Pendugaan Infiltrasi Menggunakan Data Neraca Air Di Sub Daerah Aliran Sungai Watujali, Gombong (Estimation of Infiltration Based on Water Balance Method at Watujali Sub Watershed, Gombong)

Infiltration rate in a watershed is very important for water management. There are many methods for estimating the rate of infiltration in a watershed. Among of them are direct measurements, hydrograph analysis and water balance calculation. The purpose of this study was to estimate infiltration in the sub watershed under pine forest. The method was based on a relationship between water balance and regression of monthly rainfall and discharge. The results showed that the infiltration rate of pine forest in Watujali Sub Watershed range from 125 mm/year up to 1,193 mm/year. The infiltration rate was highly depended on rainfall as the input. In 2010 with 5,826 mm rainfall, the infiltration rate reached 1,193 mm/year. Estimation of infiltration using water balance data was easy to implement because it only used data of streamflow, rainfall and evapotranspiration

Hasil Air Hutan Jati Pada Dua Sub Daerah Aliran Sungai Dengan Luas Berbeda (Water Yield of Teak Forest at Two Different Catchment Sizes)

Effects of catchment sizes on hydrological responses were still being debated. Therefore, a study on hydrological effects of different catchment sizes was conducted in teak catchments. The catchments were Cemoro and Modang with their sizes were 13.5 and 3.4 km2, respectively. Research sites were in Forest Management Sub Unit (BKPH) Pasar Sore, Forest Management Unit (KPH) Cepu, and administratively were located in Blora Regency. Physical conditions of these catchments were similar. Rainfall was measured everyday at 07.00 a.m. Stream Water Level (SWL) data were collected from tide gauge measurements which were constructed at the outlet of the catchments. Discharge data were obtained by convertion of the SWL into discharge based on regression equations between direct discharge measurements in the field and SWL. Data analysed from 2001 to 2015 showed that Cemoro catchment had higher annual runoff than Modang. Generally, monthly runoff from Cemoro catchment was higher than Modang catchment, only for several years the Modang catchment had higher monthly runoff than Cemoro catchment. Annual runoff coefficient of Cemoro catchment was always higher than Modang catchment during 2001 to 2015. The runoff coefficient ranged from 0.20 to 0.62 and from 0.06 to 0.38 for Cemoro and Modang catchments, respectively

Temporal Distribution of Sediment Yield From Catchments Covered by Different Pine Plantation Areas

Soil erosion and sedimentation are environmental problems faced by tropical countries. Many researches on soil erosion-sedimentation have been conducted with various results. Quantifying soil erosion-sedimentation and its temporal distribution are important for watershed management. Therefore, a study with the objective to quantify the amount of suspended sediment from catchments under various pine plantation areas was conducted. The research was undertaken during 2010 to 2017 in seven catchments with various percentage of pine coverage in Kebumen Regency, Central Java Province. The rainfall data were collected from two rainfall stations. A tide gauge was installed at the outlet of each catchment to monitor stream water level. The water samples for every stream water level increment were analyzed to obtain sediment concentration. The results showed that monthly suspended sediment of the catchments was high in January to April and October to December, and low in May to September. The annual suspended sediment fluctuated during the study period. Non-linear correlations were observed between suspended sediment and rainfall as well as suspended sediment and percentage pine areas. The line trend between suspended sediment and percentage of pine areas showed that the increase in pine areas decreased suspended sediment, with the slope of the graph is sharp at the percentage of pine areas from 8% to 40%, then is gentle for pine plantation areas more than 40%

Pengaruh Persentase Penutupan Hutan Terhadap Debit Puncak Di Sub Daerah Aliran Sungai Hutan Alam Kabupaten Tanah Laut (the Effect of Forest Coverage Percentage on Peak Discharge in the Natural Forest Sub Watershed, Tanah Laut Regency)

Persentase penutupan hutan memegang peran penting dalam mengatur tata air Daerah Aliran Sungai (DAS). Hutan dengan fungsi hidrologisnya berpengaruh terhadap debit sungai. Penelitian ini bertujuan untuk mempelajari pengaruh persentase penutupan hutan terhadap debit puncak di sub DAS hutan alam. Penelitian ini dilakukan pada tahun 2017 di Sub DAS Bakar, Sub DAS Tanjung, Sub DAS Iwakan, dan Sub DAS Langsat, Kabupaten Tanah Laut Provinsi Kalimantan Selatan. Persentase hutan alam bervariasi dari 9,7 sampai 98% dari uas sub DAS. Penelitian dilakukan dengan pengkuran langsung data curah hujan dan tinggi muka air (TMA) yang dikonversi menjadi debit puncak. Data debit puncak antar sub DAS dibandingkan menurut curah hujan dan persentase penutupan hutan alam. Hasil penelitian menunjukkan secara umum persentase penutupan hutan berpengaruh terhadap debit puncak. Penutupan hutan memberikan respon yang positif dalam menurunkan debit puncak ketika curah hujan dibawah 115 mm/hari. Sub DAS Bakar dan Tanjung yang memiliki persentase penutupan hutan alam yang rendah memiliki debit puncak yang lebih tinggi dibandingkan dengan Sub DAS Langsat dan Iwakan yang memiliki persentase penutupan hutan yang tinggi. Pengaruh persentase penutupan hutan alam terhadap debit puncak ditandai oleh koefisien determinasi sebesar 53,3%. Keberadaan hutan sangat penting sebagai pengatur hidrologi sehingga sangat penting untuk dilakukannya upaya konservasi dan penghijauan di hulu sub DAS yang diamati

Pengaruh Persentase Penutupan Hutan Terhadap Debit Puncak Di Sub Daerah Aliran Sungai Hutan Alam Kabupaten Tanah Laut (the Effect of Forest Coverage Percentage on Peak Discharge in the Natural Forest Sub Watershed, Tanah Laut Regency)

Persentase penutupan hutan memegang peran penting dalam mengatur tata air Daerah Aliran Sungai (DAS). Hutan dengan fungsi hidrologisnya berpengaruh terhadap debit sungai. Penelitian ini bertujuan untuk mempelajari pengaruh persentase penutupan hutan terhadap debit puncak di sub DAS hutan alam. Penelitian ini dilakukan pada tahun 2017 di Sub DAS Bakar, Sub DAS Tanjung, Sub DAS Iwakan, dan Sub DAS Langsat, Kabupaten Tanah Laut Provinsi Kalimantan Selatan. Persentase hutan alam bervariasi dari 9,7 sampai 98% dari uas sub DAS. Penelitian dilakukan dengan pengkuran langsung data curah hujan dan tinggi muka air (TMA) yang dikonversi menjadi debit puncak. Data debit puncak antar sub DAS dibandingkan menurut curah hujan dan persentase penutupan hutan alam. Hasil penelitian menunjukkan secara umum persentase penutupan hutan berpengaruh terhadap debit puncak. Penutupan hutan memberikan respon yang positif dalam menurunkan debit puncak ketika curah hujan dibawah 115 mm/hari. Sub DAS Bakar dan Tanjung yang memiliki persentase penutupan hutan alam yang rendah memiliki debit puncak yang lebih tinggi dibandingkan dengan Sub DAS Langsat dan Iwakan yang memiliki persentase penutupan hutan yang tinggi. Pengaruh persentase penutupan hutan alam terhadap debit puncak ditandai oleh koefisien determinasi sebesar 53,3%. Keberadaan hutan sangat penting sebagai pengatur hidrologi sehingga sangat penting untuk dilakukannya upaya konservasi dan penghijauan di hulu sub DAS yang diamati