1,721,064 research outputs found
Minimum forest cover required for sustainable water flow regulation of a watershed: a case study in Jambi Province, Indonesia
No full textIn many tropical regions, the rapid expansion of monoculture plantations has led to a sharp decline in forest cover, potentially degrading the ability of watersheds to regulate water flow. Therefore, regional planners need to determine the minimum proportion of forest cover that is required to support adequate ecosystem services in these watersheds. However, to date, there has been little research on this issue, particularly in tropical areas where monoculture plantations are expanding at an alarming rate. Therefore, in this study, we investigated the influence of forest cover and oil palm (Elaeis guineensis) and rubber (Hevea brasiliensis) plantations on the partitioning of rainfall into direct runoff and subsurface flow in a humid, tropical watershed in Jambi Province, Indonesia. To do this, we simulated streamflow with a calibrated Soil and Water Assessment Tool (SWAT) model and observed several watersheds to derive the direct runoff coefficient (C) and baseflow index (BFI). The model had a strong performance, with Nash–Sutcliffe efficiency values of 0.80–0.88 (calibration) and 0.80–0.85 (validation) and percent bias values of −2.9–1.2 (calibration) and 7.0–11.9 (validation). We found that the percentage of forest cover in a watershed was significantly negatively correlated with C and significantly positively correlated with BFI, whereas the rubber and oil palm plantation cover showed the opposite pattern. Our findings also suggested that at least 30 % of the forest cover was required in the study area for sustainable ecosystem services. This study provides new adjusted crop parameter values for monoculture plantations, particularly those that control surface runoff and baseflow processes, and it also describes the quantitative association between forest cover and flow indicators in a watershed, which will help regional planners in determining the minimum proportion of forest and the maximum proportion of plantation to ensure that a watershed can provide adequate ecosystem services
Mitigation options for improving the ecosystem function of water flow regulation in a watershed with rapid expansion of oil palm plantations
No full textThe impact of continuing rainforest transformation on hydrological functioning and other ecosystem functions in South East Asia remains uncertain. The vast majority of the local residents in our study area believe that the expansion of oil palm reduced the flow regulation function of a watershed causing more frequent flooding in the rainy season and water scarcity problems during the dry season. The research aimed to characterize surface runoff as an indicator of water flow regulation and simulate effectiveness of different mitigation options for surface runoff management in a watershed with rapid expansion of oil palm plantations. Our study started with plot experiments to characterize surface runoff used to adapt curve number (CN) values of the different land-use types required for SWAT modeling. Further, we carried out small watershed experiments to adapt the CN values of different mitigation options. The SWAT model performance was in satisfactory agreement with the Nash–Sutcliff efficiency values of 0.88 and 0.82 for calibration and validation, respectively. After successful model calibration and validation, we simulated the effectiveness of the following mitigation options: (a) frond pile management, and (b) frond pile management and silt pit treatment with a density of 20 units per ha. Both options were chosen for their simple construction enhancing their adoption and sustainable application. Frond pile management and the combination of frond pile and silt pit treatment reduced total surface runoff in a watershed scale from 151 mm to 141 mm (10{\%}) and from 151 mm to 109 mm (31{\%}), respectively. The mitigation options which were evaluated in this study were ecologically effective in regulating water flow through reduction of surface runoff. They were also economically viable, because the mitigation options increased the availability of water which can increase oil palm production while the implementation costs are low due to the simple design using frond leaves residues abundantly available onsite. Due to the fulfillment of at least two sustainability pillars, these mitigation options should be adopted as one evaluation criterion in the certification process carried out by Indonesian certification body for sustainable palm oil (ISPO). Further research is still needed to study optimal design criteria for mitigation options including their dimension, density and spatial distribution in a watershed
Kajian Perubahan Penutupan Lahan pada Ekosistem Mangrove di Wilayah DAS Besitang Kabupaten Langkat Provinsi Sumatera Utara Tahun 2008-2018
No full textThe purpose of this study was to analyze land cover, spatial distribution of land cover types and changes in mangrove land cover that occurred in the Besitang Watershed (DAS) in 2008, 2013 and 2018. Mangrove cover in the Besitang Watershed at the study site was divided into eight types. Land cover, mangrove is the most dominant type. Based on Landsat Image analysis, in the span of 10 years, there was a decrease in mangrove cover from 57.05% (2008) to 40.56% (2018). Plantation is the type of land cover that experienced the largest increase from 3.44% (2013) to 14.05% (2018). Changes in mangrove land cover to open land indicate the conversion of mangrove land to oil palm plantations, which society considers more profitable economically. The change in land cover was triggered by a change in the function of the forest area to become an area for other uses (APL), and the plan to create rice fields in Kampai Island Village. The results of the analysis of mangrove vegetation in the besitang watershed, Rizhopora apiculata is the most dominant type of mangrove with an Importance Value Index (IVI) of 72.99% seedlings, 86.16% saplings and 162.44% trees. One of the efforts to conserve mangroves is to provide access to management for the community through social forestry activities. Forest Management Units (KPH) as forest area managers at the site level can provide facilitation / assistance for mangrove utilization through permits (HTR, HKm, HD), or carry out forestry partnerships / forest utilization collaborations in KPH. Sustainable mangrove management with community involvement is expected to prevent land conversion, increase community income while preserving the existing mangrove ecosystem.Tujuan dari penelitian ini adalah untuk menganalisis tutupan lahan, sebaran spasial jenis tutupan lahan dan perubahan tutupan lahan mangrove yang terjadi di wilayah Daerah Aliran Sungai (DAS) Besitang tahun 2008, 2013 dan 2018. Tutupan mangrove di DAS Besitang pada lokasi penelitian dibagi menjadi delapan tipe tutupan lahan, mangrove merupakan jenis yang paling dominan. Berdasarkan analisis Citra Landsat, pada rentang tahun 10 tahun, terjadi penurunan tutupan mangrove dari 57,05% (2008) menjadi 40,56% (2018). Perkebunan merupakan tipe tutupan lahan yang mengalami peningkatan terbesar dari 3,44% (2013) menjadi 14,05% (2018). Perubahan tutupan lahan mangrove menjadi lahan terbuka menunjukkan terjadinya konversi lahan mangrove menjadi perkebunan kelapa sawit, yang dianggap masyarakat secara ekonomi saat ini lebih menguntungkan. Perubahan tutupan lahan dipicu oleh perubahan fungsi kawasan hutan mejadi Areal Penggunaan Lain (APL), dan rencana pencetakan sawah di Desa Pulau Kampai. Hasil analisis vegetasi mangrove pada DAS besitang, Rizhopora apiculata merupakan jenis mangrove yang paling dominan dengan Indeks Nilai Penting (INP) tingkat semai 72,99%, pancang 86,16% dan pohon 162,44%. Salah satu upaya pelestarian mangrove adalah memberikan akses kelola kepada masyarakat melalui kegiatan Perhutanan Sosial. Kesatuan Pengelolaan Hutan (KPH) sebagai pengelola kawasan hutan di tingkat tapak dapat melakukan memberikan fasilitasi/pendampingan pemanfaatan mangrove melalui izin (HTR, HKm, HD), atau melakukan kemitraan kehutanan/kerjasama pemanfaatan hutan pada KPH. Pengelolaan mangrove secara lestari dengan pelibatan masyarakat diharapkan dapat mencegah konversi lahan, meningkatkan pendapatan masyarakat sekaligus melestarikan ekosistem mangrove yang ada.69 HalamanTesis Magiste
Analysis of Mangrove Change Dynamics in Deli Serdang Regency North Sumatra Province 2008-2023
No full textMangrove forests play an essential role as natural coastal protectors, habitats for marine organisms, and carbon sinks. However, in recent decades, mangrove areas have experienced deforestation due to land-use change and natural factors. This study aims to analyze changes in mangrove land cover in Deli Serdang Regency, North Sumatra, during the period 2004–2023. The analysis used Landsat satellite imagery and a supervised classification method employing the Random Forest algorithm on the Google Earth Engine platform. The results show that land conversion to aquaculture ponds, rice fields, settlements, and oil palm plantations has significantly contributed to the decline in mangrove area. The largest loss occurred during the 2004–2008 period, amounting to 4,162.90 hectares. A limited recovery was observed in 2013, with an increase of 2,124.32 hectares, followed by further declines in 2018 and 2023, amounting to 359.53 hectares and 333.15 hectares, respectively. These findings indicate the urgent need for planned conservation and restoration efforts to maintain the sustainability of mangrove ecosystems in the region.66 PagesSkripsi Sarjan
Analisis Spasial Tingkat Bahaya Erosi dan Arahan Konservasi Tanah di DAS Percut
No full textErosion is the process of transporting fertile topsoil so that affects soil productifity. Erosion can be calculated using the USLE method by calculating the related factors, that is rain erosivity, soil erodibility, slope, land cover factors and conservation measures. Watersheds have an important function for human life because there are places where human activities take place. Administratively, the Percut Watershed located in three regencies/cities, that is Medan City, Deli Serdang Regency and Karo Regency. This research is to analyze the amount of erosion in the Percut Watershed using the USLE method and to analyze the direction of soil conservation in the Percut Watershed according to the erosion hazard obtained. The result showed that erosion level in Percut Watershed has varied from very light to very heavy. The very light erosion hazardous level covered areas 9.311,80 ha, the light erosion hazardous level covered areas 9.937,91 ha, the moderate erosion hazardous level covered areas 15.472,08 ha, the heavy erosion hazardous level covered areas 3.566,03 ha and the very heavy erosion hazardous level covered areas 2.648,51 ha. The recommended conservation direction in the Percut Watershed is by vegetative method, that are maintaining forest functions, reforestation, enrichment of perennials, application of agroforestry systems and mixed gardens, planting according to contours, planting cover crops, crop rotation and utilization of crop residues.Erosi merupakan proses terangkutnya tanah bagian atas yang memiliki tingkat kesuburan tanah cukup baik sehingga terjadinya erosi dapat mempengaruhi produktivitas tanah. Erosi dapat dihitung dengan menggunakan metode USLE dengan memperhitungkan faktor-faktor yang terkait yaitu erosivitas hujan, erodibilitas tanah, kemiringan lereng, faktor tutupan lahan dan tindakan konservasi. Daerah aliran sungai memiliki fungsi penting bagi kehidupan manusia karena merupakan tempat aktivitas manusia berlangsung. Secara Administratif DAS Percut terletak di tiga kabupaten/kota yaitu Kota Medan, Kabupaten Deli Serdang dan Kabupaten Karo. Penelitian ini bertujuan untuk menganalisis besarnya erosi di DAS Percut dengan menggunakan metode USLE dan menganalisis arahan konservasi tanah di DAS Percut sesuai dengan bahaya erosi yang didapat. Hasil penelitian menunjukkan bahwa besarnya erosi di DAS Percut bervariasi dari sangat ringan sampai sangat berat. Erosi dengan kelas sangat ringan yaitu seluas 9.311,80 ha, kelas ringan yaitu seluas 9.937,91 ha, kelas sedang yaitu seluas 15.472,08 ha, kelas berat yaitu 3.566,03 ha dan kelas sangat berat yaitu seluas 2.648,51 ha. Arahan konservasi yang disarankan untuk dilakukan di DAS Percut adalah metode vegetatif yaitu dengan mempertahankan fungsi hutan, melakukan reboisasi hutan, pengkayaan tanaman keras, melakukan sistem agroforestri dan kebun campur, penanaman menurut kontur, menanam tanaman penutup tanah, pergiliran tanaman dan penggunaan sisa tanaman.68 halamanSkripsi Sarjan
Identifikasi Tingkat Kekritisan Lahan Menggunakan Sistem Informasi Geografis (SIG) di Kabupaten Pakpak Bharat Provinsi Sumatera Utara
No full textMore than 80% of Pakpak Bharat Regency is a forest area. The narrowness of agricultural land causes the community to encroach on forest areas, where encroachment triggers the emergence of critical land. This study aims to determine the extent and percentage of critical land in Pakpak Bharat Regency using Geographic Information System (GIS). This research was conducted in May-July 2017 in Pakpak Bharat Regency. Identification of critical land is done based on (2) the function of the area, namely the protected area and the cultivation for the agricultural business. Critical land determinants include land cover, slope, erosion class, land management, land productivity, and rock outcrops. The results showed that the criticality of the land in Pakpak Bharat Regency is classified as a critical potential, which has an area of 55.856,38 Ha or equivalent to 42,30%, where criteria are very critical to have an area of 12.851,33 Ha or equal to 9.73%, and the criteria at least is a critical type, which has an area of 2.795,36 ha or equivalent 2,12% of the total area.Lebih dari 80% wilayah Kabupaten Pakpak Bharat adalah kawasan hutan.Sempitnya lahan pertanian mengakibatkan masyarakat melakukan perambahan kawasan hutan, dimana perambahan memicu timbulnya lahan kritis. Penelitian ini bertujuan untuk mengetahui luas dan persentase lahan kritis di Kabupaten Pakpak Bharat menggunakan Sistem Informasi Geografis (SIG). Penelitian ini dilakukan pada bulan Mei-Juli 2017 di Kabupaten Pakpak Bharat. Identifikasi lahan kritis dilakukan berdasarkan (2) fungsi kawasan, yaitu kawasan lindung dan budidaya untuk usaha pertanian. Parameter penentu lahan kritis antara lain penutupan lahan, kemiringan lereng, kelas erosi, manajemen lahan, produktivitas lahan, dan singkapan batuan. Hasil penelitian menunjukkan bahwa tingkat kekritisan lahan di Kabupaten Pakpak Bharat tergolong potensial kritis, yang memiliki luas 55.856,38 Ha atau setara dengan 42,30%, dimana kriteria sangat kritis memiliki luas 12.851,33 Ha atau setara 9,73%, dan kriteria yang paling sedikit adalah jenis kritis, yang memiliki luasan 2.795,36 Ha atau setara 2,12% dari keseluruhan kawasan.Skripsi Sarjan
Pemetaan Tingkat Bahaya Erosi dengan Metode USLE (Universal Soil Loss Equation) Berbasis Sistem Informasi Geografis (SIG) di Pulau Samosir
No full textSumber daya alam yang berupa hutan, tanah dan air mempunyai peranan
yang besar untuk kelangsungan pembangunan dan kehidupan manusia. Tanah
yang produktif dan tersedianya air yang cukup teratur penting bagi kelanjutan
kehidupan manusia serta mahluk-mahluk hidup lainnya. Tanah merupakan media
utama dimana manusia bisa mendapatkan bahan pangan, sandang, papan. Air
merupakan zat kehidupan, dimana tidak satupun mahluk hidup di planet bumi ini
yang tidak membutuhkan air.
Seiring dengan peningkatan laju pertumbuhan penduduk, maka
pemanfaatan sumber daya alam tersebut juga semakin meningkat. Kebutuhan
manusia dipenuhi dengan pemanfaatan hutan, tanah dan air yang ada. Namun
dalam pemanfaatan tersebut sering kali diikuti oleh kerusakan dari sumber daya
alam itu sendiri. Hal ini disebabkan oleh tindakan pemanfaatan yang tidak diikuti
oleh kegiatan pengelolaan yang baik.61 HalamanSkripsi Sarjan
Analisis Tutupan Lahan Daerah Aliran Sungai Bah Bolon Bagian Hulu Menggunakan Citra Sentinel 2
No full textDaerah Aliran Sungai Bah Bolon bagian hulu memiliki peran penting
karena Bah bolon termasuk DAS Prioritas. Penggunaan kawasan hutan di
wilayah hulu DAS Bah Bolon berdampak pada respon hidrologi DAS. Perlu
identifikasi tutupan lahan dan penggunaan kawasan hutan di wilayah ini untuk
mitigasi bencana. Penelitian ini bertujuan untuk mengidentifikasi tipe tutupan
lahan dan mengevaluasi penggunaan kawasan hutan di wilayah hulu DAS Bah
Bolon. Identifikasi tutupan lahan dilakukan dengan dengan metode klasifikasi
terbimbing menggunakan citra Sentinel 2 yang terdiri dari 2 scene. Sebanyak 10
kelas tutupan lahan diidentifikasi sebarannya yaitu Sawah, badan air, hutan, kebun
sawit, kebun teh, kebun campuran, pemukiman, pertanian lahan kering, awan dan
bayangan awan. Hasil penelitian menunjukkan klasifikasi citra mempunyai
akurasi overall accuracy adalah sebesar 99,63% dan 99,67%, besarnya kappa
accuracy adalah 99,63% dan 99,67 secara berturut-turut untuk scene N0209_R061
dan sene N0214_R061. Pada kelas kemiringan terjal dan sangat terjal didominasi
oleh tutupan lahan kebun sawit yang mencapai luasan 19.266,1021 Ha (29,30%).
Pada areal dengan jarak dari sungai antara 0-100 meter didominasi oleh tutupan
lahan pertanian lahan kering yang mencapai luasan 11.208,3433 Ha (17,05%).
Pada areal dengan ketinggian lebih dari 1200 meter di dominasi oleh tutupan
lahan pertanian lahan kering yang mencapai luasan 2.945,8635 Ha (4,48%). Hasil
evaluasi tutupan lahan pada kawasan hutan, diperoleh hasil terdapat tutupan lahan
non hutan seluas 5.367,5195 yang setara dengan 63,32% dari total luas kawasan
hutan di Hulu DAS Bah Bolon. Luas tutupan hutan di daerah ini relatif kecil
dibandingkan dengan luas DAS (hanya 10,97%). Mengingat luas tutupan lahan
hutan di wilayah ini yang relative kecil dibandingkan dengan luas daerah aliran
sungai, maka perlu upaya rehabilitasi DAS.The upstream of Bah Bolon Watershed has an important role because includes
the Priority Watershed. The use of forest areas in the upstream watershed has an
impact on the hydrological response of the watershed. It is necessary to identify
land cover and the use of forest areas in the region for disaster mitigation. This
study aims were to identify the type of land cover and evaluate the use of forest
areas upstream of the Bah Bolon watershed. Identification of land cover was
done by a supervised classification method using Sentinel 2 imagery which
consisting of 2 scenes. A total of 10 classes of land cover were identified as rice
fields, water bodies, forests, oil palm plantations, tea plantations, mixed gardens,
settlements, dryland farming, clouds and cloud shadows. The results show that
the classification of imagery has overall accuracy is 99.63% and 99.67%, the
kappa accuracy is 99.63% and 99.67 respectively for scenes N0209_R061 and
sene N0214_R061. In the steep and very steep slope class dominated by the oil
palm plantation land cover that reaches an area of 19,266,1021 ha (29.30%).
The area with a distance from the river between 0-100 meters is dominated by the
dry land agriculture cover that reaches an area of 11,208,3433 ha (17.05%). In
an area with an altitude of more than 1200 meters dominated by the dry land
agriculture cover that reaches an area of 2,945.8635 ha (4.48%). We obtained
the use of forest area for other non-forest cover covering an area of 5.367,5195
hectares which is equivalent to 63,32% of the total forest area in the Upper Bah
Bolon watershed. The area of forest cover in this area is relatively small
compared to the area of watersheds (only 10,97%), it is necessary to rehabilitate
the watershed.87 HalamanSkripsi Sarjan
Klasifikasi Tutupan Lahan Berbasis Objek dengan Algoritma Decision Tree di Kecamatan Medan Belawan
No full textThe pixel-based land cover classification has been widely applied, but
information related to the assessment of object-based land cover classification
(OBIA) with high-resolution imagery namely SPOT imagery in Medan Belawan
District, has not been carried out. The use of decision tree algorithms in the
classification of object-based land cover depends on the sample of the object
used. This study aims to analyze the type of land cover in Medan Belawan District
using the OBIA method. This research was conducted for five months (December
2019 - April 2020). As many as 14 lands cover types were used according to the
real conditions in the field. The segmentation scale use of 50 gives the highest
accuracy; however, the lowest accuracy obtained from the segmentation scale of
150. The 50 segmentation scales obtained an overall accuracy (OA) of 100%,
kappa accuracy of 100%, and a correlation of 0.57. In comparison, the 150
segmentation scales obtained 97% for OA and kappa accuracy, and only 0.46 for
correlation value. The validation test was resulting values of 91.46% for the 50
scales segmentation and 81.66% for the 150 scales segmentation. This study
shows that the use of SPOT imagery for the classification of object-covered land
cover gives good results.Klasifikasi tutupan lahan berbasis piksel sudah banyak diterapkan, namun
informasi terkait pengkajian klasifikasi tutupan lahan berbasis objek (OBIA)
dengan citra resolusi tinggi yaitu citra SPOT di Kecamatan Medan Belawan
belum dilakukan. Penggunaan algoritma decision tree dalam klasifikasi tutupan
lahan berbasis objek tergantung pada sampel obyek yang digunakan. Penelitian
ini bertujuan untuk menganalisis tipe tutupan lahan di Kecamatan Medan Belawan
menggunakan metode OBIA. Penelitian ini dilakukan selama 5 bulan (Desember
2019 – April 2020). Penelitian ini menghasilkan 11 tipe tutupan lahan sesuai
dengan kondisi di lapangan. Skala segmentasi 50 menghasilkan nilai akurasi
tertinggi sedangkan nilai akurasi terendah pada skala segmentasi 150. Penggunaan
skala segmentasi 50 memberikan akurasi tertinggi dengan akurasi keseluruhan
dan akurasi kappa 100%, dan korelasi sebesar 0,57. Akurasi terendah diperoleh
pada skala 150 dengan akurasi keseluruhan (overall accuracy) dan akurasi kappa
97%, dan korelasi sebesar 0,46. Hasil validasi terhadap peta tutupan lahan yang
dihasilkan diperoleh nilai sebesar 91,46% untuk skala segmentasi 50 dan sebesar
81,66% untuk skala segmentasi 150. Hasil penelitian ini menujukkan bahwa
penggunaan citra SPOT untuk klasifikasi tutupan lahan berbasis obyek
memberikan hasil yang baik.60 HalamanSkripsi Sarjan
Spatial Analysis of Land Drought and Selection of Mitigation Strategies in the Belumai River Watershed (DAS)
No full textThe impact of the natural phenomena El Nino and La Nina is land drought that occurs during the dry season. Drought is a natural disaster that occurs in the Belumai Watershed. This study aims to analyze the spatial distribution of drought vulnerability in the Belumai watershed and analyze land drought mitigation efforts in the Belumai watershed. The method used in this study is to use weighting or scorring of each drought parameter, namely rainfall, land use, soil type and NDVI (Normalized Difference Vegetation Index) based on the seasonal period according to BMKG, namely DJF (December, January, February), MAM (March, April, May), JJA (June, July, August) and SON (September, October, November). The validation used is NDDI (Normalized Difference Drought Index) and NDWI (Normalized Difference Water Index). The results showed that the most dominating vulnerability class level was moderate vulnerability. The MAM 2023 period found an area of 44.463,50 Ha for the medium vulnerability class. Land drought mitigation is important, especially in classes with moderate, severe and very severe drought to minimize the risk of drought. Mitigation strategies that can be done based on the land cover are by replanting trees with strong roots and tree species that can withstand drought.68 PagesSkripsi Sarjan
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