구자웅 Koo Ja Woong , 손재권 Son Jae Gwon , 조재영 Cho Jae Young

DOI: JKWST Vol.48(No.2) 3-9, 2006

---

The chemical fractions of phosphorus were investigated in the soils of reclaimed and natural tidelands of southwest coastal area of Korea. The content of total-P varied to ranged from 322 to 614 mg/kg dry weight with a mean value of 467 mg/kg. The order of different fractions of phosphorus in reclaimed tideland soils was as follows: 1) inorganic phosphorus: Ca-P > Fe-P > Al-P > reductant soluble Fe-P. 2) organic phosphorus: Inositol-P > nucleic acid-P > phospholipid-P. The content of Al-P showed negative correlation with organic matter content but showed positive correlation with pH. The content of Fe-P showed negative correlation with clay mineral content but showed positive correlation with organic matter content. Reductant soluble Fe-P and Ca-P were no correlation with soil properties. The content of inositol-P showed highly positive correlation with clay mineral, organic matter content, and CEC.

이주용 Joo Yong Lee , 김선주 Sun Joo Kim , 김필식 Phil-shik Kim

DOI: JKWST Vol.48(No.2) 13-23, 2006

---

In Korea, upland irrigation generally depends on the ground water or natural rainfall since irrigation water supplied from dams is mainly used for paddy irrigation, and only limited amount of irrigation water is supplied to the upland area. For the stable security of upland irrigation water, storage level of irrigation dams was simulated by the periods. A year was divided into 4 periods considering the irrigation characteristics. Through the periodical management of storage level, water utilization efficiency in irrigation dams could be enhanced and it makes available to secure extra available water from existing dams without new development of water resources. Two study areas, Seongju and Donghwa dam, were selected for this study. Runoff from the watersheds was simulated by the modified tank model and the irrigation water to upland crops was calculated by the Penman-Monteith method. The analyzed results showed that relatively sufficient extra available water could be secured for the main upland crops in Seongju area. In case of Donghwa area, water supply to non-irrigated upland was possible in normal years but extra water was necessary in drought years such as 1998 and 2001.

김필식 Kim Phil Shik , 김선주 Kim Sun Joo

DOI: JKWST Vol.48(No.2) 27-35, 2006

---

Large dams are managed with operation standard and flood forecasting systems, while small dams do not have management method generally. Shortage of water resources and natural disasters due to drought and flood raised public concerns for management of small dams. Most of small dams are irrigation dams, which need diversified water uses. However, the lack of systematic management of small dams have caused serious water wastage and increased natural disasters. Storage management method and system were developed to solve these problems in small dams. The system was applied to Seongju dam for effective management. The storage management method was established considering hydrology simulation and statistical analysis using the system. This method can bring additional available water, even in the same conditions of the water demand and the supply conditions of watershed. It can improve the flood control capacity and water utilization efficiency by' the flexible operation of storage space.

권형중 Kwon Hyung Joong , 김성준 Kim Seong Joon

DOI: JKWST Vol.48(No.2) 37-43, 2006

---

A hydrological drought index, MSWSI (Modified Surface Water Supply Index) was suggested based on SWSI (Surface Water Supply Index). With the available data of spatially distributed observation station of precipitation, dam storage, stream water level and natural groundwater level, South Korea was divided into 32 regions. This was conducted to represent the calculated index as a spatially distributed information. Monthly MSWSI was evaluated for the period of 1974 and 2001. It is necessary to compare this result with PDSI (Palmer Drought Severity Index) and SPI (Standard Precipitation Index), and check the applicability of the suggested index in our hydrological drought situation.

장태일 Jang Taeil , 김상민 Kim Sang Min , 강문성 Kang Moon Seong , 박승우 Park Seung Woo

DOI: JKWST Vol.48(No.2) 45-55, 2006

---

This study analyze the hydrologic conditions and the effects of selected runoff characteristics as an attempt to estimate the optimal dredge amount for Asan Lake in Korea. The runoff feature was calculated by utilizing the water balance simulation from DIROM (Daily Irrigation Reservoir Operation Model), which allowed changes in landuse to be quantified using remote sensing for 14 years. The distribution of prospective sediment deposits was been tallied based on the changes in landuse, and quantity of incoming sediment estimated. From these findings, we were then able to simulate the fluctuation of water level, gauging the pumping days not already in use, to determine the frequency of the distribution for around the requirement annual water storage and the changing water level. The optimal dredge amount was calculated on the basis of the distribution of frequency, taking into account the design criteria for agricultural water with the 10-year frequency of resistant capacity.

성찬용 Sung Chan Yong

DOI: JKWST Vol.48(No.2) 59-66, 2006

---

This study is performed to evaluate freezing and thawing properties of polypropylene fiber reinforced eco-concrete using soil, natural coarse aggregate, soil compound and polypropylene fiber. The mass loss ratio is decreased with increasing the content of natural coarse aggregate and soil compound, but it is increased with increasing the content of polypropylene fiber. The ultrasonic pulse velocity, dynamic modulus of elasticity and durability factor are increased with increasing the content of natural coarse aggregate and soil compound, but it is decreased with increasing the content of polypropylene fiber. The mass loss ratio, ultrasonic pulse velocity, dynamic modulus of elasticity and durability factor are 1.49~3.32%, 1,870~2,465m/s, 77X10²~225X10² MPa and 84.6~92.8 after freezing and thawing 300 cycles, respectively. These eco-concrete can be used for environment-friendly side walk and farm road.

김형중 Kim Hyung Jong , 김선주 Kim Sun Joo , 김필식 Kim Phil Shik , 안열 An Yeul , 양용석 Yang Yong Suck

DOI: JKWST Vol.48(No.2) 69-76, 2006

---

Fallow paddy areas have been increased due to the import of cheap agricultural product, and the unbalance between farming cost and rice price since 1990. The increasing fallow paddy area needs to be protected from the devastation by weed breeding for the re-cultivation. In this study, two fallow paddy fields managed with different water depth were selected for monitoring and analysing of water quality, water balance and plant body change. The managed fallow paddy fields were more effective in water quality purification and plants growth control than non-managed fallow paddy fields. And the fallow paddy field managed with some degree of water depth was the most effective field in terms of weed control.

윤춘경 Chun-gyeong Yoon , 한정윤 Jung-yoon Han , 정광욱 Kwang-wookjung , 장재호 Jae-ho Jang

DOI: JKWST Vol.48(No.2) 77-87, 2006

---

The reuse of wastewater for agricultural irrigation may cause human health risk as a result of exposure to pathogens. This study conducted the quantitative microbial risk assessment in paddy field irrigated with treated wastewater. Six treatments were used to irrigate the paddy field from Year 2003 to Year 2005: biofilter-effluent, UV-disinfected water (6, 16, 40, 68 mWscm^-2), pond-treated water, wetland-treated water, conventional irrigation water and tap water. Total coliforms, fecal coliforms and E. coli were monitored during rice growing period. Beta - Poisson model was employed to calculate the microbial risk of pathogens ingestion that may occur to farmers and neighbor children. Uncertainty of risk was estimated using Monte Carlo simulation. In this study, the microbial risk was higher during initial cultivation (end of May~June), and it decreased with time. Biofilter effluent (secondary effluent) irrigation showed higher risk values than others (>10^-4) and irrigation with UV-disinfected water has the lowest risk range (10^-6~10^-5). The risk value estimated in 2005 was lower than risk value in 2003 and 2004, it is likely due to clean tap water irrigation in initial transplanting stage. It is suggested that irrigation with UV-disinfected water and pond-treated water would reduce the microbial risk associated with wastewater irrigation in paddy field. In addition, the first irrigation water quality significantly affected the subsequent microbial risk.