Khammouane Province is located in the center of the country. It covers an area of 16,315 square kilometres and is mostly of forested mountainous terrain. The province is bordered by Bolikhamsai Province to the north and northwest, Vietnam to the east, Savannakhet Province to the south, and Thailand to the west. Many streams flow through the province to join the Mekong River. The vast forests of the Nakai-Nam Theun Biodiversity Conservation Area are an important watershed that feed many Mekong tributaries as well as form the catchment area for Nam Theun 2, one of the largest hydropower projects in Laos. The Xe Bangfay, Nam Hinboun and Nam Theun are the main rivers of the province.

The province’s forest areas consists of three reserve areas. These are the Nakai – Nam Theun National Biodiversity Conservation Area (NBCA), which covers an area of 352,200 ha of the Annamite mountains and the adjacent Nakai Plateau in the provinces of Khammouane and Bolikhamxay, the Hin Nam No National Biodiversity Conservation Area with an area of 86,229 ha, and the Phou Hin Poun National Biodiversity Conservation Area with an area of 150,000 ha. These forests have many natural caves.  

The 68,125 hectare Hin Nam No (also Hin Namno) Important Bird Area (IBA) is within the Hin Namno NBCA. Its topography features limestone karst outcrops, undulating limestone hills, as well as valleys.

Part of the province, particularly Yommalath District, was badly affected by floods in July 2011, affecting rice farmland in the district, inundating almost 700 hectares, destroying dozens of fishponds and killing 112 cattle. There are several major operating mining companies in the province, including Mining Development Economy Corporation mining gypsum in Thakhek District, LAVICO Co. Ltd, which is a Laos-Vietnam joint venture mining gypsum in Xebangfay District, V.S.K. Co. Ltd mining limestone in Thakhek District), and Lao-North Korea Tin Mines mining tin in Hinboun District.

References:

1. Wikipedia ‘Khammouane province’: https://en.wikipedia.org/wiki/Khammouane_Province