Hydroclimatic Extremes in the Limpopo River Basin, South Africa, under Changing Climate

Christina M Botai,Thabo Makgoale,Abiodun M Adeola,Miriam D Murambadoro,Henerica Tazvinga,Eric K Wamiti,Nosipho N Zwane,Michael G Mengistu,Patrick Hayombe,Jaco P De Wit,Joel O Botai,Katlego P Ncongwane

doi:10.3390/w12123299

Abstract

This research study evaluated the projected future climate and anticipated impacts on water-linked sectors on the transboundary Limpopo River Basin (LRB) with a focus on South Africa. Streamflow was simulated from two CORDEX-Africa regional climate models (RCMs) forced by the 5th phase of the Coupled Model Inter-Comparison Project (CMIP5) Global Climate Models (GCMs), namely, the CanESM2m and IPSL-CM5A-MR climate models. Three climate projection time intervals were considered spanning from 2006 to 2099 and delineated as follows: current climatology (2006–2035), near future (2036–2065) and end of century future projection (2070–2099). Statistical metrics derived from the projected streamflow were used to assess the impacts of the changing climate on water-linked sectors. These metrics included streamflow trends, low and high flow quantile probabilities, the Standardized Streamflow Index (SSI) trends and the proportion (%) of dry and wet years, as well as drought monitoring indicators. Based on the Mann-Kendall (MK) trend test, the LRB is projected to experience reduced streamflow in both the near and the distant future. The basin is projected to experience frequent dry and wet conditions that can translate to drought and flash floods, respectively. In particular, a high proportion of dry and a few incidences of wet years are expected in the basin in the future. In general, the findings of this research study will inform and enhance climate change adaptation and mitigation policy decisions and implementation thereof, to sustain the livelihoods of vulnerable communities.

Highlights

Adverse repercussions attributed to climate change and variability on socio-economic sectors, such as water resources, energy, agriculture, health and ecosystem services, are gradually becoming a major concern to various communities, locally, nationally, regionally and even globally [1].there are growing calls for government institutions to revise and enhance the existing mitigation and adaptation planning strategies, to prepare the most vulnerable communities exposed to stressors of climate change [1]
The impacts of climate change on water resources in the Limpopo River Basin (LRB) were investigated based on the assessment of trends using three hydrological statistical parameters, namely, the annual mean, annual minima and annual maximum of streamflow, computed from the observed and simulated streamflow from the Agricultural Catchment Research Unit (ACRU) hydrological model based on the Coordinated Regional Downscaling Experiment (CORDEX) models, viz, CanESM2, IPSL-CM5A and Ensemble
Comparison of the values of the shape parameter with the classes of GEV family of distributions suggests that the simulated streamflow extremes across the CORDEX models under both the RCPs and timescales are best described by the Fréchet type II extreme value distribution

Summary

Introduction

There are growing calls for government institutions to revise and enhance the existing mitigation and adaptation planning strategies, to prepare the most vulnerable communities exposed to stressors of climate change [1]. Hydrological extremes such as floods and drought cause more increased havoc yearly—these impacts include loss of life and agricultural produce as well as the destruction of infrastructure at various spatial and temporal scales [2]. Variations in rainfall patterns coupled with land-use change effects can intensify soil erosion affecting renewable groundwater resources Such variations can have an impact on groundwater-surface systems, including wetlands and other groundwater dependent ecosystems. Groundwater systems are essential for effective monitoring, planning and management of water resources, under the changing climate [3,4]

Objectives

Methods

Results

Discussion

Conclusion