Water Yield Analysis on Area Coveredby Pine Forest at Kedungbulus Watershed Central Java, Indonesia

The analysis of water yield is conducted to provide information on the availability of water resources at a particular location in a watershed. Kedungbulus watershed is located at an area with plantation of pine forest. The pine forest area varies from 7% to 95% of the sub watershed areas. The plantation of this kind of vegetation (Pinusmerkusii) in some regions may cause water availability problem due to it may consume much more water rather than others. The objective of this study is to analyze the effect of pine forest area and its characteristics on the water yield in several of sub watershed at Kedungbulus Watershed. Direct measurement and prediction were used to estimate the water yield. A Thorthwaite and Mather method was used in this study to estimate the water yield. It was completed with data of rainfall, air temperature, soil properties, and land cover. Stand density varies from 388 to 644 stand/hectare and diameter at breast height (DBH) varies from 20 to 40 cm. The annual rainfall during the year of 2015 at the location was 2525 mm. It was found that the water yield tends to decrease with the increase of pine forest area. The water yield of the watershed with pine forest covered of 7% was 1520 mm/year, while watershed with pine forest covered 95% was lower (1289 mm/year). In order to increase the water yield, the pine forest plantation is not recommended in a certain area with low rainfall. Modified Thorthwaite-Mather Water Balance method was successfully applied to this case with a significant increase in determination coefficient from 0.3 to 0.7

Reklasifikasi Peta Penutupan Lahan untuk Meningkatkan Akurasi Kerentanan Lahan

Land vulnerability is an important information to formulate land rehabilitation activities since it indicates the response of that particular land to erosion. It was determined by several factors such as slope, soil types, rainfall, and land cover. The land cover could be managed to maintain the land vulnerability. Inaccuracies of land cover classification would produce different vulnerabilities, which can cause miscalculation in land rehabilitation planning and implementation. This research is to adjust the existing land cover classification in order to detect land vulnerabilities. The analysis is done by comparing the classification of the existing land cover map with land cover criteria for land vulnerability analysis. The classification result then overlayed with land system map to determine the land vulnerability. The result of a study in Cisadane watershed shows that inaccuracy in determining unirrigated farming into shrub land or moor/open field could affect the shifting of vulnerable class to very vulnerable. Differences in determining plantations and unplanted estate areas with open field could also raise the extent of land vulnerability to 12.3%. Settlement in an urban area that turned into buildings would reduce the level of land vulnerability to 2.1%. Buildings could reduce the land vulnerability due to the impermeable layer would decrease erosion. However, from the hydrological point of view, the impermeable layers would increase the hydrological vulnerability due to the increased runoff and reduced ability to absorb water. Land cover data selection as input to determine the land vulnerability is very important and sensitive. For that reason, in the Cisadane Watershed, dryland farming should be classified as open field and settlement in urban areas should classify as buildings

Pemodelan Prediksi Erosi Dan Debit Puncak Menggunakan Soil And Water Assessment Tool (SWAT) Di Subdas Cirasea Kabupaten Bandung

Cirasea Sub-watershed is part of the Upper Citarum Watershed, where it is one of 15 priority watersheds in Indonesia. The Upper Citarum watershed has been severely damaged in terms of water quality, sedimentation and erosion, requiring serious handling. Cirasea Sub-watershed has an area of 20.852 ha, located in Bandung Regency, West Java Province. The objectives of this study are 1). Knowing the spatial distribution of erosion levels in Cirasea sub-watershed using SWAT 2). Predicting the peak discharge in Cirasea watershed using SWAT 3). Knowing the level of accuracy of the prediction results of erosion and peak discharge using the SWAT model. This study uses secondary data, the research method used in this study is secondary data analysis using SWAT, and the data analysis method used is quantitative and spatial analysis. The results of this study indicate that 1). The level of erosion in Cirasea Sub-watershed is 21.53% high, and 30.16% very high, while the average erosion in Cirasea Sub-watershed is 511.9 ton / ha / year. The high erosion that occurs in the Cirasea Sub-watershed is caused by the use of dry agricultural land which dominates in the Cirasea Sub-watershed, as well as the high intensity of rain, where dry agricultural land itself is very prone to erosion by rainwater. 2). The peak discharge in Cirasea Sub-watershed was 46.37 m3 / second which occurred on November 10, 2016, this was caused by rainfall that occurred on November 10, 2016, which experienced the highest rainfall during the simulation period. 3). The results of model validation by comparing the simulation discharge value with the observed discharge value = 0.61. which means that the model is acceptable if the value is> 0.5

Pemodelan Soil And Water Assessment Tool (SWAT) Untuk Prediksi Erosi Dan Konservasi Tanah Di Sub-Das Ciwidey Kabupaten Bandung

The Ciwidey sub-watershed is part of the Upper Citarum watershed, where the watershed is one of the 15 priority watersheds in Indonesia. Where the Upper Citarum watershed suffered very heavy damage in terms of water quality, sedimentation, and erosion, so it required serious handling. The Ciwidey sub-watershed is located in most of Bandung Regency and a small part of West Bandung Regency. The Ciwidey sub-watershed is a series of the upstream Citarum watershed, precisely in the southern part of the Citarum watershed. The aims of this study are 1) Analysis of the magnitude of erosion per HRU in the Ciwidey sub-watershed using the Soil and Water Assessment Tools (SWAT) model 2). Determining the accuracy of the data from the calculation of erosion prediction for the Ciwidey Sub-watershed using Soil Water Assessment Tools (SWAT) 3). Determine the right conservation technique at the point where erosion occurs in the Ciwidey Sub-watershed. This study uses secondary data, the research method used in this study is secondary data analysis using SWAT, and the data analysis method used is quantitative and spatial analysis. The results of this study indicate that 1). The overall rate of erosion in the Ciwidey sub-watershed is 2179.36 tons/ha/year. The erosion value goes through the stages of calculating rainfall, land use, and soil type. 2). The level of accuracy of the data calculated through SWAT shows an accurate number, namely 0.56 where the number is included in the acceptable category, with a minimum data accuracy value or R2 of 0.5. 3). The results of the calculation of the erosion value are used to determine the appropriate soil conservation techniques, namely vegetative soil conservation techniques by planting soil strengthening plants and increasing infiltration, including avocado, jackfruit, durian trees which are applied to dry agricultural land

Baseflow and lowflow of catchments covered by various old teak forest areas

Drought has become a severe disaster faced by several regions in Java, Indonesia due to land cover changes including forest conversion and the increase in air temperature. In this regards, the availability of forests related to lowflow has been a controversial debate. Forest in Java is dominated by teak; however, the hydrological teak forest has not been well known. Therefore, a research has been undertaken to know the baseflow and low-flow of teak catchments covered by various old teak forest areas. The research areas were in Blora District, Central Java, Indonesia. Data of2008-2015 from five catchments with areas of 3.38, 13.47, 20.14, 27.79, 64.80, and 69.20 ha and covered by old teak forests of 82, 82, 74, 70, and 53% of the catchment were analyzed. In this study, baseflow is the delayed flow from bank storage, and low-flow is stream flow in the dry season. The results showed that baseflow is affected by the percentage of old teak plantation areas, rainfall and antecedent soil moisture condition. Areas of the old teak plantation and the baseflow show negative and non-linear correlation. High low-flow occurs in the catchments with the percentage of old teak plantation about 74 to 70%

Distribution of Water Infiltration Rate in Ciliwung Watershed

Floods in Jakarta showed that the Ciliwung watershed and surrounding areas in critical condition. More than 50 % of land cover Ciliwung watershed is residential. Planting trees in residential areas have been insufficient to infiltrate as much water into the ground. Infiltration well is one possibility for absorbing water in residential areas. The purpose of this study was to determine the variation in the level of water absorption Ciliwung watershed and surrounding areas. The method used is overlaying analysis of the factors that determine the rate of water infiltration with geographic information system. Each of these factors gave weights and scores to obtained variations Ciliwung water infiltration rate. The results showed that the regions with the highest levels found in the upper catchment area and the city of Bogor, middle absorbtion water area was in Bogor Regency, low water absorption areas in Depok , South Jakarta , and East Jakarta . While in North Jakarta, Central Jakarta and West Jakarta the water absortion is very low level due to the shallow ground water level and very low soil permeability. Map variations in water absorption can be used as a material consideration for determining the locations of recharge wells effectively

Distribution of Water Infiltration Rate in Ciliwung Watershed

Floods in Jakarta showed that the Ciliwung watershed and surrounding areas in critical condition. More than 50 % of land cover Ciliwung watershed is residential. Planting trees in residential areas have been insufficient to infiltrate as much water into the ground. Infiltration well is one possibility for absorbing water in residential areas. The purpose of this study was to determine the variation in the level of water absorption Ciliwung watershed and surrounding areas. The method used is overlaying analysis of the factors that determine the rate of water infiltration with geographic information system. Each of these factors gave weights and scores to obtained variations Ciliwung water infiltration rate. The results showed that the regions with the highest levels found in the upper catchment area and the city of Bogor, middle absorbtion water area was in Bogor Regency, low water absorption areas in Depok , South Jakarta , and East Jakarta . While in North Jakarta, Central Jakarta and West Jakarta the water absortion is very low level due to the shallow ground water level and very low soil permeability. Map variations in water absorption can be used as a material consideration for determining the locations of recharge wells effectively

THE POTENTIAL OF FOREST BUFFER TO PREVENT STREAM FROM WATER POLLUTANTS:A CASE STUDY IN GROJOKAN SEWU SUB-WATERSHED, KARANGANYAR DISTRICT, CENTRAL JAVA

Population growth leads to water scarcity in terms of both quality and quantity. Agricultural and urban watersheds potentially produce more pollutantsthan forested area. It is considered that forested area has potential in storing and protecting water supply in such a way that water distribution and quality can be guaranteed. The objective of  the study was to determine the relationship between the percentages of forested area in a watershed with the water quality. Thestudy was conducted in 2010in GrojokanSewu Sub-watershed, Karanganyar District, Central Java. Using GIS (Geographic Information System), this sub-watershedwas divided into four sub-sub-watershedswith different percentages of forested areas. Water samples were collected in each sub-sub-watershedto find out the relationship between the forested area and the total dissolvedsolids, turbidity, sodium, nitrite, nitrate, sulfate and organic matters. The statistical analysis indicates relationships in quadratic form between sodium, nitrite, TDS, sulfate and organic matters with the percentage of  forested area (R2=0.99, R2=0.99, R2=0.98, R2=0.95 and R2=0.77, respectively). The relationships are different from those of turbidity and nitrate that have low R2 (R2=0.28 and R2=0.36) values. It implies that the forested area is capable to reduce sodium, nitrite, TDS, sulfate and organic matters, and thus water pollutants can be reduced by forest formation as it can filter water through retention of sediments and nutrients

Teknik mitigasi:banjir dan tanah longsor

1+38hal.;21c

PROCEEDING SEMINAR ENERGI INDONESIA PERAN TEKNOLOGI INFORMASI DAN KOMUNIKASI UNTUK MENDUKUNG KEMANDIRIAN ENERGI

PROCEEDING SENENDO 201