Case 1 - Forestry and Watershed Management:

Forest Land Rehabilitation Program for the Wonogiri Reservoir

This study case deals with the problem of sedimentation in the Wonogiri Reservoir reflecting inappropriate land use management in the upper Basin and inadequate cooperation of different land use sectors. In this respect it demonstrates the management challenges concerning an ecosystem approach.

a) The case

The Wonogiri Reservoir was established in 1982 for multiple purposes, particularly for flood control, for clean water supply and as electricity power plant. The Wonogiri Reservoir is located in Sub Das Solo Hulu (upper Basin) with characteristics as follow: volcanic origin soil (alluvial soil) which is highly fragile to surface soil erosion. The type of soil in sloping Mt.

Merapi and Mt. Lawu as well as the upper valley of the Basin is very suitable for growing rice (see Table 5.1). In line with the increasing population pressure (see Table 5.7), paddy areas slowly but surely shift to dry land farming and then are transformed into settlements (see Table 5.3). Forests cover about one-fourth of the catchment area, and are predominantly assigned to permanent production function (17%) while only 2 % of the total catchment area is designated for protective functions (see Table 5.6).

The Reservoir was expected to have 75-100 years lifetime. However, it was rapidly filled with sediments transported from the catchment. In the mid 2001, just 20 years after the establishment, a ‘surge prevention project’ was proposed to dredge about 250.000 m³ of sediments that closed the portal channel in order to save the inflow. In early 2004, a proposal for future prevention of sedimentation in the Wonogiri Dam was launched, including a watershed conservation plan (JICA and DepKimpraswil 2004).

According to a study that modelled the surface water runoff in the upper Solo Basin (Alif Noor Anna et al. 2010), the intense change of land use is the most significant parameter that causes increased surface runoff in the study area. Land use has changed from cultivated areas with forests to settlements with mixed gardens and from rice paddies fields to settlements (partly with home gardens). Even desiccated river areas have been converted.

This has reduced the surface infiltration capacity and caused flooding in Solo, Sukoharjo and Sragen in 2008. It is also indicated by the change of the runoff coefficient (Co), particularly in the sub Basin Pepe which has an outlet in the city of Surakarta.

Another study (DepKimpraswil 2004 and personal communication) emphasizes, that the unfavourable development in the Wonogiri Reservoir was not only caused by inappropriate land use change, but also due to missing mechanisms for coordination and integrated watershed management between the Bengawan Solo Water Council (under Public Work, Ministry of Infrastructure and Settlement) and the Watershed Management Agency/BPDAS (before: Land Rehabilitation and Soil Conservation/BRLKT) under the Ministry of Forestry, although the concerned office locations are just tens of meters apart.

According to JICA and DepKimpraswil (2004), massive investments in reservoirs, dams, irrigation systems, water supply works, and flood control structures are jeopardized by the effects of decades of inappropriate urbanization processes in the Bengawan Solo River Basin’s uplands. Such structural measures are technically effective just for the first couple of

years. After that, much depends on non-structural measures like broadening forest/vegetation cover, particularly on steep slopes, or green belt improvement. Hence watershed conservation plans that combine both of these measures and involve community participation were suggested.

b) Conclusions and recommendations concerning forest functions arrangement and management

Natural erosion risks and the protection functions of land cover / land use types for soil and water have to be considered. This involves at least two essential degradation indicators, namely forest conversion in upper lands into agriculture land, plantations or settlement areas on the one hand; and extreme water fluctuations between dry and wet seasons on the other.

In this respect, Sudradjat (2011) identified the following coherences in the BS Basin, based on land use simulation by using hydrology and environmental geology modelling:

 Land use change from forests into plantations (including tree gardens), mixed- and home gardens, rice fields and settlements causes flooding (peak and volume).

 The flood volume from sub-rivers also depends on the type of soil and hydrology characteristics like elevation and river’s length.

 Potential flooding areas are located in sub-basins with soil types of high infiltration capacity (infiltration area) and also in lower sub-basins with soil types of less infiltration capacity.

 The current land use composition in the lower Basin, where the land use for residential and shrubs increased simultaneously with the decrease of land for rice field, orchards and forests, caused a greater flood compared to the composition before 1964.

 Restore land uses into forests with better respective function capacity, at least in particular areas in combination with the implementation of Low Impact Development (LID) will significantly reduce floods (in peak and volume).

Four different situations concerning the relations between land uses and land capacity have been identified in the study area (Sudradjat 2011):

(1) Land use that is appropriate for the land capacity (no area identified to represent this category).

(2) Land use in fragile areas with medium capacity (like the areas that have affected sedimentation to the Wonogiri Reservoir, including Cawas, Wonogiri-Eromoko, Giriwoyo, Tirtomoyo, Slogohimo and, Wonokerto).

(3) Areas with low land capacity and should not be developed (including Cawas, Eromoko, Tirtomoyo, Slogohimo, and Wonokerto)

(4) Areas with rehabilitation needs concerning protective functions (including Boyolali, Klaten, Gresik, Solo, Madiun, Magetan, Ponorogo, and Tuban.

These areas were targeted in the national FLR program which was conducted from 2003 to 2007. Based on own observations, there was no strong mechanism for rehabilitation at the field level. Likewise, the own observations revealed that, although the seeds had been prepared and provided by each local district (for example. in Wonogiri), there was only rather limited participation of each community. Planting success is usually carried out under the coordination of the Head of the District. Generally, the Head of the District asked the local military forces. Even worse, and in flagrant contradiction to the rehabilitation agenda that was declared later, the Bengawan Solo Water Council /BBWS under the Ministry of Infrastructure and Settlement cleared up all relatively old plants (planted 30 years ago) in the green-belt areas of Wonogiri Lake in 2003 (Suara Merdeka 2013).

All in all the study case demonstrates, that

(1) Urbanization processes and respective land use changes may lead to major sedimentation and flooding problems. Thus FLR programs need to address the entire catchment area and involve cooperation with other institutions that determine land use.

(2) Critical areas, like peat-swamp and other water retention areas or river and lake buffer zones, have to be considered with respect to their key role in hydrological processes and respective regulation functions. However, they are still not indicated under the forestry law system. In fact, only the Spatial Planning Law indicate them as protective sphere, providing the criterion and the management model.

(3) The obvious lack of formal or informal direct communication and collaboration between the Watershed Management Unit of the Forestry sector and other respective administrative units has to be overcome.