Phu Chong Na Yoi National Park covers some parts of Buntharik, Na Chaluai, and Nam Yuen District in Ubon Ratchathani Province. It borders with the Lao People's Democratic Republic and Cambodia. The forest areas are part of Phanom Dong Rak mountain range and mostly are plains with slopes downward to the south. It comprises many small and complex mountain ranges such as Phu Chong Na Yoi, Phu Chong Nam Sap, Phu Chan Daeng, and Phu Phlan Yao. The average altitude is about 300-600 meters. The forest conditions are generally dry evergreen forests, mixed deciduous forests, and deciduous dipterocarp forests. Phu Chong Na Yoi National Park has dense vegetation, accounting for about 75% of the total area, with beautiful natural conditions. The forest conditions are perfect, and many "Ton Chong," or Malva nut trees, have been found in the area, which is the origin of the park's name, and "Na Yoi" comes from the word "Nam Yoi," (dropping water) which represents a wealth of watersheds and streams. There is water flowing down from the overhang stones adjacent to the waterfall. There are also various important rivers such as the Lam Dome Noi, the Lam Dome Yai, and the Luang Creek. In Phu Chong Na Yoi National Park, apart from still being dense with forests and abundant wildlife, there are many interesting sights and attractions.

Water Resources, Watersheds, Watershed Quality Classification

          The main watersheds of Phu Chong Na Yoi National are the Mun River Basin and its tributary basins which are Lam Dome Yai and Lam Dome Noi River basins, most of which are classified into the watershed class 3,  accounting for 34.12%, followed by the class, covering the parking area for 51.76%.

        Characteristics of the canal area within Phu Chong Na Yoi National Park are long, flowing in the direction from the west to the east, consisting of Lam Dome Yai, originated from the headwater in the Nam Yuen District, flowing towards north to converge with the Mun Stream at Phibusmangsahan District, Ubon Ratchathani Province, and flowing into the Mun River, and Lam Dom Noi, whose watershed is in the area of Buntharik District, Ubon Ratchathani Province.

          Other important surface water resources in the vicinity of  Phu Chong Na Yoi National Park are medium-sized reservoirs, namely Huai Plan Suea Reservoir (Huai Phueng) and Huai Chanla Reservoir and small-sized reservoirs, namely Waichaluai and Huai Pongling reservoirs.

         Phu Chong Na Yoi National Park's has 62 sub-catchments with a total water intake area of approximately 71,060 square kilometers. Based on the estimation of the water volume model in the stream, the average rainfall during the last 30 years was about 1,587.4 mm. As shown in Figure 8, the average annual water volume of the river is about 17 million cubic meters or approximately 132.28 mm. in height. The month with the highest water content in the stream is September, with an average of about 43 million cubic meters and January is a month with very little water (less than 1 million cubic meters).

             Phu Chong Na Yoi National Park is located in the tropical Savannah climate zone, which means a clear difference between the rainy and dry seasons. There is a long day in summer. The annual average high temperature is about 35.9 degrees Celsius. The yearly average rainfall is 1,125.6  mm; the average maximum rainfall in August is about 322.6 mm; and the annual average relative humidity is 72.9%.

Biological Resources

       Phu Chong Na Yoi National Park’s forest conditions can be divided into different types based on topographic factors, climate, soil characteristics and plant characteristics as follows.

 Decidouous Forest Plant Community

     (1) Deciduous Dipterocarp Forest: The forests are generally sparse. The soil is not ideal, the topsoil is shallow, and the trees are small, with the exception of some areas where the topsoil is thick and has not been disturbed excessively. The trees are a mix of large and medium-sized. The essential plants are Burma Sal, Shorea siamensis, White - Meranti, Hairy Keruing, and Dipterocarpus intricatus Dyer.

      (2) Mixed Deciduous Forest or mixed deciduous forest.

The Evergreen Forest community by the (1) Dry Evergreen Forest 

Wildlife
         Due to the relatively fertile forest conditions of Phu Chong Na Yoi National Park and its bordering with Laos and Cambodia, it is home to a variety of animal species (fauna) as follows.

    (1) Mammals: Mammals are found such As Serow, Sambar Deer, Barking Deer, Lesser Mousedeer, Wild Boar, Civet Musk, Binturong, Dhole, Hog Badger, Burmese Hare, Gibbon,  Bull, etc.

      (2) Birds: There are about 150 species of birds, the most important of which are ducks.

     (3) Reptiles such as Tokay, Lizards, Elongated Tortoises, Ground Lizards, Burmese Pythons, King Cobras, Cobras, etc.

     (4) Amphibians such as Asian Common Toads, Stripe-Backed Frogs, Chinese Edible Frogs, and Tree Frogs.