Path: TopS3-DissertationsEngineering Science2008

KARAKTERISTIK, MEKANISME, DAN MODEL TEMPORAL HIDROMETEOROLOGI DAERAH ALIRAN SUNGAI CITARUM HULU DAN TENGAH

CHARACTERISTICS, MECHANISMS, AND TEMPORAL MODEL OF HYDROMETEOROLOGY IN THE UPPER AND MIDDLE CITARUM RIVER BASIN

PhD Theses from JBPTITBPP / 2008-07-22 14:55:45
Oleh : RUMINTA (NIM 32403003), S3 - Engineering Sciences
Dibuat : 2008, dengan 7 file

Keyword : rainfall, discharge, global phenomena, wet and dry periods, chaotic mono-fractal, return periods, cyclic, long-term trends, ANFIS, temporal models

Penelitian terhadap karakteristik, mekanisme dan model temporal hidrometeorologi telah dilakukan di daerah aliran Sungai Citarum Hulu dan Tengah, Jawa Barat. Penelitian tersebut menggunakan data bulanan hasil observasi curah hujan, evapotranspirasi, kelembapan, dan debit sungai dari Januari 1968 hingga Desember 2000 dan data bulanan fenomena global dari analisis National Centers for Environmental Prediction (NCEP) dan National Geophysical Data Center (NGDC). Identifikasi karakteristik komponen hidrometerologi didasarkan pada analisis statistik meliputi jumlah kumulatif, variabilitas, korelasi dimensi, probabilitas empirik, periode ulang, power spektrum, kecenderungan jangka panjang, dan sensitivitas. Sedangkan identifikasi model dinamika temporal hidrometeorlogi didasarkan pada analisis Adaptive Neuro-Fuzzy Inference System (ANFIS). Hasil penelitian menunjukkan bahwa curah hujan mempunyai dua persistensi yang tegas yaitu periode basah dan kering. Curah hujan dan debit sungai mempunyai variabilitas sangat tinggi masing-masing 73% dan 62%. Hal ini menunjukkan bahwa proses curah hujan dan debit sungai sangat chaotic. Pola variabilitas curah hujan dan debit sungai cenderung naik, hal ini mengindikasikan bahwa kejadian kekeringan dan banjir semakin ekstrim. Proses hidrometeorologi daerah aliran sungai Citarum adalah chaotic dimensi rendah (korelasi dimensi, .<4). Nilai . untuk curah hujan, evapotranspirasi, kelembapan, dan debit sungai masing-masing adalah 1.83, 1.68, 1.23, dan 2.05, menunjukkan jumlah variabel optimum dalam model dinamik proses hidrometeorologi tersebut masing-masing adalah 2, 2, 2, dan 3. Curah hujan dan debit sungai adalah bersifat chaotic monofraktal (qD<2) menunjukkan proses deterministik lebih dominan sedangkan evapotranspirasi dan kelembapan adalah bersifat chaotic multi-fraktal (qD>2) menunjukkan proses stokastik lebih dominan. Periode ulang nilai ekstrim curah hujan dan debit sungai masing-masing adalah 5 dan 25 bulan. Curah hujan dan debit sungai mempunyai tiga siklik utama yang sama yaitu 5-7, 9-25, dan 100-125 bulanan. Fakta ini menunjukkan bahwa curah hujan dan debit sungai berkaitan dengan osilasi monsun, quasi biennial, dan sunspot. Proses hidrometeorologi daerah aliran sungai Citarum merupakan hasil dari proses aliran tanpa batas karena mempunyai nilai spektrum eksponensial (ß) lebih kecil dari satu. Curah hujan dan debit sungai cenderung menurun masing-masing sebesar 3.64% dan 1.11% untuk setiap 100 bulan. Penurunan curah hujan dan debit sungai terutama disebabkan oleh adanya penurunan pembentukan awan dan hujan konvektif sebagai akibat dari penurunan luas hutan dan variabilitas iklim global. Evapotranspirasi dan kelembapan udara cenderung meningkat masing-masing sebesar 3.88% dan 4.21% untuk setiap 100 bulan. Peningkatan evapotranspirasi dan kelembapan udara tersebut disebabkan oleh tingginya pemindahan uap air dari permukaan ke atmosfer melalui baik evaporasi maupun transpirasi. Debit sungai sangat sensitif tehadap perubahan curah hujan, terutama debit sungai periode Juni-Juli-Agustus. Air cadangan cenderung turun sementara itu koefisien limpasan cenderung naik, hal ini mengindikasikan jumlah reservoir dan penutupan lahan oleh vegetasi telah mengalami penurunan sehingga kejadian kekeringan dan banjir semakin ekstrim. Curah hujan dan debit sungai di daerah aliran Sungai Citarum Hulu dan Tengah sangat dipengaruhi oleh fenomena global terutama temperatur global, dipole mode India, osilasi selatan, monsun India, dan potensi air atmosfer. Model dinamika temporal hidrometeorologi berbasis ANFIS dapat men-simulasi data observasi secara akurat. Model tersebut mampu memperkecil nilai bias dan kesalahan (RMSE) dan memperbesar nilai presisi (E). Model temporal curah hujan dan debit sungai tahunan dapat memberikan hasil prediksi yang lebih akurat dibanding model temporal bulanan. Model temporal hasil indentifikasi ANFIS tersebut sangat potensial dipergunakan untuk memprediksi curah hujan dan debit sungai. Hasil penelitian karakteristik, mekanisme, dan model temporal hidrometeorologi dapat memberikan masukan informasi bagi peningkatan manajemen tata air yang terintegrasi di daerah aliran Sungai Citarum.

Deskripsi Alternatif :

A study on characteristics, mechanisms, and temporal models of the hydrometeorology was carried out in the Upper and Middle Citarum River Basin, West Java. The investigations based on monthly observations data of the rainfall, evapotranspiration, humidity, and river discharge from January 1968 to December 2000 and monthly data of global phenomena from reanalysis National Centers for Environmental Prediction (NCEP) and National Geophysical Data Center (NGDC). Identification of hydrometeorolgical components characteristics was based on statistics analysis i.e., cumulative sum (CUSUM), variability, correlation dimension, empirical probability, return periods, power spectrum, long-term trends, and sensitivity. While identification of the temporal dynamical model of the hydrometeorology based on Adaptive Neuro-Fuzzy Inference System (ANFIS) analyses. The results indicated that rainfall had two firm persistence i.e. wet and dry periods. The rainfall and river discharge have very high variability i.e., 73% and 62%, respectively. These data indicated that the processes of the rainfall and river discharge were very chaotic. Variability patterns of the rainfall and river discharge had increasing trends, the facts indicated that drought and flood events can to be extreme. The hydrometeorological processes in the Citarum river basin was low-dimension chaotic (correlation dimension, .<4). The .-values of the rainfall, evapotranspiration, humidity, and river discharge are 1.83, 1.68, 1.23, and 2.05 respectively that showed a minimum numbers of the main variables in the dynamic model of the hidrometeorological processes are 2, 2, 2, and 3 respectively. The rainfall and river discharge are chaotic mono-fractal (qD<2) that showed deterministic processes but the evapotranspiration and humidity are chaotic multi-fractal (qD>2) that showed stochastic processes. The extreme values of the rainfall and river discharge had return periods i.e., 5 and 25 months respectively. The rainfall and river discharge had the same three main cyclic there are 5-7, 9-25, and 100-125 monthly. The facts indicated that rainfall and river discharge had controlled by monsoon, quasi biennial, and sunspot oscillations. The hydrometeorological processes in the Citarum river basin was the results of the unbounded cascade processes because that had the value of exponent spectrum (B) less than one. The rainfall and river discharge had been decreased by about 3.64% and 1.11% respectively for every a hundred months. The decreasing trend in the rainfall and river discharge had controlled mainly by the decreasing of the clouds and convection rains formation as a consequence of the deforestation and global climate variability. The evapotranspiration and air humidity had been increased by about 3.88% and 4.21% respectively for every a hundred months. The increasing trend in the evapotranspiration and air humidity had been influenced by the increasing of the water vapour removal from vegetation lands surface to the atmosphere by both evaporation and transpiration. The river discharge is very sensitively against the rainfall's fluctuation, especially in June-July-August periods. Water storages had been decreased and coefficient of runoff had been increased, that facts indicated that reservoirs while land cover by vegetation had been decreased so that drought and flood events can to be extreme. The rainfall and river discharge in the Upper and Middle Citarum River Basin were influenced by global phenomena, especially Global Temperature, Indian Oceans Dipole Mode, Southern Oscillation, Indian Monsoon, and Precipitable Water. The temporal dynamical model of the hydrometeorology based on ANFIS can simulate the observations data accurately. The model is capable to minimize the bias and root mean squared error (RMSE) values and maximize the precision (E) value. Annually temporal models can predict more accurately rainfall and river discharge than theses of the monthly temporal models. The hydro-meteorological temporal model results of the ANFIS indentification very potential used to predict the rainfall and run off. The results of study on characteristics, mechanisms, and temporal models of the hydrometeorology can give an information for improvement of an integrated water management in the Citarum River Basin.

Copyrights : Copyright Â(c) 2001 by ITB Central Library. Verbatim copying and distribution of this entire article is permitted by author in any medium, provided this notice is preserved.

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