Application of Meteorological and Hydrological Drought Indices to Establish Drought Classification Maps of the Ba River Basin in Vietnam

Abstract

The objective of this study was to establish drought classification maps to simulate and calculate the lack of discharge in the Ba River basin in Vietnam. The maps were established using three meteorological drought indices (the Standardized Precipitation Index (SPI), the Drought Index (J), and the Ped Index (Ped)), the Soil and Water Assessment Tool (SWAT) model, and the hydrological drought index (KDrought). The results from the calculation of the SPI, Aridity Index (AI), and Ped at three stations (An Khe, Ayunpa, and MDrak) showed that the J index was suitable for the study area. Based on the J index, an extreme drought was predicted to occur at the Ayunpa, An Khe, and MDrak stations. During the calibration process, the SWAT Calibration Uncertainties Program (SWAT-CUP) model, with automatic algorithms, was used to select the parameters to optimize the SWAT model. For the calibration and validation, the observed discharge at two hydrology stations, An Khe and Cung Son, from the periods 1981–1991 and 1992–2002, respectively, were used. The simulated discharge was found to be acceptable, with the Nash–Sutcliffe efficiency (NSE), Percent bias (PBIAS), and R2 reaching good levels in both calibration and validation. The results from the calculation of the drought index (KDrought), and the established drought classification maps in 2016, showed that the most affected areas were the communes of the Gia Lai and Dak Lak provinces. The results from the simulation and calculations were found to be consistent with the situation that occurred in practice. The application of meteorological and hydrological drought indices, as well as the hydrological model, to support impact assessments of drought classification in space and time, as well as the establishment of forecasting and warning maps, will help managers to effectively plan policy responses to drought.

The Temporal Variability of Rainfall and Streamflow into Lake Nakuru, Kenya, Assessed Using SWAT and Hydrometeorological Indices

“…Hydrological models such as the hydrologic modeling system (HEC-HMS) [7,8], the Australian water balance model (AWBM) [9], the soil moisture accounting and routing (SMAR) model [10], the topography-based hydrological model (TOPMODEL) [11,12] and the soil and water assessment tool (SWAT) [13] are useful for simulating the runoff from ungauged catchment based on the data availability and complexity of the hydrological system. Many studies have demonstrated that SWAT is an effective and promising tool to use for simulating flows and sediments for large-scale watersheds and complex basins with different land uses and various soil types (Access et al [14], Brouziyne et al [15], Palani et al [16], Amatya et al [17], and Tri et al [18], among others). The advantages of using SWAT include its applicability to larger watersheds with more than 100 km 2 , its interface with a geographic information system (GIS), its ability to perform continuous simulations, and its ability to characterize a watershed in high spatial detail [19].…”

Trends and Extremes of Drought Episodes in Vietnam Sub-Regions during 1980–2017 at Different Timescales

“…Vietnam is likely to be one of the countries most affected by climate change because of its long coastline and strong reliance on agriculture, natural resources, and forestry [34,[38][39][40][41]. Few publications have investigated the characteristics of droughts in this region (e.g., [32,35,[42][43][44][45]). Tue and co-authors [32] investigated drought over the Central Highland using the Standardized Precipitation Index (SPI) with different observed and modeled monthly precipitation datasets for the period 1990-2005.…”

“…Although the country is narrow, spatial differences of meteorological drought severity for South Central and the Central Highlands are documented [42]. In the north of the country, the Cai River Basin has also experienced relatively high drought severity in the period of 1982 to 2012 [43], while extreme drought affected the Ba River basin in South-Central Vietnam during 2013 and 2016 [44]. Other authors, such as Vu-Thanh et al [45], investigated the occurrence of drought through several drought indices for the period 1961-2007, considering Vietnam divided into seven sub-regions.…”

“…In terms of drought impacts, these have been quantified for well-known dry periods, such as the extremely strong drought event in 1982-1983, which had severe impacts on the environmental and socio-economic sectors of Vietnam [49]. Another example is the 1997-1998 drought, when the total losses in terms of agricultural production were about 400 million US dollars [44,50]. Furthermore, the drought episode that occurred in 2003 caused the main impacts on the coffee sector of Vietnam, thereby emphasizing the role of the detection of drought as an important issue [29].…”

Assessment of probability distributions and minimum storage draft-rate analysis in the equatorial region

“…Droughts have considerable economic, societal, and environmental impacts. Drought can typically be classified into four types depending on different kinds of drought impacts in different areas: meteorological, hydrological, agricultural and socioeconomic (Hasan et al, 2019;Tri et al, 2019). Any types of drought are dynamic and defined by various characteristics such as frequency, severity, duration, and magnitude.…”