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Journal : Agromet

ANALISIS PERUBAHAN IKLIM LOKAL DAN DEBIT SUNGAI DI DAS CIDANAUANALYSIS OF LOCAL CLIMATE CHANGE AND DISCHARGE IN CIDANAU WATERSHED Fadli Irsyad; Satyanto Krido Saptomo; Budi Indra Setiawan
Agromet Vol. 25 No. 1 (2011): JUNE 2011
Publisher : PERHIMPI (Indonesian Association of Agricultural Meteorology)

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (737.29 KB) | DOI: 10.29244/j.agromet.25.1.17-23

Abstract

Climate change causes uncertainty in water availability. The change may include annual rainfall, evapotranspiration and the shift of rainy and dry seasons, thus, it affects hydrological response in the region. Water demand will increase over time with population, industrial and business growth but the water availability has not been ascertained to sustainably satisfy those needs.  Cidanau Watershed has wetland ecosystem so-called the Rawa Danau (Caldera), with an area of around 2,500 ha. This watershed receives average annual rainfall around 2,500 mm. Climate change especially the local climate in the region of Cidanau was analyzed to illustrate how the relationship with Cidanau river discharge. It is expected that climate change does not affect the water availability in the watershed. In this study, the analysis of local climate change and its impact on the availability of water resources on Cidanau Watershed was based on climate trends, water balance analysis, and estimation of  discharge of Cidanau Watershed. This research was carried out using climate data and discharge from 1996 until 2010. The results showed that climate variables have changed from 1996 to 2010. This change mainly occurred in temperature, annual rainfall, and evapotranspiration. Based on the analysis, the discharge of Cidanau Watershed will decrease due to changes in rainfall and evapotranspiration. The estimated minimum river discharge of Cidanau Watershed ranges from 0.5 to 1 m3/s until 2050.
Penentuan Awal dan Durasi Musim Kemarau Menggunakan Fungsi Polynomial dengan Aplikasi Visual Basic for Applications (VBA) Fadli Irsyad; Satyanto Krido Saptomo; Budi Indra Setiawan
Agromet Vol. 28 No. 1 (2014)
Publisher : PERHIMPI (Indonesian Association of Agricultural Meteorology)

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (497.975 KB) | DOI: 10.29244/j.agromet.28.1.40-46

Abstract

Forecasting the occurrence of the onset of dry season and its length is important in determining the availability of water for irrigation, domestic and industrial uses. The length of dry season is used for reference in calculating water demand. Prediction of drought can be studied based on the rainfall patterns that have occurred. This is possible because there is a tendency that the rain will repeat a certain pattern at a certain time. The purpose of this study was to predict the onset of dry and rainy seasons as well as their length. Determination of the onset of dry season and its length was conducted using polynomial function of the cumulative amount of rain every single day based on the rain data. The research was conducted using rainfall data from Climate Station III in Serang from 1989 to 2010. The sum of daily rainfall could form a polynomial function. If the magnitude of daily rainfall in a certain period of time is less than the slope of the cumulative annual rainfall, then at that time the dry season is occurred. Determination of the dry season peak can be done by finding the maximum (extreme) point from the polynomial function by getting the second derivative which value is close or equal to zero. In average, the dry season occurred in Serang city started on the 132nd until 300th day. Deviation value for the onset of dry and rainy seasons were 23 and 38 days, respectively, with an average of length of 168 days. The average of R2 value for polynomial function was 0.9937.