• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.538-538
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• 2015

농업가뭄에 대한 연구는 주로 가뭄지표의 개선과 제안 등에 초점이 맞추어져 있으며 관개기의 강수량에 중점을 둔 사례가 대부분이다. 그러나 대부분의 논 관개용수는 저수지를 통하여 공급되기 때문에 관개가 시작되는 4월 초순의 저수량은 상당히 중요한 가뭄 대응 요소이다. 이에 따라 가뭄에 대비하기 위해서는 관개가 종료되는 10월부터 이듬해 3월까지 충분한 저수량이 확보될 필요가 있다. 그러나 기후변화에 의해 대부분의 강우가 관개기에 집중될 수 있으며 이에 따라 미래에는 비관개기 동안 충분한 저수량을 확보하는데 어려움이 발생할 수 있다. 이에 본 연구에서는 기후변화에 따른 비관개기의 강수량을 확률기반으로 분석하고, 이를 관개기 필요저수량과 비교하여 저수지의 미래 가뭄 대응 능력을 분석하고자 하였다. 기후변화에 따른 비관개기의 강수량 변화를 분석하기 위하여 RCP(Representative Concentration Pathways) 시나리오를 적용하여 미래 비관개기 동안의 연도별 비관개기 누적강수량을 분석하였다. 과거와 미래시기를 30년 단위로 구분하여 1995s, 2025s, 2055s, 2085s의 비관개기 동안의 비초과확률 10%, 50%, 90%의 강수량을 분석하였다. RCP 4.5 시나리오를 기반으로 모의한 미래강우의 비초과확률 10% 누적강수량 산정 결과에 따르면 주요 곡창지대인 전라남북도는 1995s에는 10월부터 이듬해 3월까지의 누적강수량이 약 215mm 정도로 나타났으나 2025s에는 약 150mm로 줄어드는 것으로 나타났다. 즉, 비초과확률 10%의 강우가 내릴 경우 비관개기 동안에 충분한 저수량의 확보가 어렵게 되고 관개기의 심각한 가뭄을 초래할 수 있었다. 비관개기 누적강수량과 저수량변화의 관개를 모의한 개운저수지와 계룡저수지의 경우 그 관계식은 y=1.442x-198.81, y=5.8105x-752.92와 같이 나타났다. y는 비관개기의 저수량변화를 나타낸 것이고 x는 비관개기의 누적강우량을 나타낸 것이다. 식을 통해 향후 100년 중 비초과확률 10%의 강수를 가정한다면 개운저수지는 관개종료시점의 저수율이 최소 96.93% 이상이여야 다음해 관개시작시점의 저수위가 만수위가 될 수 있었고, 계룡 저수지는 최소 86.84%의 저수위를 만족해야 다음해 관개시작시점의 저수위가 만수위가 될 수 있었다.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.4
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• pp.285-293
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• 2023

This study was conducted to determine the sowing limit period and predict growth in the northern region based on accumulative temperature for each growth stage of soybean cultivated in the southern regions of the Korean Peninsula. First, the results of a demonstration test in the central region (Yeoncheon) of the Korean Peninsula were very similar to the predicted and actual values on the date by growth stage obtained through cultivation. This method was then applied to seven agricultural climatic zones in the northern Korean Peninsula. The results predicted that regardless of ecotype, soybean could be grown and harvested in the southern and northern parts of Mt. Suyang, south of the East Sea, and in the central and northern inland areas. However, it was predicted that no ecotype could be grown and harvested normally in the northern alpine region. Furthermore, north of the East Sea, the prediction indicated that early and mid-maturing cultivars could be grown and harvested normally, but middle-late maturing cultivars appeared to lack the number of growth days. The sowing limit period also varied depending on the ecotype, although it was reached earlier as higher latitudes were approached; the period ranged from May 16 to June 26 in the northern and southern parts of Mt. Suyang, north and south of the East Sea, and central and northern inland areas. Furthermore, all ecotypes of the northern alpine region, as well as mid-late maturing cultivars in the north of the East Sea, were predicted to be unable to grow normally owing to the lack of number of days required for soybean growth and development.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.5
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• pp.321-327
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• 2006

In Korea, there is a growing competitive for water resources between industrial, domestic and agricultural consumer, and the environment as many other OECD countries. The demand on water use is also affecting aquatic ecosystems particularly where withdrawals are in excess of minimum environmental needs for rivers, lakes and wetland habits. OECD developed three indicators related to water use by the agriculture in above contexts : the first is a water use intensity indicator, which is expressed as the quantity or share of agricultural water use in total national water utilization; the second is a water stress indicator, which is expressed as the proportion of rivers (in length) subject to diversion or regulation for irrigation without reserving a minimum of limiting reference flow; and the third is a water use efficiency indicator designated as the technical and the economic efficiency. These indicators have different meanings in the aspect of water resource conservation and sustainable water use. So, it will be more significant that the indicators should reflect the intrinsic meanings of them. The problem is that the aspect of an overall water flow in the agro-ecosystem and recycling of water use not considered in the assessment of agricultural water use needed for calculation of these water use indicators. Namely, regional or meteorological characteristics and site-specific farming practices were not considered in the calculation of these indicators. In this paper, we tried to calculate water use indicators suggested in OECD and to modify some other indicators considering our situation because water use pattern and water cycling in Korea where paddy rice farming is dominant in the monsoon region are quite different from those of semi-arid regions. In the calculation of water use intensity, we excluded the amount of water restored through the ground from the total agricultural water use because a large amount of water supplied to the farm was discharged into the stream or the ground water. The resultant water use intensity was 22.9% in 2001. As for water stress indicator, Korea has not defined nor monitored reference levels of minimum flow rate for rivers subject to diversion of water for irrigation. So, we calculated the water stress indicator in a different way from OECD method. The water stress indicator was calculated using data on the degree of water storage in agricultural water reservoirs because 87% of water for irrigation was taken from the agricultural water reservoirs. Water use technical efficiency was calculated as the reverse of the ratio of irrigation water to a standard water requirement of the paddy rice. The efficiency in 2001 was better than in 1990 and 1998. As for the economic efficiency for water use, we think that there are a lot of things to be taken into considerations to make a useful indicator to reflect socio-economic values of agricultural products resulted from the water use. Conclusively, site-specific, regional or meteorogical characteristics as in Korea were not considered in the calculation of water use indicators by methods suggested in OECD(Volume 3, 2001). So, it is needed to develop a new indicators for the indicators to be more widely applicable in the world.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.2
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• pp.149-155
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• 2017

To establish cultivation areas for the stable production of yacon, this study investigated the productivity and functional component contents of yacon in eight regions of Korea from 2011 to 2013. The results of principal component analysis using these data were as follows. A survey of 16 agricultural traits and meteorological data in the eight yacon cultivation areas showed that five factors (average temperature, maximum temperature, minimum temperature, frost-free days, and fructooligosaccharide content) were highly significant at the p < 0.001 level. Among the 16 agricultural traits and meteorological data used in the main component analysis of yacon cultivation areas, approximately eight contributed to the first principal component, and approximately four contributed to each of the second and third principal components. In particular, factors related to productivity, fructooligosaccharide content, and temperature change were considered important criteria for the classification of cultivation areas. The cultivation areas were divided into three groups by principal component analysis. In Group I, containing the Jinbu and Bonghwa areas in the mid-highland region at 500-560 m above sea level, the product yield was the highest at 2,622-3,196 kg/10a, the fructooligosaccharide content was also the highest at 9.04-9.62%, and the mean temperature was $17.3-18.5^{\circ}C$. In Group II, the areas Suncheon, Okcheon, Yeoju, and Gangneung, at 20-180 m above sea level, had the lowest yield, relatively lower fructooligosaccharide content, and the highest temperature. The areas in Group III showed values intermediate between those of Group I and Group II. For the different yacon cultivation areas, the product quantity and fructooligosaccharide content differed according to the environmental temperature, and the temperature conditions and number of frost-free days are considered important indicators for cultivation sites. Therefore, in terms of producing yacon with high quality, cultivation at 500-560 m is considered to give a higher yield and functional fructooligosaccharide content.

• Journal of Wetlands Research
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• v.15 no.2
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• pp.179-189
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• 2013

The Haean basin is a unique geographical feature formed by differential erosion and it borders the military demarcation line. Recently the basin has become an interest of civilians due to security tour, highland vegetables and wetland. After the civil war, the population decreased but it has increased since 2007. The annual mean air temperature in the basin has increased with a rate of $+0.016^{\circ}C/yr$ and the annual precipitation also has increased with a rate of +10.41 mm/yr. The precipitation occurring in June~August (wet season) occupied most of the total precipitation increase. In addition, recently the number of groundwater wells and its use have gradually increased and most of them are for agriculture including cultivation of rice and highland vegetables. If the air temperature further increases in the future according to the climate change scenarios, the highland vegetables cultivation will be difficult. Furthermore, if the rainstorm in the summer will be enforced, the groundwater recharge and water management will be aggravated. Therefore, an evaluation for sustainable groundwater development in the basin and a reform of the current agriculture (change of cultivating crops) depending on much water are essentially required.

• Korean Journal of Agricultural and Forest Meteorology
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• v.13 no.1
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• pp.20-27
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• 2011

High-definition, geo-referenced digital climate maps can be produced by applying watershed-specific modules to adjust synoptic observations for local effects including cold air drainage. Since there is no information available on North Korean watersheds, existing geospatial technology for digital climate mapping cannot be transferred to North Korea. We applied a watershed extraction algorithm based on ArcHydro to the North Korean portion of ASTER GDEM and utilized geographical information on major rivers and mountains to adjust the products. Proposed hydrologic zoning system for North Korean watersheds consists of 21 river basins, 93 stream basins and 885 catchments. Combined with the existing 840 South Korean hydrologic units, we now have a complete set of 1,725 catchments which may serve a framework for digital climate modeling across whole land area of the Korean Peninsula.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.55 no.3
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• pp.214-219
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• 2010

In order to evaluate the benefits of global warming on the double cropping with staple crops in North-Korea, four aspects such as the increasing rate of air temperature, the wintering temperatures for winter crops, the causing temperature of cool injury to rice and the securing of accumulated temperature for the double cropping in the different agricultural climate zones were analyzed by comparing the differences between the past 22 years from 1973 to 1994 and the recent 5 years from 2002 to 2006. The warming rate in recent daily mean air temperature of $8.96^{\circ}C$ in North Korea was higher by $0.64^{\circ}C$ than that in the past with large regional variations ranging from $1.06^{\circ}C$ in Samjiyeon of northern inland semi-alpine zone to $12.26^{\circ}C$ in Jangjeon of east central coastal zone. With the accumulated temperatures of more than $3,150^{\circ}C$ and $2,650^{\circ}C$, it was possible to apply the double cropping patterns with winter wheat and for cropping patterns with spring potato, respectively, to the whole region except for the northern inland semi-alpine zone. However, the wintering temperature higher than $-15^{\circ}C$ of average daily minimum air temperature of January, cropping patterns were impossible to northern inland semi-alpine zone and most regions of the northern mountainous zone. The days passed by below $17^{\circ}C$ in daily mean air temperature, causing the spikelet sterility at meiotic stage of rice in July, were a lot recorded from 21 to 29 days in northern inland semi-alpine zone and from 2 to 10 days in east-northern coastal zone, respectively. Therefore, a reasonable utilization of heat / temperature resources would relieve the limiting factors in double cropping for stable production of staple crops in North-Korea.

• Journal of the Korean association of regional geographers
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• v.16 no.6
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• pp.623-634
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• 2010

The elevated water storage tanks highly crowded in the western region in Jeju island is an important landmark of Jeju island. This study examines the reasons that the elevated water storage tanks appeared in a high density. After examination, this study found that the elevated water storage tanks formed under the influences of climate, hydrogeologic structure, soil, topography and land use. In particular, the elevated water storage tanks in Jeju are closely related to the crapping system with which water has to be supplied using sprinkler due to well drained soil and hydrogeological characteristics. The results of this study show that elevated water storage tank landscape in the western region of Jeju island is an agricultural landscape particularly made in the course of farmers' adaptation to the natural environment of Jeju island.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.473-473
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• 2021

새만금 유역의 하류 평야지대는 농업 관개 및 배수가 제수문의 영향을 받고 있으며, 상류 축산밀집시설에 따라 농업 비점오염원 유입이 수계 환경오염에 미치는 영향을 평가하는 것이 필요하다. 본 연구에서는 새만금 유역의 하류 제수문을 대상으로 유역 모형과 전산유체역학 모형을 이용하여 유입, 유출 그리고 오염원 등의 영향을 분석하고자 한다. SWAT (Soil and water assessment tool)은 유역 모형으로 수문순환 및 비점오염원을 모의하기 위해 개발한 모형이다. CFD(Computational fluid dynamics)는 구조물을 설계하고 유체, 기체 등의 역학을 모의할 수 있다. SWAT 모형을 이용하여 농촌 소유역을 대상으로 하류 제수문 위치를 출구로 지정하여 수문을 모의하고 그 결과자료는 CFD에 입력할 수 있다. CFD는 하류 제수문 구조물을 설계하고 SWAT 모형의 수문자료를 입력하여 제수문의 유입 및 유출 영향을 평가할 수 있다. SWAT 모형 구축을 위해 2015-2018년까지 기상, 수위, 유량 관측자료를 수집하였으며, 보정기간과 검증기간은 각 2년이며, 모형 성능 검증에 사용한 적합성 평가 지수는 R² (Determine coefficient), RMSE (Root mean square error), 그리고 NSE (Nash-sutcliffe efficiency coefficient)를 사용하였다. 모형의 보정은 SWAT-CUP 자동보정프로그램을 사용하였으며, 모형의 보정지수는 NSE를 사용하였고, 1,000회 반복 수행을 통해 매개변수를 최적화하였다. CFD 모형은 제수문의 실제 규격을 바탕으로 동일한 구조를 고려하였으며, 수문조작을 고려하여 유입 및 유출을 모의하였다. 본 연구는 유역차원과 구조물 차원의 모델링을 연계하는 것으로 최근 기후변화에 따라 급격히 변화하는 유역환경에 대처할 수 있는 방안이 될 수 있을 것이며, 제수문 시설을 관리하는 기관에서도 합리적인 운영방안에 대한 기초자료로 기여할 수 있을 것으로 사료된다.

• Korean Journal of Environmental Agriculture
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• v.27 no.2
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• pp.120-132
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• 2008

Remotely sensed images from a satellite can be applied for detecting and quantifying spatial and temporal variations in terms of landuse & landcover, crop growth, and disaster for agricultural applications. The purposes of this study were to analyze topography using DEM(digital elevation model) and classify landuse & landcover into 10 classes-paddy field, dry field, forest, bare land, grass & bush, water body, reclaimed land, salt farm, residence & building, and others-using Landsat TM images in North Korea. Elevation was greater than 1,000 meters in the eastern part of North Korea around Ranggang-do where Kaemagowon was located. Pyeongnam and Hwangnam in the western part of North Korea were low in elevation. Topography of North Korea showed typical 'east-high and west-low' landform characteristics. Landcover classification of North Korea using spectral reflectance of multi-temporal Landsat TM images was performed and the statistics of each landcover by administrative district, slope, and agroclimatic zone were calculated in terms of area. Forest areas accounted for 69.6 percent of the whole area while the areas of dry fields and paddy fields were 15.7 percent and 4.2 percent, respectively. Bare land and water body occupied 6.6 percent and 1.6 percent, respectively. Residence & building reached less than 1 percent of the country. Paddy field areas concentrated in the A slope ranged from 0 to 2 percent(greater than 80 percent). The dry field areas were shown in the A slope the most, followed by D, E, C, B, and F slopes. According to the statistics by agroclimatic zone, paddy and dry fields were mainly distributed in the North plain region(N-6) and North western coastal region(N-7). Forest areas were evenly distributed all over the agroclimatic regions. Periodic landcover analysis of North Korea based on remote sensing technique using satellite imagery can produce spatial and temporal statistics information for future landuse management and planning of North Korea.