PREDICTING COASTLINE CHANGES IN DAERAH ISTIMEWA YOGYAKARTA USING ONE-LINE MODEL

The dynamics of coastal areas causing coastal areas prone to various natural problems, one of which is the problem of coastal erosion. Erosion leads to various problems in the coastal environment. The fundamental problem is the shoreline change changes. Coastline changes occur as a result of various natural phenomena that happened in the oceans such as wind, wave, tidal and so forth. Those natural phenomenon takes place continuously so that coastal areas will be under pressure, thus eventually coastline will change.This research predicts changess in the coastline change located in South Beach Yogyakarta. The analysis was performed using one-line models with the help of GENESIS 3.0 software. The modeling was performed by entering data in the form of shoreline coordinates x and y, wave data includes height, period, and direction of the waves. Wave data were obtained from wind data analysis of BMKG Maritime Cilacap in the form of daily wind data from 2001-2005. Wind data was processed into the wind rose. Shoreline change then was simulated for the next 10 years.The output of the GENESIS program was in the form of a total volume of sediment transport, major changes in coastlines, and prediction of shoreline position. Sediment transport occured at -3.69E + 05 m3. The biggest abrasion occurred at the point 38 is equal to 13.88 m and the biggest accretion occured at a accretion occurred at a point 193 which is 20 m. Abrasion occurred in the village of Parangtritis amounted to 6.05 Ha, 6.40 Ha at Tirtohargo, 6.35 Ha at Srigading, Gadingsari reached 1.74 Ha, 5.76 Ha at Poncosari, 5.5 Ha at Banaran, 0.39 Ha at Karangsewu, 0.29 Ha at Bugel, 0.09 Ha at Pleret, 0.90 Ha at Garongan, Karangwuni was 3.44 Ha, Glagah was 3.47 Ha, 0.84 Ha at Palihan, Sindutan at 0 Ha, and Jangkaran amounted to 9.93 Ha. Accretion that occurred in the village of Parangtritis amounted to 7.55 Ha, Tirtohargo of 4.82 Ha, Srigading of 6.37 Ha, Gadingsari of 2.35 Ha, 3.43 Ha at Poncosari, 8.08 Ha at Banaran, 0.57 Ha at Karangsewu, 2.55 Ha at Bugel, Pleret of 0.86 Ha, 0.76 Ha at Garongan, Karangwuni of 1.74 Ha, Glagah of 5.18 Ha, Palihan of 0.44 Ha, Sindutan amounted to 0.60 Ha and Jangkaran amounted to 8.68 Ha. Kata-kata Kunci: South Beach Yogyakarta, Windrose, One-line models, GENESIS 3.0