Meilasari, Nabilla (2017) Kajian Limpasan Permukaan Dan Erosi Tanah di Berbagai Tingkat Kerapatan Kanopi Pohon Sistem Agroforestri DAS Rejoso, Pasuruan- Jawa Timur (Studi Kasus: Di Jenis Tanah Latosol). Sarjana thesis, Universitas Brawijaya.
Abstract
Daerah Aliran Sungai (DAS) memiliki fungsi hidrologis untuk mempertahankan kuantitas serta kualitas air yang ada di suatu wilayah yang dibatasi oleh topografi. Karakteristik DAS yang didalamnya mencakup topografi, jenis tanah, geomorfologi, vegetasi dan penggunaan lahan sangat mempengaruhi kuantitas serta kualitas air yang merupakan salah satu indikator kesehatan DAS. DAS Rejoso adalah salah satu DAS di Pasuruan, Jawa Timur yang teridentifikasi mengalami gangguan. Gangguan tersebut disinyalir disebabkan oleh perubahan penggunaan lahan. Pada Latosol non berbatu banyak ditemukan sistem agroforestri yang memiliki kerapatan kanopi pohon berbeda. Dalam penelitian ini kelas kerapatan kanopi di sistem agroforestri dibagi kedalam kelas sangat rapat (>80%), rapat (60-80%), sedang (40-60%), dan jarang (20-40%). Penelitian ini dilaksanakan selama 5 bulan (Januari 2017- Mei 2017) meliputi kegiatan survey, persiapan pengamatan, pengamatan, dan anlisis erosi tanah. Lokasi penelitian berada di blok jenis tanah latosol dengan geomorfologi non batu DAS Rejoso, Pasuruan- Jawa Timur. Penelitian menggunakan metode survey dengan pendekatan Stratified Random Sampling. Terdapat 2 variabel pengamatan dalam penelitian ini yakni variabel biofisik (Kanopi Pohon, Seresah, Tanaman Bawah, dan Kekasaran Permukaan/Cekungan) dan variabel hidrologi (Curah Hujan Harian, Limpasan Permukaan, dan Erosi). Plot erosi yang digunakan sebagai sub plot indikator kesehatan DAS Rejoso, berukuran 2x6 m2. Masing-masing lahan pengamatan terdapat 3 plot erosi, sehingga plot erosi yang teramati sebanyak 12 plot. Pengamatan variabel hidrologi dilakukan setiap hari setelah kejadian hujan selama 2 bulan, sedangkan variabel biofisik hanya diukur 1 kali dalam luasan 20x20 m2. Hasil penelitian menunjukan bahwa sistem agroforestri dengan tingkat kerapatan kanopi pohon, memiliki perbedaan nilai limpasan permukaan dan erosi tanah. Karakteristik hujan dan kondisi biofisik lokasi pengamatan menjadi penyebab nilai limpasan permukaan dan erosi di lokasi pengamatan berbeda. Di setiap blok pengamatan curah hujan di lokasi penelitian menunjukan, mayoritas hujan yang terjadi adalah curah hujan ringan (<20 mm/hari), sedangkan selama 2 bulan pengamatan tidak pernah terjadi curah hujan tinggi (>100mm/hari). Semakin rapat penutupan kanopi pada suatu sistem agroforestri semakin rendah nilai rasio LP/CH nya (0,13 0,62). Sedangkan erosi tanah terendah terjadi pada kelas kerapatan rapat (2,10 ton/ha) dan erosi tanah tertinggi ada pada kelas kerapatan jarang (11,82 ton/ha). Faktor pengendali limpasan permukaan dan erosi tanah di DAS rejoso menunjukan pengaruh penurunan yang berbeda. Kanopi pohon merupakan faktor utama yang paling berpengaruh dalam mengendalikan limpasan permukaan dan erosi di DAS Rejoso. Akan tetapi penurunan yang ditimbulkan akibat penambahan 1% penutupan kanopi lebih kecil (0,0065 dan 0,16) dari pada faktor kekasaran (0,045 dan 0,91) dan seresah (0,37 dan 0,69).
English Abstract
The Watershed (DAS) has a hydrological function to maintain the quantity and quality of water present in an area bounded by topography. Characteristics of watersheds that include topography, soil type, geomorphology, vegetation and land use greatly affect the quantity and quality of water that is one indicator of watershed health. The Rejoso watershed is one of the watersheds in Pasuruan, East Java that has been identified as having problems. The disturbance was allegedly caused by changes in land use that occurred in the upper of Rejoso watershed. In the non rocky type of Latosol many agroforestry systems are found that have different tree canopy densities. In this study the density class of canopy in the agroforestry system is divided into very dense (> 80%), dense (60-80%), medium (40-60%), and infrequent (20-40%) classes. The study was conducted for 5 months (January 2017- May 2017) which are survey activities, observation preparation, observation, and soil erosion analysis. The research location is located in the latosol type of soil block with the geomorphology of non-rocks of the Rejoso watershed, Pasuruan-East Java. The research used survey method, with Stratified Random Sampling approach. There are 2 observation variables in this research, biophysical variables (Tree Canopy, Litter, Lower Plants, and Surface Roughness / Basin) and hydrological variables (Daily Rainfall, Surface Runoff, and Erosion). The erosion plot used as sub plot of Rejoso DAS health indicator, measuring 2x6 m2. In each land research there are 3 erosion plots, so the observed plot of erosion is 12 plots. Observation of hydrological variables is in every day after the incidence of rain for 2 months, whereas the biophysical variables are measured only once in the area of 20x20 m2. The results showed that agroforestry system with density of tree canopy level, has different surface runoff value and soil erosion. The characteristics of rain and biophysical conditions of observation location cause the value of surface runoff and erosion at different observation sites. In each observation block of rainfall at the location of the study showed that the majority of rainfall was mild rainfall (<20 mm / day), while during 2 months observation never happened high rainfall (> 100mm / day). The more dense a cover of canopy in agroforestry system, then the value of the ratio LP/CH will low (0.13 - 0.62). While for the density class (2.10 tons / ha) and soil erosion of the class is in the rare density class (11.82 tons / ha). The control factor of surface runoff and soil erosion in Rejoso watershed shows different effect of decrease. Tree canopy is the most mainly factor in the control of surface runoff and erosion in the Rejoso watershed. Less will be caused by the addition of 1% canopy cover is smaller (0,0065 and 0,16) than factors roughness (0,045 and 0,91) and litter (0,37 and 0,69).
| Item Type: | Thesis (Sarjana) |
|---|---|
| Identification Number: | SKR/FP/2017/771/051710988 |
| Uncontrolled Keywords: | - |
| Subjects: | 600 Technology (Applied sciences) > 631 Specific techniques; apparatus, equipment materials > 631.4 Soil science > 631.45 Soil erosion |
| Divisions: | Fakultas Pertanian > Ilmu Tanah |
| Depositing User: | Budi Wahyono Wahyono |
| Date Deposited: | 22 Dec 2017 00:46 |
| Last Modified: | 11 Nov 2020 03:30 |
| URI: | http://repository.ub.ac.id/id/eprint/7420 |
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