CASE STUDY from MACHANG - MALAYSIA (Penilaian Air Tanah Di Dserah Pertanian, Studi Kasus Di Machang Malaysia)
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J. MANUSIA DAN LINGKUNGAN, Vol. 17, No.3, Novernber 2010: t9l-199 GROUNDWATER ASSESSMENT IN AGRICULTURAL AREA, CASE STUDY FROM MACHANG - MALAYSIA (Penilaian Air Tanah di Dserah Pertanian, Studi Kasus di Machang Malaysia) Nur Islami Program Studi Fisika - PMIPA - UNIVERSITAS RIAU email : wis74@)yahoo. com Diterima: l2 Juli 2010 Disetujui: 2l Oktober 2010 Abstract The study area is located in Machang, North Kelantan - Malaysia. The North Kelantan plain is covered with Quaternary sedirnents overlying granite bedrock. The drainage system is dendritic with the main river flowing into the South China Sea. Hydrogeochemical method was used to study groundwater of shallow aquifer characters within the area. Based on water samples analysis col- lected tiom the study area, it can be deduced that the cations and anions concentration are good fbr domestic use except in the southern region which the nitrate concentration is higher (more than 20 inglt) compared to the northern region (relatively zerc).The areas that possibly possess nitrate-con- taminated groundwater have been mapped along with groundwater flow patterns. The southenr and middle part of the study area has an east to west groundwater flow pattern, rnaking it irnpossible for contaminated water from the southern region to enter the northern area, despite in the northern area has lower elevation. Keywords: Groundwater, N itrate. Abstrak Lokasi area .studi udalah berada di Machang, Kelantan Utara - Malaysiu. Duturutr tctnuh v,iluyult Kelantan Utura dilapisi oleh batuan Sedimen Kuarter yang n ana batuan granil sebugai butuan dusu'. Sistem pengairun adaluh berbentuk.jaringan dendritik dengan sungai tttunn ntengulir ke Luut Cinu Selatan. Metoclu hl,drogeochemical digunakan untuk mempelajuri kurukter uir lunuh luri ukuilitr' dangkal unttrk keseluruhon qree stucli. Berdusqrkan pacla analisa air yung tliperoleh duri areu stutli, dapat disimpulkan bahwa konsentrasi kation dan anion baik digunakan untuk kehitlupan sehori huri kecuali air tunah di areq sehelah selatan yang mana kandungan nitrutnyu tinggi (lebih duri 20 ng/l) dibandingkan di areo sebeluh utarq (hampir titluk ada kandungan nitrat). Areu S'utrg mentungkinkun memiliki konsentrasi nitrut peda air tanuh dipetakan clengan kombinerci pola ulinm uir tunuh. Polu aliran air tanuh di ureu beluhan selutcrrt clun bagictn tengah udeiluh duri tirrtur kc burut .r'ctttg tnutut tidak ntenrungkinktnnyu air tcmah ))ung terkontaminusi oleh nitrut di beluhutr .st,lututt tttrtuk tttu.sttk ke areu belahun uturu v,ulcutpun cli beluhutr utaru udaluh duturun renduh. Kutu kunci: Airtunuh, Nitt'ut. t92 J. MANUSIA DAN LINGKUNGAN Vol. 17, No.3 INTRODUCTION Review oJ'Geology Srudy Area The total extent of study area covers ap- Groundwater is among the Norlh Kelantan's proximately 98 square kilorneters (kma). The most important natural resources. It provides southern part of the area is defined by Kam- drinking water to urban and rural communities, pung Tok Bok and is bounded in the north by supports inigation and industry, sustains the Kampung Ketereh. The study area is covered flow of streams and rivers, and maintains ripar- with Quaternary sedirnents overlying granite ian and wetland ecosystems. The importance of bedrock. It is drained mainly by short rivers groundwater for the existence of human sociefy and streams which flow into the South China cannot be overemphasized. Sea. The thickness of the Quatemary deposits Like other places, in the study area, chemi- varies from 20 m inland to about 200 m near the cal fertilizers are rigorously used to enhance the coast. The loose quaternary sediments consist agricultural establishment (Yang, et al., 2006) of alternating layers of coarse gravels to silts of crude palm oil. Fertilization is conducted or mixtures of the two (Saim, 1999). lt can be every two months using fertilizers of different clearly seen that the study area is bounded by chemical content. For example, at the begin- Kelantan River at the west side and the high ning of the year, 400 kilograms of Urea with hill at the east side (Figure l). The hill is a part 60% nitrogen is used for a two hectare palm of the Boundary Range Composite Batholith. It plantation. Two months later, another fertilizer consists of two major components, the Mach- with 15% Nitrogen, 30% Phosphorus, and ang Batholith which is 100 x 20 km, and the 55% Potassium (NPK) is applied to further smaller Kerai Batholith situated on the western improve the production of palm. This process flank (Cobbing, and Pitfield, 1992).Around the is repeated in the middle of the same year and hill, a lot of exposed granite can be found espe- continues till the end of the year. All in all, at cially at Sungai Buluh Quarry. Other exposed least 800 kilograms of urea is employed for granite can also be found in Kampung Pulai the fertilization of palm trees in a two hectare Condong around 4 km to the west of Machang area per year. Batholith Boundary Range. Figure I shows the Other agricultural activities within study location map of the research area. The RSO area include the cultivation of paddy fields West Malaysia and Kertau 1946 are used as the and rubber trees. However, in comparing the coordinate system and datum in the map. intensity of the fertilization process for paddy and rubber trees with that of palm oil, it is much METHODOLOGY less than that of palm oil. The farmers in study area plant paddy only once ayear on average, A hydrogeochemical method was used to although some plant paddy up to twice a year study the groundwater characters in this area. ln over several areas. Paddy fields consume a the study, special emphasis was given to the first mere 100 kilograrns of urea per two hectare a aquifer (shallow aquifer) because it is the main year:For rubber trees, 200 kilograms of urea is sourcp of the water supply for domestic uscs. utilized for every two hectare per year. Samples of groundwater were collected frorn Contaminant leaching (especially nitrate) the existing wells, and in-situ parameters suclr from agricultural soils has been widely studied as welldepth, water level, total dissolved solid, (Almasri and Kaluarachchi, 2004; Saadi and pH, conductivity, salinity and temperaturc wel'e Maslouhi 2003). In this study attention has been measured. Water sarnples of 500mlwcre kept in focused mainly on assessment of groundwater plastic bottles and maintained at a ternperaturc within sandy soils in the shallow aquifer. Clay of 40C. This was done for detcrmining thcir soils are usually not considered to have a high major ion contents analysis with IC and ICP nitrate leaching potential. in the hydrogeology lab. Physical infonuation November 2010 ISLAMI, N. : GROUNDWATER ASSESSMENT r93 about water samples were retrieved directly RESULTS AND DISCUSSION from existing wells or piezometers whereas the physical information about these well, like The amounts of different clements includ- well location, well depth, depth to water were ing in-situ wafer, physical well parameters and obtained from the well owner. hydrogeochemical content have been presentcd The hydrogeochemical data obtained from in milligrams per litre (mg/l) for the testcd this study were used in the interpretation of the water samples, these figures are tabulated in overall data. Major ion concentration, electricpl Table l. condpctivity, and total dissolved solids were Ninety five percent of the groundwater in among the hydrogeochemical parameters used the shallow aquifer possssses a hydrogen ion in the characterization of the groundwater. concentration (pH) that is moderately acidic (4 Meter 200 100 50 40 35 30 25 20 15 10 465000 470000 E o,"", fl Area 1 fl nuuuer riero [] ,"'' r,u'o t_-j Paddy Field Figure l. Location of study area. t94 J. MANUSIA DAN LINGKUNGAN Vol. 17, No.3 - 6.5) whercas the remaining 5% is indicative from mineral breakdown. Also, in seditnentary of a more neutral pH condition (6.5-7.8), Thus rocks, fhe major soqrce of chloride in ground- it is generally good for some other domestic water is due to evaporate. The conceutration uses. Thirty percent of the water sample is of rain water by evapotranspiration tnay be an less than 5 on the pH scale and is considered important source of chloride in the area (Egbu- not good for human consumption if untreated. nike, 2007),Another comlnon source of chlo- The fact that the hydrogen ion concentration is ride in groundwater is the leaching ol'chloride more or less neutral affects the aggressiveness fertilizing over longperiods time. The influenco of the solution. ofthe fertilizing factor in the chloride content of Malnesium ion (Mg2+) concentration is the groundwater around thc southcrn part of the generally low. The availability of magnesium study area can be found in water sarnple frotn ion in the groundwater of the area can be ex- the borehole at A006 with chloride concentra- plained by the occurrence of magnesium with tion of 12.10 mgl. The chloride concentration calcium carbonate cetnent in sedimentary in the water samples are within the accepted formation. The low values of magnesium ion limits for human consumption. concentration may be a result of deficiency of The concentration of nitrate in the mapped minerals capable of yielding magnesium ion in area is generally good and falls within the water. This implies, however, that the magne- accepted limit except in the palnr oil field sium content of groundwater in the area renders area around surface water termination (,{002, it suitable for human use. A003,4004, S00l and 5002). However, out of There are notably low values of sodiurn (Na) the exceptional area, the nitrate safe drinking and potassium (K) in the water samples of the water concentration of l0 rng/l (WHO, 1984). mapped area. The possibility of contributory The potential source of nitrate in the area may factor is an impurity in the cementing material include fertilizing activities, animal exc remen t, where sodium ions permeate the carbonate lat- and probably the atmosphere.