images from year 1988, 1990, 2000, 2007, and 2013 to detect forest cover change. We also made use Carnegie Landsat Analysis System–Lite (CLASlite) fractional cover module to differentiate undisturbed (intact), disturbed (logged) forest and also oil palm growing stages on Landsat images. Our study showed that, there were only 8% of oil palm plantation development occurred by direct clearing of intact forest in the study area in the last 25 years. Oil palm concessions in the last 25 years were mostly developed on logged forest, agroforests, and shrub lands

OPTIMASI PERENCANAAN PENGGUNAAN LAHAN MENGGUNAKAN SISTEM INFORMASI GEOGRAFI (SIG) DAN SOIL AND WATER ASSESSMENT TOOL (SWAT) (SUATU STUDI DI DAS CIJALUPANG, BANDUNG, JAWA BARAT)

The use and management of land resource which are unsuitable with its land capability will cause physical, chemical and biological-damage to the land and will disturb  its hydro-orological function. The damage of land resources in a watershed needs improvement to increase its land quality. Optimal land use management planning based on its land suitability and hydrological aspects become important and need to be applied. The objectives of the study were: 1) To analyze land use change at Cijalupang Watershed, 2) To evaluate SWAT capability to predict impact of land use change on the hydrologic characteritics of the watershed, and 3) To provide land use plan based on land quality and hydrologic characteritics of the watershed. The result showed that optimizing land use management by integrating GIS and SWAT model at the Cijalupang Watershed was capable to increase land quality of the watershed. This was shown by the improvement of its land use capability to create better hydrological condition by decreasing run off 2.1 % and increasing base flow and lateral flow 0.4% and 0.4%  respectively

Pengelolaan Penggunaan Lahan untuk Stabilisasi Tepian Hutan Tropis Menggunakan Agent-Based Land-Use Modelling

Tropical forest margin conversion to agriculture land in in Lore Lindu National Park has reached an alaming rate. The conversion was trigered by insufficient revenue to support minimal living standard amounted to                  Rp15.000.000,00/year/household obtained from unproductive cacao farming. Each household required another 1 ha new land to at least reach that minimal living standard. Therefore 218 ha of forest land are potentially cleared by farmerin the near future to extend their farming area. Increasing productivity using innovative agro-technolgy should be considered as one important alternative to reduce the need to clear another forest area. Due to the complexity of interrelated variable affected by using innovative agro-technolgy, a model should be used to take account every affected variable such as availability of labour and liquidity in adopting new agro-technology. In this research, agent-based modeling with mixed integer linear programming model (MILP) using MPMAS software (Mathematical Programming for Multy Agent System) was used to analyze impact of balanced fertilizing and irrigation technology to increase cacao land productivity. Balanced fertilizing was insufficient to reach minimum standard living of Rp15.000.000,00 with existing area of cacao land (1 ha/HH), due to the severe water deficit during month of January until February. Combining balanced fertilizing with irrigation water supply can increase productivity reaching minimum standard of living. It was obvious from the modeling that in the ealier period of cacao growth (1-5 year old), deficits in liquidity and labour was encountered. Interplanting cacao with maize at the earlier phase with additional income from livestock can alleviate liquidity shortage

Pengelolaan Penggunaan Lahan untuk Stabilisasi Tepian Hutan Tropis Menggunakan Agent-Based Land-Use Modelling

Tropical forest margin conversion to agriculture land in in Lore Lindu National Park has reached an alaming rate. The conversion was trigered by insufficient revenue to support minimal living standard amounted to                  Rp15.000.000,00/year/household obtained from unproductive cacao farming. Each household required another 1 ha new land to at least reach that minimal living standard. Therefore 218 ha of forest land are potentially cleared by farmerin the near future to extend their farming area. Increasing productivity using innovative agro-technolgy should be considered as one important alternative to reduce the need to clear another forest area. Due to the complexity of interrelated variable affected by using innovative agro-technolgy, a model should be used to take account every affected variable such as availability of labour and liquidity in adopting new agro-technology. In this research, agent-based modeling with mixed integer linear programming model (MILP) using MPMAS software (Mathematical Programming for Multy Agent System) was used to analyze impact of balanced fertilizing and irrigation technology to increase cacao land productivity. Balanced fertilizing was insufficient to reach minimum standard living of Rp15.000.000,00 with existing area of cacao land (1 ha/HH), due to the severe water deficit during month of January until February. Combining balanced fertilizing with irrigation water supply can increase productivity reaching minimum standard of living. It was obvious from the modeling that in the ealier period of cacao growth (1-5 year old), deficits in liquidity and labour was encountered. Interplanting cacao with maize at the earlier phase with additional income from livestock can alleviate liquidity shortage

Infiltrasi dan Aliran Permukaan pada Agroforestri dan Kelapa Sawit

Forest to oil palm plantations conversion has changed soil's physical properties significantly. It caused significant changes in the hydrological cycle and affects the water resources around the research site. One of the strategies that could minimize the negative impact of monoculture oil palm plantations is better plantation management by implementing a mixed cropping system (agroforestry). This study aims to analyze the infiltration, surface runoff, and surface runoff coefficient in agroforestry and monoculture oil palm. This observation was conducted in the oil palm plantation area of PT Humusindo Makmur Sejati, Bungku Village, Bajubang District, Batanghari Regency. The infiltration rate was calculated according to the Horton method, and the amount of runoff in agroforestry and oil palm monoculture used the soil conservation service-curve number method. The results showed differences in infiltration, surface runoff, and runoff coefficients between the agroforestry land and the monoculture oil palm. The highest infiltration is in A48, which is 42,00 cm/hour in the dry season and 18,00 cm/hour in the rainy season. The lowest runoff is in A23, which is 70.14 mm with a runoff coefficient of 0.04. The highest runoff occurred in S48 of 339.88 mm, with a runoff coefficient of 0.19. The differences in infiltration, surface runoff, and runoff coefficient in this study are affected by the vegetation density and the amount of litter.   Keywords: agroforestry, infiltration, oil palm, runoff coefficients, surface runof