Sightseeing

At 23rd July 2008, the author and other participants of international seminar (The 5th International Workshop on Coastal Disaster Prevention) visited Samas beach to see green belt, after the seminar was held in Hyatt Yogyakarta Hotel one day before. The seminar was talked about disaster prevention in coastal area.
Back to Samas beach, the green belt which has function to detain tsunami and wind was formed of cemara udang (Casuarinas equisetifolia) trees that spread from Samas beach to Pandansimo in limited population.
This plant is firstly planted by Prof. Suhardi from Forestry Faculty of UGM, which then continued by local people. Cemara udang originated from Madura. This plant was chosen as green belt because from many types of vegetation planted before in south beach area, cemara udang was the only tree that can survives. This plant is cultivated through cutting or shoot. Cemara udang has a strong stem and many branches; this was the reason why cemara udang can sturdily detain wave and wind. Within age of 5-6 years, this plant was strong enough to detain tsunami wave. This plant’s height can achieve 15 meters. Survivability of this plant is categorized into good because although it is supplied with minim water, but it can survive well. Spacing of this plant was also possible to bunch up, as long still under water. Beside that, this plant also contributed to decrease the impacts of global warming. Cemara udang also capable to keep salt in order to not reach the land, thus soil and sand located behind this plant are suitable to cultivate for agriculture in sandy area. Before planted with cemara udang, plants planted in sandy area such as red onion, peanut, and soybean were unevenly spreads stacked by strong wind from the beach.

Cemara udang also can improve beauty of the beach; its dense is very beautiful. When the author came into its dense, the author feels amazed; unfortunately its population is minim. As we know that this vegetation has many benefits, then the government must pay more attention to its population, maintenance, and of course its survival.

After sight seeing cemara udang, we also saw agriculture area behind the green belt. Then, we went to Depok beach for lunch.

The journey then continued to Nglepen village to see anti-earthquake houses that very unique. Its form is similar to igloo, Eskimo’s house. These houses were built by NGOs from America named Domes for the World in order to help people in Nglepen village due to earthquake attacked Jogja in 27th May 2006. Because of this earthquake, land in Nglepen village, Sumberharjo, Prambanan, Sleman was shifted to form an indent like a canyon with depth approximately of 6 meters. This caused severe damage on houses in Nglepen village, even there were many houses mired in soil.

The ‘teletubbies’ houses (many people said like this because form of the house is similar to teletubbies’ house, a kid serial on television) were made from concrete. From sites read by the author on the web, the benefit of this house is more stabile thus more strong, more easy and faster to build, more economical, thus this house if cheaper than the cost to build a house in common.

visual monitoring of bridge

Bridge is a construction purposed to connect roads through a lower hindrance. This hindrance commonly formed of water route or common land traffic. Usually, economical period of a bridge needs maintenance; this is because more old some bridge, then its structure will be degraded, whether caused by material durability of bridge’s components, environmental condition surrounds the bridge, or natural disasters which ultimately degrade the capacity of bridge both its safety and comfort for the user. Besides that, it is also for anticipation due to development or change on type and capacity of vehicles, which increases both its volume and weight out of the prediction. Thus, a bridge needs evaluation and maintenance in order to function well.

Indonesia has many bridges, hundreds of thousand; some of these are bridges located in Wonolelo Wonoseto village, Donoharjo, Ngaglik, Sleman, Yogyakarta. This bridge also must be maintained and evaluated. However, it is seen that the bridges are lack in maintenance which actually is a must.

Lack of maintenance is can be observed in each bridge’s component :
1. Grasses sprout up in the surface border of the bridge,
2. Corrosions are found almost in all surfaces of steel’s frame,
3. There is some parts of steel’s part that corrugated,
4. There is porous found in several joints,
5. Corrosions in vertical and parallel thunders,
6. There are crack, voids, and spalling in the deck,
7. Bearing is dirty and grasses sprout up surround it,
8. There is crack on concrete abutment and many wild plants sprout up surround it and in its body.
9.There is little sliding in the slope of bridge.

Accorded to the writer, damages found in this bridge are possibly caused by:
1. Corrosion of steel’s frame :
There are no maintenances for the bridge, such as painting in the frame, causing bridge more susceptible towards atmosphere corrosions.
Waste dumping in the abutment area which cause atmosphere more acidic around this place.
Rain water or non-evaporated dew, especially in the hidden parts (joints), causing more corrosion.
2. Damages on the deck of bridge, i.e. crack and spalling which probably caused by improper pouring, besides volume of vehicles. When the crack occurs, water permeates into the concrete and reaches the frame, causing corrosion. Due to this condition, the plane surface becomes wider because there is electrolyte added from other frame parts; the wider frame then presses the concrete then ultimately causes the concrete’s surface detached. If it is not immediately repaired, then there will be spalling in other parts of the deck and it is harm the stability of structure.
3. Damages on the sloping of oprit are maybe because there is no proper sticking between new river stone and the old one. Thus, the new match declines. If it is continue to happened, probably the old match will be scraped too and water reaches the ground, causing heap ground water rises thus decreases soil heap in the oprit.

Recommendations suggested by the writer for better development of the bridge are:
1. Clearing on the pavement of the bridge thus water can be flowed from it which makes the pavement stay longer. And making drainase thus the water can't flow to truss.
2. Clearing of abutment from trashes and plants because it causes pollution and damages the structure.
3. Clearing of corrosion through wiping and smoothing with sandpaper then painting, thus the steel stay longer in its life. For bent shaft, better it is replaced because it is clearly lack its capability.
4. The making of abutment structure from concrete in east side to replace the structure from stone match is much recommended.
5. The slope on the bridge’s oprit is also more supports. Make sure that the implementation is proper with the technical standard, especially the sticking power between new match with the old one in order to avoid declining on the match of river stone.
6. Damages on the deck part such as crack are can be repaired through injection using epoction material), voids and spalling are can be repaired through shotcrete system (by spraying mortar or concrete on the surface of repaired deck using pressed equipment, mortar or concrete are sprayed with high pressure, thus results strong stickiness on the old surface of concrete).