Bokiraiya Latuamury
Fakultas Geografi Universitas Gadjah Mada

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HUBUNGAN ANTARA INDEKS VEGETASI NDVI (NORMALIZED DIFFERENCE VEGETATION INDEX) DAN KOEFISIEN RESESI BASEFLOW PADA BEBERAPA SUBDAS PROPINSI JAWA TENGAH DAN DAERAH ISTIMEWA YOGYAKARTA

Jurnal Teknosains Vol. 2 No. 2 tahun 2013
Publisher : Sekolah Pascasarjana UGM

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Abstract

The background of this research is the decrease of environment capacity in cacthment ecosystem, especially impact of vegetation forest on behavior streamflow. The indicators of cacthment destruction can be seen through hydrograph characteristics. Evaluation of cactment respons of flow hydrographic as an evaluation tools of river catchment responses becomes very important to analyze because it is a benchmark in determination several policy about flood, drough, sedimentation and landslide handling. The research purpose is to analyze the relationship between vegetation index NDVI (Normalized Difference Vegetation Index) and the characteristic of baseflow recession coefficient at several subcatchment areas in province of Central Java and Specific District of Yogjakarta.The method of this research is surveillance on data recording of AWLR (Automatic Water Level Recorder) and data of River Flow Measuring Stations in order to separate the baseflow by calibration curve, and image interpretation of Landsat ETM+ for the transformation of vegetation index (NDVI-Normalized Difference Vegetation Index).The analysis on recession coefficient data (Krb) and NDVI were correlated to analyze the strength of relationship between these two parameters. The results of statistical analysis on index NDVI and recession coefficient showsthat NDVI and recession coefficient value at R2 is 0.1427, F = 2.17 which is not significant at 1% significance level of 0.1646. The result shows a very weak correlation of 0.077 which mean that vegetation density (NDVI index)has a very weak control on low flows. Basically, river baseflow is a genetic component of river flow which comes from aquifer storage and/or other low flow sources. Thus, geology and soil have a significant effect on baseflow.

HUBUNGAN ANTARA INDEKS VEGETASI NDVI (NORMALIZED DIFFERENCE VEGETATION INDEX) DAN KOEFISIEN RESESI BASEFLOW PADA BEBERAPA SUBDAS PROPINSI JAWA TENGAH DAN DAERAH ISTIMEWA YOGYAKARTA

Jurnal Teknosains Vol 2, No 2 (2013): June
Publisher : Universitas Gadjah Mada

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Abstract

The background of this research is the decrease of environment capacity in cacthment ecosystem, especially impact of vegetation forest on behavior streamflow. The indicators of cacthment destruction can be seen through hydrograph characteristics. Evaluation of cactment respons of flow hydrographic as an evaluation tools of river catchment responses becomes very important to analyze because it is a benchmark in determination several policy about flood, drough, sedimentation and landslide handling. The research purpose is to analyze the relationship between vegetation index NDVI (Normalized Difference Vegetation Index) and the characteristic of baseflow recession coefficient at several subcatchment areas in province of Central Java and Specific District of Yogjakarta.The method of this research is surveillance on data recording of AWLR (Automatic Water Level Recorder) and data of River Flow Measuring Stations in order to separate the baseflow by calibration curve, and image interpretation of Landsat ETM+ for the transformation of vegetation index (NDVI-Normalized Difference Vegetation Index).The analysis on recession coefficient data (Krb) and NDVI were correlated to analyze the strength of relationship between these two parameters. The results of statistical analysis on index NDVI and recession coefficient showsthat NDVI and recession coefficient value at R2 is 0.1427, F = 2.17 which is not significant at 1% significance level of 0.1646. The result shows a very weak correlation of 0.077 which mean that vegetation density (NDVI index)has a very weak control on low flows. Basically, river baseflow is a genetic component of river flow which comes from aquifer storage and/or other low flow sources. Thus, geology and soil have a significant effect on baseflow.

KAJIAN KONSEPTUAL PEMODELAN PERUBAHAN PENGGUNAAN LAHAN UNTUK STUDI ILMU LINGKUNGAN

Jurnal Teknosains Vol 3, No 1 (2013): December
Publisher : Universitas Gadjah Mada

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Abstract

Modeling is one of the methods in the portfolio of techniques and approaches available to unravel the dynamics of the land-use system. In this perspective, models are used as a learning and communication tool between researchers to formalize knowledge on the dynamics of land-use change. Land-use system is a very complex system, such that computer modeling is needed as a computational laboratory to estimate and test hypotheses about the process of land-use change. One of the major difficulties in multi-disciplinary research is to find ways to express oneself, which are acceptable to all the disciplines involved and free from the connotation of any or all of them. Land-use change models play an important role in exploring possible future developments in the land-use system. This paper attempts to show the methods and approaches to be used as a communication and learning environment for stakeholders involved in the decision making about land-use change systems in the field of environment

Pengaruh Kerapatan Vegetasi Penutup Lahan terhadap Karakteristik Resesi Hidrograf pada Beberapa Subdas di Propinsi Jawa Tengah Dan Propinsi DIY

Majalah Geografi Indonesia Vol 26, No 2 (2012): September 2012
Publisher : Fakultas Geografi, Universitas Gadjah Mada

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Abstract

ABSTRAK Penelitian ini dilakukan di Propinsi Jawa Tengah dan Propinsi DIY, dilatarbelakangi oleh penurunan daya dukung lingkungan seperti rusaknya kawasan hutan dan berkurangnya luas tutupan lahan hutan, yang dapat mempengaruhi perilaku aliran air. Dengan adanya perubahan tutupan lahan akan berdampak pada berubahnya sifat-sifat hidrologi seperti koefisien aliran, debit dan karakteristik hidrograf aliran. Indikator kerusakan hutan dapat dilihat dari karakteristik hidrograf. Evaluasi respon DAS berupa hidrograf aliran akibat adanya perubahan penutup lahan menjadi sangat penting untuk dianalisis karena merupakan tolok ukur dalam setiap penentuan kebijakan terkait dengan penanganan banjir dan tanah longsor. Oleh karena itu, penelitian ini bertujuan untuk (1). mengkaji karakteristik kerapatan vegetasi penutup lahan dan keterkaitannya dalam ekosistem DAS, (2). mengkaji karakteristik aliran dasar (koefisien resesi)  pada beberapa sub-DAS tersebut, dan (3). menganalisis pengaruh kerapatan vegetasi penutup lahan terhadap karakteristik hidrograf aliran khususnya aliran dasar pada sub DAS yang diteliti. Metode penelitian yang digunakan adalah metode survei data sekunder pada rekaman data AWLR/SPAS untuk analisis resesi hidrograf dan koefisien resesi (Krb), dan interpretasi citra Landsat ETM+ untuk transformasi indeks vegetasi NDVI dikorelasikasi dengan data kerapatan vegetasi untuk mempresentasikan karakteristik kerapatan vegetasi. Selanjutnya hasil transformasi indeks vegetasi NDVI kemudian diujikorelasikan dengan karakteristik resesi (koefisien resesi) untuk menganalisis pengaruh kerapatan vegetasi penutup lahan terhadap karakteristik resesi hidrograf. Hasil uji statistik NDVI dengan koefisien resesi menunjukkan terdapatnya korelasi antara nilai NDVI dan koefisien resesi pada R2 = 0,1427, F = 2.17 tidak berpengaruh nyata pada taraf signifikan 1% sebesar 0.1646 (lampiran 1.2b). Analisis korelasi antara variabel independen (NDVI penutup lahan) dengan variabel dependen (koefisien resesi) memiliki korelasi sangat lemah sebesar 0,077. Hasil ini menunjukkan bahwa parameter kerapatan vegetasi NDVI sangat lemah untuk mengontrol keberadaan aliran-aliran rendah. Karena besarnya simpanan (storage) airtanah tergantung pada besarnya air yang mencapai akuifer. Setelah sumbangan air pada akuifer terhenti, maka air yang tertampung di akuifer akan mengalami pengatusan yang besarnya tergantung kondisi akuifer tersebut. Gerakan air pada akuifer disebabkan oleh gaya gravitasi, kecepatan dan jumlahnya terutama dipengaruhi oleh karakteristik batuan. Karakteristik batuan mempengaruhi pergerakan airtanah, diketahui dari daya hantar hidrolik batuan tersebut.  ABSTRACT This research was conducted in Central Java and DIY province, as a respond to the decrease of environment capacity such as forest destruction and widespread loss of forest land cover which affect water flow behavior. Land cover change will affect the hydrological properties such as coefficient, rate, and hydrograph characteristics of flow. The indicators of forest destruction can be seen through hydrograph characteristics. Flow hydrographic as an evaluation of river catchment responses to land cover change becomes very important to analyze because it is a benchmark in determination any policy about flood and landslide handling. Therefore, the aims of this study are: (1) to examine the characteristic of land cover vegetation density and its association in river catchment ecosystem, (2) to examine base flow characteristics (coefficient of recession) at these river catchments, and (3) to analyze the influence of land cover vegetation density on flow’s hydrograph characteristic, especially base flow at river catchments. The method used in this research is secondary data survey on AWLR/SPAS data record in order to analyze hydrograph recession and coefficient of recession (Krb), and to interpret ETM Landsat image for NDVI vegetation index transformation for the characteristic of vegetation density. The results of NDVI vegetation index transformation then tested it’s correlated with recession characteristics (coefficient of recession) to analyze the influence of land cover vegetation density on hydrograph recession characteristic. The results showed there is an average value of vegetation density (NDVI) for the river catchments and most of it has mediocre vegetation density level with the percentage of land cover vegetation less more than 30%. Most of base flow recession characteristic (coefficient of recession) lay on relatively high range, i.e. 0.661 to 0.980. Correlation analysis between independent variable (land cover NDVI) with dependent variable (coefficient of recession) is very weak, only 0.077. This result shows that the parameter of NDVI vegetation density can be combined with aquifer formation to control the existence of lower flow. Because the magnitude of soil water storage is depend on water volume that reach the aquifer, the arrangement of optimal hydrogeology condition along dry season (no rain season) depend on geological aquifer condition. 

PENGARUH VARIASI PENGGUNAAN LAHAN PADA BERBAGAI FORMASI GEOLOGI TERHADAP RESESI ALIRAN DASAR DI DAS WURYANTORO PROPINSI JAWA TENGAH

Jurnal SPATIAL Wahana Komunikasi dan Informasi Geografi Vol 17 No 1 (2017): WAHANA KOMUNIKASI DAN INFORMASI GEOGRAFI
Publisher : Program Studi Pendidikan Geografi

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Abstract

In the environmental viewpoint, water and land characteristics are strongly influenced by some aspects such as layout, position, landscape development, natural factors and human activity impact.Spatial aspects of land and water resources are the asset of spatial-based national development. Land resources management need to consider the characteristic of both renewable and nonrenewable land resources.Hydrological characteristics is a result of interaction and interrelation of human socio-economic parameters with some watershed physical factors. Apart from that,  besides land use as physical factors, there are some other factors such as morphometry, lithology, geomorphology and geology. They are all naturally come from a watershed that cannot be altered by a human (unmanageable). Some combination of watershed physical factors and the manageable factors such as land use plan, slope, and slope length will give a specific watershed response to the rainfall. Eventually, this affects the large-small of river flows behavior. Baseflow river is an essential substance for the development of water resource management strategies at watershed scale. Therefore, this study aimed to estimate baseflow river recession at various geological formation. It also influences characteristics of baseflow recession in Wuryantorosub-watershed at Wonogiri district. Simultaneous Statistical Analysis (ANOVA) and partial (t-test) analysis show that there is a significant influence on the variation of land use in diverse geological formations toward the baseflow recession, with a determination coefficient value - Adjusted R-square is 58.1%.The simultaneous analysis describes a simultaneously effect of recession baseflow coefficient with value test of the test F table > F count at a level of confidence by 5%, and a partial analysis shows that all land use variations in three geological formations significantly influence baseflow recession. Recession model of these two relations is  Y = 1.426 + 0,583X1 + 0,384X2 + 0,269X3. This condition indicates that baseflow recession is influenced by some basic by a number of entire environmental attributes. Thus, there will be a sustainable synergy of baseflow recession management that maintain river pattern by the surrounding inhabitant as an alternative water supply for local communities. Keywords: Baseflow, perennial river, variations in land use, geological formations