Arda (Maritsa tributary) in the context of "Kastanies"

The Tundzha (Bulgarian: Тунджа [ˈtund͡ʒɐ]; Turkish: Tunca [tund͡ʒa]; Tonsus in antiquity) is a river in southeastern Bulgaria and northwesternmost Turkey, a left tributary of the Maritsa. With a length of 390 km, of which 350 km are in Bulgaria, it is Maritsa's longest tributary, though in terms of discharge it is second after the Arda. Tundzha Glacier on Livingston Island in the South Shetland Islands, Antarctica is named after Tundzha River.

The Topolnitsa (Bulgarian: Тополница [toˈpɔɫnit͡ʃɐ]) is a river in southern Bulgaria, an important left tributary of the Maritsa. The river's name is derived from the Bulgarian word топола, topola ("poplar"). Reaching length of 155 km, the Topolnitsa is the fourth longest river in the Maritsa drainage, following the Tundzha (390 km), the Arda (290 km) and the Ergene (281 km).

The Stryama (Bulgarian: Стряма [ˈstrʲamɐ], known in Antiquity as Syrmus) is a river in southern Bulgaria, an important left tributary of the Maritsa. It originates in the Balkan Mountains. The river is 110 kilometres in length and is the sixth longest in the Maritsa drainage, following the Tundzha (390 km), the Arda (290 km), the Ergene (281 km), the Topolnitsa (155 km) and the Sazliyka (145 km). According to the Bulgarian linuist Yordan Zaimov, the etymology of the river derived from Thracian serm, meaning flow.

The Vacha (Bulgarian: Въча) is a river in southern Bulgaria, a right tributary of the river Maritsa. The 112 km long Vacha is the 23rd longest river of Bulgaria and the second longest in the Rhodope Mountains, following the Arda (272 km), another major Maritsa tributary. The Vacha drains significant area of the western Rhodope Mountains, including the ridges Batak Mountain, Veliyshko–Videnishki, Pereliksko–Prespanski and Chernatitsa.

The Cherna (Bulgarian: Черна) is a 48 km long river in southern Bulgaria, a left tributary of the Arda of the Maritsa drainage.

The source of the river is the westernmost point of the whole Arda basin and springs in the Pereliksko–Prespanski Ridge of the western Rhodope Mountains at an altitude of 1,770 m, some 5 km southeast west of the village of Mugla. Throughout its course it flows eastwards in a narrow canyon-like valley, with a single wide section at the town of Smolyan. It flows into the Arda at an altitude of 128 m about 800 m south of the village of Leshtak. It drains the southeastern slopes of the highest section of the Pereliksko–Prespanski Ridge and the northern slopes of the Kaynadinski Ridge.