Huai Khanun Dam

Chong An Ma

Tat Hai Waterfall

Tham Khun Si Waterfall

Don Tuan Castle

Pha Mo I Daeng

Bas-relief

Twin stupas

Sa Trao

Historic flagpole

         The general geography is mostly mountains, part of the Phanom Dong Rak Mountain range, bordering between Thailand-Cambodia. The area is covered with dry evergreen forest, mixed deciduous forest, and deciduous dipterocarp forest. It contains many important tree species including an giant blue-and-white vines, found in the nature trail, spreading and wrapping the trees in a wide area of 100-400 meters Undergrowth plants and epiphytes are widely distributed, including various types of herbs. The important ones include Stephania venosa, which has the properties as a medicinal herb and can treat many diseases. There are also particularly interesting plants such as orchids, living in trees and rocks. They are very abundant, especially on the Khao Phra Wihan Orchid Nature Trail.

          Khao Phra Wihan National Park is mainly composed of rocky Cretaceous Lower-Middle (Lower-Middle-Cretaceous) rocks, Jurassic Middle-Upper (Middle-Upper Jurassic) rocks, and a little Jurassic Lower-Upper (Lower-Upper Jurassic) in the mountainous Kingdom of Cambodia. The Cretaceous Lower-Middle belongs to the Khorat Soil Group, the Phu Phan formation. The rocks are composed of sandstone and gravel sandstone and are brown-gray, pink-and-orange, gray, orange have a thick layer, a crossbedding sedimentation, siltstone and reddish-brown shale. Stones from this era are most commonly found in Khao Phra Wihan National Park from the eastern part to
the western part of the area. Sandstone usually decomposes into the soil quickly and is very sandy which is the reason why the soil in the Khao Phra Wihan National Park area is very sandy and low in infertility. The bottom area is large slabs or wide rock slopes. Therefore, when the land moves, geological changes occur.
Water Resources
          Khao Phra Wihan National Park: It is the source of many streams and waterfalls. There is a lot of water in the rainy season, but there is almost no water in the summer or dry season, sometimes even no water. The important waterfalls are Sai Takhian Waterfall, Khun Si Waterfall, Sai Noi Waterfall, Tat Hai Waterfall, etc. Khao Phra Wihan National Park and nearby areas also have reservoirs to receive water from many mountains such as Lan Phu Man Weir, Ban Ban Phum Saron Reservoir, Khuean Huai Khanun Reservoir, Sa Trao and many other small reservoirs.

          Important water sources and creeks in the Khao Phra Wihan National Park area are: 

- Khuean Huai Khanun Reservoir is located in the area of the National Park Ranger Station Kho Ho No. 1, (Khuean Huai Khanun) and is an irrigation reservoir that receives water from 2 streams, namely Dan Creek, flowing down from the Phu Phong Summit in the south and Ta Aek Creek, a large creek, flowing down from the Phu Phong Summit in the east. In the dry season, the creeks have no water.

- Nong Wa Reservoir is located in Phu Pha Mok Sub-district, Kantharalak District, Sisaket Province, receving water flowing from Fon Met Creek, Don Tuan Castle. During the rainy season, there will be some water flowing.

- Sa Trao is in the western part of the National Park. It is a water source that receives water from two streams, Tani Creek and Tamaria Creek. Tani Creek receives water from two watercourses. The first one runs from the east through the broken stairway in the area of Preah Wihan and the second one receives water that flows from the west. They converge at the creek located behind the shops and the community near the entrance of the Prasat Khao Phra Wihan (Preah Wihan Temple), then flow through Khun Si Waterfall and into the pond below which is in the territory of Thailand. Tamaria Creek receives water flowing from Phu Makhuea, which is in the western part of the park. This Tamaria creek is also used as a boundary line between Khao Phra Wihan National Park and Phanom Dong Rak Wildlife Sanctuary.

- Khun Si Waterfall is a waterfall originating from Tani Creek on the western part of Sa Trao, near the sidewalk leading to Khao Phra Wihan Castle. There is s a lot of water flowing down during the rainy season, but there is no water during the dry season. This makes Khun Si Waterfall a tourist attraction only in certain seasons.

- Tat Hai Waterfall is located in the eastern part of Khao Phra Wihan National Park. It receives water from Chong Phuang Creek that flows down from the south side of Phu Lam Duan, from Plantawong and Plantoey which are large stone terraces. There is water only in the rainy season, but in the dry season there is no water. Tat Hai Waterfall is therefore a tourist attraction only in certain seasons, like Khun Si Waterfall.

- Bon Creek is a creek in the eastern part of the National Park. There is water almost all year round, especially in the rainy season, there will be a lot of water, but there will be no water next season. Bon Creek is a small creek that is the boundary line between Khao Phra Wihan National Park and Yot Dom Wildlife Sanctuary.

          The seasons of Nam Phong National Park can be divided into three seasons:

- Summer: from Marth to May, the average temperature is very high in April.

- Rainy season: From June to October, rainfall Rainfall is abundant from August to October,

- Winter: From November to February, the minimum average temperature is in January which is influenced by a high-pressure from the southern part of China.

 Flora
          Most areas are hillly and sloping mountains, consisting of these following forests. Mixed deciduous forest : Plant species are mixed with one another such as Burma Padauk, Afzelia xylocarpa, Iron Wood, Rosewood, Red Sandalwood, Ebony, Cotton tree, etc. Deciduous dipterocarp forest : Small and medium-sized trees grow scatterly. Undergrowth plants include different types of grasses, especially, Vietnamese Coriander. Plant species found include Burma Sal, Shorea siamensis, Velvet Tamarind, Ceylon Oak, etc. Dry evergreen forest: It is found in flat areas or valleys. Plants discovered include Hopea odorata, tracwood, Tetrameles nudiflora, Hydnocarpus ilicifolius King, Walsura trichostemon Miq, Streblus ilicifolius (Vidal) Corner, Dipterocarpus, Barking Deer's Mango, etc. Undergrowth plants are various plants of the ginger and galanga family.

            Due to the fact that Khao Phra Wihan and the forest on the left side of Lam Dom Yai River in Phanom Dong Rak Mountain range are still fertile, there are many wild animals such as Wild Boars, Crab-eating Macaques, Mongooses, Hares, Roof Rats, Finlayson's Squirrels, Northern Treeshrews, Painted Bats, Striped Swallows, Bar-winged Flycatcher-shrikes, Black-headed Bulbuls, and Greater Racket-tailed Drongos, Pin-striped Tit Babblers, Eurasian jay, Siamese leaf-toed gecko, Sandstone Gecko, Orange-winged flying lizards, Common Forest Skink, Bengal monitor, blind snakes, Reticulated python, Boigas, Linne's Water Snake, rice field frog, Puddle Frog, Stripe-backed frog, Chinese edible frog, Common tree frog, Dark-sided chorus frog (Microhyla heymonsi), Dark-sided Chorus Frog, etc. In the area of water resources, there are many species of fish living such as Eye-spot Barb, Red tailed Tinfoil, Mrigal Carp, Channa striata, Mozambique Tilapia, and Batrachian walking catfish.