MONITORRING OF ORGANIC POLLUTANTS IN STREAMS AND A RESERVOIR

MONITORRING OF ORGANIC POLLUTANTS IN  STREAMS AND A RESERVOIR

(case study in Selorejo Dam, Malang ,Jawa Timur, Indonesia)

BAMBANG PARI PURWANTO

Brawijaya University, Malang, East of Java, Indonesia

Jl. Mayjen Haryono No.167, Telp. 0341-553286, 587710, 587711, Fax. 0341-551430 Malang 65145

Email : goparipung@yahoo.com

ABSTRACT

The Efect of fertilizer in land agriculture has become decreasing water quality that couse Eutrophication. Analysis Method that used is analysis model with AVSWAT 2000, at characteristic of study area are : 237.312 km2 catchment area of Selorejo Dam, simulation devide in 62 subwatershed area cacthment, including : Forest 0.395 %, mix-dry field 0.128 %, Rice Field 0.214 %, dry land 0.154 %, Urban 0.088 %, lake  0.021 %. The result show that the power river concerning to load polutant is calss III,that value is minimaly for categoried on good water quality . The result of simulation model 2003-2005 has become decreasing lake water quality, 18.5 % dan 23.5 %, total N (Mesotrophic)and Total P (Eutrophic). Meanwhile, the alteration of landuse in 2010 latters couses increasing load pollutant in lake of Selorejo DAM. The deviation of Model AVSWAT 2000, concerning to discarge model and measurement, R2 value is 0.9303, significance level ≤10, concerning to load polutant, R2 value is 0.907, significance level ≤10. The result of models are nonhomogeneous form time by time but homogeneous form space model and measurement.

Keywords : power river, Mesotrophic, Eutrophic

INTRODUCTION

In lake of selorejo, identifacated that load pollutan condition has increased, that proofed by measurement record : 

Figure.4  Measurement Record of NO3 in Lake Of Selorejo

So that condition needs control and monitorring as early as possible.

PURPOSE OF STUDY

The aim of the study is to give a information about value and patern of pollutan distribution because of crop management in location study, as a particularly reference concerning risk monitoring water quality in lake of selorejo and for instrument test a correctness of the AVSWAT 2000 Model (Soil and Water Assessment Tool 2000).

Purpose Of The Study : Predicate of risk level Eutrophication couse agriculture pollutant from N and P element..

THE STUDY AREA

A. Location

The Brantas River basin is located in east Java province on the island of Java, Indonesia and lies between 110⁰ 30⁰ and 112⁰ 55⁰ east longitude and   7⁰ 01⁰ and 8⁰ 15⁰ south latitude. The Brantas River originates on the slopes of Mt Arjuno (3400 msl), and follows a clockwise direction through Malang and Kediri, and branching into two distributaries at Mlirip, the Surabaya and Porong river. It has a watershed area of about 11,800 km², stretches 320 km. The six sub basin are Lesti Basin (625 km²), Konto Basin (687 km²), Widas Basin (1,539 km²), Brantas Basin (6,719 km²), Ngorowo basin (1600 km²) and Surabaya basin (631 km²),

The study area is Selorejo Reservoir that located at upper of Konto River. It has a Catchment area of 235 km² at dam site of Selorejo Reservoir, and maximum reservoir capacity is 62.30 million m³, with an effective reservoir capacity of 50.10 million m³.

B. Land Use and Soil Type

Stream water quality monitoring can be used to determine the impacts from different land uses in watershed to the overall water quality. In watershed with mixed land uses (forest, agricultural and urban), stream commonly show elevated nutrient concentration (Spahr and Wynn, 1997). Typically one of the highest sources of nutrient in the Selorejo watershed are the agricultural areas, this is due to the application of fertilizer/pesticides and disturbance of soil for agricultural production purpose.

The land use categories in the Selorejo River Basin were development using satellite imager.

Land use information was collected using Global Positioning System (GPS) equipment and transferred to GIS using Arc View software (ESRI. 2004). Five land use type were considered: urban area, dry field, rice field, mixed-dry field and Forest

 

Table 4. Distribution of Soil Type in Selorejo Catchment area

Soil Type	Area (km2)	% Total
Regosol	16.41	6.976
Grumosol	164.31	69.869
Mediteran	27.03	11.492
Andosol	27.42	11.662
Total (km2)	235.17	100%

 

Water quality monitoring for nutrient requires accurate of stream surface water velocity. For this reason the sampling method, frequency and analysis are some of the principal factor to consider for constituent loads determination. Due to the negative impacts that excess of nutrient can cause to water bodies (eutrophication) it is important to determinate concentration, trends and loads of these pollutants and associates then to possible contributors (NPS or PS). To exactly determinate of Nutrient load is difficulty. Several methods can be applied for this purpose like, interpolation, regression and average techniques.

The primary water pollutant load in study area was two categories, first from Agriculture area and second from urban area.  According from Department of Agriculture Malang-East Java data, commonly farmers in study area using fertilizing with Urea (Ca(NH₂)₂); TSP (Ca(H₂PO₄)₂); KCL and ZA. (see Table 5). Farmers on the site study use much fertilizer and pesticides more than normal regulation. Wastewater from urban area was calculated which assumed that human faces contain 14,5 g.N/day/person;1,9 g.P/day/person and Urine contain 7 g. N/day/person, 2 g.P/day/person. (Dyah, R., 2002,. 11-12)

Table 5. Using fertilizer for each plant.

Plant	Fertilizer (kg/ha)
	Urea	TSP	KCL	ZA
Rice	250-300	50-100	50-75	100
Corn	200	100	50	100
Soybean	50	50	50	50

RESULTS AND DISCUSSION

Result of SWAT simulation was divided into tree phases, first in land area, second in stream and finally at reservoir.

RESERVOIR PHASE SIMULATION

 

Conclusion

The SWAT model was the first time applied to the Selorejo reservoir Catchment area which is located in Brantas River basin East Java. The model was calibrated for the flow and initial results are presented for the nitrogen and phosphorous loadings in the watershed.

In general, the change of land cover in the land would be effected to increase runoff especially for nutrient loading on reservoir. 

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