Ứng dụng chỉ số cán cân nước và công cụ GIS xác định mức độ ảnh hưởng của hạn khí tượng đến vùng đất cát ven biển miền Trung

Abstract

The Central coastal sandy area has a great potential in terms of area that can be used for agricultural, aquacultural production as well as some other economic sectors. However, due to the many disadvantages of the natural features, the exploitation and use of sandy soil areas is still limited, of which meteorological drought is one of the important factors that make coastal areas difficult in the storage and creation of water resources to serve people and agricultural production. The characteristic of meteorological drought in this area is not due to low rainfall, but mainly due to large evaporation, along with the soil characteristics of sandy soils that are difficult to retain water. This study focuses on using the ratio coefficience between evaporation and rain, to assess the degree of meteorological drought of coastal sandy soils. The series of rain and evaporation monitoring data from 1977 at 19 meteorological stations along the central coastal area were used to analyse, showing many years when there was a big difference between evaporation and rain in the dry season, especially in 1977, 1988, 2005, 2014 ... The period of high drought usually occurs from April to July in the north and from February to June in the south of the Central coastal areas. Especially in the southern region from Phu Yen to Binh Thuan, the probability of a degree of "very dry" in the period from February to May exceeds 70% of the analysed years. The GIS tools are also used to develop the water balance index map, which serves as a basis for determining the rate of area under different degrees of drought, confirming that most localities have more than 50% of the area to be determained above light drought levels.