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

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

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

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

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

IMPACT OF CHANGES IN CLIMATE AND LAND USE ON THE FUTURE STREAMFLOW FLUCTUATION

Beside land use change, future climate change potentially alters streamflow fluctuation of a river basin in Indonesia. We investigated relative impact of changes in climate and land use on the streamflow fluctuation of a watershed for future condition (2025). To account for the climate change, we simulated future rainfall and temperature scenarios using the downscaled rainfall and mean surface temperature of 24 CMIP5 GCM outputs with moderate scenario of RCP4.5. We used distributed hydrologic model (SWAT) to simulate relative impact of changes in climate and plantation expansion on the future streamflow fluctuation.  The SWAT model performed well with the Nash-Sutcliff efficiency values of 0.80-0.85 (calibration) and 0.84-0.86 (validation). The results indicated that the climate change caused 32% decrease of the low flows during dry season and 96% increase of the flooding peak discharge during rainy season. Meanwhile, the plantation expansion led to 40% decrease of the low flow in the dry season and 65% increase of the flooding peak discharge in wet season. Both changes indicated strong impact on the extreme events such as flooding peak discharge and low flows. The impact of the climate change on the increased peak discharge was stronger compared to that of land use change.  Meanwhile, the impact of the land use change on the low flow was stronger compared to that of the climate change. The results of this study pointed out that both climate change and the plantation expansion potentially become crucial factors for the future water security in Indonesia

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

Impact of Land Use Change and Land Management on Irrigation Water Supply in Northern Java Coast

In Indonesia, paddy irrigation covers an area of 7,230,183 ha. Ten percent (10%) of those area or 797,971 ha were supplied by reservoirs. As many as 237,790 ha (30%) of those area supplied by reservoirs are situated downstream of Citarum Watershed called Northern Java Coast Irrigation Area or Pantura. Therefore, Citarum watershed is one of the most important watershed in Indonesia. Citarum is also categorized as one of most degraded watershed in Java. The study aimed to evaluate influence of land use change on irrigation water supply in Citarum watershed and land management strategies to reduce the impact. Tremendous land use change occurred in the past ten years in Citarum watershed. Settlement areas increases more than a double during 2000 to 2009 (81,686 ha to 176,442 ha) and forest area decreased from 71,750 ha to 9,899 ha in the same time period. Land use change influences irrigation water supply through 2 factors: a) decreasing storage capacity of watershed (hydrologic functions) for dry season, and b) decreasing storage capacity of reservoirs due to the sedimentation. Change of Citarum  watershed hydrologic function was analyzed using 24 years’ time series discharge data (1984-2008) in combination with rainfall data from 2000 to 2008. Due to the land use change in this time period, discharge tend to decrease despite of increasing trendof rainfall. As a result irrigation area decreased 9,355 ha during wet season and 10,170 ha during dry season in the last ten years. Another threat for sustainability of water irrigation supply is reservoir sedimentation. Sedimentation rate in the past 10 years has reduced upper Citarum reservoir (Saguling) half-life period (½ capacity sedimented) from 294 to 28 years. If proper land management strategies be carried out, the half-life period of Saguling reservoir can be extended up to 86,4 yearsKeywords: Citarum watershed, improved land management, irrigation water supply, land use change, sedimentation [How to Cite: Tarigan SD and RK Tukayo. 2013. Impact of Land Use Change and Land Management on Irrigation Water Supply in Northern Java Coast. J Trop Soils 18 (2): 169-176. Doi: 10.5400/jts.2013.18.2.169][Permalink/DOI: www.dx.doi.org/10.5400/jts.2013.18.2.169]REFERENCESAsdak. 2004. Hidrologi dan Pengelolaan Daerah Aliran Sungai. Gadjah Mada University Press. Yogyakarta (in Indonesian).BBWSC [Balai Besar Wilayah Sungai Citarum]. 2011.  Peta Informasi Citarum 2011.  Direktorat Jenderal Sumber Daya Air Departemen Pekerjaan Umum (in Indonesian).Bols PL. 1978. Iso Erodents Map of Java Madura. Technical  Assistant Project ATA 105. Soil Research Institute, Bogor, Indonesia. 39 ppBPDAS [Balai Pengelolaan Daerah Aliran Sungai] Citarum Ciliwung. 2008a. Pengelolaan DAS Terpadu – DAS Citarum (Buku I: Laporan utama). BPDAS Citarum Ciliwung, Ditjen RLPS Dephut. Bogor (in Indonesian).BPDAS [Balai Pengelolaan Daerah Aliran Sungai] Citarum Ciliwung. 2008b. Pengelolaan DAS Terpadu – DAS Citarum (Buku II: Data dan Informasi). BPDAS Citarum-Ciliwung, Ditjen RLPS Dephut. Bogor (in Indonesian).Bruijnzeel LA.  2004. Hydrological functions of tropical forests: Not seeing the soil for the trees? Agric Ecosyst Environ 104: 185-228.Cita. 2012. Dua puluh dua (22) Hotspost in the Citarum River Basin. www.citarum.org. Accesed on 10 October 2012.ICWRM [Integrated Citarum Water Resources Management]. 2012.  Atlas Pengelolaan Sumberdaya Air Terpadu Wilayah Sungai Citarum. Cooperation between ADB and Bappenas (in Indonesian). Kimwaga RJ, F Bukirwa, N Banadda, UG Walic, I  Nhapi and DA Mashauri. 2012. Modelling the impact of land use changes on sediment loading into lakeVictoria using SWAT model: A Case of Simiyu Catchment Tanzania. 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TA 7189-INO: Institutional Strengthening for Integrated Water Resources Management (IWRM). 6Ci’s River Basin Territory, Component B2: Spatial planning.Wang G, H Jiang, Z Hu, L Wang and W Yue. 2012. Evaluating the effect of land use changes on soil erosion and sediment yield using a grid-based distributed modelling approach. Hydrol Processes 23: 35790-3592.Yan B., NF Fang, PC Zhang and ZH She.  2013. Impacts of land use change on watershed stream flow and sediment yield: An assessment using hydrologic modelling and partial least squares regression. J Hydrol 484: 26-37.Yang  H  H, O Jaafar, A El-Shafie and S Mastura, 2011. Impact of land-use changes toward base-flow regime in Lui and Langkat Dengkil sub-basin. Int J Phys Sci 6: 4690-4976. Zheng  H, L Zhang, R  Zhu, C  Liu, Y  Sato and Y Fukushima, 2009. Responses of streamflow to climate and land surface change in the headwaters of the Yellow River Basin. Water Resour Res 45 (W00A19). doi: 10.1029/2007WR006665

Analisis Respons Hidrologi untuk Mendukung Perencanaan Pengelolaan Sub-DAS Opak Hulu, Daerah Istimewa Yogyakarta

Land use change is one of the causes of the decreasing of hydrological function that affects the hydrological response of a watershed. Planning of watershed management needs to be conducted to improve the hydrological function of the watershed. This study aims to determine the hydrological response in supporting watershed management planning in Opak Hulu Watershed. This research was conducted using the Soil and Water Assessment Tool (SWAT) hydrological modeling. The method used included data collection, processing of input data, running of SWAT model, calibration, validation, and the decision of the best watershed management scenarios. The results of the analysis of land use changes in the Opak Hulu Watershed in 2012–2017 had a significant increase in mixed upland agriculture (3.21%) and shrubs (1.43%). Meanwhile, open field (2,31%) and dry land agriculture (1.71%) decreased significantly. Based on the analyzed hydrological scenario, Soil and Water Conservation techniques can decrease the surface runoff and increase the lateral flow and base flow. The scenario is able to decrease the surface runoff by 542.22 mm (27.09%). It increases lateral flow and base flow by 321.82 mm (13.15%) and 797.28 mm (18.32%), respectively. The best watershed management planning with Soil and Water Conservation technique is able to reach Annual Flow Coefficient value to 0,33 (moderate) and 69,85 (moderate) for Flow Regime Coefficient. Keywords: land use, soil and water conservation techniques, SWAT model, watershe