Jin Yong Choi

Estimating water footprint of paddy rice in Korea

The purpose of this article is to examine the issues of low grain self-sufficiency and the high portion of agricultural water use in South Korea, and to trace the water footprint (WF) of rice products. In this study, different types of water use were described as green, blue, and gray WFs and were analysed using suitable estimation methods to determine irrigation water requirements in South Korea. Virtual water (VW) import and export of rice product were calculated based on international trade statistics during 2004–2009, and the WF of the national consumption was estimated. The WF of rice was 844.5xa0m3/ton, and green, blue, and gray water accounted for 294.5, 501.6, and 48.4xa0m3/ton, respectively. The VW import and export were 404.17 and 2.03xa0Mm3/year, respectively, against an import 199.5 times that of the export. Three countries (China, USA, and Thailand) accounted for over 95xa0% of the total VW imports of rice products into South Korea. The total WF was 5,712.08xa0Mm3/year, thus the WF per capita for rice was estimated at 118.1xa0m3/year. The internal WF of rice consumption was 5,308.05xa0Mm3/year, and the external WF was 404.03xa0Mm3/year. The WF of total agricultural water use should be analyzed for sustainable agricultural production and water management, and these results should be applied in establishing long-term policies for agricultural water resources.

Estimation of the international virtual water flow of grain crop products in Korea

The Korean 2008 self-sufficiency rate for grain was only 26.2%. Because of this, the quantity virtual water (VW) for crop product imports is much greater than that of other countries. International VW trade is especially important to Korea due to its dependency on foreign imports to maintain food security and to establish an agricultural water resource policy. Using international crop products trade statistics during 2003–2007, this study analyzed the virtual water content (VWC) and international virtual water flow (VWF) of major crops. The national water savings and global water savings were also estimated. Major grain products, including 28 products made from 13 crops, were selected for the analysis, based on the net import and export of products totaling more than 10,000 tons. VWCs were computed for the selected major crop products using the VWC of the primary crop of Korea. International VWFs were estimated using the VWC of each crop products. The amount of imported VW was 16,804 and 226xa0Mxa0m3 was exported, so that the net imported VW was 16,578xa0Mxa0m3. VW import is concentrated in wheat, rice, maize (corn), and soybean crops. A small number of countries, including the USA, China, Brazil, etc., account for over 96% of the imported VW, indicating Korea’s heavy dependence on these countries. The average national water savings for Korea and the average global water savings according to crop were estimated using VW flow from international crop products trade during 2003–2007. The estimate of national water savings was 23,870.3xa0Mxa0m3. Three major crops, namely wheat, maize and soybean, account for 95.3% of this total VW saving. Global water savings from the VW trade amounted to 7,253.0xa0Mxa0m3. Korea depends heavily on VW imports concentrated in specific crops and which are primarily imported from a particular set of countries. This indicates that Korea is vulnerable to disruptions in the international grain harvest such as those caused by natural disasters such as floods and drought. Any such disruption could easily become a critical issue for governmental planners who establish food and water supply policies for Korea.

Assessment of Irrigation Efficiencies using Smarter Water Management

Efficient water operation and management of an irrigation system plays an important element in the sustainability of irrigated agriculture. An agricultural water is delivered in many open canals of irrigation delivery system by reservoirs. The poor water distribution and management in an irrigation system is a major factor leading to low water efficiency. It is necessary to compare the estimated irrigation demands with the actual water supplies for decision making to maintain the water supply according to demand strategy. Smarter water management, new technologies and improvement of water management system, is essential to solve the problem of water efficiency and availability. In this paper, the irrigation efficiencies according to water delivery performance indicator were measured with automatic water gauge at irrigation canals, and calculated from spatial and temporal distribution of water supply for the lack of planning in water delivery. The analysis of results are obtain an insight into possible improvement methods to develop canal water management policies that enable irrigation planners to optimally manage scarce available water resources.

Agricultural Drought Risk Assessment using Reservoir Drought Index

Drought risk assessment is usually performed qualitatively and quantitatively depending on the definition a drought. The meteorological drought indices have a limit of not being able to consider the hydrological components such as evapotranspiration, soil moisture and runoff, because it does not consider the water demand in paddies and water supply in reservoirs. Agricultural drought was defined as the reservoir storage shortage state that cannot satisfy water requirement from the paddy fields. The objectives of this study were to suggest improved agricultural drought risk assessment in order to evaluate of regional drought vulnerability and severity studied by using Reservoir Drought Index (RDI). The RDI is designed to simulate daily water balance between available water from agricultural reservoir and water requirement in paddies and is calculated with a frequency analysis of monthly water deficit based on water demand and water supply condition. The results indicated that RDI can be used to assess regional drought risk in agricultural perspective by comparing with the historical records of drought in 2012. It can be concluded that the RDI obtained good performance to reflect the historical drought events for both spatially and temporally. In addition, RDI is expected to contribute to determine the exact situation on the current drought condition for evaluating regional drought risk and to assist the effective drought-related decision making.

A Wireless Sensor Network (WSN) application for irrigation facilities management based on Information and Communication Technologies (ICTs)

A wireless sensor network application for irrigation facilities management is proposed.A real-time information management using ICTs is based on RFID and QR codes.A WSN system was applied to a pilot site for irrigation canals and facilities.We explain the design, installation, and evaluation of an integrated WSN system. Irrigation facilities that supply agricultural water are distributed at low density across areas with water demand and require efficient operation and maintenance. Traditional manual irrigation facilities management faces critical limitations, such as delays/losses resulting from data handling errors, and facility misidentification. Therefore, an information system for irrigation facilities management could be more efficient if it includes a wireless sensor network (WSN) that uses information and communication technologies (ICTs). We propose a wireless sensor network application for irrigation facilities management based on radio frequency identification (RFID) and quick response (QR) codes. The system was installed in a pilot site in the I-dong irrigation districts in Gyeonggi, South Korea, and was determined to be beneficial for the inspection of agricultural irrigation facilities in the irrigation districts. Real-time information downloading, collecting field data, and updating the condition of the irrigation facilities in terms of operational conditions and maintenance requirements can improve management. The operation results demonstrated the applicability of the ICTs and WSN to agricultural water management and that it provided good portability, recognition, and information gathering abilities in the field.

Projection of Consumptive Use and Irrigation Water for Major Upland Crops using Soil Moisture Model under Climate Change

The impacts of climate change on upland crops is great significance for water resource planning, estimating crop water demand and irrigation scheduling. The objective of this study is to predict upland crop evapotranspiration, effective rainfall and net irrigation requirement for upland under climate change, and changes in the temporal trends in South Korea. The changes in consumptive use and net irrigation requirement in the six upland crops, such as Soybeans, Maize, Potatoes, Red Peppers, Chinese Cabbage (spring and fall) were determined based on the soil moisture model using historical meteorological data and climate change data from the representative concentration pathway (RCP) scenarios. The results of this study showed that the average annual upland crop evapotranspiration and net irrigation requirement during the growing period for upland crops would increase persistently in the future, and were projected to increase more in RCP 8.5 than those in RCP 4.5 scenario, while effective rainfall decreased. This study is significant, as it provides baseline information on future plan of water resources management for upland crops related to climate variability and change.

Development of Operation Rules in Agricultural Reservoirs using Real-Time Water Level and Irrigation Vulnerability Index

The efficient operation and management strategies of reservoirs in irrigation periods of drought events are an essential element for drought planning and countermeasure. Korea Rural Community Corporation has developed the real-time water level observation system of agricultural reservoirs to efficiently operate reservoirs, however, it is not possible to predict drought conditions, and only provides information of current situation. Hence, it is necessary to evaluate accurate irrigation vulnerability and efficiently reservoir operation rules using current water level. In this paper, the improvement methods of reservoir operation planning were developed with water supply vulnerability characteristic curves comparing to automatic water gauge at agricultural reservoirs. The 11 reservoirs were simulated applying the reservoir operation rules which was determined by irrigation vulnerability characteristic curves criteria and real time water level, and evaluated water supply situation in 2012 year. The analysis of results can be identified probabilistic possibility of water supply failures compared with the existing reservoir operation criteria. These results of efficient reservoir operation rules can be achieved enable irrigation planners to optimally manage available water resources for decision making, and contributed to maintain the water supply according to demand strategy for agricultural reservoirs management.

Mobile device development using RFID and QR code technology for real time information management of irrigation facilities

Irrigation facilities are spread over a demand area in a low density and exposed in the field requiring efficient operation and maintenance. Thus, it is necessary to manage a computer based system using wireless information network to maintain the irrigation facilities appropriately. Real time download, collection and update the information about the irrigation structure conditions in the field in terms of operation and maintenance can provide a better support of the irrigation facilities management efforts. In this study, mobile devices using RFID (Radio Frequency Identification) reader and smart phone utilizing RFID and QR (Quick Response) code technology were developed. This paper describes the applications and implementation results of two methods while operating the devices in real time for field information communication of the irrigation facilities, and the devices demonstrated beneficial usability for inspection of agricultural irrigation facilities in the field.

Wireless Sensor Network Development using RFID for Agricultural Water Management

Irrigation facilities are spread over a demand area in a low density and exposed in the field requiring efficient operation and maintenance. Thus, it could be more efficient to manage an irrigation system when it comes with wireless sensor network (WSN) using RFID (Radio Frequency Identification) application. A WSN, a kind of ubiquitous sensor network composed of wireless network, RFID and database management system was developed for agricultural water management in terms of operational status and maintenance requirements. Identification code for RFID tag was designed and an application for RFID reader was developed for field data collection, and a database management system was constructed for managing irrigation facility attributes. The system was installed in I-dong irrigation districts in Gyounggi-province, Korea and the operated results showed the applicability of the WSN for agricultural water management.

Estimating Blue, Green and Grey Water of Paddy Rice in Korea

The degree of grain self-sufficiency is currently about 27% in South Korea which is why Korea is one of the largest net virtual water import countries. Agricultural water resources have been heavily developed from early 1970 for rice self sufficiency and agricultural water use is 48% to the total fresh water resources in Korea. Tracing the water footprint is quite important to set up the national water resources policy because agriculture for crop cultivation consumes a large amount of water. Thus, when considering the low food self-sufficiency and high portion of water use in agriculture, estimation of virtual water for paddy rice in Korea is required to analyze the national water balance. The aim of this study is to estimate the green, blue and grey water footprint of rice, using a higher spatial resolution than earlier studies and applying local data on actual irrigation. Green and blue water from rice fields is calculated using the water balance model in paddy field. The grey water footprint is estimated by referencing the several researches regarding discharge of T-N and T-P in paddy field. The total national water footprint for rice production was 9,275.9 m3/yr, and the direct and indirect water use accounted for 5,358.6 m3/yr and 3,917.3 m3/yr, respectively. Green, blue and grey water for rice production were estimated to be 1,865.4 m3/yr, 3,184.3 m3/yr, and 308.9 m3/yr except for indirect water use including percolation and residual soil moisture. The total volume of water used for one ton of rice was 840.8 m3/ton, and the green, blue, and grey water accounted for 292.8 m3/ton, 499.5 m3/ton, and 45.5 m3/ton, respectively. The results of this study are expected to be used as basic data for national agricultural water footprint and to assist the national water resources policy.