Land resources and use in the Chao Phraya basin

"Over 90% of the area of the Basin is either used for agriculture or covered with forest, with the proportions of these land uses being roughly equal. Within the Basin, the largest sub-basins (in terms of area) are in descending order, the Ping, Nan, Chao Phraya and Tha Chin. The Yom and Pasak sub-basins are intermediate in size and the two smallest sub-basins are the Wang and the Sakae Krang. Agricultural land is concentrated in the southern sub-basins and ranges from 78% in Chao Phraya, 63% in Pasak and 55% in Tha Chin compared to 20 to 45% in the four northern sub-basins (Ping, Wang, Yom and Nan). The majority of forest cover occurs in the northern sub-basins where the percentage of forest ranges from 50-75% in Ping, Wang, Yom and Nan to 30% in Pasak and only 7% in Chao Phraya. In recent years there has been steady encroachment of people into forest areas for conversion to agricultural purposes while cultivated land near urban centres has been converted to residential or industrial use. The need to protect the upper catchment of the Chao Phraya basin from degradation and soil erosion has already been identified as a priority by government. Urban land use ranges from 1 to 3% in all sub-basins except the Chao Phraya where it is 10% of the total area.

Water availability is the key factor constraining future developments in agriculture in the Central Plain, being the core of diversification and of multi-cropping. Water resources are coming under pressure and their management is the challenge for the future, involving the following main aspects:


Water quantity, which governs the possible extension of second rice cropping or other field crops in the dry season, and the pressure on underground water resources through increasing sinking of wells.
Water management, which must aim at achieving greater equity and efficiency in water deliveries at the basin, project and on-farm level.
Flood control and warning where improved flood management minimises damage to crops and to physical structures in urban areas particularly.
Water quality and sustainability, particularly pollution and salinisation which can have serious effects on agricultural production.
Patterns of land use where the attainment of high water use efficiency through crop diversification is dependent on much greater local level control on water deliveries.
Woman fish vendor at Kanchanaburi market
Livestock and fresh water fisheries are also important elements of the agricultural scene in the Chao Phraya basin. They provide important additional sources of family income."

from http://www.unesco.org/water/wwap/case_studies/chao_phraya/index.shtml