Agromet
Not a member yet
291 research outputs found
Sort by
The Use of Dam Environmental Vulnerability Index (DEVI) for Assessing Vulnerability of Bengawan Solo Watershed, Indonesia
Full text linkBengawan Solo is the longest river in Java, but current conditions show that its watershed is in a critical condition. Deforestation was very intensive in the last three decades that contributed to degradation of the watershed. Other factor contributing to the degradation is dam construction. However, our knowledge on the impact of dam construction on the environment and its vulnerability is poorly understood. Here, we assessed vulnerability of the watershed based on physical properties such as existing dams, morpho-dynamic activities, and deforested area. The study aims to identify the vulnerability of the Bengawan Solo watershed based on dam environmental vulnerability index (DEVI) approach, and to analyse the dominant variable contributing to DEVI. For calculating DEVI, several data were needed including land cover, rainfall, stream water stage, soil type, stream network, and dams. The results showed that Bengawan Solo watershed had moderate to high vulnerability (60%). Moderate level was identified for Madiun and Wonogiri sub-watershed, while high level was in Cepu and Babat sub-watershed. Our findings revealed that morpho-dynamic activities as represented by sediment rate and stream water stage had contributed to the high DEVI value as in Cepu and Babat sub-watershed. Further, influence of dams in this research was not dominant implying that any improvement to the DEVI approach remains research challenges. The improvement of the approach is expected to better identify the impact of dam construction on environment, situated in other regions than Amazon, where it was firstly developed
Implementation of Bayesian Model Averaging Method to Calibrate Monthly Rainfall Ensemble Prediction over Java Island
Full text linkBayesian Model Averaging (BMA) is a statistical post-processing method for producing probabilistic forecasts from an ensemble prediction in the form of predictive Probability Density Function (PDF). BMA is commonly used to calibrate Ensemble Prediction System (EPS) in a shorter-range forecast. Here, we applied the BMA for a longer forecast at a seasonal interval. This study aimed to develop the implementation of the BMA method to calibrate the seasonal forecast (long range) of monthly rainfall from the RAW output of the EPS European Center for Medium-Range Weather Forecasts (ECMWF) system 4 model (ECS4). This model was calibrated with observational data from 26 stations over Java Island in 1981-2018. BMA predictive PDF was generated with a gamma distribution, which was obtained based on two training schemes, namely sequential (BMA-JTS) and conditional (BMA-JTC) training windows. Generally, both of BMA-JTS and BMA-JTC were able to produce better distribution characteristics of ensemble prediction than that of RAW model ECS4. Both BMA methods showed a good performance as indicated by a high accuracy, small bias, and small uncertainty to the observed rainfall. Our findings revealed that BMA-JTC was able to improve the quality of probabilistic forecasts of below and above normal events. The improvement was shown in most stations over Java Island, in which the model was a good skill forecast based on Brier Skill Score (BSS)
The Use of SST Anomaly to Predict Seasonal Rainfall during the Second Planting Period in the Tanoh Abee Irrigation Area, Aceh Besar
Full text linkIrrigation in Tanoh Abee is used for agricultural activities especially during the second planting season during dry season. However, the availability of irrigation water is controlled by total rainfall received. An accurate prediction of rainfall, which traditionally used “keneunong” local wisdom, is urgently required. The objective of the study is to obtain the best predictor of seasonal rainfall based on the Pacific sea surface temperature (SST) anomaly and the monthly lead time of prediction. We employed monthly rainfall from six stations surrounding the study area and combined with principal component analysis to eliminate rainfall autocorrelation. Seasonal rainfall (quarterly average) was calculated from monthly data. The results showed that 1-month lead time strongly correlated to seasonal rainfall in Tanoh Abee (r<-0.7, α=5%) for the second planting period. On other hand, the 2-month and 3-month lead time were useful to predict seasonal rainfall in March-April-May (MAM) only. For April-May-June (AMJ) and May-June-July (MJJ), the correlation between SST anomaly and seasonal rainfall was weak. This finding indicated that the accuracy of prediction decreases with the longer lead time. Based on our analysis, coordinates of 170° E – 175° E; 5° N - 5° S in Niño 4 region have strongly correlated with seasonal rainfall in MAM, AMJ, and MJJ periods. Moreover, further research is necessary to combine any approaches that will improve our prediction skill for another 2- or 3-month lead time
Effect of Rainfall Intensity on Glyphosate Herbicide Effectiveness in Controlling Ageratum conyzoides, Rottboellia exaltata, and Cyperus rotundus Weeds
Full text linkGlyphosate is one of herbicide active ingredient which is mostly used to control weeds in crops. However, in rain season herbicide effectiveness decreases as it is washed by rain. This research aimed to study effect of rainfall intensity on the effectiveness of herbicide (Round up 486 SL 2.5 l/ha.) with isopropilamina glyphosate as the active ingredient in controlling specific weeds Ageratum conyzoides, Rottboellia exaltata, and Cyperus rotundus. The experiment was consisted of six treatments and arranged in randomized block design with 8 replications. The treatments were level of rain intensity which were 5 mm/hour, 10 mm/hour, 20 mm/hour, 40 mm/hour, no rain and control (no herbicide no rain). Rainfall intensity was determined by conducting simulation trials prior to the treatments and applied 30 minutes after herbicide applications. The results showed that herbicide effectiveness decreased as the rainfall intensity incresed, even though with longer time the herbicide was still able to control the weeds. The effect of rainfall intensity on herbicide effectiveness was different for different weeds. Up to intensity 40 mm/hour herbicide was capable to control weeds but with level of weeds destruction 20-60%
Determinant Factors of Food Farming Vulnerability in Banten Province To Support Climate Change Adaptation
Full text linkFood crop is one of the most impacted agricultural sectors by climate related disaster. The negative impacts of climate related disaster could be assessed by its vulnerability level that depends on various indicators including exposure, sensitivity, and adaptive capacity. This paper aims to identify the determinant factors that influence the vulnerability of food farming based on the characteristics of land resources, climate and water, and socio-economic factors at the district level in Banten Province, and to develop recommendations on climate adaptation. Identification of the dominant factors, which most contribute to the level of vulnerability, is one of the main considerations to determine the strategy of adaptation. Our results showed that the main determinant factors varied among districts. The most important factors were Oldeman’s climate type (SEI12), the ratio of the number of extension agents to rice field area (ACI3), and the ratio of the number of farmer groups to rice field area (ACI4). SEI12 deals with the climate, whereas ACI3 and ACI4 are related human resources and institutions. Further, although urban area had high exposure and sensitivity as in rural area, but the adaptive capacity for the urban area was still high. Therefore, the level of vulnerability was reduced in urban, but still high in rural area. More efforts are expected to adapt climate related disaster in rural area.Food crop is one of the most impacted agricultural sectors by climate related disaster. The negative impacts of climate related disaster could be assessed by its vulnerability level that depends on various indicators including exposure, sensitivity, and adaptive capacity. This paper aims to identify the determinant factors that influence the vulnerability of food farming based on the characteristics of land resources, climate and water, and socio-economic factors at the district level in Banten Province, and to develop recommendations on climate adaptation. Identification of the dominant factors, which most contribute to the level of vulnerability, is one of the main considerations to determine the strategy of adaptation. Our results showed that the main determinant factors varied among districts. The most important factors were Oldeman’s climate type (SEI12), the ratio of the number of extension agents to rice field area (ACI3), and the ratio of the number of farmer groups to rice field area (ACI4). SEI12 deals with the climate, whereas ACI3 and ACI4 are related human resources and institutions. Further, although urban area had high exposure and sensitivity as in rural area, but the adaptive capacity for the urban area was still high. Therefore, the level of vulnerability was reduced in urban, but still high in rural area. More efforts are expected to adapt climate related disaster in rural area
The Efficiency of Water in Supporting Local Wisdom and Food Sustainability in Subak Sange, Bali Indonesia
Full text linkSubak is local wisdom in Bali that has been practiced for centuries in managing irrigation water. Here we present the uniqueness of Subak to manage water with an example of Subak Sange, Gianyar, Bali. The field activity was carried out from April-September 2019. The research objectives were to analyze: (i) the characteristics of local wisdom in Subak Sange, (ii) the effect of irrigation water frequency on pest and disease outbreaks on tobacco yield, and (iii) the efficiency of water use in chili-tobacco intercropping. We combined several approaches to achieve the objectives, including an interview with farmer, diversity analysis, Romijn method, and revenue cost ratio. The results showed that the harmony of relations between farmers was bound by a belief in three elements socio-agrarian-religious. The excessive irrigation gave more pest and disease outbreaks, as shown in 6-irrigation frequencies. In addition, the occurrence of rotten root outbreaks was the highest (29%). The optimal frequency irrigation for yield of tobacco was 4-times, which produced 11.5 tons of dry chopped tobacco per hectare, and this frequency irrigation was much more efficient water use by 79% than rice plants. Based on revenue cost ratio analysis, the chili-tobacco intercropping with four times irrigation was feasible. The findings indicate that management of irrigation water in Subak Sange is promising to support food sustainability in the region
Canopy Microclimate Modification with Reflective Mulches Under Oil Palm and Its Role to Soybean Growth
Full text linkLand utilization under oil palm plantation is constrained by the condition of low light intensities. Modification of the microclimate through the use of reflective mulch, as a reflector, will increase its ability to reflect the land surface radiation under the tree stand. This modification may suitable for intercropping system between soybean and oil palm. The study aimed to determine the effect of microclimate modification, using reflective mulch, under the stand of oil palm, and to evaluate its effect on soybean productivity. The research was conducted at PTPN-VIII Cimarga Banten using a nested random design with two factors and three replications each. The first factor is the oil palm age, which consists of: (i) control (open land), (ii) 4 years, (iii) 5 years, and (iv) 8 years age of oil palm. The second factor is the reflective mulch, as a solar radiation reflector, which consists of three levels: (i) without mulch (control), (ii) inorganic reflective mulch/silver black plastic mulch, and (iii) organic reflective mulch/dried oil palm leaves. The application of inorganic and organic reflective mulch increased the distribution of reflected land surface radiation (59%-157%), reduced the soil temperature fluctuation (0.30C-1.20C), and maintained soil water content (45.2%-45.8%). An increased of plant growth rates (56%-86%), relative growth rates (16%-21%), and seed weight production per plant (74.8%-86.2%) also reported, as well as the reduction of the etiolation ratio (9.6%-12.5%). The use of organic and inorganic reflective mulches can improve the microclimate and increase the production of soybean under intercopping system with oil palm.Land utilization under oil palm plantation is constrained by the condition of low light intensities. Modification of the microclimate through the use of reflective mulch, as a reflector, will increase its ability to reflect the land surface radiation under the tree stand. This modification may suitable for intercropping system between soybean and oil palm. The study aimed to determine the effect of microclimate modification, using reflective mulch, under the stand of oil palm, and to evaluate its effect on soybean productivity. The research was conducted at PTPN-VIII Cimarga Banten using a nested random design with two factors and three replications each. The first factor is the oil palm age, which consists of: (i) control (open land), (ii) 4 years, (iii) 5 years, and (iv) 8 years age of oil palm. The second factor is the reflective mulch, as a solar radiation reflector, which consists of three levels: (i) without mulch (control), (ii) inorganic reflective mulch/silver black plastic mulch, and (iii) organic reflective mulch/dried oil palm leaves. The application of inorganic and organic reflective mulch increased the distribution of reflected land surface radiation (59%-157%), reduced the soil temperature fluctuation (0.30C-1.20C), and maintained soil water content (45.2%-45.8%). An increased of plant growth rates (56%-86%), relative growth rates (16%-21%), and seed weight production per plant (74.8%-86.2%) also reported, as well as the reduction of the etiolation ratio (9.6%-12.5%). The use of organic and inorganic reflective mulches can improve the microclimate and increase the production of soybean under intercopping system with oil palm
Analysis of Synoptic Disturbance in Maritime Continent Using Spherical Harmonics Transformation Method
Full text linkThis study aims to modify the idea of WK99-analyzing the existence of signature in wave-number and frequency spectrum when the analyzed Outgoing Longwave Radiation (OLR) data is associated with a unique phenomenon in Maritime Continent (MC), Borneo vortex (BV). Although BV is often related to easterly equatorial wave disturbances, there was no specific study to examine its behavior in the spectral domain. The purpose of this study is to develop a method to diagnose certain signatures of BV through spectrum analysis of OLR data when BV occurs.
In contrast to previous studies, to present the unique phenomenon in MC as a target for diagnostics, spectrum analysis is performed by Spherical Harmonics (SH). The results of the OLR data spectrum comparison when BV occurs with the OLR data spectrum when BV does not occur that in the anti-symmetrical component when BV occurs, the tropical depression-mixed Rossby gravity (TD-MRG) wave spectrum is stronger, especially in zonal wave-numbers 5 to 10 and frequencies 0.12 to 0.2. Similar to the anti-symmetrical component, the TD-MRG spectrum of the symmetrical component is also stronger at zonal wave-numbers 5 to 10 and frequencies 0.12 to 0.2. Moreover, the westward-propagating inertio-gravity (WIG) wave spectrum in the symmetrical component is also stronger at the time of BV than when there is no BV, especially at zonal wave-numbers 7 to 13 and frequencies 0.38 to 0.5. It can be concluded that when BV occurs, equatorial waves that propagate to the west, especially the types of TD-MRG and WIG waves are stronger than when BV did not occur. The results of durational grouped spectrum analysis of OLR data when BV occurs indicate that the longer the duration of BV occurs, the stronger the spectrum of TD-MRG and WIG wave types gets.This study aims to modify the idea of WK99-analyzing the existence of signature in wavenumber and frequency spectrum when the analyzed Outgoing Longwave Radiation (OLR) data is associated with a unique phenomenon in Maritime Continent (MC), Borneo vortex (BV). Although BV is often related to easterly equatorial wave disturbances, there was no specific study to examine its behavior in the spectral domain. The purpose of this study is to develop a method to diagnose certain signatures of BV through spectrum analysis of OLR data when BV occurs. In contrast to previous studies, to present the unique phenomenon in MC as a target for diagnostics, spectrum analysis was performed by Spherical Harmonics (SH). This method used trigonometric and associated Legendre functions which present zonal and meridional structure, respectively. Hence, the separation of antisymmetric and symmetric patterns to the equator in this method was considered better than WK99. The results showed that the spectral signatures of BV were characterized by enhancements of westward propagating mixed Rossby gravity (MRG) with zonal wavenumbers of 5-10 and frequencies of 0.12-0.2 cycle per day (cpd) (periods of 5-8 days). Moreover, the spectrum of the wave is getting stronger for longer BV duration
Modeling of Heavy Rainfall Triggering Landslide Using WRF Model
Full text linkThis study revealed the behavior of heavy rainfall before landslide event based on the Weather Research Forecasting (WRF) model. Simulations were carried out to capture the heavy rainfall patterns on 27 November 2018 in Kulonprogo, Yogyakarta. The modeling was performed with three different planetary boundary layer schemes, namely: Yonsei University (YSU), Sin-Hong (SH) and Bougeault and Lacarrere (BL). Our results indicated that the variation of rainfall distribution were small among schemes. The finding revealed that the model was able to capture the radar’s rainfall pattern. Based on statistical metric, WRF-YSU scheme was the best outperforming to predict a temporal pattern. Further, the study showed a pattern of rainfall development coming from the southern coastal of Java before 13:00 LT (Local Time=WIB=UTC+7) and continued to inland after 13:00 LT. During these periods, the new clouds were developed. Based on our analysis, the cloud formation that generated rainfall started at 10:00 LT, and hit a peak at 13:00 LT. A starting time of cloud generating rainfall may be an early indicator of landslide.This study revealed the behavior of heavy rainfall before landslide event based on the Weather Research Forecasting (WRF) model. Simulations were carried out to capture the heavy rainfall patterns on 27 November 2018 in Kulonprogo, Yogyakarta. The modeling was performed with three different planetary boundary layer schemes, namely: Yonsei University (YSU), Sin-Hong (SH) and Bougeault and Lacarrere (BL). Our results indicated that the variation of rainfall distribution were small among schemes. The finding revealed that the model was able to capture the radar’s rainfall pattern. Based on statistical metric, WRF-YSU scheme was the best outperforming to predict a temporal pattern. Further, the study showed a pattern of rainfall development coming from the southern coastal of Java before 13:00 LT (Local Time=WIB=UTC+7) and continued to inland after 13:00 LT. During these periods, the new clouds were developed. Based on our analysis, the cloud formation that generated rainfall started at 10:00 LT, and hit a peak at 13:00 LT. A starting time of cloud generating rainfall may be an early indicator of landslide
The Effect of Car Free Day (CFD) on Pollutant Emissions at Alternative Roads (Case Study: RE Martadinata Street, Bogor City)
Full text linkCar Free Day (CFD) is a social campaign aimed to reduce the dependence of people on vehicle uses, which occurs once per week in Bogor. The idea intends to decrease the vehicle emissions. However, CFD is often to cause a new problem like the congestions, which are found on the nearby alternative roads, as happened in RE Martadinata Street, Bogor City. This study aims to compare the emission load and the concentrations of pollutants in ambient air during CFD (06.00-09.00 am) and non-CFD days in alternative road. We measured the following pollutants: CO, HC, NOx, PM10 and SO2. This research first applied Fixed-Box Model to estimate concentration of pollutants, then we used the Finite Length Line Source (FLLS) to estimate dispersion of pollutants. The results showed that there was no substantial difference in pollutant emissions between CFD and non-CFD days. But if we separate between weekdays and weekend, our analysis revealed that emissions during the weekend are bigger than that of weekdays. This was consistent with an increase of number of vehicles during the weekends by 17.2%. Based on our analysis, motorcycle contributes to an increased of CO, HC, PM10 pollutants, whereas SO2 and NOx pollutants were generated by cars. Our findings suggest that a short time of CFD does not contribute a lot to reduce the emissions