• Journal of Korean Society of Forest Science
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• v.84 no.4
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• pp.502-516
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• 1995

The objective of this study was to estimate throughfall, stemflow, interception loss and net rainfall in relation to rainfall interception, and to understand the factors affecting interception process at Pinus taeda stand and Pinus densiflora stand in the Research Forests of Seoul National University, located in Choosan, Kwangyang, Chollanamdo. 1. The gross rainfall during the period of field observation was 3,107.6mm(average 1,035.9mm/year). Most of the daily rainfall intensity was under 30mm, which was 90% in 1992, 81% in 1993 and 88% in 1994. 2. In this study the throughfall, stemflow, interception loss and net rainfall were expressed separately as a function of gross rainfall. The overall throughfall collected during the period of field observation was 2,432.5mm(78.3%) at Pinus taeda stand and 2,699.6mm at Pinus densiflora stand, out of total rainfall of 3107.6mm. The canopy storage capacity, which was determined by the prediction equation between gross rainfall and throughfall was 1.1mm at Pinus taeda stand and 1.3mm at Pinus densiflora stand. 3. The sums of stemflow from measurement of total rainfall at Pinus taeda stand and Pinus densiflora stand was 227.3mm(7.3%) and 62.7mm(2.0%), respectively. The minimum rainfall causing stemflow was estimated as 7.2mm at Pinus taeda stand and 1.9mm at Pinus densiflora stand. 4. Interception loss accounted for 447.8mm(14.4%) at Pinus taeda stand and 345.3mm(11.1%) at Pinus densiflorra stand. 5. Net rainfall was 2,659.8mm(85.6%) at Pinus taeda stand and 2,762.3mm(88.9%) at Pinus densiflora stand. 6. The rates of throughfall and stemflow increased with increasing the gross rainfall. However, the amounts of throughfall and the stemflow were constant above 30mm at Pinus taeda stand and 50mm at Pinus densiflora stand. The rates of interception loss decreased with increasing the gross rainfall. However, the amount of interception loss was constant above 50mm at Pinus taeda stand and Pinus densiflora stand.

• Journal of Korean Society on Water Environment
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• v.20 no.5
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• pp.415-421
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• 2004

Litter wastes on highway runoff are gradually being considered one of the major pollutants of concern in protecting the integrity of receiving waters for beneficial use. The California State Water Resources Control Board has identified in their 303(d) list at least 36 water bodies where trash or litter is considered a pollutant of concern. The first TMDL adopted by the Region 4 (Los Angeles area) of the California State Water Quality Control Board was for trash in the Los Angeles River. The first flush characteristic study was developed to obtain first flush water quality and litter data from representative stormwater runoff from standard highway drainage outfalls in the Los Angeles area. Total captured gross pollutants in stormwater runoff were monitored at six Southern California highway sites over two years. The gross pollutants were 90% vegetation and 10% litter. Approximately 50% of the litter was composed of biodegradable materials. The event mean concentrations show an increasing trend with antecedent dry days and a decreasing trend with total runoff volume or total rainfall. Event mean concentrations were ranged 0.0021 to 0.259g/L for wet gross pollutants and 0.0001 to 0.027g/L for wet litters. The first flush phenomenon was evaluated and the impacts of various parameters such as rainfall intensity, drainage area, peak flow rate, and antecedent dry period on litter volume and loading rates were evaluated. First flush phenomenon was generally observed for litter concentrations, but was not apparent with litter mass loading rates. Litter volume and loading rates appear to be directly related to peak storm intensity, antecedent dry days and total flow volume.

• Korean Journal of Environment and Ecology
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• v.12 no.3
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• pp.259-270
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• 1998

This study, as an essential research to develope a mountainous runoff model, was conducted to clarify the hydrologic character and water budget equation of Pinus densiflora and Quercus acutissima. Net rainfall quantity division for two species was investigated at Youngsung experiment forest and Yeungnam University for 30 months(Sep. 1995-Jun. 1998). The results were summarized as follows; 1. The percentages of throughfall and stemflow to gross precipitation are 73.8% and 0.8% in the Pinus densiflora, and 76.9% and 3.8% in the Quercus acutissima, respectively 2. In the Pinus densiflora, regression fomula of stemflow, throughfall, and net rainfall to gross precipitation are S$_{f}$ = 0.01GP-2.05 ($r^2$=0.54) T$_{f}$ = 0.79Gp - 26.04 ($r^2$=0.92), N$_{r}$ = 0.81Gp - 28.09 ($r^2$=0.92). Stemflow and throughfall increased in direct proportion to gross precipitation. 3. In the Quercus acutissima, regression fomula of stemflow, throughfall, and net rainfall to gross precipitation are S$_{f}$ = 0.03Gp + 12.25 ($r^2$=0.74), T$_{f}$ = 0.78Gp + 19.75 ($r^2$=0.96), N$_{r}$ = 0.81Gp + 3199 ($r^2$=0.96), respectively. Comparing with two species, gross precipitation has a much larger effect on the stemflow and throughfall of Quercus acutissima than those of Pinus densiflora. 4. In the analysis of intercorrelation between stemflow and throughfall of each species and crown area(CA), diameter at breast height(DBH), and gross precipitation(Gp), correlation coefficient was higher by following order at each species; Gp>CA>DBH on stemflow of Pinus densinora, Gp>DBH>CA on stemflow of Quercus acutissima, and Gp>CA>DBH on throughfall of Pinus densiflora and Quercus acutissima.ssima.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.41-44
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• 2002

It is unreasonable to calculate the amount of agricultural water use by applying unit demand method, because it is different from other water use due to the return flow and reuse in the recycle of watershed. Data from irrigation pumping station and reservoir were analysed. Factors for water balance are precipitation, evapotranspiration, percolation, runoff, and management loss, etc. Here in the study, the amount of agricultural water was defined in the way of three different categories. First one is "Gross water" including evapotranspiration, percolation, and management loss. Second one is "Agricultural water" including Gross water and effective rainfall. Third one is "Broad water" which is abstracting the return flow from Agricultural water.

• Journal of Korea Water Resources Association
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• v.43 no.11
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• pp.995-1009
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• 2010

Accelerated soil erosion due to extreme climate change, such as increased rainfall intensity, and human-induced environmental changes, is a widely recognized problem. Existing soil erosion models are generally based on the gross erosion concept to compute annual upland soil loss in tons per acre per year. However, such models are not suitable for event-based simulations of erosion and deposition in time and space. Recent advances in computer geographic information system (GIS) technologies have allowed hydrologists to develop physically based models, and the trend in erosion prediction is towards process-based models, instead of conceptually lumped models. This study aims to propose an effective and robust distributed rainfall-sediment yield-runoff model consisting of basic element modules: a rainfall-runoff module based on the kinematic wave method for subsurface and surface flow, and a runoff-sediment yield-runoff model based on the unit stream power method. The model was tested on the Cheoncheon catchment, upstream of the Yongdam dam using hydrological data for three extreme flood events due to typhoons. The model provided acceptable simulation results with respect to both discharge and sediment discharge even though the simulated sedigraphs were underestimated, compared to observations. The spatial distribution of erosion and deposition demonstrated that eroded sediment loads were deposited in the cells along the channel network, which have a short overland flow length and a gentle local slope while the erosion rate increased as rainfall became larger. Additionally, spatially heterogeneous rainfall intensity, dependant on Thiessen polygons, led to spatially-distinct erosion and deposition patterns.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.518-518
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• 2016

Agriculture is the lifeblood of the economy in Ghana, employs about 42% of the population work force and accounts for 30% of the Gross Domestic Product (GDP). Corn (maize) is the major cereal crop grown as staple food under rain fed conditions, covers over 92% of the total agricultural area, and contributes 54% of the caloric intake. Issues of hunger and food insecurity for the entire nation are associated with corn scarcity and low production. The climate changes are expected to affect corn production in Ghana. This study evaluated variations of corn yields based on different climate conditions of rain-fed area in the Dangbe East District of Ghana. AquaCrop model has been used to simulate corn growing cycles in study area for this purpose. The main goal for this study was to predict yield of corn using selected climatic parameters from 1992 to 2013 using different climate scenarios. The Model was calibrated and validated using observed field data, and the simulated grain yields matched well with observed values for the season under production giving an R squared (R2)of 0.93 and Nash-Sutcliff Error(NSE) of 0.21. Study results showed that rainfall reduction in the range of -5% to -20% would reduce the yield from 1.315ton/ha to 0.421ton/ha (-21. 3%) whereas increasing temperature from 1% to 7% would result in the maximum yield reduction of -20.6% (1.315 to 1.09 ton/ha.). On the other hand, increasing rainfall from 5-20% resulted in yield increment of 68% (1.315-2.209 ton/ha) and decreasing temperature produce 7% increase in yield ( 1.315 to 1.401ton/ha). These results provide useful information to adopt strategies by the Government of Ghana and farmers for improving national food security under climate change.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.219-227
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• 1996

Since the introduction of animal traction technologies(ATT) in many Sub Saharan Africa (SSA) countries, attempts to propagate its widespread use in the continent have suffered several setbacks. Many factors are responsible of this. However, developments in the African economies are believed to be a prominent factor. This study provides empirical evidence of the impact of economic growth on the performance of ATT-in Sub-Saharan Africa(SSa). The analysis uses 1971-1990 time-series data on ATT from botswana. The performance of ATT is measured on the basis of changes year covered under this study. The models used, are a regression model and a trend projection model. Although the regression model is representing a simplified view of the relationship between ATT and economic growth , it takes account of the influence of annual amounts of rainfall. It is concluded that economic growth has had a negative impact on the performance of ATT in Botwana. As the country's Gross Domestic Pro uct (GDP) steadily increased over the period of the analysis, the number of households using ATT declined at a rate of 2.5% per year. The impact of the GDP on ATT was directly associated with increases in the use of tractor, food imports and beef exports. The results have serious policy implications for agricultural development in many African countries that are not capable of sustaining their economic growth.

• International Journal of Computer Science & Network Security
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• v.23 no.9
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• pp.17-28
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• 2023

Today Agriculture segment is a significant supporter of Indian economy as it represents 18% of India's Gross Domestic Product (GDP) and it gives work to half of the nation's work power. Farming segment are required to satisfy the expanding need of food because of increasing populace. Therefore, to cater the ever-increasing needs of people of nation yield prediction is done at prior. The farmers are also benefited from yield prediction as it will assist the farmers to predict the yield of crop prior to cultivating. There are various parameters that affect the yield of crop like rainfall, temperature, fertilizers, ph level and other atmospheric conditions. Thus, considering these factors the yield of crop is thus hard to predict and becomes a challenging task. Thus, motivated this work as in this work dataset of different states producing different crops in different seasons is prepared; which was further pre-processed and there after machine learning techniques Gradient Boosting Regressor, Random Forest Regressor, Decision Tree Regressor, Ridge Regression, Polynomial Regression, Linear Regression are applied and their results are compared using python programming.

• Korean Journal of Environmental Agriculture
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• v.30 no.3
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• pp.268-274
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• 2011

BACKGROUND: A large scale of sediment load delivered from watershed causes substantial waterway damages and water quality degradation. Controlling sediment loading requires the knowledge of the soil erosion and sedimentation. The various factors such as watershed size, slope, climate, land use may affect sediment delivery processes. Traditionally sediment delivery ratio prediction equations have been developed by relating watershed characteristics to measured sediment yield divided by predicted gross erosion. However, sediment prediction equations have been developed for only a few regions because of limited sediment data. Besides, little research has been done on the prediction of sediment delivery ratio for asia monsoon period in mountainous watershed. METHODS AND RESULTS: In this study Tank model was expanded and applied for estimating sediment yield to Oship River of east coast. The rainfall-runoff in 2006 was verified using the Tank model and we derived good result between observed and calculated discharge in 2009 at the same conditions. In relation to sediment yield, the sediment delivery rate of 2006 was very high than 2009 regardless of methods for estimating sediment load. It was thought to be affected by heavy rainfall due to the typhoon. CONCLUSION(s): For estimating sediment volume from watershed, long-term monitoring data on discharge and sediment is needed. This model will be able to apply to predict discharge and sediment yield simultaneously in ungauged area. This approach is more effective and less expensive method than the traditional method which needs a lot of data collection.

• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.3
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• pp.59-73
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• 2021

The purpose of this study is to investigate transition of pumping technology, irrigation water requirement, and unit area drainage discharge at the Pumping station-based Irrigation Associations (PIAs) in South Korea during Japanese colonial period (1910-1945). The PIAs established pumping stations and embankments along rivers for the purpose of irrigation, drainage and flood prevention until the mid-1920s. From the late 1920s after major river improvement projects, newly established PIAs did not include the flood prevention in their purpose of establishment. The design criteria of the irrigation and drainage projects, such as irrigation water requirements, design rainfall, and allowable ponding duration were decided according to the circumstances of PIAs. The gross irrigation water requirement of paddy fields increased from the 1920s to the 1940s, and reached the level of 0.0020 m³/s/ha (19 mm/d) in the 1940s for the fairly good irrigation status in the drought. The great floods of 1930, 1933, and 1934 triggered the increase in drainage discharge in the late 1930s, leading to the unit area drainage discharge of 0.9-2.6 m³/s/km² for natural drainage and 0.3-1.1 m³/s/km² for pump drainage. Therefore, several PIAs near the major rivers could avoid repetitive floods damage.