Solo River - Geography

Geography

The Solo River (or Bengawan Solo) has its source by the volcano of Mount Lawu, on the border between Central Java and East Java. It passes through the major city of Surakarta (called Solo by the local inhabitants). An important early tributary to the Solo river is the Dengkeng River, which has its source in Mount Merapi. After passing through Solo, the river flows northward around Mount Lawu, and then turn eastward into East Java in the Ngawi regency.

After Ngawi the river turns northward again, forming the boundary between Blora Regency of Central Java and Bojonegoro regency of East Java. From the town of Cepu in Blora, the river turns eastward and passes through Bojonegoro regency's capital city. From there, it continues eastward through the Lamongan and Gresik regencies. The last part of the river's basin (roughly starting from Bojonegoro regency) is mostly flat land.

Bengawan Solo's delta is located near the town of Sedayu in Gresik regency. The present delta is redirected by a human made canal. The original delta flowed into the Madura Strait, but in 1890 a 12 km canal was made by the Dutch East Indies authority to redirect the Solo River into Java Sea. This is done to prevent sedimentation of mud from filling the Madura Strait and thereby preventing sea access to the important port city of Surabaya.

The Solo river delta has a huge mud sedimentation flow that deposited 17 million tonnes of mud per year. This sedimentation in the delta form a cape, which has average longitudinal growth of 70 m per year. This delta is known as Ujung Pangkah (Pangkah Cape).