MONITORING AND MANAGEMENT OF IRRIGATION WATER QUALITY ??2013-09-14MONITORING AND MANAGEMENT OF IRRIGATION WATER QUALITY IN JAPAN ... AA Water supply class 1, ... irrigation water quality monitoring,

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<ul><li><p>1</p><p>MONITORING AND MANAGEMENT OF IRRIGATION WATER QUALITY IN JAPAN</p><p>Yutaka MatsunoDepartment of Environmental Management,</p><p>School of Agriculture, Kinki UniversityJapan</p><p>ABSTRACT</p><p>This paper primarily discusses the water quality standard of Japan, the development of water quality monitoring program for irrigation and drainage water, the water quality management of agricultural drainage, and the case of Hachiro-Kata, Japan for water quality monitoring and management. Japan's Environmental Water Quality Standard for water pollutants was established to achieve and maintain the levels of water quality for the healthy environment of public waters. In 2007, the Ministry of Agriculture, Forestry, and Fisheries (MAFF) introduced guidelines for agricultural water quality monitoring. The guidelines contain water quality for crop production, the aquatic environment of irrigation and drainage canals and reservoirs, and concerns for sediment outflow from paddy fields. Physical interventions for water quality improvement are physical, chemical, and biological treatments; sediment removal; aeration, dilution and filtration; and change of canal alignment. Other management interventions include irrigation scheduling, land preparation, fertilizer and pesticide management, drainage control, and recycling of irrigation water. Hachiro-Kata located in Akita Prefecture exemplifies a case where water quality monitoring and management were well established. The programs activities were intended to attain sustainable development of agriculture and fisheries and improve the natural environment of the rural community. With these objectives, major activities implemented include use of less water for land preparation to reduce sediment flow to the lake; improved management of tidal gate and pumps to enhance the circulation of water within the lake; biological treatment of drainage water; establishment of protected zone for constructed wetland; modernization of sewage system and expansion of the sewage network; and cultivation of foreign fish species to remove nutrients in the lake and use it as organic fertilizer. In 2007, these activities resulted in reduced incidence of algal bloom in the lake and improved water quality. The participation of farmers and local communities in the program and the seminars and workshops for residents and school children contributed in the improvement of the lake environment.</p><p>Key words: environmental water quality standards, agricultural water quality, Japan </p><p>INTRODUCTION</p><p>Paddy rice is the major crop in monsoon Asia and is often perceived as the largest water consumer in basins. Since hydrological impact of paddy irrigation is significant in this region, the water quality of paddy irrigation and drainage becomes an important issue in water resources management in Asia amidst increasing concern for the environment. Japan experienced rapid economic growth and industrialization since the early 1960s. </p><p>Agricultural land in 2005 was approximately 4.7 million ha, more than half of which were paddy fields. The average land size of a farm household was approximately 1.8 ha. With urbanization and industrialization, the demand for domestic and industrial water has increased. However, the total requirement for agricultural water has not decreased in proportion to the reduced farmland area. The urban sprawl resulted in meeting the requirement for a certain volume of canal water flow to reach scattered paddy fields and </p></li><li><p>2</p><p>a bigger unit of water requirement because of the increased multi-cropping patterns in agricultural lands. As such, the agricultural sector remains the largest water consumer (Matsuno et al. 2007). Consequently, because of this mixture of land uses in many peri-urban areas of Japan, domestic and industrial wastewater flows into irrigation and drainage canals affecting crop production and the environment in downstream water bodies. Also, the importation of vast amounts of food stuff in the country makes the nutrient balance of Japan overloaded. This results in increased eutrophication in many stagnant water bodies. It was estimated that 1,090,000 tons of nitrogen and 117,000 tons of phosphorus were annually loaded into water bodies in Japan (Takeda 2001). This paper describes: 1) the water quality standard of Japan; 2) the development of water quality monitoring program for irrigation and drainage water; 3) the water quality management of agricultural drainage; and 4) a case of Hachirou-Kata, Japan for water quality monitoring and management. </p><p>WATER QUALITY STANDARD AND STATUS OF WATER QUALITY IN JAPAN</p><p>Environmental Water Quality Standard was established decades ago in Japan, and since then has been revised several times. Environmental Water Quality Standard for water pollutants aims to achieve and maintain the levels of water quality for the healthy environment of public waters. The standards have two major goals: protection of human health, and conservation of the environment. The first goal is supposed to be achieved by setting uniform national standards for all public waters. To meet the second goal, rivers, lakes, reservoirs, and coastal waters were classified according to water usage, and the standard values for each class were established (Ministry of the Environment 2008). The Japanese government has been implementing nationwide water quality-monitoring program in major water bodies to assess the state of water qualities with respect to the guidelines. Fig. 1 shows a time series of the rate of non-compliance with the water quality </p><p>Fig. 1. Rates of non-compliance with the water quality standards for the protection of human health (Source: Ministry of the Environment, Japan).</p><p> %</p><p>fiscal year</p></li><li><p>3</p><p>standards for human health. The rates for heavy metals were significantly reduced after the 1970s owing to strict enforcement of the regulation by the government and increased public concern for industrial pollution during the early stage of rapid economic growth. Table 1 shows an example of the Environmental Quality Standards for conservation of the environment, and Table 2 shows the rate of compliance to the Environmental Quality Standards for the environmental conservation for fiscal year 2004. As shown in Table 2, half of lakes and reservoirs did not meet the standard </p><p>concentrations, while almost 90% of river water quality was satisfied. This indicates the need for improving water quality of stagnant water bodies in Japan, and better understanding and management of material loadings in lakes and reservoir.</p><p>CHARACTERISTICS OF AGRICULTURALWATER QUALITY</p><p> Agricultural practices cause downstream water quality problems because of excessive application of pesticides, nitrogen leaching, phosphorus, and sediments that flow through the water system. However, changes in water </p><p>Table 1. Environmental Quality Standards for conservation of the environment for rivers</p><p>Class Item Standard vlaue</p><p> Water use pH BOD SS DO Total coliform</p><p>AA Water supply class 1, 6.5-8.5 1 mg/1 or 25 mg/1 7.5 mg/l 50 conservation of natural less or less or more MPN/100ml environment, or less</p><p>A Water supply class 2, 6.5-8.5 2 mg/1 or 25 mg/1 7.5 mg/l 1000 fisheryclass1, less orless ormore MPN/100ml or less</p><p>B Water supply class 3, 6.5-8.5 3 mg/1 or 25 mg/1 5 mg/l 5000 fisheryclass2, less orless ormore MPN/100ml or less</p><p>C Fishery class 3, 6.5-8.5 5 mg/1 or 50 mg/1 5 mg/l - industrial water class 1, less or less or more</p><p>D Industrial water class 2, 6.5-8.5 8 mg/1 or 100 mg/1 2 mg/l - less or less or more</p><p>E Industrial water class 3, 6.5-8.5 10 mg/1 or Floating 2 mg/l - and conservation of less matter such or more environment as garbage should not be observed</p><p>Source: Ministry of the Environment, Japan.</p><p>Table 2. The rate of compliance with the environmental water quality standard in year 2004 </p><p> Compliance rate (%) Number of Number of samples that samples met the guidelines Total 85.2 3313 2824 Rivers 89.8 2552 2291 Lake and reservoirs 50.9 169 86 Sea and coastal areas 75.5 592 447Source: Ministry of the Environment, Japan.Note: The rate of compliance is based on BOD values for rivers and COD values for lakes &amp; reservoirs and sea &amp; coastal areas.</p></li><li><p>4</p><p>quality with paddy rice production may be advantageous, depending on the quality of the incoming water, the irrigation and drainage system, and on fertilizer and pesticide management (Comprehensive Assessment of Water Management in Agriculture 2007). In some instances, a paddy field or artificial wetland may be constructed, such that water is purified if the incoming irrigation water contains high concentrations of nitrogen and phosphorus. Tabuchi (1998) reported that natural water purification occurred when the nitrogen concentration in the inflow was 2-3 mg/L or greater, and conversely, the nitrogen concentration in the flooded water increased when the concentration was lower than 2-3 mg/L. The flooding condition of a paddy field increases denitrification (Yamaoka et al. 2003) and the volcanic ash soil, which is the major soil in many paddy fields of Japan, readily absorbs phosphorus (Shiratani et al. 2003, Takeda and Fukushima 2004). The denitrification rate of paddy fields is reported to be between 0.02 and 0.8 g/m2 per day (Tabuchi 1998). On the other hand, nitrate pollution of groundwater under paddy fields exceeded the 10 mg/L limit for safe drinking water only when highly fertilized vegetables were included in the cropping system in the Philippines (Bouman, Castaeda, and Bhuiyan 2002). Even though the input of water is less than that for paddy rice system, upland cropping systems have high risk of becoming sources of groundwater pollution because of the soils aerobic condition, such that nitrogen readily penetrates into the soils in the form of </p><p>nitrate. Also, chemical input to non-paddy land is normally much higher than that for paddy land. Table 3 shows the fertilizer and pesticide inputs for various cultivation systems. </p><p>DEVELOPMENT OF MONITORING PROGRAM FOR AGRICULTURAL WATER QUALITY</p><p>Any water quality monitoring program must have well-defined objectives and well-developed systems to achieve the objectives. Principal elements of the monitoring may be the following (UNEP/ WHO 1996): Describing water resources and </p><p>identifying actual and emerging problems of water pollution; Formulating plans and setting priorities </p><p>for water quality management; Developing and implementing water </p><p>quality management programs; and Evaluating the effectiveness of </p><p>management actions. There are basically two main concerns for agricultural water quality: 1) quality of irrigation water going to agricultural land; and 2) quality of water draining out of agricultural land. The former may involve monitoring the quality of water sources and domestic and/industrial effluents coming into irrigation water, and the latter may involve monitoring the quality of downstream water bodies such as lakes and reservoirs. For the establishment of water quality monitoring program, the following should be considered: Parameters (including non-quality </p><p>parameters);</p><p>6222271861077832Recommended</p><p>Paddy rice</p><p>360.1827509163177169903269Other upland</p><p>600.12138791261255275248580Flowers (house)</p><p>3021117397125131141133890Flowers </p><p>4212318487124179184357382Fruits (house)</p><p>580011475921702122103821217Vegetable (house)</p><p>290821626179233214220 5797Vegetables</p><p>TotalWeedicideFungicideInsecticideTotalKPN</p><p>Pesticidekg/ha)</p><p>Chemical Fertilizer N Kg /ha)Organic matter input</p><p>N kg/ha)Sample </p><p>#Crop type</p><p>6222271861077832Recommended</p><p>Paddy rice</p><p>360.1827509163177169903269Other upland</p><p>600.12138791261255275248580Flowers (house)</p><p>3021117397125131141133890Flowers </p><p>4212318487124179184357382Fruits (house)</p><p>580011475921702122103821217Vegetable (house)</p><p>290821626179233214220 5797Vegetables</p><p>TotalWeedicideFungicideInsecticideTotalKPN</p><p>Pesticidekg/ha)</p><p>Chemical Fertilizer N Kg /ha)Organic matter input</p><p>N kg/ha)Sample </p><p>#Crop type</p><p>Table 3. Fertilizer and pesticide inputs to agricultural land in Japan</p><p>Source: Ministry of Agriculture, Forestry, and Fisheries, Japan 1999.</p></li><li><p>5</p><p> Sampling points; Sampling frequency and timing; Method of analysis; Transport; Human resources; Use and management of the data; Quality assurance; and Budget.</p><p> As an example of parameters for irrigation water quality monitoring, Table 4 shows irrigation water quality guidelines for paddy rice system in Japan. It was formulated in 1969 and since then has not been officially revised. Heavy metals are, of course, concerns for the health of consumers. Nitrogen concentration is also of concern due to a potential of over nutrition that may result in </p><p>productivity decline and falling down of rice straw before harvest. Professionals believe that the guideline value for nitrogen of 1 mg/L is not realistic. Most nitrogen concentrations in Japans irrigation water exceed this value, and many believe that up to 3 mg/L is acceptable (Msawa 1999). The Ministry of Agriculture, Forestry, and Fisheries (MAFF) of Japan recently introduced the guidelines for water quality monitoring (Tables 4 and 5). The guidelines contain the water quality for crop production as well as the aquatic environment of irrigation and drainage canals and reservoirs. In addition, there has been increased concern for sediments outflow from paddy fields through the drainage, especially during land preparation period. </p><p>MANAGEMENT OPTIONS FOR WATER QUALITY IMPROVEMENT</p><p>Developing the strategy for water quality improvement depends on the results of water quality monitoring. The options for intervention can be categorized as follows: Physical intervention</p><p> Treatment (physical, chemical, biological), sediment removal, aeration, dilution, filtration, change of canal alignment; and</p><p> Management alternation Irrigation scheduling, land preparation, </p><p>Table 4. Irrigation water quality standards for paddy rice in Japan</p><p>Component Prescribed standard</p><p> pH 6.0 - 7.5 COD &lt; 6 mg/l SS &lt; 100 mg/l DO 5 mg/l &lt; T-N &lt; 1 mg/l EC &lt; 300 mS/cm Heavy metal As &lt; 0.05 mg/l Zn &lt; 0.5 mg/l</p><p> Cu &lt; 0.02 mg/l </p><p>Frequent in periods of land preparation, planting, fert . application, pump operation, snow melting, etc. </p><p>Outlets to river, inlet from field </p><p>Flow, Temp., BOD or COD, SS, EC, TN, TP </p><p>Drainage Water </p><p>More than 5 times during in irrigation season, 2 times in non - irrigation season, more frequent if contaminated. </p><p>Diversion point, inlet to field, up &amp; down streams of contamination source </p><p>Flow, Temp. , COD, pH, SS, DO, EC, TN </p><p>Irrigation Water </p><p>Once/month or seasonal sampling, same time in the morning </p><p>Inlets and outlets of reservoir </p><p>Water level, Temp., pH, SS, DO, EC, Transparency, TN, TP, chlorophyll a </p><p>Reservoir Water </p><p>Frequencies Sites Parameters </p><p>Frequent in periods of land preparation, planting, fert . application, pump operation, snow melting, etc. </p><p>Outlets to river, inlet from field </p><p>Flow, Temp., BOD or COD, SS, EC, TN, TP </p><p>Drainage Water </p><p>More than 5 times during in irrigation seaso...</p></li></ul>

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