• Journal of Wetlands Research
• /
• v.25 no.4
• /
• pp.297-305
• /
• 2023

The recycled irrigation is a type of irrigation that uses downstream water to fulfill irrigation demand in the upstream agricultural areas; the used irrigation water returns back to the downstream. The recycled irrigation is advantageous for securing irrigation water for plant growth, but the returned water typically contains high levels of nutrients due to excess nutrients inputs during the agricultural activities, potentially deteriorating stream water quality. Therefore, quantitative assessment on the effect of the recycled irrigation on the stream water quality is required to establish strategies for effective irrigation water supply and water quality management. For this purpose, a watershed model is generally used; however no functions to simulate the effects of the recycled irrigation are provided in the existing watershed models. In this study, we used multi-reservoir model coupled with the Hydrological Simulation Program-Fortran (HSPF) to estimate the effect of the recycled irrigation on the stream water quality. The study area was the Gwangok stream watershed, a subwatershed of Gyeseong stream watershed in Changnyeong county, Gyeongsangnam-do. The HSPF model was built, calibrated, and used to produce time series data of flow and water quality, which were used as hypothetical observation data to calibrate the multi-reservoir model. The calibrated multi-reservoir model was used for simulating the recycled irrigation. In the multi-reservoir model, the Gwangok watershed consisted of two subsystems, irrigation and the Gwangok stream, and the reactions (plant uptake, adsorption, desorption, and decay) within each subsystem, and fluxes of water and materials between the subsystems, were modeled. Using the developed model, three scenarios with different combinations of the operating conditions of the recycled irrigation were evaluated for their effects on the stream water quality.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.54 no.2
• /
• pp.37-46
• /
• 2012

The change of rainfall pattern and hydrologic factors due to climate change increases the occurrence probability of agricultural reservoir water shortage. Water supply assessment of reservoir is usually performed current reservoir level compared to historical water levels or the simulation of reservoir operation based on the water budget analysis. Since each reservoir has the native property for watershed, irrigation district and irrigation water requirement, it is necessary to improve the assessment methods of agricultural reservoir water capability about water resources system. This study proposed a practical methods that water supply vulnerability assessment for an agricultural reservoir based on a concept of probabilistic reliability. The vulnerability assessment of water supply is calculated from probability distribution of water demand condition and water supply condition that influences on water resources management and reservoir operations. The water supply vulnerability indices are estimated to evaluate the performance of water supply on agricultural reservoir system, and thus it is recommended a more objective method to evaluate water supply reliability.

• Environmental Engineering Research
• /
• v.11 no.4
• /
• pp.194-200
• /
• 2006

Recently, the population growth, industrial and agricultural development are rapidly undergoing in the Lower Rio Grande Valley (LRGV) in Texas. The Lower Rio Grande Valley (LRGV) composed of the 4 counties and three of them are interesting for Non-point and point source pollutant modeling: Starr, Cameron, and Hidalgo. Especially, the LRGV is an intensively irrigation region, and Texas A&M University Agriculture Program and the New Mexico State University College of Agriculture applied irrigation district program, projects in GIS and Hydrology based agricultural water management systems and assessment of prioritized protecting stream network, water quality and rehabilitation based on water saving potential in Rio Grande River. In the LRGV region, where point and non-point sources of pollution may be a big concern, because increasing fertilizers and pesticides use and population cause. This project objective seeks to determine the accumulation of non-point and point source and discuss the main impacts of agriculture and environmental concern with water quality related to pesticides, fertilizer, and nutrients within LRGV region. The GIS technique is widely used and developed for the assessment of non-point source pollution in LRGV region. This project shows the losses in $kg/km^2/yr$ of BOD (Biological Oxygen Demand), TN (total Nitrogen) and TP (total phosphorus) in the runoff from the surface of LRGV. Especially, farmers in Cameron County consume a lot of fertilizer and pesticide to improve crop yield net profit. Then, this region can be created as larger nonpoint source area for nutrients and the intensity of runoff by excess irrigation water. And many sediment and used irrigation water with including high nutrients can be discharged into Rio Grade River.

• Korean Journal of Agricultural Science
• /
• v.50 no.4
• /
• pp.903-916
• /
• 2023

This study aims to establish basic data for efficient management of rural water by analyzing regional irrigation facilities and benefitted areas in the statistical yearbook of land and water development for agriculture at the watershed level. For 511 domestic rural water use areas, water storage facilities (reservoirs, pumping & drainage stations, intake weirs, infiltration galleries, and tube wells) are spatially distributed, and the benefitted areas provided at the city/county level are divided by water use area to provide agricultural water supply facilities. The characteristics of rural water district areas such as benefitted area, were analyzed by basin. The average area of Korea's 511 rural water districts is 19,638 ha. The average benefitted area by rural water district is 1,270 ha, with the Geum River basin at 2,220 ha and the Yeongsan River basin at 1,868 ha, which is larger than the overall average. The Han River basin at 807 ha, the Nakdong River basin at 1,121 ha, and the Seomjing River basin at 938 ha are smaller than the overall average. The results of this basic analysis are expected to be used to set the direction of various supply and demand management projects that take into account the rational and scientific use and distribution of rural water and the characteristics of water use areas by presenting a quantitative definition of Korea's agricultural water districts.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.18 no.3
• /
• pp.4195-4205
• /
• 1976

The purpose of this study is to evaluate the existing methods for calculating or estimating the consumptive use (Evaportranspiration) of any agricutural development project area. In determing the consumptive use water in the project area, there will require the best way for estimating irrigation requirement. Many methods for computing the evaportranspiration have been used, each of them with its merits and demerits at home and abroad. Some of these methods are listed as follows: 1.The Penman's formula 2.The B1aney-Criddle method 3.The Munson P.E. Index method 4.The Atmometer method 5.The Texas Water Rights Commission (TWRC) method 6.The Jensen-Haise method 7.The Christiasen method Therefore, the authors will introduce the more widely used method for calculating Consumptive Use by G.H. Hargreaves. The formula is expressed in the form Ep= K·d·T (1.0-0.01·Hn) Hn=1.0+0.4H+0.005H2. This method was adopted for the first time to determine the Irrigation requirements of Ogseo Comprehensive Agricultual Development project (Benefited area:100,500ha) in Korea. This method is presented in somewhat greater detail than the others. Formula is given for the computation of evaportranspiration (with various levels of data availability) Sampel computation of irrigation requirements for Ogseo irrigation project is included. The results and applied materials are summarized as follows. 1. In calculating the Hargreaves formula, the mean temperature relative, humidity, length of day, and percentage of sunshine from three stations of Iri, Jeonju, and Gunsan were used. 2. Monthly evaporation values were calculated by using the formula. 3. Meteological data from the three stations records for the ten years (1963∼1972) were used. 4. The annual irrigation requirements is 1,186mm per hectare, but the case to consider effective rainfall amount takes the annual irrigation demand being 700mm per hectare.

• Environmental Engineering Research
• /
• v.18 no.2
• /
• pp.85-90
• /
• 2013

This study is an attempt to quantify rainwater utilization and miscellaneous water demand in Tokyo's 23 special wards, the core of the urban area in Tokyo, Japan, in order to elucidate the potential of further rainwater utilization. The rainwater utilization for miscellaneous appropriate water demands, including toilet flushing, air conditioning, and garden irrigation, were calculated for six different types of building: residential house, office, department store, supermarket, restaurant, and accommodation. Miscellaneous water demands in these different types of building were expressed in terms of equivalent rainfall of 767, 1,133, 3,318, 1,887, 16,574, and 2,227 (mm/yr), respectively, compared with 1,528 mm of Tokyo's average annual precipitation. Building types, numbers and its height were considered in this study area using geographic information system data to quantify miscellaneous water demands and the amount of rainwater utilization in each ward. Area precipitation-demand ratio was used to measure rainwater utilization potential for miscellaneous water demands. Office and commercial areas, such as Chiyoda ward, showed rainwater utilization potentials of <0.3, which was relatively low compared to those wards where many residential houses are located. This is attributed to the relatively high miscellaneous water demand. In light of rainwater utilization based on building level, the introduction of rainwater storage mechanisms with a storage depth of 50 mm for six different types of buildings was considered, and calculated as rainfall of 573, 679, 819, 766, 930, and 787 (mm), respectively. Total rainwater utilization using such storage facilities in each building from 23 wards resulted in the retention of 102,760,000 $m^3$ of water for use in miscellaneous applications annually, and this volume corresponded to 26.3% of annual miscellaneous water demand.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.47 no.3
• /
• pp.15-25
• /
• 2005

Ninety tow percent of over 1,800 gate controlled dams in Korea are classified as small dams. The primary purpose of these small dams is to supply irrigation water. Therefore, while large dams can store as much as 80 percent of precipitation and thus are efficient to control flood, small dams are often lack of flood control function resulting in increased susceptibility drought and flood events. The purpose of this study is to develope a storage management model for irrigation dams occupying the largest portion of small dams. The proposed Storage Management Model (STMM) can be applied to the Seongju dam for efficient management. Besides, the operation standard is capable of analyzing additional available water, considering water demand and supply conditions of watershed realistically. And the model can improve the flood control capacity and water utilization efficiency by the flexible operation of storage space. Consequently, if the small dams are managed by the proposed Storage management model, it is possible to maximize water resources securance and minimize drought and flood damages.

• Journal of Korean Society on Water Environment
• /
• v.35 no.2
• /
• pp.131-144
• /
• 2019

Climate Change affects the hydrological cycle in agricultural watersheds through rising air temperature and changing rainfall patterns. Agricultural watersheds in Korea are characterized by extensive paddy fields and intensive water use, a resource that is under stress from the changing climate. This study analyzed the effects of climate change on river flows for Geum Cheon and Eun-San Choen watershed using STREAM, a semi-distributed watershed model. In order to evaluate the performance and improve the reliability of the model, calibration and validation of the model was done for one flow observation point and three reservoir water storage ratio points. Climate change scenarios were based on RCP data provided by the Korea Meteorological Administration (KMA) and bias corrections were done using the Quantile Mapping method to minimize the uncertainties in the results produced by the climate model to the local scale. Because of water mass-balance, evapotranspiration tended to increase steadily with an increase in air temperature, while the increase in RCP 8.5 scenario resulted in higher RCP 4.5 scenario. The increase in evapotranspiration led to a decrease in the river flow, particularly the decrease in the surface runoff. In the paddy agricultural watershed, irrigation water demand is expected to increase despite an increase in rainfall owing to the high evapotranspiration rates occasioned by climate change.

• Journal of Korea Water Resources Association
• /
• v.50 no.7
• /
• pp.503-511
• /
• 2017

In order to estimate the demand for water resources planning and operation, methodology for determining the size of water supply facilities has been mainly applied to agricultural water, unlike living and industrial water, which reflects actual usage trends. This inevitably leads to an overestimation of agricultural water and can lead to an imbalance in the supply and demand of each use in terms of the total water resources plan. In this study, the difference of approaches of concept of net consumption was examined in comparison with the existing methodology and the characteristics of agricultural water demand were analyzed by applying it to whole Jeju Island. SWAT model was applied to estimate the amount of evapotranspiration, which is a key factor in estimating demand, and watershed modeling was performed to reflect geographical features, weather, runoff and water use characteristics of Jeju Island. For the past period (1992~2013), demand of Jeju Island as a whole was analyzed as 427 mm per year, and it showed a relatively high demand around the eastern and western coastal regions. Annual demand and seasonal variation characteristics of 10 river basins with watershed area of $30km^2$ or more were also analyzed. In addition, by applying the cultivated area of each crop in 2020 in the future, it is estimated that the demand corresponding to the 10-year frequency drought is 54% of the amount demanded in the previous research. This is due to the difference in approach depending on the purpose of the demand calculation. From the viewpoint of water resource management and operation, additional demand is expected as much as the net consumption. However, from the actual supply perspective, it can be judged that a facility plan that meets the existing demand amount is necessary. In order to utilize the methodologies and results presented in this study in practice, it is necessary to make a reasonable discussion in terms of policy and institutional as well as engineering verification.

• Journal of Food Hygiene and Safety
• /
• v.32 no.5
• /
• pp.396-403
• /
• 2017

The purpose of this study was to investigate water quality for irrigation water used in Napa cabbage cultivation. The water samples were analyzed for physiochemical and microbiological quality for a total of 111 samples including surface water (n = 75) and groundwater (n = 36) collected from five different regions where Napa cabbage is massively grown. As a conclusion, the levels of fecal indicators for surface water were higher than those for groundwater. The numbers of coliform from surface water and groundwater were 1.96-4.96 and 0-3.98 log MPN/100 mL, respectively. Enterococci were detected in 95% (72/75) of surface water samples and 22% (8/36) of groundwater samples. Besides, 97% (73/75) of surface water samples were observed being contaminated with Escherichia coli, and 22% (8/36) of groundwater sample was positive for E. coli. In the case of surface water, E. coli and coliform correlate to T-P, and enterococci showed relevance to the suspended solid (SS) and biochemical oxygen demand (BOD). In groundwater, fecal indicator bacteria showed relevance to the SS and chemical oxygen demand (COD). These results could be provided as fundamental date for establishing microbial standard of water used in leafy vegetables cultivation.