River discharge has to be monitored reliably for effective water management. As river discharge cannot be measured directly, it is usually inferred from the water level. This practice is unreliable at places where the relation between water level and flow velocity is ambiguous. In such a case, the continuous measurement of the flow velocity can improve the discharge prediction. The emergence of horizontal acoustic Doppler current profilers (HADCPs) has made it possible to continuously measure the flow velocity. However, the profiling range of HADCPs is limited, so that a single instrument can only partially cover a wide cross section. The total discharge still has to be determined with a model. While the limitations of rating curves are well understood, there is not yet a comprehensive theory to assess the accuracy of discharge predicted from velocity measurements. Such a theory is necessary to discriminate which factors influence the measurements, and to improve instrument deployment as well as discharge prediction. This paper presents a generic method to assess the uncertainty of discharge predicted from range‐limited velocity profiles. The theory shows that a major source of error is the variation of the ratio between the local and cross‐section‐averaged velocity. This variation is large near the banks, where HADCPs are usually deployed and can limit the advantage gained from the velocity measurement. We apply our theory at two gauging stations situated in the Kapuas River, Indonesia. We find that at one of the two stations the index velocity does not outperform a simple rating curve.
Large expansion of oil palm plantation on peatland has changed its important role for carbon sink into a carbon source. Conversion of peat swamp forest with high carbon density into a monoculture of oil palm has released the significant amount of carbon into atmosphere either carbon previously stored in forest biomass or carbon stored in peat organic matter. Drainage canal to artificially lower groundwater level as a prerequisite of oil palm cultivation provides the favorable condition for soil microbes activities in decomposing peat organic matter resulted in CO2 flux increase. The fluctuation of groundwater level and variation of environmental factors near the peat surface may regulate the rate of CO2 released from the soil. We aimed to measure CO2 fluxes from two sites of oil palm plantation with different peat characteristics and analyzed the correlation with groundwater level, soil temperature, air temperature, gravimetric water content, peat pH, oxidative reductive potential, and crop age. The measurement has been conducted from September 2016 to April 2017 in West Kalimantan, Indonesia by using portable infrared gas analyzer EGM 4. In addition to soil sampling at the same time as the gas measurement, we collected soil samples for some peat characteristics analysis consist of bulk density, particle density, porosity, soil organic matter, ash content, carbon, and nitrogen content prior to CO2 flux measurement. Our result shows that the difference of peat chemical characteristics between two sites has resulted in different CO2 flux. Oil palm ages seemed to affect CO2 flux by regulating microclimatic condition around crop canopy. Another finding is the insignificant relationship between CO2 fluxes and groundwater level unless the groundwater level reached more than 50 cm from the peat surface. It implies that maintaining groundwater level-up to 50 cm resulting in similar CO2 flux.
The Sintang City, located in West Borneo, is annually inundated by flood during rainy season. The city itself is growing in the Y-junction of two big rivers i.e. Kapuas and Melawi, or geomorphologically growing on the major floodplain/alluvial plain of those rivers. Once, flood disaster has occured several days in 1963, inundating most of settlements and there were many of victims and damages. Although in the last recent days the floods were moderate, but such big event could be repeated in the future time. For reducing such disaster, flood study and mitigation program should be performed. The aims of this research are (1) to analyses and to map flood hazard and risk zones and (2) to evaluate the Sintang's land use planning (RDTR) based on flood hazard. Geomorphological approach is used for analyzing flood hazard based on morphogenesis and morphology parameters and history of floods. Vulnerability (based on actual land use) and flood hazard maps are then used for analyzing flood risk. Scoring for geomorphological and land use parameters and GIS spatial overlay is used for assessing hazard, risk, and evaluation of RDTR. The result shows that 95% of study area is composed of fluvial landforms, whereas flood hazard assessment indicates that 0.80% of Sintang's area is classified as very low of hazard, 57.2% low, 31.5% moderate, and 10.5% high. As for the risk assessment based on hazard and vulnerability, it shows that 0.90% of city's area has very low risk, 70.1% low, 22.5% moderate, and 6.50% high. These two later classes almost cover one-third of developed areas, such as residential, office, and commercial areas. The evaluation of RDTR based on flood hazard demonstrating thatalmost half of RDTR's developped areas (44.4%) is clasified as moderate risk zone and 4.10% as high risk zone. It indicates that flood mitigation program should be placed on high priority by Government for reducing the risk.
Pemanfaatan lahan gambut untuk perkebunan kelapa sawit selalu disertai dengan pemupukan, seperti pupuk hayati dan NPK. Namun kegiatan pemupukan ini berpotensi meningkatkan aktivitas mikroorganisme dalam mendekomposisi bahan organik gambut yang selanjutnya menghasilkan emisi CO2. Penelitian ini bertujuan untuk mengukur emisi CO2 sebelum dan sesudah pemupukan hayati dan NPK dari perkebunan kelapa sawit fase belum menghasilkan (umur tanaman 3 tahun) dan fase menghasilkan (umur tanaman 12 tahun). Penelitian ini dilaksanakan pada perkebunan kelapa sawit di Kalimantan Barat. Emisi CO2 yang diukur pada enam belas subplot dengan metode sungkup tertutup menggunakan sensor CO2 Vaisala GMP343. Pengukuran emisi CO2 dilakukan seminggu sekali dari bulan Agustus sampai Oktober 2020. Bersamaan dengan pengukuran emisi CO2 dilakukan pengukuran suhu tanah, suhu udara dan kedalaman muka air tanah yang diikuti pengambilan sampel tanah untuk analisis pH, Eh dan kadar air gravimetrik. Pengambilan sampel tanah terganggu untuk analisis kesuburan gambut dilakukan sebanyak tiga kali yaitu seminggu sebelum pengukuran emisi CO2, setelah aplikasi pupuk hayati dan setelah aplikasi pupuk NPK. Hasil penelitian menunjukan emisi CO2 sebelum dan sesudah pemupukan tidak berbeda nyata. Rerata emisi CO2 setelah pemupukan hayati cenderung lebih rendah dan kembali meningkat setelah pemupukan NPK. Besaran emisi CO2 pada tanaman belum menghasilkan sebelum pemupukan sebesar 0,65 ± 0,36 g CO2 m-2 jam-1, setelah pemupukan hayati sebesar 0,56 ± 0,28 g CO2 m-2 jam-1 dan setelah pemupukan NPK sebesar 0,60 ± 0,32 g CO2 m-2 jam-1. Sedangkan rerata emisi CO2 pada lokasi tanaman menghasilkan sebelum pemupukan yaitu 0,53 ± 0,24 g CO2 m-2 jam-1, setelah pemupukan hayati 0,38 ± 0,18 g CO2 m-2 jam-1 dan setelah pemupukan NPK meningkat menjadi 0,66 ± 0,43 g CO2 m-2 jam-1.ABSTRACTFertilization is a common practice when utilizing peatlands for oil palm plantation. It includes bio fertilizer and compound NPK fertilizer. However, fertilization may potentially increase microorganism activities leading to higher CO2 emission. This study aims to measure CO2 emissions before and after application of bio fertilizer and compound NPK fertilizer to oil palm plantations. This research was conducted on palm plantations in West Kalimantan. There are two plots of measurements i.e. immature oil palm, about 3 years of age and producing oil palm about 12 years of age, and every plot consists eight subplots. The measurement of CO2 emissions carried out according to closed chamber method using Vaisala GMP343 CO2 sensor once a week from August to October 2020. Along with measurement of CO2 emissions, environmental factors were also measured, i.e. soil temperature, air temperature and groundwater level, pH, Eh and gravimetric water content. Sampling of disturbed soil for peat fertility analysis was carried out three times, a week before measuring CO2 emissions, after application of bio-fertilizers and after application of compound NPK fertilizer. The results showed that CO2 emissions before and after fertilization were not significantly different. The average CO2 emission after biological fertilization tends to be lower than that before fertilizer application and tend to increase after NPK fertilization. The amount of CO2 emission in immature plot before fertilization is 0,65 ± 0,36 g CO2 m-2 hour-1, after biological fertilization is 0,56 ± 0,28 g CO2 m-2 hour-1 and after NPK fertilization is 0,60 ± 0,32 g CO2 m-2 hour-1. Meanwhile, the average CO2 emission at the location of the plant produced before fertilization was 0,53 ± 0,24 g CO2 m-2 hour-1, after biological fertilization was 0,38 ± 0,18 g CO2 m-2 hour-1 and after NPK fertilization increased to 0,66 ± 0,43 g CO2 m-2 hour-1.
Tanaman kelapa sawit adalah salah satu komoditas yang banyak dikembangkan di lahan gambut saat ini. Kegiatan budidaya kelapa sawit ini mengubah kondisi alamiah gambut yang selalu tergenang menjadi relatif lebih kering. Selain itu, budidaya kelapa sawit memerlukan pemupukan untuk memperbaiki status hara lahan gambut agar dapat menunjang pertumbuhan tanaman secara optimal. Sisi lingkungan, aktivitas budidaya tersebut dapat mempengaruhi laju dekomposisi bahan organik gambut yang selanjutnya menentukan laju emisi CO2 yang dilepaskan ke atmosfer. Emisi CO2 yang diakibatkan oleh fluktuasi muka air tanah sudah banyak dilaporkan, namun data emisi CO2 sebagai dampak pemupukan belum banyak tersedia. Penelitian ini bertujuan untuk mengukur emisi CO2 pada lahan gambut yang telah dipupuk menggunakan pupuk hayati dan pupuk NPK. Penelitian dilaksanakan di salah satu perkebunan swasta di Kabupaten Kubu Raya, Kalimantan Barat selama dua bulan, Oktober sampai November 2020. Pengukuran emisi CO2 dilakukan dengan metode sungkup tertutup, dengan sensor Vaisala GMP343, dan dilakukan setiap minggu. Bersamaan dengan pengukuran emisi CO2 juga dilakukan pengukuran variabel lingkungan dan beberapa sifat gambut. Hasil penelitian ini menunjukkan emisi CO2 pada lahan kelapa sawit yang telah dipupuk berkisar antara 50-110 ton CO2 ha-1 . Ada kecenderungan peningkatan emisi CO2 pada minggu pertama setelah pemupukan NPK, namun peningkatan ini tidak signifikan.
DAS Sibau merupakan salah satu daerah aliran sungai yang ada di Kabupaten Kapuas Hulu dengan pola penggunaan lahan yang intensif dan terus mengalami perubahan seiring dengan bertambahnya jumlah dan kebutuhan penduduk. Perubahan penggunaan lahan yang disebabkan oleh aktivitas antropogenik secara umum dapat menyebabkan potensi erosi tanah yang bersifat fluktuatif dan dipengaruhi oleh faktor lingkungan yang lainnya. Tujuan penelitian ini untuk menganalisis perubahan penggunaan lahan dan pengaruhnya terhadap potensi erosi yang ditimbulkan. Penelitian ini menggunakan SIG (System information Geografis) dengan metode USLE (Universal Soil Loss Equation) dengan parameter erosivitas Hujan (R), erodibilitas tanah (K), kemiringan lereng (LS) dan pengunaan lahan (CP), perhitungan potensi erosi yang dilakukan yaitu tahun 2009, 2015 dan 2018. Berdasarkan penelitian yang telah dilakukan diketahui bahwa penggunaan lahan di DAS Sibau masih didominasi oleh hutan, dengan perubahan lahan terbesar tahun 2009 hingga 2015 yaitu lahan terbuka (245,48%), sedangkan tahun 2015 hingga 2018 yaitu lahan terbuka mengalami penurunan (83,15%), kemudian peningkatan pada kebun campuran (149,45%) dan pertanian lahan kering sebesar (496,74%). Tingkat Bahaya Erosi (TBE) DAS Sibau masih tergolong aman karena didominasi oleh kategori sangat ringan dan ringan.
Effect of the composition of planting media on the growth of pearl grass variagated (Axonopus Compresuss). Pearl grass variagated (Axonopus compresuss), is a kind of ornamental grass used as landscape grass or carpet grass. Planting pearl grass variegated at this time, just plowing land, only ultisol. These conditions cause the growth of slow grass, easy soil erosion, then it takes quite a long time to cover the land. Because Ultisol is poor for nutrients and has a solid soil structure, it requires a mixture of organic composition to add nutrients and improve soil structure to loose. Therefore Organic materials used such as sawdust and cow dung manure. The objective of the research is knowing the composition of planting media consists of, Ultisol (PMK), sawdust (SG) and cow‘s manure (KS) on planting of pearl grass variegated. Planting is done on the map with size 0.5 m x 0.5 m. This research used Completely Randomized Design () with 6 treatments, 5 replicates, each replication consist 25 plant and sampling 20%. Treatment for compositions such as m0 (PMK 100%), m1 (PMK 75%: SG 25%), m2 (PMK 75%: PS 25%), m3 (PMK 50%: SG50%), m4 (PMK 50%: PS 50%), m5 (PMK 50%, PS 25%, SG 25%). The research was done for approximately 3 months from mid August to November 2017 in experimental garden Faculty of Agriculture UNTAN. The Research shows that the composition of planting media have significant effect on observation variables, such as number of tillers, stolon length, cover area, root length and dry weight. The result of this research shows, the treatmen of m4(PMK 50% : PS 50%) has higher value among of other treatment.
Suhu udara di kawasan perkotaan mengalami peningkatan yang dapat mempengaruhi kenyamanan dan produktivitas masyarakat. Ruang terbuka hijau (RTH) terdiri dari berbagai jenis pohon yang memiliki peran ekologis untuk menanggulangi hal tersebut. Penelitian ini bertujuan untuk mengevaluasi kesesuaian karakteristik pohon pada RTH dalam ameliorasi iklim mikro sehingga diketahui sejauh mana efektivitas dalam memenuhi fungsi ekologisnya serta memberikan rekomendasi jenis-jenis tumbuhan yang mendukung pengelolaan dan konservasi RTH. Penelitian dilakukan dengan melakukan penilaian kesesuaian karakteristik pohon dengan fungsi ekologisnya berdasarkan KPI (Key Performance Index) pada beberapa ruang terbuka hijau di Kota Pontianak. Hasil penelitian menunjukkan bahwa angsana (Pterocarpus indicus), tanjung (Mimusops elengi), trembesi (Samanea saman), dan mahoni (Swietenia mahagoni) merupakan jenis pohon yang efektif dalam memodifikasi suhu dan kelembapan udara serta sebagai pemecah angin.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.