Concern of Indonesia Integrated Water Resources Management (IWRM): Part 1 - Drought and Flood

Jakarta - artificial giant pool in rainy season

Inland waters in Indonesia covering areas of 534.000 km2, consists of 394.000 km2 swampy areas, 119.500 km2 catchment areas and flood plains, 16.000 km2 man-made lakes and 5000 km2 natural lakes. There are 521 lakes, of which  fourteen (14) of them have  more than 100 m depth,  eight (8) lakes with more than 200 m depth, and three (3) with more than 400m depth.  The biggest lake is 1.130 km2 wide with 590 m depth. Totally, these lakes contain 500 km3 freshwater. As a whole, freshwater is abundant in Indonesia reaching an average annual quantity of 15,500m3 per capita; the availability of freshwater is quite huge, about 25 times when compared to that of the world which is only about 600 m3 per capita annually.⁴ Indonesia has water potentials of 3,221 billion m³/year, is ranked as the fifth country in the world. From the 3,221 billion m³/year water reserve potential, 691.3 billion m³/year could be utilized. About 175.1 billion m³/year have been used to supply domestic needs, municipal, industry, and irrigation. 80.5% or 141 billion m³/year used for irrigation demands, 6.4 billion m³/year to supply household and municipal water demands, and 27.7 billion m³/year for industrial uses. The largest water potential is in Kalimantan Island in number of 1.008 billion m³/year with per capita water availability of 98.800 m³/capita/year. While, the lowest water potential is in West Nusa Tenggara and East Nusa Tenggara Island with 60 billion m³/year. Per capita water availability in these islands is of 5.500 m³/capita/year.⁵ Contradictive from being stated as the 5^th country that have big water potentials, Indonesia is facing water resources problems which are drought and flood,  clean water provisioning and distribution, and water pollution. This problems is showing that IWRM implementation in Indonesia is failed

1.1.  DROUGHT AND FLOOD

Disaster Prevention National Agency (BNPB) stated that 86 regencies/cities in 20 provinces faced drought. Drought event is commonly found in Java and Southeast Nusa, with the highest numbers of regency is facing drought (18 regencies) is owned by Middle Java Province.  Sumatera, Sulawesi, and Borneo have some of their provinces face drought events.⁶ The drought events on Java and Southeast Nusa become yearly event and are getting worse year by year. Based on water balance in 2003, there 3 island having water deficit in dry season, and those islands are Java, Bali, and Southeast Nusa. 

Table 1. Water balance for each island in 2003.⁷

Islands	Water Availability (Millions M3)		Water Demands (Millions M3)
	Rainy Season	Dry Season	Rainy Season	Dry Season
Sumatera	384.774	93.197	8.319	11.647
Java and Bali	101.161	25.290	27.433	38.406
Southeast Nusa	37.940	4.216	1.440	4.320
Borneo	389.689	167.010	2.041	2.857
Sulawesi	129.400	14.378	6.433	9.007
Papua	381.764	163.613	57.2	80

Drought events have been impacting crop harvesting and the recorded are below:^8;9

·  During the growing season in 1991, drought has made 22.5% paddy field from 843.917 ha dried paddy field failed to harvest. The percentages of paddy field failed to harvest increase up to 30% in 1994

·  At least 29.000 ha West Java paddy field, 2.349 ha in Southeast Nusa paddy field and 1.715 ha East Lombok paddy field failed to harvest in August 2002.

·  Based on water need calculation for irrigation water, Indonesia needed 37.2 million m3 water to irrigating 4.482.875,60 ha field, while in the dry season of 2002 the water capacity in 235 reservoir was only 9.328 million m3.

·  During the year of 2003-2011, the numbers of drought event recorded are 1.411 and damaged 1.667.766 ha of crop fields.

Drought event in 2014 has made villager in Tabir village, Jambi had to consume water from a swamp which being used for cattle husbandry need.¹⁰ In other regency like Sukabumi regency (West Java), the consumer of government-owned drinking water company (PDAM) Sukabumi had to experience water distribution rotation because PDAM raw materials volume shrunk massively.¹¹ Drought and Flood, both disaster suffers more on common people especially farmers. The worst flood ever recorded in Indonesia happened in 1861 in Eastern Java, when four days of continued rain caused some rivers to swell 12-18 m above their mean level. Plantations and gardens were destroyed, irrigated rice fields washed away, and fields and pastures in the plains were covered with mud and rubble, in some places one meter deep. Fortunately, not all floods reach such catastrophic proportions, mainly because island watersheds are relatively small. Yet the consequences of many minor disasters are still serious, especially since flooding always brings significant disruption to economic activity and everyday life.¹² Another flood events that became disastrous and influence economy is the Jakarta flood on 2 February 2007 affected 80 districts in Jakarta, causing traffic chaos and paralyzing the city. More than 70,000 houses were inundated with water levels ranging from 10 cm to 5 m and 69 people were killed and an estimated 420,440 people were displaced. The Indonesian government estimated that losses amount to Rp 4.1 trillion (US$ 450 million).¹³ Problems that many people neglect during or after heavy rainfall and or floods is soil erosion and sedimentation. Government hasn’t measured the economy impact of soil erosion and sedimentation. These problems are being caused by the land use changing particularly in catchment areas. 

Table 2. Sediment yield from different catchment in Indonesia as is being cited by van Dijk (2002) from several references. ¹⁵

Land Use	Sediment yield (ton/ha/year)
Rainforest	4-7
Logged pine plantation forest	34
Mustistrata agriculture	10-12
Annual crop based agriculture on bench terraces	19-25
Vegetables on steep slopes with terraces	42-75

Digging and digging for a small pool of water

Soil erosion and sedimentation have been causing big problems for reservoir and dams in Indonesia. Brantas river basin gives good illustration for land use impact on the soil erosion rate and sedimentation to the Sengguruh reservoirs. Sengguruh Reservoir was established with the total initial storage of 7.6 million ton, and designed for trapping the sediments flow to Sutami reservoir located in the downstream that produces electrical hydropower energy from the power generation of 29,000 kW. The upper Brantas river basin which are Lesti and Amprong river basin, produces sediment which contributes to the shallowness of Sengguruh reservoir. The estimated of soil erosion rate in the forest hillslope and cultivated land in the 2 river basin were 0.4 ton/ha/year and 11.1 ton/ha/year. The sedimentation from cultivated land was estimated approximately 30% and surface erosion was one of the primary sediment source. Also the total sediment production from both forest hillslope and cultivated land in upper Brantas river basin was calculated approximately 800.000 ton/year which explained almost 30% of average annual sedimentation in Sengguruh reservoir.¹⁶ Due to the increasing of erosion rate, the Sengguruh lifetime was decreased from 20 years to 12 years (1988-2000). Although the dredging of sediment to handle the shallowness of reservoir has transferred the volume of sludge of 0.6 ton during the period of 9 years: 1995– 2004, it was reported in 2005 that the effective storage capacity of Sengguruh reservoir was 882.886 ton.¹⁷ Sediment loads in Indonesia are increasing at a higher rate than in other tropical regions because of large-scale deforestation. The increasing sediment loads pose a serious threat to coastal coral reef ecology. It is being found that a 30–60 % reduction of coral species diversity at land-affected reefs over a period of 15 yr in Indonesia. The observed reef degradation is partly due to the increased sediment loads. Turbidity reduces photosynthesis and reduces the maximal depth where corals can survive.¹⁸