Sedimentation Problem

EFFECT OF VOLCANIC ERUPTION ON RESERVOIR SEDIMENTATION PROBLEM

Case Study of Mt. Kelud in Brantas River Basin, East Java - Indonesia

ABSTRACT

Mt. Kelud with a summit elevation at 1,724 m above sea level is the active member of a volcanic cluster in East Java - Indonesia, located at about 35 km east of Kediri City and 24 km north of the repeatedly lahar-stricken city of Blitar.This volcano lies between the volcanic massif of Mt. Wilis (2,169 m) to the West and the complex of Mt. Kawi (2,639 m) and Mt. Butak (2,868 m) to the East around which Brantas River (320 km length) that is the second largest stream in Java Island is swirling. More than 30 eruptions of Mt. Kelud had been recorded in historical times with 3 to 30 years interval or 15 years on an average, resulted tremendous damage over the area.

Mt. Kelut Crater Lake (before erupts)

Mt. Kelud has such a particular morphology as forming a deep crater lake, which always stores several to ten mil. cubic meter of rainwater. Retained water in the crater was used to be the prime mover at every time of the eruption, which had brought hazardous hot debris flows, mixed the ejection with lake water. The primary lahar mostly flowed down along the slope of western half of volcanic area via dissected stream radiating from the crater, and then deposited on the slope thickly with the ash fallen becoming major source of the hazardous secondary lahar, which will be moved by surface runoff.

Based on the Master Plan for Mt. Kelud Volcanic Debris Control, many sabo facilities had been constructed since 1970. Some of the structures had fulfilled with the sediment, and most of them couldn’t retain the material and then will flow directly to Brantas River through its tributaries and finally deposit in Wlingi Multipurpose Dam and cause heavy reservoir sedimentation there. Although the reservoir also planned to have a function of trapping debris flows but the sediment rate is much higher than the expected value. In order to maintain the reservoir storage capacity, bypass channel was constructed and sediment removal measures by hydraulic flushing and dredging were carried out regularly.

Wlingi Multipurpose Dam

In the future, to prevent and mitigate sediment related disaster in this area, it is essential to develop integrated sediment management by conducting rehabilitation of the existing facilities, constucting additional sabo facilities, extending the bypass channel and providing new dredging system.

Key words: volcano, eruption, sedimentation, reservoir, and sabo

Presented on MPMD-2005, International Conference on Monitoring, Prediction and Mitigation of Water-Related Disaster, January 12-15, 2005, Clock Tower Centennial Hall, Kyoto University, Japan, by:

- Director of Technical Affairs, Perum Jasa Tirta I,

- Head of Research and Development Bureau, Perum Jasa Tirta I,

- Staff of Research and Development Bureau, Perum Jasa Tirta I.

After this article created and presented, on Nov 2007, Mt. Kelut Show its eruption activity which showed by increasing temperature of crater lake, increasing frequency of treamor earthquake.

on November 2007, Mt. Kelut Shows its Eruption Activity

But, big explosion doesn’t happened as predicted before. Eruption activity only makes tremor earthquake with over schale. That acticaty makes big heap shows up on the existing crater lake.

big heap shows up on existing crater lake

Eutrophication

INTEGRATED WATER QUALITY MANAGEMENT

Case Study of Eutrophication Problem in Karangkates Reservoir,

the Brantas River Basin, Indonesia

by

Jasa Tirta I Public Corporation[1]

1. Introduction

The Brantas River basin, one of the largest river systems in Indonesia, is located in the eastern part of the Java Island, Indonesia, between 110⁰30’ and 112⁰55’ East Longitude and 7⁰01’ and 8⁰15’ South Latitude. It covers catchment area of 11,800 km² in total and its main stream, the Brantas River, runs about 320 km long. Annual precipitation is around 2,000 mm on average, with roughly 80% occurring in the wet season. Mean annual temperature range from 24.2⁰C at Malang City (445 m above sea level) to 26.6⁰C at Porong in the Delta, and relative humidity varies seasonally between 55%-95%.

The Karangkates Reservoir, the largest reservoir in the basin, is located about 40 km downstream of Malang City along the main course of the Brantas. This reservoir which completed in 1970 has catchment area of 2,052 km² and plays a vital role on the economic development in the region and for the country as a whole. The reservoir has functions as flood control, hydropower generation of 900 Million kWh per year, water supply for irrigation of 83,000 ha paddy field (or 2.6 MCM/year), domestic and industrial use of 300 MCM/year and recreation.

2. Eutrophication Problem

Present serious problem encountered in Karangkates Reservoir is contamination of reservoir water by nutrients flowing into reservoir from agricultural, domestic and industrial sources from upstream cities and villages; agriculture lands; paper mills, sugar and tapioca factories along the rivers.

In Karangkates Reservoir, the indication of pollution has revealed a few years ago but some significant indications happened in June 2001. At the end of February 2002, the similar case happened again and it became worst in March-April 2002. Water surface around dam site colored in blue and brown, clods contained pollution material revealed on every side of the reservoir. Then, blooms of blue-green algae have appeared, as a sign of more advanced eutrophication. Furthermore, in September 2002, water quality in the reservoir much deteriorated that noticed by dead fish and unpleasant odors disturbed and annoyed humans’ breathing system that live near the reservoir.

A comprehensive study conducted by Water Resources Research and Development Center, Ministry of Settlement and Regional Infrastructures, Government of Indonesia, has analyzed water quality on total Nitrogen (N) and Phosphate (P) parameters from Karangkates Reservoir on June 19-20, 2003 are summarized in Table 1.

According to the OECD standard, based on several measurements done by Jasa Tirta I Public Corporation and Water Resources Research and Development Center as summarized in Table 2, the Karangkates Reservoir could be classified into eutrophic level. From the above analysis, if N-inorganic (N-NO₃, NO₂ and PO₄) > 0,3 mg/l and orthophosphate > 0,01 mg/l, this condition will accelerate algae growing more rapidly.

At that time, severe oxygen depletion occurred in Karangkates Reservoir water caused:

· Fish within the reservoir died

· Abundance of algae, which float and suspend in the water finally, trapped in some flanks and reservoir bays then became flocks and decomposed resulting unpleasant odors. An assessment done by Biological Laboratory of Brawijaya University, Malang in March-May 2002 showed the existing of Microcystis, a kind of Blue Green Algae that its growth influenced by excessive nutrient (phosphate and nitrate) in the reservoir. The plankton analysis in the Karangkates Reservoir on June 19-20, 2002 is summarized in Table 3.

3. Pollution Sources of Karangkates Reservoir

A. Domestic source

Direct discharge of sewage, not connected to treatment plants, from domestic sources in the upstream of Brantas River, will eventually make its way into Karangkates Reservoir. Household detergents, often with high phosphate content, add to the nutrients in sewage effluents. According to the population in the upstream of Brantas River, total potential pollution loads from domestic source is estimated at 30.80 ton N/day and 5.59 ton of P/day as summarized in Table 4.

B. Solid waste (Garbage)

Effluents leaching from solid waste (garbage) mainly come from Final Disposal Site in Supit Urang Village, Sukun Sub-Regency, Malang City, flow into Banger River, a tributary of Metro River and then flows to Brantas River. Until today, total potential pollution loads from leaching of solid waste in the basin has not been estimated yet.

C. Industrial source

In the upstream of Karangkates Reservoir there are many industries producing high nutrient levels that finally pour into the reservoir. Those are sugar-processing factories, tapioca factories, leather processing factories, paper factory, rubber-processing factory, cigarette factory, shrimp-processing factory, slaughter house. Total pollution loads from industry sector flow into Karangkates Reservoir estimated at 32.15 ton BOD/day.

D. Agricultural source

Farming practices, including use of fertilizers and pesticides rich in N and P in the upstream of Karangkates Reservoir deposit increased amounts of these nutrients in the soil then run-off from these farms to reservoir believed as one cause of eutrophication there. Total pollution loads on N and P parameters from this source which flow into Karangkates Reservoir estimated at 94.28 ton/day and 1.05 ton/day respectively as summarized in Table 6.

E. Animal husbandry waste

Intensive animal husbandry in the upper stream of Karangkates Reservoir managed by some large and small-scale corporations consist of 27,000 cattle, 15,700 pigs and 2 millions poultry. Liquid wastes from these animals husbandry come from cage cleaning activities. Total pollution loads on N and P parameters from this sector which flow into Karangkates Reservoir estimated at 10.24 ton/day and 3.15 ton/day respectively as summarized in Table 7.

F. Sediment

Reservoir sedimentation in Karangkates believed contributes significant nutrient. Deforestation in some area in the basin has worsened this condition. Total Nitrogen and total Phosphate from eroded soils flowing to Karangkates estimated at 1,025 ton N/year (2,81 ton N/day) and 102.5 ton P/year (0.28 ton P/day).

G. Atmosphere

Combustion of fossil fuels in industrial and energy production and in transportation in the basin is an important source of gaseous oxides of nitrogen. Total pollution loads on N and P parameters from atmosphere, which consumed by algae in Karangkates Reservoir, estimated at 0.02 ton/day and 0.0041 ton/day respectively.

4. Impacts

The impact of eutrophication on recreation and tourism in Karangkates Reservoir is probably the most sensitive for the public. It may severely alter the recreational value of its water bodies and impair related activities (fishing, etc.) as a result of the objectionable aspect of the waters, such as reduced transparency, odor, and increased incidence of stinging insects, swimmer's itch, etc. Both social impacts and economic losses are very important and make eutrophication control necessary.

5. Measures

a. Research

Preliminary study on pollution problem in Karangkates Reservoir has been done. The objectives of the study were to understand conditions of pollution, to identify potential point sources of pollution, to establish recommendations for mitigating and controlling water pollution in short and long terms for the recovery of Karangkates Reservoir water quality.

b. Inspection and law enforcement

Agencies in Malang Regency and East Java Province i.e. Regional Government, Police Department, Forensic Laboratory and Laboratory of Environmental Health on May 2002, conducted inspection to Karangkates Reservoir. They found some industries considered contribute significant effluent (tapioca factories) and some illegal disposal channels. By a coordination meeting among agencies, it was decided to dismantle and close some illegal disposal channels.

c. Algae harvesting and cleaning

On 16^th October 2002, Jasa Tirta I Public Corporation, in co-operation with Malang Regencial Office of Environmental Impact Management Agency and Provincial Fisheries Service disseminated the reservoir water pollution control program to fishermen from Sukowilangun Village, Sub District of Kalipare, Malang Regency. On 17^th October 2002, the first pilot algae harvesting was implemented based on the recommendation given by the Water Resources Research Center in order to recover of this reservoir pollution.

d. Fish sow to increase the population of certain fish species

To maintain ecosystem balance in Karangkates Reservoir, Jasa Tirta I Public Corporation and Regional Government of Malang Regency conducted fish sow in 1998-2002 with 300,000 species of Oreochromis sp (Nila Merah) and Tillapia mossambica (Mujaer).

e. Water quality monitoring in Karangkates Reservoir as part of the whole Brantas River basin water quality monitoring

In Karangkates Reservoir, monitoring has been conducted routinely since 1994 in the middle of the reservoir consist of 4 (four) depths i.e. 1 m, 5 m, 15 m and 25 m. According to the data from 1998s to 2002s, annual total Nitrogen flowing into Sengguruh Reservoir from Brantas River (Kedung Pedaringan Station) and Lesti River (Wonokerto Bridge Station) estimated at 2.535-3.823 mg/liter and 1.961-3.377 mg/liter respectively. Then, from Metro River, annual total N flowing into Karangkates River estimated at 1.856-2.939 mg/liter.

Jasa Tirta I Public Cooperation in cooperation with Indonesian Institute of Science (LIPI) implements the Brantas River Water Quality and Pollution Management Project (BRWQPMP). The BRWQPMP system consists of:

1) Setting of telemetering system of online water quality monitoring in 23 locations and additional online water quantity monitoring in 14 locations.

2) Development of Management Information System to endure Decision Support System (DSS).

3) Development of new water quality laboratory in Malang and improvement of the existing one in Mojokerto.

4) Development of wastewater treatment plant model in 3 locations i.e. 1 (one) domestic wastewater treatment plant, 1 (one) wastewater treatment plant of slaughterhouse and 1 (one) treatment plant installation of leather processing industry) and Industrial waste monitoring (Industrial Flow Meter/IFM) in 13 industries.

Jasa Tirta I Public Corporation also implements offline system of water quality monitoring (see Attachment 4) instead of online system that consist of 51 (fifty one) of monitoring points in the Brantas River (including reservoirs), 56 (fifty-six) of monitoring points in industrial disposal outlets and 11 (eleven) of monitoring points in domestic disposal outlets of hospitals, hotels and public sanitation channel.

6. Program

To cope with sustainable eutrophication problem in Karangkates Reservoir, it requires active participation from all stakeholders particularly in Malang Regency and Municipality. Comprehensive prevention and mitigation programs to eutrophication should be determined, planned and implemented integratedly with water quality management program in the whole basin. These programs are arranged and divided into 3 (three) stages as follows:

a. Emergency program (2002)

Some measures had been done in this stage are:

- Promotion of a partnership approach to eutrophication management, at both local and regional level, by establishment of a mitigation team work headed by Major/Regent of Malang since some solutions are generally beyond the remit of any one regulatory body or other party.

- Removal of decayed algae in the reservoir surface manually and algae harvesting by plankton net as well.

- Conducting advanced water quality monitoring activity in reservoirs, rivers and outlets of industry, hotels and hospital and law enforcement.

b. Short term program (2003-2004)

Some measures will be done in this stage are:

- Further assessment on Karangkates Reservoir eutrophication in order to get accurate prevention and mitigation strategy and program.

- Preparing Regional Regulation, Governor and Regents/Majors Instructions on reservoir pollution and detail design of domestic wastewater treatment plan.

- Arranging technical guides on fertilizer-pesticide use and pollution control, using of waste from animal husbandry, aquaculture, disposal and treatment of domestic and industrial waste.

- Re-greening in upstream of Brantas River basin and reservoir areas.

- Improvement of all aspects of agricultural practices which contribute nutrients to water bodies should be encouraged, with special reference to control of the amount, period and methods of fertilizer application in order to achieve minimal loss and optimum up-take by crops and to control over-irrigation (fertilizer leaching to ground waters).

- Implementation of waste water discharge license and contribution.

c. Long term program (2005-2010)

At this stage, some structural and non-structural measures will be conducted to decrease effluent loads from industrial, domestic, agriculture and animal husbandry sources flowing into rivers. Some measures will be done in this stage are:

- Development of industrial waste water treatment, communal domestic wastewater treatment in Malang Regency and Municipality including Batu City, aeration system in the bottom layer of reservoir, dredging activity to dredge sediment contains high organic matter and nutrients in specific location then embank using sanitary landfill system and artificial rain to increase inflow into the reservoir.

- Modification or substitution of some industrial products (detergent) which containing high Nitrogen and Phosphate.

- Relocation of industries that produce high effluent loads and development water recycling.

- Implementation of clean production to industries;

7. Conclusion

a. Present serious problem encountered in Karangkates Reservoir is contamination of reservoir water by nutrients flowing into reservoir from agricultural, domestic and industrial sources.

b. To cope with eutrophication problem in Karangkates Reservoir, it requires active participation from all stakeholders. Comprehensive prevention and mitigation programs should be determined, planned and implemented integratedly with water quality management program in the whole basin.

Table 1. Water Quality Analysis of Karangkates Reservoir on Total Nitrogen (N) and Phosphate (P) Parameters dated June 19 – 20, 2002

Station	Contents
	Total N (mg/l)	Total P (mg/l)
Upstream	3.273	0.1678
Middle stream 1	1.798	0.0848
Middle stream 2	1.503	0.0380
Middle stream 3	1.934	0.0886
Bay	2.415	0.9265
Dam	2.013	0.1516

Table 2. Measurement of Total Nitrogen (N), Phosphate (P), Chlorophyll a and Transparency in Karangkates Reservoir

Trophic Category	Variable (Annual Mean Value)
	Total Nitrogen (mg/l)	Total Phosphate (mg/l)	Chlorophyll a (mg/l)	Transparency (m)
Oligotrophic	-	-	-	-
Mesotrophic	-	-	-	-
Eutrophic	2.398 [2] 0.925–2.581[3] 1.503-3.273 [4]	0.090 3 0.101-0.362 4 0.038-0.9265 5	0.0014 – 1.736 5	0.0-1.8 5

Table 3. Plankton Analysis in the Karangkates Reservoir on June 19 – 20, 2002

No	Plankton Type	Observation Station
		A Individual/liter	B Individual/liter	C Individual/ liter	D Individual/ liter	E Individual/ liter	F Individual/ liter
1	Microcystis aeruginosa	8,800	8,580	9,460	1,974,500	124,300	198,000
2	Phormidium tenue	126,280	140,580	119,240	115,500	286,000	122,100
3	Closterium aciculare	18,480	33,880	20,240	77,000	45,100	15,400
4	Ceratium hirundinella	2,420	15,840	7,260		30,800	6,600
5	Anabaena affinis	1,760	6,600	7,260	5,500	13,200	8,800
6	Trachelomonas oblonga	440
7	Pediastrum sp	440	220	-	-	1,100	-
8	Nitzia sp	2,200	-	-	-	-	-
9	Straurastrum pingue	-	220	-	-	1,100	-
	Total	160,820	205,700	163,460	2,172,500	500,500	350,900

Note: A = upstream, B = middle stream 1, C = middle stream 2, D = bay, E = middle stream 3, F = dam site

Table 4. Estimation of Total Nitrogen (N), Phosphate (P) and BOD from Domestic Source in the Upstream of Karangkates Reservoir (ton/day)

Regency/ Municipality	People Discharge [5] Waste to River Directly	Feces		Urine		BOD [6]
		Total N [7]	Total P [8]	Total N [9]	Total P [10]
Malang Regency (rural area) incl. Batu	1,072,676	15.55	2.04	7.51	2.15	37.54
Malang City (urban area)	359,902	5.22	0.68	2.52	0.72	16.56
Total	1,432,578	20.77	2.72	10.03	2.87	54.10

Table 5. Estimation of Total BOD from Industrial Source in the Upstream of Karangkates Reservoir

No.	Industry Name	Type	Effluent Discharge m3/day	River	BOD Ton BOD/day
Malang City
1	PT. Kebalen Timur	Leather	15	Brantas	0.0012
2	CV. Nasional	Rubber	30	Brantas	0.0016
3	CV. Usaha Loka	Leather	200	Brantas	0.0102
4	PT. Kasin	Leather	60	Brantas	0.0177
5	Slaughter House	Meat	60	Brantas	0.0672
Malang Regency
6	PT. Penamas	Cigarette	5	Metro	0.0128
7	UD. Caragenan	Seaweed	Na	Brantas	Na
8	PG. Kebun Agung	Sugar	350	Metro	0.005
			7500	Irrigation Ch.	0.3929
9	PG. Krebet Baru	Sugar	42508	Brantas	15.552
10	PD. Singkong A. Mas	Tapioca	850	Metro	7.32122
11	PT. Intaf Turen	Tapioca	600	Lesti	0.325
12	PT. Sumber Tani	Tapioca	700	Lesti	1.266
13	PT. Sumber Timur	Tapioca	680	Lesti	0.648
14	PT. Eka Mas Fortuna	Paper	7500	Lesti	3.795
15	PT. Bumi Menara Laut	Cold Storage	250	Lesti	0.091
16	PT. Naga Mas Sakti	Tapioca	600	Biru	2.941
17	Pers. Delta Peniwen	Pigs	30	Biru	0.0953
18	Pers. Bali Gunawan	Pigs	30	Metro	0.0028
19	Pers. Babi B. Gunawan	Pigs	30	Lesti	Na
20	Pers. Sempulur	Pigs	25	Biru	0.032
TOTAL					32.1459

Table 6. Estimation of Total Nitrogen (N), Phosphate (P) and BOD from Agricultural Source in the upstream of Karangkates Reservoir

Regency/ Municipality	Type	Area [11] (ha)	Total Load Nitrogen [12] (ton N/day)	Total Load Phosphate [13] (ton P/day)
Malang Regency incl. Batu	Paddy field	37,580	25.50	0.19
	Non irrigated field	64,655	19.90	0.32
Malang City	Paddy field	1,726	1.17	0.009
	Non irrigated field	1,837	0.57	0.009
Total	Paddy field	39,306	26.67	0.19
	Non irrigated field	66,492	20.47	0.33

Table 7. Estimation of Total Nitrogen (N) and Phosphate (P) from Animal Husbandry in the upstream of Karangkates Reservoir

Regency/ Municipality	Type	Number [14]	Manure [15] kg/day	Total Load Nitrogen [16] (ton N/day)	Total Load Phosphate [17] (ton P/day)
Malang Regency	Cattle	2,905	46,480	0.2789	0.1227
	Poultry	2,000,000	400,000	4.0000	0.7040
Batu	Pig	8,660	62,352	0.3118	0.0480
Malang City	Cattle	24,180	386,880	2.3213	1.0214
	Pig	5,849	42,113	0.2106	0.0324
Total	Cattle	27,085	433,465	2.6002	1.1441
	Pig	14,509	104,465	0.5224	0.0804

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[1] Jl. Surabaya 2 A Malang, Indonesia, 65115 Ph. +62-341-551971 Fax. +62-341-551976

Email : mlg@jasatirta1.go.id http://www.jasatirta1.go.id

[2] Average measurement value for June 2001 – May 2002 by Jasa Tirta I Public Corporation

[3] Measurement done by Jasa Tirta I Public Corporation dated June 8, 2002

[4] Measurement done by Jasa Tirta I Public Corporation and Water Resources Research and Development Center dated June 19 – 20, 2002

[5] Data obtained from BPS, Malang 1999/2000

[6] BOD contents for rural = 35 gram BOD/individual/day, for urban = 46 gram BOD/individual/day

[7] N content for feces = 14.5 gram N/individual/day

[8] P content for feces = 1.9 gram N/individual/day

[9] N content for urine = 7 gram N/individual/day

[10] P content for urine = 2 gram N/individual/day

[11] Data obtained from Agricultural Service Malang 2000/2001

[12] Urea (N) = 45% per kg

[13] TSP (P) = 1.2% per kg

[14] Data obtained from BPS Malang 1999/2000 and Animal Husbandry Service Malang 2000

[15] Manure from cattle = 16 kg/species/day, pig = 7.2 kg/species/day, poultry = 0.2 kg/species/day

[16] Nitrogen contents (N) from manure of cattle = 0.6%, pig = 0.5%, poultry = 1%

[17] Phosphate contents (P) from manure of cattle = 1.2%, pig = 0.35%, poultry = 0.8%