Blended Drought Index: Integrated Drought Hazard Assessment in the Cuvelai-Basin

Abstract

Drought is one of the major threats to societies in Sub-Saharan Africa, as the majority of the population highly depends on rain-fed subsistence agriculture and traditional water supply systems. Hot-spot areas of potential drought impact need to be identified to reduce risk and adapt a growing population to a changing environment. This paper presents the Blended Drought Index (BDI), an integrated tool for estimating the impact of drought as a climate-induced hazard in the semi-arid Cuvelai-Basin of Angola and Namibia. It incorporates meteorological and agricultural drought characteristics that impair the population's ability to ensure food and water security. The BDI uses a copula function to combine common standardized drought indicators that describe precipitation, evapotranspiration, soil moisture and vegetation conditions. Satellite remote sensing products were processed to analyze drought frequency, severity and duration. As the primary result, an integrated drought hazard map was built to spatially depict drought hot-spots. Temporally, the BDI correlates well with millet/sorghum yield (r = 0.51) and local water consumption (r = −0.45) and outperforms conventional indicators. In the light of a drought's multifaceted impact on society, the BDI is a simple and transferable tool to identify areas highly threatened by drought in an integrated manner.

Drought sensitivity in the Cuvelai Basin: empirical analysis of seasonal water and food consumption patterns

“…oshana), are a key characteristic of the endorheic watershed, carrying water during the rainy season and regularly leading to fl ood events (Mendelsohn & Weber, 2011). The rainfall variability over time is pronounced, resulting in changes in soil moisture and vegetation conditions (Luetkemeier et al, 2017).…”

“…C A tool that combines a physical hazard perspective (Luetkemeier et al, 2017) and empirical information on the coping capacities of the population into a single composite indicator, the Household Drought Risk Index (HDRI) (Luetkemeier, ISOE, unpubl. ) .…”

A novel generalized combinative procedure for Multi-Scalar standardized drought Indices-The long average weighted joint aggregative criterion

“…CDI consists of the weighted average of the Vegetation Drought Index (VDI), 2-decked lagged Precipitation Drought Index (PDI) and Temperature Drought Index (TDI). Accordingly, Luetkemeier et al (2017) have proposed Blended Drought Index (BDI) by integrating SPI, SPEI, and Standardized Soil Moisture Index (SSMI) in copula equation (Hao, and AghaKouchak, 2013). Recently, Ali et al (2019a) have provided a Probabilistic Weighted Joint Aggregative Drought Index (PWJADI) criterion for combining temporal classification of three drought indices namely SPI, SPEI, and SPTI.…”

Evaporation loss along the Calueque-Oshakati Canal in the Cuvelai-Etosha Basin (Northern Namibia): evidence from stable isotopes and hydrochemistry

“…This study focuses on Northern Namibia, where socio-cultural and economic aspects have a large impact on water resources management practices [11][12][13][14]. Problems include, amongst others, loss of traditional knowledge on water usage caused when providing external water sources, population increase, frequent flooding and droughts.…”

“…Problems include, amongst others, loss of traditional knowledge on water usage caused when providing external water sources, population increase, frequent flooding and droughts. Rising population numbers in the already relatively densely populated area, and drought index classification after [13], indicate a rising water demand. Since 1973, Kunene River water has been carried from the Calueque reservoir in Angola along a 160-km concrete canal to the city of Oshakati in the central part of the Cuvelai Etosha Basin (CEB).…”