The vegetative belt extends into the desert along creeks and arroyos. Many of the valleys of these rivers and arroyos are inhabited. Natural arroyos are made through the process known as arroyo-cutting. Normally-dry rivers in arid zones are often identified as arroyos or other regional names. There are some small ponds and arroyos. Superficial water flows mostly in arroyos east to the Grande or Santiago River. Flash flooding can cause the deep arroyos or deposition of sediment on flooded lands. The desert dry wash biome is restricted to the arroyos of the southwestern United States. Many of the state's streams and arroyos empty into the Salado. Flash floods are common in arroyos following thunderstorms. Beans were planted in arroyos that had been recently flooded by summer rain. The Rio Grande and other arroyos provided the water for irrigation. A number of arroyos also run from the Sierra to the coastal plain. Research has been conducted in the hydrological modeling relative to arroyos. It is the administrative seat of Tres Arroyos Partido.