Environmentasia

EnvironmentAsia AvailableAvailable online online at www.tshe.org/EA at www.tshe.org/EA The international journal published by the Thai Society of Higher Education Institutes on Environment EnvironmentAsiaEnvironmentAsia 28(1) (2009) (2015) 50-54 41-52

GenotoxicityUsing SWAT Assessment to Assess the of CriticalMercuric Areas Chloride and Nonpoint in the Marine Source Fish Pollution Therapon Reduction jaruba Best Management Practices in Lam Takong River Basin, Thailand Nagarajan Nagarani, Arumugam Kuppusamy Kumaraguru, Velmurugan Janaki Devi Netnapa Pongpetch a, Pongthepand ChandrasekaranSuwanwaree a, Chatpet Archana Yossapol Devi b, Songkot Dasananda c and Thongplew Kongjun d Center for Marine and Coastal Studies, School of Energy, Environment and Natural Resources, a School of Biology, InstituteMadurai of Science, Kamaraj Suranaree University, University Madurai-625021, of Technology, NakhonIndia Ratchasima, Thailand b School of Environmental Engineering, Institute of Engineering, Suranaree University of Technology, Nakhon Ratchasima, Thailand Abstractc School of Remote Sensing, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, Thailand d Office of Water Management and Hydrology, Royal Irrigation Department, Ministry of Agriculture and Cooperatives, The aim of the present study was to standardize andThailand to assess the predictive value of the cytogenetic analysis by Micronucleus (MN) test in fish erythrocytes as a biomarker for marine environmental contamination. Micronucleus frequencyAbstract baseline in erythrocytes was evaluated in and genotoxic potential of a common chemical was determined in fish experimentally exposed in aquarium under controlled conditions. Fish (Therapon jaruba) were exposed for 96 hrs toHydrological a single heavy models metal are (mercuric essential chloride). tools for waterChromosomal resource damageand nonpoint was determined source pollution as micronuclei management. frequency This study in fishaimed erythrocytes. to evaluate critical Significant areas andincrease best management in MN frequency practices was (BMPs) observed of sediment in erythrocytes and nutrient of fish loads exposed in Lam toTakong mercuric River chloride.basin, Northeastern Concentration Thailand, of 0.25 using ppm SWAT induced (Soil the and highest Water MN Assessment frequency Tool) (2.95 model. micronucleated The model wascells/1000 calibrated cells and compared validated tousing 1 MNcell/1000 daily data of streamflow,cells in control sediment, animals). NO3-N The and study TP in revealed Lam Takong that micronucleusRiver from 2007-2008 test, as anand index 2009, of respectively. cumulative In exposure,general, the appears simulated to bestreamflow a sensitive and model sediment to evaluate were in reasonablegenotoxic compoundsagreement with in fishthe undermeasured controlled values with conditions. coefficient of determination (R2) and Nash-Sutcliffe model efficiency coefficient (NSE) greater than 0.50 and the percent bias (PBIAS) Keywords:less than 25%. genotoxicity; Additionally, mercuric nutrient chloride; loads showed micronucleus a fair relationship between observation and simulation with R2 values more than 0.6 and PBIAS values less than 25%. From simulation, September was the month with the highest sediment,

NO3-N and TP yields while January and December were the lowest months. From the model, SWAT identified 1 severe and

1 high soil erosion subbasins. Two subbasins were classified into medium loading for NO3-N. However, 9 subbasins were 1.classified Introduction into high loading rate of TP. For BMPs, the 30-m laboratorywide filter strip and fieldwas the conditions. best scenario In reducing2006 Soumendra 100% of both sediment and TP, and 97.27% of NO3-N. These results could etbe al a .,useful made tool an forattempt water to resources detect genetic managements biomarkers and soil conservationIn India, planning about in200 Lam tons Takong of Rivermercury basin. and its in two fish species, Labeo bata and Oreochromis compounds are introduced into the environment mossambica, by MN and binucleate (BN) annuallyKeywords: as hydrological effluents frommodel; industries nitrate; phosphorus; (Saffi, 1981). soil erosion;erythrocytes watershed in the gill and kidney erythrocytes Mercuric chloride has been used in agriculture as a exposed to thermal power plant discharge at fungicide, in medicine as a topical antiseptic and Titagarh Thermal Power Plant, Kolkata, India. disinfectant,1. Introduction and in chemistry as an intermediate in districtsThe presentof three study provinces was conducted including toPracheenburi, determine the production of other mercury compounds. The theNakhon acute Nayokgenotoxicity and Nakhon of the heavy Ratchasima metal compound provinces. Nonpoint source (NPS) pollution of streams, lakes The dominant land use is agriculture land. Many contamination of aquatic ecosystems by heavy HgCl2 in static systems. Mercuric chloride is toxic, metalsand estuaries and pesticides has created has agained critical increasing concern throughout attention solvableorganizations, in water such hence as it the can Hydrology penetrate the and aquatic Water inthe recentworld. Agriculturaldecades. Chronic activities exposurehave been identifiedto and animals.Management Mutagenic Center studies for the with Lower native Northeastern fish species accumulationas the primary sourcesof these of chemicals NPS pollutants. in aquatic In Thailand, biota representRegion, the an Pollutionimportant Control effort inDepartment determining (PCD), the canwater result pollution in tissue is largely burdens associated that produce with urbanization, adverse potentialRegional effectsEnvironmental of toxic Office agents. 11 This and studyMunicipality was effectsindustrialization not only inand the agricultural directly exposed activities. organisms, The main carriedof Nakhon out toRatchasima, evaluate the have use studied of the micronucleushydrology and butpollutants also in humanfor surface beings. water quality problems are testwater (MN) quality for ofthe Lam estimation Takong of River. aquatic Water pollution quality sediments,Fish provides nutrients a suitableand other model chemical for monitoring substances usingdegradation marine hasedible been fish observed under lab for conditions. more than two aquatic(Office ofgenotoxicity Natural Resources and andwastewater Environmental quality Policy decades, as a result of urbanization and intensive becauseand Planning, of its 2012).ability However,to metabolize the governing xenobiotics policies and 2.farming Materials (Pollution and Control methods Department, 2008). Previous accumulatedon watershed managementpollutants. A in micronucleus the past, did not assay appreciate has studies did not evaluate temporal and spatial sediment beenthe importance used successfully of NPS pollution in several (Simachaya, species (De 2003) Flora, and 2.1.and nutrientSample loads Collection at basin level which can sufficiently etfew al strategies., 1993, Al-Sabtiexist for andremediating Metcalfe, the 1995).issue (Babel The reduce NPS pollution. micronucleuset al., 2004; Pollution (MN) Control test has Department, been developed 2006). TheContinuous fish species water selected quality for monitoring the present isstudy very together Lam Takongwith DNA-unwinding River basin is crucial assays to asthe wasexpensive, collected time from consuming Pudhumadam and spatially coast impractical of Gulf of at perspectiveNortheastern regionmethods of Thailand. for mass More monitoring than 880,000 of Mannar,the watershed Southeast level. Therefore, Coast of mathematical India. Therapon modeling clastogenicitypeople reside withinand genotoxicity Lam Takong in fishRiver and basin. mussels The jarbuahas become belongs a primary to the technology order Perciformes for analyzing of theNPS (Dailianisriver is 220et km al., long 2003). and originates from Sangampang familypollution Theraponidae. and its spatial Thedistribution fish species, (Chu et Therapon al., 2004). RangeThe in MN Khao tests Yai Nationalhave been Park. successfully It covers about used nine as jarbuaExamples(6-6.3 of thesecm in models length andare: 4-4.25the physically g in weight) based a measure of genotoxic stress in fish, under both was selected for the detection of genotoxic effect N. Pongpetch et al. / EnvironmentAsia 8(1) (2015) 41-52 event Areal Non-point Source Watershed Environment Mueang Nakhon Ratchasima and Chaloem Phra Response Simulation (ANSWERS) model, the Kiat districts in Nakhon Ratchasima province (Royal physically based Dynamic Watershed Simulation Model Irrigation Department, 2004). At Ban Kong Rae, Kham (DWSM) model and the Soil and Water Assessment Thale So district, Lam Boriboon River diverges from Tool (SWAT) model. When comparing the models, Lam Takong River for 35 km and then rejoins Lam SWAT is the most capable for long-term simulations Takong River at Ban Kanphom before flowing into the in watersheds dominated by agricultural land (Arnold Moon River at Tha Chang Sub district, Chaloem Phra and Fohrer, 2005; Arnold et al., 1998). It is designed to Kiat district in Nakhon Ratchasima province (Nakhon assess the impact of land use and management practices Ratchasima Municipality, 2006). on water, sediments and agricultural chemicals. The Lam Takong River basin is influenced by the model has proven to be an effective tool for assessing southwest and northeast monsoons. There are three NPS for a wide range of scales and environmental seasons including rainy, winter and summer seasons. conditions (Gassman et al., 2007). The United States From May to October, the southwest monsoon brings (Arabi et al., 2006); Europe (Panagopoulos et al., moisture from the Indian Ocean that falls as rain, 2011) and other parts of the world have incorporated peaking in August and September. The average amount SWAT into NPS assessment on a broad scale (Bouraoui of rainfall is 1,454.3 mm. From October to February, the et al., 2005; Cheng et al., 2007). In Thailand, SWAT wind direction is reversed, and a cooler, drier northeast was successfully used to study water flow in Lam Sonthi monsoon wind blows off the Asian landmass, bringing watershed, the Pasak watershed (Phomcha et al., 2011), a cold season. Temperature then continuously rises with Upper Mae Tuen basin (Thanasiriyakul, 2003) and a slightly drop in a short transitional period between the Chaophraya River basin (Vathananukij, 2006); water monsoons during March and April. Lam Takong River supply for irrigation in the Songkhla Lake basin basin has an average annual temperature of 25.4oC, and (Prachayasittikul, 2006); water use efficiency for a maximum and minimum relatively humidity of 83.4% agriculture in Mae Tha watershed (Keawmuangmoon, and 47.8%, respectively. 2009); effect of land use changes on runoff in the According to Land Development Department Upper Nan basin (Vesurai, 2005) and Mae Jang basin (2009), land use Lam Takong River basin is dominated (Intaruksa, 2012). Suspended sediment at Thoung- by agricultural land (55.73%), followed by forested naklang and Failuang weirs, Uttraradit province, areas (21.28%) and urban areas (11.81%) (Fig. 2). using SWAT,but only temporal variation was apparent Various soil series are present, including Khao Yai, (Suwanlertcharoen, 2011). However, SWAT was also Kabinburi, Khorat and Lam Narai series. Soil drainage unsuccessfully used to evaluate nutrients in Utapao is medium to good. The soil layers alternate between River Basin to Songkhla Lake (Punyawattano, 2010). shallow and deep areas with universally moderate In this paper, the SWAT2009 model was used to fertility. study temporal and spatial variability of watershed characteristics, and then identify critical areas in Lam 2.2. Model description Takong River basin. Moreover, the best management practices (BMPs) were used to evaluate the reduction The United States Department of Agriculture and of NPS pollution to meet water quality criteria without Agricultural Research Service (USDA-ARS) developed disturbing environmental quality. The results may be SWAT as a hydrologic/water quality model (Arnold incorporated into BMP planning for water resource et al., 1998). Outputs provided by SWAT include: management and soil conservation in Lam Takong streamflow and in-stream loading or concentration River basin. estimates of sediment, organic nitrogen, nitrate, organic phosphorus, soluble phosphorus and pesticides 2. Materials and methods (Gassman et al., 2007). The SWAT model can predict the impact of land management practices on water, 2.1. Study area sediment and agricultural chemical yields in large complex watersheds with varying soils, land uses and Lam Takong River basin is a part of the Moon management conditions over long periods of time watershed, in the Northeastern region of Thailand (Neitsch et al., 2011). (Fig. 1). The basin has a total area of 3,518 km2, In SWAT, a watershed is divided into multiple covering nine districts of three provinces including: subbasins, which are further subdivided into hydrologic Prachantakham district in Pracheenburi province, Pak response units (HRU) that consist of homogeneous Plee district in Nakhon Nayok province, Pak Chong, land use, management, and soil characteristics. In this Sikhio, Sung Noen, Kham Thale So, Dan Khuntod, study, the Lam Takong River basin was divided into

N. Pongpetch et al. / EnvironmentAsia 8(1) (2015) 41-52

Figure 1. Lam Takong River basin and sampling stations

FigureFigure 1. Lam1. Lam Takong Takong River River basin basin and a samplingnd sampling stations stations

Figure 2. Land use types of Lam Takong River basin Figure 2. Land use types of Lam Takong River basin 63 subbasins, which in turn were subdivided into 308 There are 4 stations along Lam Takong River. HRUs.2.2.Figure However,M o2.d Landel descripti useonly typ theoesn subbasins of Lam Ta levelkong wasRiver described basin Only 2 stations were used for this study because they in this study. have complete data of both sediment and water quality 2.2. Model description The United States Department of Agriculture anford theAgricultur period aofl Researchstudy from Service 2007 (USto 2009.DA-ARS) The other 2.3.develop Input dataed SWAT as a hydrologic/water quality modeltwo,(Arnold however, et haveal., 1998). incomplete Outputs or mismatchedprovided by data; The United States Department of Agriculture and Agricultural Research Service (USDA-ARS) SWAT include: streamflow and in-stream loading ortherefore, concentratio they nare estimates unusable. of Thesedimen M89t ,station organic in Pak nitrogendevelope, dnitrate, SWAT or agsanic a hydrolo phosphgorus,ic/water solub quleality phosphor modelus(Arnold and pesti etc idesal., 1998).(Gassm Outputsan et al .,pr 2o0vided07). The by SWATLam Takonginclude: River stre basinamflow information and in-stream was obtained loading orChong concentratio district nis estimatesa representative of sedimen of thet, organicUpper Lam fromSWAT variousmodel agencies can pr edictas secondary the impact data of land(Table managemen 1). Takongt practices River o nwhich water, has sed beeniment affected and agricultural primarily by chemicanitrogenl, yieldsnitrate, in or lagrgeanic comple phosphxorus, watersheds solubl ewith phosphor varyinugs soils,and pesti landc idesuses (Gassand mmaannagementet al., 2 c0onditions07). The These data were input into SWAT to simulate stream- agriculture. On the other hand, the M164 station in overSWAT lonmg odelperiods can ofpr edicttime (Neitsthe imcphact et ofal., land 201 1).management practices on water, sediment and agricultural flow, sediment and nutrient loads. In this study, we Mueang Nakhon Ratchasima district was chosen to chemicaIl nyields SWAT, in large watershed comple xi swatersheds divided in towith multiple varyin gsubbasins, soils, landw useshich andare mfuarthernagement subdi cvonditionsided into focus only on NPS pollution because it applies to the represent the Lower Lam Takong River which has been hydroloover longgic periods respons ofe time units (Neits (HRUch )et thatal., 201con1).sist of homogeneous land use, management, and soil entire basin.In The SWAT, PS pollution a watershed locations is divided are difficult into multiple to mainly subbasins, affectedw byhich urbanization. are further subdivided into obtain,hydrolo becausegic respons most factoriese units are (H farRU from) that Lam co Takongnsist of ho mogeneousTwo yearsland (2007-2008) use, management, of data wereand soilused to River. The effect from factories, should be minimal calibrate SWAT, a single year (2009) was used to except in the case of accidents. PS pollution effects in validate the model, by observing daily streamflow,

Lam Takong River basin were excluded from this study sediment, NO3-N and TP loads at M89 and M164 because they are already covered in previous studies. stations in Lam Takong River (Fig. 1). These data were

43 N. Pongpetch et al. / EnvironmentAsia 8(1) (2015) 41-52

Table 1. Data inputs for Lam Takong River basin

Data type Agency Period of time Digital Elevation Map (30 × 30 m2 resolution) Land Development Department 2004 Land use Land Development Department 2008 Flow of water/run off Royal Irrigation & Meteorology Department 1990 - 2009 Reservoir Royal Irrigation Department 1990 - 2009 Wind Thai Meteorology Department 1980 - 2005 Solar, humidity Thai Meteorology Department 1980 - 2009 Rainfall Thai Meteorology Department 1990 - 2009

obtained from the Hydrology and Water Management 2.5. Classification maps Center for the Lower Northeastern Region and Regional Environmental Office 11, Nakhon Sediment load maps were built by using soil loss

Ratchasima, Thailand. tolerance rate (Stone and Hilborn, 2000). NO3-N load maps were classified according to Wu et al. (1997). 2.4. Data analysis Finally, TP load maps were classified according to the Gurung et al. (2013) standard. A wide range of statistics has been used to evaluate SWAT hydrologic predictions. The most widely 2.6. Management scenarios used statistics (Gassman et al., 2007) for hydrology calibration and validation are the: regression correlation Watershed level reductions include cumulative coefficient (R2), the Nash-Sutcliffe model efficiency load reductions considering overland pollutants and (NSE) coefficient (Nash and Sutcliffe, 1970) and their routing through the stream network. Simulations percent bias (PBIAS). They are calculated according of BMPs are a term used in the Lam Takong River to formula (1), (2) and (3): basin to describe a type of water pollution control. BMPs are analyzed under alternative scenarios which simulate the effects of several specific scenarios. In this study, the analysis simulated the effects of 13 specific � � � �∑�� scenarios of change in land cover, filter strip, terrace � � R � � � �1� and combination (Table 2). ∑�� ∑�� ∑�� Table 2. Scenario descriptions for Lam Takong River basin � �� 1 � � � � �� ∑ �� Scenarios Description �� ∑� � o � �� 100 1 Agriculture → deciduous forest, if slope > 12 �� o ∑ � 2 Orchard→ agriculture, if slope > 12 Where, is the number Where, of measured n is the numberdata, of and measured are thedata, measured Oi and and predicted data at o time i, and are the meansP are of the measured measured and and predicted predicted data. data at time i, O and 3 Agriculture → orchard,if slope > 12 � i �� Soil Erosion is Pcomputed are the means with ofthe measured Modified and Universalpredicted data.Soil Loss Equation4 (MUSLE)6-m filter strip � � (Williams, 1975). Then SWAT Soil uses Erosion the modified is computed Environmental with theImpact Modified Policy Climate5 (EPIC)10-m model filter strip (Izaurralde et al., 2006) toUniversal compute Soilnutrient Loss yield Equation and cycling (MUSLE) from (Williams, the sub-watersheds. 6 The 15-mnutrient filter strip concentration is converted to mass (kg/ha) by multiplying it by the depth of the soil layer and soil bulk 1975). Then SWAT uses the modified Environmental 7 20-m filter strip density and performing appropriateImpact Policy unit conversions.Climate (EPIC) SWAT model is interfaced (Izaurralde with ArcGIS (ArcSWAT), 8 25-m filter strip all soil sediment and nutrientet al loading., 2006) results to compute were clas nutrientsified inyield different and cyclinglevels and presented in maps. from the sub-watersheds. The nutrient concentration is 9 30-m filter strip 2.5. Classification maps converted to mass (kg/ha) by multiplying it by the depth 10 Terrace of the soil layer and soil bulk density and performing 11 Terrace, 6-m filter strip Sediment load mapsappropriate were built unit by conversions. using soil SWATloss tolerance is interfaced rate with(Stone and 12Hilborn,Terrace, 2000). 50-m filter strip in Muang district, NO3-N load maps were classifiedArcGIS according(ArcSWAT), to Wu all etsoil al .sediment (1997). Finally, and nutrient TP load maps were classified6-m filter strip for the rest according to the Gurung et al. (2013) standard. loading results were classified in different levels and 13 50-m filter strip in Muang district, 6-m filter presented in maps. strip for the rest 2.6. Management scenarios

Watershed level reductions include cumulative load reductions considering overland pollutants and their routing through the stream network. Simulations of BMPs are a term used in the Lam Takong River basin to describe a type of water pollution control. BMPs are analyzed44 under alternative scenarios which simulate the effects of several specific scenarios. In this study, the analysis simulated the effects of 13 specific scenarios of change in land cover, filter strip, terrace and combination (Table 2).

Table 2. Scenario descriptions for Lam Takong River basin

Scenarios Description

1 Agriculture  deciduous forest, if slope > 12o 2 Orchard agriculture, if slope > 12o 3 Agriculture  orchard,if slope > 12o 4 6-m filter strip 5 10-m filter strip 6 15-m filter strip 7 20-m filter strip 8 25-m filter strip 9 30-m filter strip 10 Terrace 11 Terrace, 6-m filter strip 12 Terrace, 50-m filter strip in Muang district, 6-m filter strip for the rest 13 50-m filter strip in Muang district, 6-m filter strip for the rest N. Pongpetch et al. / EnvironmentAsia 8(1) (2015) 41-52

Group A: Land use change. Since Land filter strip near the banks of every water way. The Development Department (2009) suggests that at slope 2007 Ministerial Regulations for Nakhon Ratchasima’s > 12o, the recommended land use should be forest type. Principle City Plan also suggested 50-m empty space We evaluate different land use type changes in areas parallel to the sides of water bodies. with this slope. Group B: Filter strip. Filter strips are strips of 3. Results and discussion herbaceous vegetation situated between cropland, grazing land, or any disturbed land and an environ- 3.1. Calibration and validation of SWAT model mentally sensitive area. Filter strips trap sediment, thereby reducing the sediment and sediment-bound Simulated values of both streamflow and sediment contaminants in runoff. Filter strip was represented in were very close to the observed values (Fig. 3) as R2 terms of edge-of-field filter strip (FILTERW) variable in and NSE were greater than 0.5 (Table 3) and PBIAS SWAT. In this study, filter strips with 6 different widths was less than 25% (Moriasi et al., 2007; Santhi et al., were evaluated including 6, 10, 15, 20, 25 and 30 m. 2001). It indicated that this model was able to predict The 6-m filter strip refers tothe ministerial regulations streamflow and sediment loads consistently. Although, for Nakhon Ratchasima’s principle city plan. NSE at M164 did not exceed 0.5 during the validation Group C: Terraces. Terraces are broad earthen period, PBIAS was still less than 25%. Therefore, embankments or channels constructed across the slope SWAT was successful in streamflow and sediment yields of a field to intercept runoff water and control erosion. prediction for the entire period. Terraces effectively decrease hill-slope length, help On the other hand, the model calibration and prevent the formation of gullies, and redirect intercepted validation of NO3-N and TP showed a fair relationship runoff to a safe outlet. In this study, terraces were between observed and simulated NO3-N and TP loads, represented by conservation support practice factor with R2 values greater than 0.6 and PBIAS values

(P-factor) and CN. The P-factor (PUSLE) is defined as the less than 25% (Table 3). The NSE was not used based ratio of soil loss with a specific support or conservation on the insufficient, irregular data (only 10 samples). practice to the corresponding loss with cultivation The simulated NO3-N and TP loads were above or up-and-down the slope. In the scenario basis condition, below the 1:1 line, indicating that the model did not P-factor was set to 1.0 and 0.6 whereas in Scenario exhibit any tendency to systematically overestimate or 10 condition P-factor of the terraced areas was set to underestimate due to data limitations. 0.10, 0.12, 0.16, 0.18 and 0.2 depending on the average upland slope and also considering waterways or graded 3.2. Temporal sediment and nutrient loads channel outlets in conjunction with terraces. Curve number values were reduced by 5 from the calibration For the simulation period (2007-2009), the model CN values; this is a common practice and has been used calculated a 616 mm mean annual evapotranspiration by others such as Bracmort et al. (2006) and Secchi rate and an 1138.7 mm mean annual precipitation. et al. (2007). Sediment, NO3-N and TP loads showed temporal Group D: Combination scenario. We combined fluctuation (Fig. 4). TP was closely linked to sediment terrace and different filter strip widths here. The 1975 in SWAT whereas NO3-N was governed more directly Town and Country Planning Act suggested using 6-m by runoff. Overall, all parameters were very low in

Table 3. Summary of streamflow, sediment and nutrient calibration and validation

Period Variable M89 M164 R2 NSE PBIAS (%) R2 NSE PBIAS (%) Calibration (2007-2008) Streamflow 0.69 0.61 0.02 0.68 0.50 1.32 Sediment 0.65 0.54 0.75 0.64 0.63 1.87

NO3-N 0.84 - 1.42 0.60 - 0.63 TP 0.94 - 1.82 0.91 - 2.96 Validation (2009) Streamflow 0.72 0.58 8.72 0.49 0.40 17.39 Sediment 0.80 0.80 6.74 0.52 0.47 1.08

NO3-N 0.95 - 6.29 0.66 - 5.07 TP 0.96 - 14.25 0.67 - 9.85

N. Pongpetch et al. / EnvironmentAsia 8(1) (2015) 41-52

Figure 3. Comparison between the simulated and observed streamflow and sediment values of M89 and M164 Figure 3. Comparison between the simulated and observed streamflow and sediment values of M89 and M164 the dry season (NovemberOn tothe April) othe r attributedhand, the tomodel a 0.46cali bkg/haration of and TP load).validation The significantof NO3-N alossnd TPof NOsho3-Nw ed a fair 2 significant reductionrelation in srunoff.hip betwee Theyn reachedobserved the an dfirst simulate duringd NO the3-N summer and TP has loads, been w ithreportedR value in sagricultural greater tha n 0.6 and peak at the beginningPBIAS ofv thealues wet less season than 25%(May) (T fromable 2). catchmentsThe NSE was (Arheimer not used and based Liden, on the 2000; insu Yevenesfficient, irreandg ular data the first round of (onlyrain storms 10 samples). but went T hedown simulat duringed the NO 3-NMannaerts, and TP loads2011). were The abovepresence or belowof stagnating the 1:1 watersline, i ndicating intermittent dry seasonthat the in modelJune. Levelsdid not climbed exhibit upany to tendencin they catchmentto system astreamtically network overestimate along withor underestim the sink ofa te due to the second and highestdata lim peakitations. in September (3.47 ton/ nitrogen from denitrification in high temperatures and ha of sediment load, 0.20 kg/ha of NO3-N load and low oxygen level condition may explain the observed

3.2. Temporal sediment and nutrient loads

For the simulation period (2007-2009), the model calculated a 616 mm mean annual evapotranspiration rate and an 1138.7 mm mean annual precipitation. Sediment, NO3-N and TP loads showed temporal fluctuation (Fig. 4). TP was closely linked to sediment in SWAT whereas NO3-N was governed more directly by runoff. Overall, all parameters were very low in the dry season (November to April) attributed to a significant reduction in runoff. They reached the first peak at the beginning of the wet season (May) from the first round of rain storms but went down during the intermittent dry season in June. Levels climbed up to the second and highest peak in September (3.47 ton/ha of sediment load, 0.20 kg/ha of NO3-N loadand 0.46 kg/ha of TP load). The significant loss of NO3-N during the summer has been reported in agricultural catchments (Arheimer and Liden, 2000; Yevenes and Mannaerts, 2011). The presence of stagnating waters in the catchment stream network along with the sink of nitrogen from denitrification in high temperatures and low oxygen level condition may explain the observed variation. Another explanation may be the increased plant uptakeN. Pongpetch and removal et al. / EnvironmentAsia by periphyton 8(1) and (2015) plants 41-52 (Flipo et al., 2007).

4.00 3.50 3.00 2.50 2.00 Loads 1.50 1.00 0.50 0.00 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Sediment (t/ha) NO3-N (kg/ha) TP (kg/ha)

Figure 4. Temporal variation of sediment, NO3-N and TP yields at basin outlet Figure 4. Temporal variation of sediment, NO3-N and TP yields at basin outlet variation.3.3. Sediment Another and explanation nutrient load may critical be the areas increased These values were higher than Lam Takong River plant uptake and removal by periphyton and plants basin because the former is in a mountainous region (Flipo et alLam., 2007). Takong River basin had an annual soil erosionwith higher of 8.134 elevation, t/ha which while was the identified latter has as verya greater low by using the soil loss tolerance rate (Stone and Hilborn,proportion 2000 of). Thisagricultural value was area less (84%). than 29.46However, t/ha Lam 3.3.of Sediment Upper Lam and Phranutrient Phloeng load critical watershed, areas the nearby basinTakong (Ongsomwang River basin’s andsoil Thinley,erosion was2009) higher due thanto in hilly topography with undulating, steep slopes and significantlyMae Phun watershedhigher rainfall at 5.4 than t/ha in (Suwanlertcharoen, Lam Takong

RiverLam Takongbasin. Other River basinstudies had also an annual reported soil erosionsoil erosion 2011) of because10.70 t/ha this for basin Arnigad has a basinlarger ofpercentage Lower of of 8.134Himalaya t/ha which(Tyagi was et al identified., 2014) and as 12.2very low t/ha byfor using Upper forestedSouth Koel area Basin (89%) in and India Songkhram (Parveen watershedand Kumar, at 3.59 2012). These values were higher than Lam Takong River basin because the former is in a mountainous the soil(Stone loss tolerance and Hilborn, rate (Stone 2000) and because Hilborn, it received 2000). wat/hater hasand more sediment flat areaof all (Nontananandh basins above Lamand Changnoi,Takong region with higher elevation, while the latter has a greater proportion of agricultural area (84%). This valuedam. was In lessaddition, than 29.46 basin t/ha 63 (Muof Upper Si subdistrict) Lam Phra was2012). identified as a high soil erosion area since it was However, Lam Takong River basin’s soil erosion waso higher than in Mae Phun watershed at 5.4 t/ha Phloenglocated watershed, at high the nearbysteep slopesbasin (Ongsomwang (more than 55.95 and ) upstreamThe simulation and subjected results to were tillage able and to identifymany major areas (Suwanlertcharoen, 2011) because this basin has a larger percentage of forested area (89%) and Thinley,rainfall 2009) dueevents. to hilly Similarly, topography the withstudy undulating, in the upper ofMekong significant River soilconcluded erosion that based the soilon erosionthe average was Songkhram watershed at 3.59 t/ha has more flat area (Nontananandh and Changnoi, 2012). steep slopesproduced and on significantly land with a steepnesshigher rainfall reaching than 59.7 in t/haannual when sediment the slope yield was for greater the total than hydrological 40° (Zhou periodet al., The simulation results were able to identify areas of significant soil erosion based on the Lam Takong2014). RiverTherefore, basin. appropriate Other studies strategies, also reported such as lawithinnd use each changes, subbasin. filter Among strips and63 subbasins terraces, shouldwithin thebe average annual sediment yield for the total hydrological period within each subbasin. Among 63 soil erosiondevised of to10.70 protect t/ha these for Arnigad critical basinareas forof Lowersoil and watercatchment, conservation subbasin practices. 48 (Lam Takong dam) had the subbasins within the catchment, subbasin 48 (Lam Takong dam) had the highest sediment loading of Himalaya (Tyagi et al., 2014) and 12.2 t/ha for Upper highest sediment loading of 33.73 t/ha (Fig. 5). It 33.73 t/ha (Fig. 5). It was identified as a severe soil erosion area using the soil loss tolerance rate South Koel Basin in India (Parveen and Kumar, 2012). was identified as a severe soil erosion area using the

Figure 5. Vulnerability of different subbasins in sediment loads

Figure 5. Vulnerability of different subbasins in sediment loads 47 The mean annual NO3-N yield of Lam Takong River basin was only 0.879 kg/ha which waslow as classified by Wu et al. (1997). This value was lower than 2.57 to 4.52 kg/ha in Banha watershed, India (Mishra et al., 2010) where cattle and poultry farms are found in residential areas. However, the value was higher than those in Honey Creek watershed, Ohio (Grunwald and Qi, 2006) which has more forested area. Subbasin 22 and 17 (Nai Mueang subdistrict) had the highest NO3-N in the basin (Fig. 6). Similarly, the Pollution Control Department (2008) and Suwanwaree and Suwannarat (2010) reported water quality in Nai Mueang subdistrict as meso-eutrophic and deteriorating. However, both subbasins were classified as medium ranges following Wu et al. (1997).

N. Pongpetch et al. / EnvironmentAsia 8(1) (2015) 41-52

Figure 6. Vulnerability of different subbasins in NO3-N losses soil loss tolerance rate (Stone and Hilborn, 2000) Subbasin 22 and 17 (Nai Mueang subdistrict) had becauseFigure it received 6. Vulnerability water and of sedimentdifferent subbasins of all basins in NO 3-Nthe losses highest NO3-N in the basin (Fig. 6). Similarly, the above Lam Takong dam. In addition, basin 63 (Mu Si Pollution Control Department (2008) and Suwanwaree subdistrict) was identifiedUnlike NO as3 -N,a high the soil mean erosion annual area TPsince yield and of LamSuwannarat Takong (2010) River basinreported was water 1.213 quality kg/ha inwhich Nai it was locatedwas considered at high steep medium slopes according (more than to 55.95Gurungo) etMueang al. (2013). subdistrict This valueas meso-eutrophic was similar andto thedeteriorating. upstream upstreamYellow and subjectedRiver, China to tillage(Ouyang and et manyal., 2009). major However, However, it was both greater subbasins than thewere Banha classified watershed, as medium India rainfall events.(Mishra Similarly,et al., 2010) the study where in paddy-cultivation the upper Mekong maderanges up 31.49% following of theWu total et al area.. (1997). Nine subbasins had high TP loading and were considered as eutrophic areas (Gurung et al., River concluded that the soil erosion was produced on Unlike NO3-N, the mean annual TP yield of land with2013). a steepness They reachingwere distributed 59.7 t/ha whenall over the slope the basinLam both Takong in agriculturalRiver basin wasand 1.213urban kg/ha areas which (Fig. was7). was greaterAgricultural than 40° land, (Zhou where et al chemical., 2014). fertilizers Therefore, or manureconsidered are deposited, medium according is the main to sourceGurung of et NO al. 3(2013).-N and TP losses (Panagopoulos et al., 2011). appropriateFigure strategies, 6. Vulnerability such as of land different use changes,subbasins filterin NO 3-NThis losses value was similar to the upstream Yellow River, strips and terraces, should be devised to protect these China (Ouyang et al., 2009). However, it was greater than critical areas forUnlike soil and NO water3-N, conservation the mean annual practices. TP yield the of Banha Lam Takong watershed, River India basin (Mishra was 1.213 et al., kg/ha2010) wherewhich was considered medium according to Gurung et al. (2013). This value was similar to the upstream The mean annual NO3-N yield of Lam Takong paddy-cultivation made up 31.49% of the total area. River basinYellow was River, only China0.879 (Ouyangkg/ha which et al waslow., 2009). as However, Nine it was subbasins greater thanhad thehigh Banha TP loading watershed, and Indiawere classified(Mishra by Wuet et al al., .2010) (1997). where This paddy-cultivation value was lower madeconsidered up 31.49% as ofeutrophic the total areas area. (Gurung et al., 2013). than 2.57 to 4.52Nine kg/ha subbasins in Banha had watershed,high TP loading India andThey were were considered distributed as eutrophic all over areas the (Gurungbasin both et al in., (Mishra2013). et al., They2010) werewhere distributed cattle and poultryall over farms the basinagricultural both in andagricultural urban areas and (Fig. urban 7). Agricultural areas (Fig. land, 7). Agricultural land, where chemical fertilizers or manure are deposited, is the main source of NO3-N and are found in residential areas. However, the value was where chemical fertilizers or manure are deposited, is TP losses (Panagopoulos et al., 2011). higher than those in Honey Creek watershed, Ohio the main source of NO3-N and TP losses (Panagopoulos (Grunwald and Qi, 2006) which has more forested area. et al., 2011).

Figure 7. Vulnerability of different subbasins in TP losses

48 N. Pongpetch et al. / EnvironmentAsia 8(1) (2015) 41-52

However, subbasins with very high vulnerability to reduced runoff volume by 43 to 99.9%, suspended solids

TP losses might be of moderate vulnerability in NO3-N by 87 to 100%, Nitrate and soluble phosphorus were losses. This can be attributed both to the uneven N reduced by 47 to 100% and by 22 to 89%, respectively. and P input to this subbasin as well as to the different Terraces were the second best method to control mechanisms governing N and P movement in the area, nonpoint source pollution. At the basin level, terraces which are associated with surface and subsurface curtailed sediment, NO3-N and TP loads by 85.62%, pathways of pollutant transport (Panagopoulos et al., 18.66% and 68.76%, respectively. It indicated that this 2011). Thus, such differences were crucial for the scenario could reduce much of the sediment and TP selection of appropriate management alternatives, loads, but moderate NO3-N. However, previous study which should be selected according to the environment showed that the regulation of USLE C and P factors target or type of pollutant. showed the greatest TN (36.5%) and TP (41.4%) reductions of among four BMPs scenarios including 3.4. Management scenarios the application of vegetation filter strip, riparian buffer system, the regulation of Universal Soil Loss Equation Filter strip was the most effective way to control P factor and the fertilizer control amount for crops (Lee nonpoint source pollution in the Lam Takong River et al., 2010). basin, followed by terrace and land use change, Changing land use types in Lam Takong River respectively (Table 4). From 13 scenarios, the 30-m basin did not affect nonpoint source pollution. A filter strip had the most effective BMP, it could reduce possible reason could be the size limitations of the

100% of both sediment and TP, and 97% of NO3-N. area, which were too small to register. The change of Reducing filter strip width would decrease the agriculture to deciduous forest, if slope > 12o was only pollution reduction. Parajuli et al. (2008) found that 2.44% of total agricultural land. People rarely farm in about 73% of sediment yield was reduced with a 10 m areas with steep slopes. However, other studies found filter strip. The 15 m removed up to 82% of sediment land use changes did indeed impact water pollution yield and the 20 m removed up to 89% of sediment yield trends. For example, Liu et al. (2013) reported that the at Upper Wakarusa watershed in Kansas. Moreover, conversion of steep sloped arable land (25o) to forests they also concluded that 100% reduction of sediment could reduce nitrogen, phosphorus and other nutrients yield needed a 30 m filter strip. Laurent and Ruelland in the Xiangxi River watershed by 20% or more. Yang (2011) studied alternative practices of nitrate flow in et al. (2011) converted Eucalyptus plantations to natural Oudon River, Western France. The results illustrated forest, if the gradient > 25o. The results showed that the efficiency of filter strips (5 m) was significant at the sediment and TP would reduce by 15.99% and 4.80%, catchment scale as 11% nitrate reduction. Patty et al. respectively. Moreover, Betrie et al. (2011) simulated (1997) showed that strips with widths of 6, 12 and 18 m reforestation scenarios (altering cropland, shrub land,

Table 4. The simulated loads of the pollution and percentage reduction (in parenthesis) in different scenarios of Lam Takong River basin

Scenarios Sediment (t/ha) NO3-N (kg/ha) TP (kg/ha) Present state 8.134 0.879 1.213 Scenario 1 7.987(1.81%) 0.877 (0.23%) 1.203 (0.82%) Scenario 2 8.366 (-2.85%) 0.884 (-0.57%) 1.224 (-0.91%) Scenario 3 8.070 (0.79%) 0.876 (0.34%) 1.204 (0.74%) Scenario 4 3.054 (62.45%) 0.363 (58.70%) 0.455 (62.49%) Scenario 5 2.223 (72.67%) 0.275 (68.71%) 0.332 (72.63%) Scenario 6 1.467 (81.97%) 0.192 (78.16%) 0.219 (81.95%) Scenario 7 0.873 (89.27%) 0.125 (85.78%) 0.130 (89.28%) Scenario 8 0.376 (95.38%) 0.069 (92.15%) 0.056 (95.38%) Scenario 9 0.000 (100%) 0.024 (97.27%) 0.000 (100%) Scenario 10 1.170 (85.62%) 0.715 (18.66%) 0.379 (68.76%) Scenario 11 1.525 (81.25%) 0.302 (65.64%) 0.211 (82.61%) Scenario 12 1.415 (82.60%) 0.196 (77.70%) 0.174 (85.66%) Scenario 13 2.856 (64.89%) 0.245 (72.13%) 0.378 (68.84%)

49 N. Pongpetch et al. / EnvironmentAsia 8(1) (2015) 41-52 barren, mixed forest, and deciduous forest into were too few. Therefore, the further works of calibrating evergreen forest), which showed that the least and validating the models should follow up by reduction of sediment loads was 11% reduction in the increasing the number of sampling stations in future Blue Nile Basin. monitoring efforts. Moreover, the in-depth study The use of a 6-m filter strip alone had a moderate of HRUs level and PS should be also considered to effect on three pollutants no greater than 62%. Terraces improve management efficiency. could significantly reduce both sediment (85.62%) and TP (68.76%) but not NO3-N (only 18.66%). When Acknowledgments combined, the 6-m filter strip could improve the The authors gratefully acknowledge funding from the reduction of NO3-N (to 65.64%) and TP (82.61%) but decrease sediment reduction. When 50-m filter strips Strategic Scholarships for Frontier Research Network for the Thai Ph.D. Program under the Office of the Higher Education were added in subbasins of Muang District, this can Commission, Thailand. We also appreciate the generous improve much of NO3-N up to 77.7% but only a little cooperation of the Hydrology and Water Management for sediment and TP due to small area size. However, Center for Lower Northeastern Region, Nakhon Ratchasima, when terraces were taken out, sediment and NO3-N Regional Environmental Office 11, the Land Development drastically dropped to 64.89% and 68.84%, respectively. Department, the Royal Irrigation Department, Department Therefore, adding a filter strip has a greater impact on of Water Resources and the Thai Meteorology Department

NO3-N than terraces do in the Lam Takong River basin. for their cooperation. We thank Mr.Colin T. Strine for editing The best combination would be scenario 12 when this manuscript. We also thank the anonymous reviewers applying terraces with 6 and 50 m filter strips. However, who gave comments improving the overall quality of the it is not possible to apply 50-m filter strip in the manuscript. Muang District due to the anthropogenic influence and References previously established human dominated landscapes on the margins of Lam Takong River. Arabi M, Govindaraju RS, Hantush MM, Engel BA. Role of watershed subdivision on modeling the effectiveness 4. Conclusions of best management practices with SWAT1. Journal of the American Water Resources Association 2006; SWAT model was successfully used to evaluate 42(2): 513-28. Arheimer B, Lidén R. Nitrogen and phosphorus concentrations sediment, NO3-N and TP loads in Lam Takong River basin. The simulated flow, sediment and nutrient loads from agricultural catchments: Influence of spatial and at the two stations in Lam Takong River were in temporal variables. Journal of Hydrology 2000; 227 (1-4): 140-59. reasonable agreement with the measured values 2 Arnold JG, Fohrer N. SWAT2000: Current capabilities and with R and NSE greater than 0.5 and PBIAS less than research opportunities in applied watershed modeling. 25%. The simulation also showed that mean annual Hydrological Processes 2005; 19(3): 563-72. sediment, NO3-N and TP at the outlet were 8.134 t/ha, Arnold JG, Srinivasan R, Muttiah RS, Williams JR. Large 0.879 kg/ha and 1.213 kg/ha, respectively. Moreover, area hydrologic modeling and assessment part I: model

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