The developments of drought in the Cai river basin – Phan Rang, Ninh Thuan province

Abstract

In Vietnam, the Cai river basin - Phan Rang in Ninh Thuan province is considered to tolerate the most serious drought, which has influenced seriously on the lives and economy of the people in the region. Using Multi-Criteria Analysis method - MCA integrated with GIS for eight factors: evaporation (ETo), rainfall, groundwater, surface water annual flow module, vegetable matter (NDVI), river density, humidity of land and slope to build a system of component maps identifying the level and the change of drought, namely meteorological one in the Cai river basin - Phan Rang, Ninh Thuan province each year. According to the average results of the study period (2000–2014), the drought at this region has 3 levels: medium drought with 0.05 %, severe drought with 80.90 %, very severe drought with 19.05 % of the studied area. At the same time, the value of factors: evaporation (ET_o) is from 1417.02–1817.00 mm, rainfall is from 640.9– 910.8 mm, groundwater is from 0–11 (1/s/km2), surface water annual flow module is from 9 – 23 (1/s/km2), vegetable matter is (NDVI) from -0.4 – 0.6, river density is from 0–1.6 km/km2, humidity of land is from 3.65–55 % and slope is from 0^o– 62.8^o. This study focuses only on the meteorological drought, we need more detailed researchs to continue estimating the 3 types of drought (agricultural, hydrological, socio-economic) to be able to recognize drought in this region more fully, thereby giving effective measures against drought.