• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.8-9
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• 2011

On 4 September 2010 an earthquake of magnitude 7.1 on the Richter scale occurred on the Canterbury Plains in the South Island of New Zealand. The Canterbury Plains are an area of extensive groundwater and spring fed surface water systems. Since the September earthquake there have been several thousand aftershocks (Fig. 1), the largest being a 6.3 magnitude quake which occurred close to the centre of Christchurch on 22February 2011. This second quake caused extensive damage to the city of Christchurch including the deaths of 189 people. Both of these quakes had marked hydrological impacts. Water is a vital natural resource for Canterburywith groundwater being extracted for potable supply and both ground and surface water being used extensively for agricultural and horticultural irrigation.The groundwater is of very high quality so that the city of Christchurch (population approx. 400,000) supplies untreated artesian water to the majority of households and businesses. Both earthquakes caused immediate hydrological effects, the most dramatic of which was the liquefaction of sediments and the release of shallow groundwater containing a fine grey silt-sand material. The liquefaction that occurred fitted within the empirical relationship between distance from epicentre and magnitude of quake described by Montgomery et al. (2003). . It appears that liquefaction resulted in development of discontinuities in confining layers. In some cases these appear to have been maintained by artesian pressure and continuing flow, and the springs are continuing to flow even now. In spring-fed streams there was an increase in flow that lasted for several days and in some cases flows remained high for several months afterwards although this could be linked to a very wet winter prior to the September earthquake. Analysis of the slope of baseflow recession for a spring-fed stream before and after the September earthquake shows no change, indicating no substantial change in the aquifer structure that feeds this stream.A complicating factor for consideration of river flows was that in some places the liquefaction of shallow sediments led to lateral spreading of river banks. The lateral spread lessened the channel cross section so water levels rose although the flow might not have risen accordingly. Groundwater level peaks moved both up and down, depending on the location of wells. Groundwater level changes for the two earthquakes were strongly related to the proximity to the epicentre. The February 2011 earthquake resulted in significantly larger groundwater level changes in eastern Christchurch than occurred in September 2010. In a well of similar distance from both epicentres the two events resulted in a similar sized increase in water level but the slightly slower rate of increase and the markedly slower recession recorded in the February event suggests that the well may have been partially blocked by sediment flowing into the well at depth. The effects of the February earthquake were more localised and in the area to the west of Christchurch it was the earlier earthquake that had greater impact. Many of the recorded responses have been compromised, or complicated, by damage or clogging and further inspections will need to be carried out to allow a more definitive interpretation. Nevertheless, it is reasonable to provisionally conclude that there is no clear evidence of significant change in aquifer pressures or properties. The different response of groundwater to earthquakes across the Canterbury Plains is the subject of a new research project about to start that uses the information to improve groundwater characterisation for the region. Montgomery D.R., Greenberg H.M., Smith D.T. (2003) Stream flow response to the Nisqually earthquake. Earth & Planetary Science Letters 209 19-28.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.4
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• pp.492-496
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• 2012

Fertigation with drip irrigation provides effective and cost-efficient way to supply both nutrient and water to crop. However, inappropriate management of fertigation systems may cause inefficient nutrient and water use, thereby diminishing expected yield benefits as well as contributing to deterioration of soil properties. In this study, greenhouse experiments were conducted to investigate the optimal concentration of N, P and K fertigation solution for maximum production of oriental melon (Cucumis melo L.) using a response surface methodology, to evaluate an efficiency of nutrients uptake and an effect on soil chemical properties. Canonical analysis of response surface and contour plot interpretation revealed that $108.3mg\;L^{-1}$ of nitrogen (N), $54.8mg\;L^{-1}$ of phosphorous (P) and $158.3mg\;L^{-1}$ of potassium (K) resulted in maximim yield of oriental melon ($2,966kg\;10a^{-1}$). Compared to conventional practice, fertigation increased fruit yield up to 23.0% (p<0.001), uptake of N and K by plant also up to 33.3% (p<0.001) and 15.7% (p<0.01), respectively. These results suggest that fertigation has the advantage of the increase in yield and fertilizer use efficiency.

• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.240-245
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• 2010

The objective of this study was to determine the effect of different height of drainpipe and growing media soilless cultivated cut rose in container culture. Two experiment were to examine the effect of the drainpipe height and media composition on yield and quality of cut rose, Four different drainpipe height (0, 3, 6, 9 cm) were treated to determine of optimal container type. Yield was the highest at 3 cm drainpipe height, but quality was not significantly affected by drainpipe height. Survival rate of rose was 100%, 100%, 92%, and 92%, respectively. Two different drainpipe height (0, 3 cm) and 7 media composition (pure coir and pelite, and mixed with two media 3 : 1, 2 : 1, 1 : 1, 1 : 2, 1 : 3 v/v) was treated to determine of media composition related to drainpipe height. The supply of nutrient solution was controlled by the signal of water potential at -5 kPa using frequency domain reflectometry (FDR) sensor in mixed coir with pelite 3 : 1, 1 : 1, 1 : 3 (v/v), respectively. Irrigation frequency reduced in high ratio of coir media and 3 cm height of drainpipe. Quality of cut rose except for flower weight and yield until 2nd harvest was not significantly affected by drainpipe height, but yield after 3rd was higher at 3 cm than 0 cm height of darinpipe. In the media composition, yield and qulity of cut rose was increased at high ratio of coir media.

• Journal of Korean Society of Rural Planning
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• v.26 no.4
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• pp.81-91
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• 2020

This study was conducted to analyse climate change impact on agriculture infrastructure and propose improved measures on vulnerable areas. Recently, Climate change has resulted in damaging effects on agricultural fields through increases in drought intensity and flood risk. It is expected that this impact will increase over time. This study shows that Gyeong-gi and Chung-nam provinces are affected by drought and Gyeong-buk and Gyeong-nam provinces are affected by heavy rain. However, there are also regional variations within each province. Agricultural infrastructure affected by drought may also be affected by heavy rain. Increased damages on the infrastructure due to increased extreme weather events require preventive measures especially in vulnerable areas. In order to minimize the damage by climate change, we need to introduce a reform in the system which selects project region by analysing climate change impacts. Furthermore, impact assessment of climate change from projects such as 'water supply diversification', 'flooded farmland improvement', and 'irrigation facility reinforcement' also need to be adopted to improve the measures. The results of this study are expected to provide a foundation for establishing measures on coping with climate change in the agricultural sector.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.3
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• pp.280-285
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• 1991

The rice culture techniques of the ancient China which have played a key role directly and indirectly, in development of ancient farming and its techniques of Korea, were established before Christ in terms of dry-farming and the spirit of the farming-first principle. Especially techniques of rice culture were developed by cultivation methods for deep plowing, storage of water and preservation use of soil fertility. Therefore, the techniques of transplanting methods, seeding in rows, use of iron-made farming tools and dam construction for irrigation were advanced. And rice varieties were differentiated to avoid disasters or to supply of rice for various uses in many areas. Also, because north China was the origin of Chinese agriculture in which population density was low and flat land was wide that were the cradle of Chinese agriculture, ‘Hwayungsunubeob’(firing and drawning weed control method) and fallowing were quickened as intensive techniques of rice culture. In connection with the view of agricuture with 'the theory of the cosmic dual forces and the five primary substances' of Han Mooje and Chamwye scholars, the techniques of seeding and selection of crops were gradually developed. From ‘Jeminyosul’ of the 6th century to ‘Wangjongnongseo’ of the 14th century, the techniques of rice culture have been developed continuously and additively, but were not improved thereafter Won dynasty. From this point of time, the time of agriculture in the end of Koryo age and by ‘Nongsajiksul’ were initiated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2B
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• pp.121-135
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• 2010

This study is to assess the effect of potential future climate change on the inflow of agricultural reservoir and its impact to downstream streamflow by reservoir operation for paddy irrigation water supply using the SLURP. Before the future analysis, the SLURP model was calibrated using the 6 years daily streamflow records (1998-200398 and validated using 3 years streamflow data (2004-200698 for a 366.5 $km^2$ watershed including two agricultural reservoirs (Geumgwang8 and Gosam98located in Anseongcheon watershed. The calibration and validation results showed that the model was able to simulate the daily streamflow well considering the reservoir operation for paddy irrigation and flood discharge, with a coefficient of determination and Nash-Sutcliffe efficiency ranging from s 7 to s 9 and 0.5 to s 8 respectively. Then, the future potential climate change impact was assessed using the future wthe fu data was downscaled by nge impFactor method throuih bias-correction, the future land uses wtre predicted by modified CA-Markov technique, and the future ve potentiacovfu information was predicted and considered by the linear regression bpowten mecthly NDVI from NOAA AVHRR ima ps and mecthly mean temperature. The future (2020s, 2050s and 2e 0s) reservoir inflow, the temporal changes of reservoir storaimpand its impact to downstream streamflow watershed wtre analyzed for the A2 and B2 climate change scenarios based on a base year (2005). At an annual temporal scale, the reservoir inflow and storaimpchange oue, anagricultural reservoir wtre projected to big decrease innautumnnunder all possiblmpcombinations of conditions. The future streamflow, soossmoosture and grounwater recharge decreased slightly, whtre as the evapotransporation was projected to increase largely for all possiblmpcombinations of the conditions. At last, this study was analysed contribution of weather, vegetation and land use change to assess which factor biggest impact on agricultural reservoir and stream watershed. As a result, weather change biggest impact on agricultural reservoir inflow, storage, streamflow, evapotranspiration, soil moisture and groundwater recharge.

• Korean Journal of Environmental Agriculture
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• v.22 no.1
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• pp.16-25
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• 2003

Manun Reservoir, located in Andong district has the capacity of 2 million tons in irrigation water supply with the drainage area of $23.8\;km^2$. Manun Reservoir is over fifty year old, and shallow in depth. The ratio of drainage area (DA) to reservoir surface area (SA) as an effective physical parameter on water quality was 56.1 and was higher than those of other agricultural reservoirs. The ratio of reservoir storage (ST) to SA in Manun Reservoir was 4.79, and the mean depth was below 8m. Both ratios of DS/SA, total area (TA)/ST and ST/SA in Manun Reservoir were relatively higher than those in other agricultural reservoir and natural lakes in Korea. These physical parameters in Manun Reservoir, however, had a eutropic potential significance. Average of COD, IN, and TP in Manun Reservoir were 11.1 mg/L 1.426 mg/L, 0.093 mg/L, respectively. In the inflow stream of Manun Reservoir, the TN ($1.426{\sim}3.809\;mg/L$) was higher than those in reservoir. Only Lyngbya spp. was dominant in phytoplankton for this study period and Gymnodinium spp., Peridinium spp., and Cryptomonas spp. were dominant in zooplankton. According to the Carlson's trophic status index, Mnnun Reservoir was eutrophic in 1996, 1997, and 1999, and hypertrophic in 1998.

• Magazine of the Korean Society of Agricultural Engineers
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• v.15 no.2
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• pp.2949-2967
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• 1973

The purpose of this study is to find out and determine the minimum consumptive use of water for Korean cabbage and turmp, so that the minimum water requirement can be secured always for a stable cultivation of these vegetables regardless of weather conditions. The experiment was conducted in two periods; first one from May to July and second one from August to October, each experiment with two varieties of cabbage and two varieties of radish with 2 replicants and 15 treatments. The results found from the above are briefly as follows: 1. Since the mean soil moisture equivalent 64 days after the treatment was 28.5% and the soil moisture content at the time was 2.67% which is far less than that of the wilting point, the crop seemed to be extremely caused by a drought. 2. The rate of 51 days after the seeding, soil moisture content of plot No.2 where irrigation has been continuous was the highest or 21.3%, whereas the plot No.14 without irrigations was 11.2% and the lowest. Therefore, the soil moisture content for the minimum qrowth seemed to be 20%. 3. The consumptive coefficient of Blaney and Criddle on cabbage in two periods were K=1.14 and 0.97 respectively, and on radish in two periods were K=1.06 and 0.86 respectively, thus, cabbage was higher than radish. The consumptive coefficient in the first experiment (May-July) was 0.17 to 0.20 higher than the 2nd experiment(August-October). 4. Nomally, cabbage and radish germinate within one week, however, the germination ot these crops which were treated with a suspended water supply from the beginning took two full weeks. 5. When it elapsed 30 days after seeding, the conditions in plot 1,2 and 3 were fairly good however, the crops in the plops other than these showed a withering and the leaves were withered and changed into high green due to an extrem drought. Though it was about same at the beginning, the drought damage on cabbage was worse than that on radish period, and the reasos for this appears in the latter that the roots are grown too deep. 6. The cabbage showed a high affinity between treated plots and varieties. Consequently, it can be said that cabbage is very suseptive to drought damage, and the yield showed a difference of 35% to 56% depending on the selection oe varieties. 7. The radish also showed a high affinity between the treated plots, however, almost us affinity existed between varieties. Therfore, the yield of radish largely depends on the extent of drought, and the selection of variety does not affect at all. 8. The normal consumptive use on cabbage is $0.62{\ell}/sec$, while that on radish is $0.64{\ell}/sec$, and the minimum optimum water requirement that was obtained in this study is $4,000cc/day/m^3$ or $0.462{\ell}/sec/ha$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.61 no.1
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• pp.17-24
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• 2016

Drought caused by global climate change is one of serious problems for rice cultivation. However, it was little reported the impact of drought on rice cultivation in Korea. In here, to assess impact of drought on rice varieties in Korean climate condition, growth characteristics and yield components of rice were compared on irrigated and partially irrigated rice paddy field. First, we have chosen 11 rice varieties including 'Saeilmi' and 'Shindongjin' which are widely cultivated in Korea. For partially irrigated rice paddy treatment, we have withheld irrigation from 25 days after transplanting and water supply was totally dependent on rainfall for rice cultivation. When we examined early plant height and tiller number of these varieties on partially irrigated rice paddy were reduced 1.6% to 18.4% and 10.4% to 33.1%, respectively, and these reduction rate were highly correlated with yield loss in our experimental conditions. Among rice yield components, panicle number was decreased 10.5% to 30.1% according to rice varieties and reduced panicle number was highly correlated with yield loss. Grain number per panicle, grain filling rate and 1,000 seeds weight did not have correlation with yield loss of rice varieties. These result means that growth stage, especially the tillering stage, is seriously affected by drought on rice cultivation in Korea. And we suggest that 'Saeilmi', 'Ilmi' and 'Ilpum' are good for rice cultivation on drought prone rice field in Korea.

• Journal of agriculture & life science
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• v.53 no.4
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• pp.19-28
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• 2019

This study was conducted to investigate the effect of nutrient solution strength and duration of nutrient starvation on the growth and development of strawberry (Fragaria x ananassa Duch.) 'Maehyang' and 'Sulhyang' at the flowering stage. Cuttings of runner plants were stuck on November 23th, 2017 and were covered with a layer of black plastic film to block light from penetrating and keep the relative humidity high. The black plastic film was removed after 16 days and rooted plants were cultivated for one month with irrigation of water. The Yamazaki nutrient solution with an electrical conductivity (EC) of 1.85 or 3.71 dS·m-1 (1x or 2x ionic strength, respectively) and pH 5.55 was fed to plants after either 0 (control), 1, 3 or 5 weeks of nutrient starvation to the end of experiment. Plant height in both cultivars decreased gradually with the increase in duration of nutritional starvation. The earlier the nutritional starvation started, the smaller the shoot fresh weight of 'Maehyang'. Hence the greatest shoot fresh weight was obtained in the control which was supplied with the nutrient solution continuously. Shoot fresh weight of 'Sulhyang' was the greatest in 1x ionic strength and one week of nutrient starvation before planting. Although number of flowers on the first flower cluster of 'Maehyang' and 'Sulhyang' showed no significant differences, 'Maehyang' had the greatest number of flowers in the 2x ionic strength solution and one week of nutrient starvation before planting, while 'Sulhyang' had that in the 1x ionic strength treatment. These results suggest that it is considered effective to supply a nutrient solution at a low concentration for a short period of time for increasing the number of flower differentiated on the first flower cluster in both cultivars.