Assessment of impacts of climate change on surface water availability using coupled SWAT and WEAP models: case of upper Pangani River Basin, Tanzania

Abstract

Abstract. This study was designed to investigate the dynamics of current and future surface water availability for different water users in the upper Pangani River Basin under changing climate. A multi-tier modeling technique was used in the study, by coupling the Soil and Water Assessment Tool (SWAT) and Water Evaluation And Planning (WEAP) models, to simulate streamflows under climate change and assess scenarios of future water availability to different socio-economic activities by year 2060. Six common Global Circulation Models (GCMs) from WCRP-CMIP3 with emissions Scenario A2 were selected. These are HadCM3, HadGEM1, ECHAM5, MIROC3.2MED, GFDLCM2.1 and CSIROMK3. They were downscaled by using LARS-WG to station scale. The SWAT model was calibrated with observed data and utilized the LARS-WG outputs to generate future streamflows before being used as input to WEAP model to assess future water availability to different socio-economic activities. GCMs results show future rainfall increase in upper Pangani River Basin between 16-18 % in 2050s relative to 1980-1999 periods. Temperature is projected to increase by an average of 2 • C in 2050s, relative to baseline period. Long-term mean streamflows is expected to increase by approximately 10 %. However, future peak flows are estimated to be lower than the prevailing average peak flows. Nevertheless, the overall annual water demand in Pangani basin will increase from 1879.73 Mm 3 at present (2011) to 3249.69 Mm 3 in the future (2060s), resulting to unmet demand of 1673.8 Mm 3 (51.5 %). The impact of future shortage will be more severe in irrigation where 71.12 % of its future demand will be unmet. Future water demands of Hydropower and Livestock will be unmet by 27.47 and 1.41 % respectively. However, future domestic water use will have no shortage. This calls for planning of current and future surface water use in the upper Pangani River Basin.

Evaluation of hydro-meteorological drought indices for characterizing historical and future droughts and their impact on groundwater

“…It may be estimated for different timescales (enlargement episodes), and calculated SPI quantities can be compared at different time and space scales. [45][46][47]49] Nevertheless, the SPI also has two significant disadvantages, which were recognized by Gidey et al [15] The quantities of SPI for various lengths of observation records can be different, because of dissimilarities in the shape and scale factors of the fitted gamma (or further) distribution for various lengths of records. Furthermore, the quantities of SPI are sensitive to the shape of the possibility distribution that is matched to the observed data as a measurement of normalization procedure.…”

Modelling the Impacts of Climate Change on Water Level Fluctuations in Water Resources in Tanzania: A Case Study of Mtera Dam

“…Different researches have been done on assessing the impacts of climate change on the fluctuation of water level in water resources for example; [5,7,8,9,13,14,19,21]. [9] studied the hydrological flow change of Usangu-Mtera ecosystem and how it links to changes in rainfall variability.…”

Impact of extreme events on conversion efficiency of wave energy converter

“…HadCM3 model was developed by Gordon et al 49 at the Hadley Centre in the United Kingdom which considered the influence of both atmospheric and oceanic parameters and includes the impact of aerosol on the climate. The model was widely used for different predictive studies such as estimation of climate change impact on groundwater recharge in arid regions of Iran, 50 water availability for different types of consumption in Tanzania, 51 water resources and soil erosion in Burkina Faso, West Africa, 52 paddy irrigation water requirements in Sri Lanka, 53 estimation of future distribution of plant species in the European continent, 54 and change in Arctic sea ice thickness and area for the future time slabs. 55 HadCM3 does not include flux adjustment due to its stable control climatology.…”