Amphiesma stolata
Sisaket (© Wolfgang Wuster) 
Lampang (© Sjon Hauser) 
Taiwan (© Gerrut Norval) 
Taiwan (© A. Jie)
English name: Buff-striped Keelback (aka: “White-striped Keelback”)
Scientific name: Amphiesma stolata
Thai name: งูลายสาบดอกหญ้า (Ngu Lai-sab Dok-ya)
Description: To 90cm long. Body is slender. Color is olive-gray to brown with characteristic white, buff, or cream stripes along each side, often indistinct near the front of the body but very distinct from the middle/back. Regular narrow dark bands also appear on most of the body, fading out near the head and tail. Head is sometimes greenish-brown to beige with dark vertical lines on the margins of most lip scales. Eyes are large. Underside is white to cream.
Relevant scale counts: 19 midbody scale rows, 7-8 supralabials, dorsal scales are keeled.
Similar Species: Yellow-spotted Keelback lacks the characteristic buff stripes.
Red-necked Keelback lacks the buff stripe on the side.
Indo-Chinese Sand Snake has brown stripes on either side of the light stripes and lacks the dark bands.
Range: Pakistan, India, and Sri Lanka west across south and southeast Asia and southern China all the way through Indonesia and the Phillipines.
Habitat: In marshes, wetlands, grassland, irrigated agriculture, and other relatively open areas near water bodies up to 1000m elevation. During rainy season they may be found in fields.
Place in the ecosystem: The Buff-striped Keelback feeds on frogs, lizards, fish, and arthropods. The juveniles are eaten by larger snakes, monitors, large fish, wading birds and birds of prey.
Danger to humans: This species is nonaggressive and will typically flee when faced with danger. Its bite appears to pose no danger to humans though extensive studies have not been done.
Conservation status and threats: No known conservation threats overall and the species is common in agricultural areas. There are historic records for Bangkok, but I know of no recent records and it is possible that its habitat in Bangkok no longer exists due to development.
Interesting facts: Like several other species of snake, the Buff-striped Keelback practices a small degree of parental care, with female snakes remaining with their eggs until they hatch.
References:
Snakes of Taiwan: Amphiesma stolatum
Reptiles of Hong Kong: Buff-striped Keelback
Wikipedia: Amphiesma stolatum
A Photographic Guide to Snakes and Other Reptiles of Peninsular Malaysia, Singapore and Thailand
A Field Guide to the Reptiles of South-East Asia
Reptiles and Amphibians of Thailand 